Connection-oriented RPC Protocol Machines

This chapter specifies the connection-oriented RPC protocol as a series of statecharts and accompanying tables of definitions.

CO_CLIENT Machine

CO_CLIENT Statechart shows the CO_CLIENT machine statechart.

CO_CLIENT Activities

The CO_CLIENT statechart defines the following activities:

Chart:

CO_CLIENT

Activity:

ABORT_RECEIVE

Description:

Flush and discard any further responses for this call. There may be numerous additional packets in the pipeline. The flush may be lazy, upon subsequent receive processing. Also, notify the run-time system and stub to reclaim any resources for this call.

Chart:

CO_CLIENT

Activity:

ABORT_SEND

Description:

Discontinue any further transmission of request data for the current call, to the best extent possible. Some error condition has caused a fault.

Chart:

CO_CLIENT

Activity:

DEQUEUE_CANCEL

Description:

If there is a pending cancel timeout for this call, dequeue it.

Chart:

CO_CLIENT

Activity:

EXCEPTION

Description:

Raise a fault and return to calling routine.

Chart:

CO_CLIENT

Activity:

HANDLE_OUT_FRAG

Description:

This activity is invoked at each received fragment evaluation of out parameters for multi-fragmented RPC responses.

The HANDLE_OUT_FRAG activity makes received data of the next fragment available to the stub for unmarshaling and the object UUID (RT_OBJ_ID) available to the manager routine. This does not require a transfer of control from the run-time system to the stub for each fragment; implementation policy determines when control is transferred.

Chart:

CO_CLIENT

Activity:

SEND_PKT

Description:

Prepare a PDU to send to the server, adding the appropriate header information as necessary. If security services were requested (conditional flag AUTH is true), apply per-message security services. Send the PDU.

The conditional flags and data items set in the run-time system (with prefix SND_) provide the appropriate input for generating the PDU data. Note that actions within the same execution step that started this activity may have assigned values to the SND_* variables which have to be taken by this instance of the activity.

After sending a request PDU, the RT_IN_FRAG pointer is incremented accordingly, to point to the remaining data in the transmit queue.

Note:

The SEND_PKT activity may be invoked simultaneously by several orthogonal states (DATA, CONTROL, CANCEL, and so on). The run-time system must catch these send requests, buffer these and the associated data, and perform the sends in sequential order.

Chart:

CO_CLIENT

Activity:

SET_PRES_CONTEXT

Description:

Set the negotiated presentation context (from RT_SERVER_PRES_CONTEXT_LIST) and save the security credentials for this call.

This activity sets the conditional flag PRES_SEC_CONTEXT_SUPPORTED true on success, otherwise false. The selected presentation context identifier is assigned to the data item RT_PRES_CONTEXT_ID for use in subsequent messages.

Chart:

CO_CLIENT

Activity:

VERIFY_AUTH

Description:

Verify the authentication trailer of PDU and decrypt message if necessary.

This activity takes as input values the PDU header field auth_proto (RT_AUTH_SPEC) and the authentication verifier (RT_AUTH_VERIFIER).

Depending on the result of the verification, the activity VERIFY_AUTH generates either the event AUTHENTICATED (success) or DENIED (authentication failure).

The algorithm applied to this activity is dependent on the security service in use (determined by RT_AUTH_SPEC). The general evaluation steps for authentication service rpc_c_authn_dce_secret are as follows (for more details see Security ):

• Check the protection level applied to the PDU (parameter in RT_AUTH_VERIFIER) against the protection level for the call (negotiated security context). If matching, proceed with verification, otherwise raise DENIED.
• Decrypt the cyphertext portion of the verifier and verify the PDU's integrity. If discrepancies are found, raise DENIED, otherwise raise AUTHENTICATED and proceed (if privacy protected).
• If privacy protection is requested, decrypt PDU body bgcolor="#FFFFFF" data.

Note:

The VERIFY_AUTH activity may be invoked simultaneously by several orthogonal states (DATA, CONTROL and CANCEL). VERIFY_AUTH must not generate the event AUTHENTICATED unless the entire requested authentication processing is completed. If VERIFY_AUTH detects an authentication failure and generates the event DENIED, the protocol machine rejects the RPC call and no further processing is required.

CO_CLIENT States

The CO_CLIENT statechart defines the following states:

Chart:

CO_CLIENT

State:

ALLOCATED

Description:

An association is allocated for current call.

Reactions
Trigger	Action
ALTER_CONTEXT_REQ	SND_PRES_CONTEXT_LIST:= DESIRED_CONTEXT_LIST; SND_REQUEST_TYPE:=ALTER_CONTEXT; st!(SEND_PKT)
en(ALLOCATED)	IF PRES_SEC_CONTEXT_SUPPORTED THEN ALLOC_ASSOC_ACK ELSE ALTER_CONTEXT_REQ END IF
CHECK_CONTEXT	IF PRES_SEC_CONTEXT_SUPPORTED THEN ALLOC_ASSOC_ACK ELSE ALLOC_ASSOC_NAK; DEALLOC_ASSOC END IF
RCV_SHUTDOWN or RESOURCES_SCARCE	tr!(SHUTDOWN_REQUESTED)
RCV_ALTER_CONTEXT_RESP	MARK_ASSOC; CHECK_CONTEXT

Chart:

CO_CLIENT

State:

ASSOCIATION

Description:

Main state for an association.

Chart:

CO_CLIENT

State:

ASSOC_DONE

Description:

Waiting for outstanding call machinery to complete.

Chart:

CO_CLIENT

State:

ASSOC_OPEN

Description:

Association available for call.

Reactions
Trigger	Action
(RCV_SHUTDOWN or RESOURCES_SCARCE) [not SHUTDOWN_OK]	tr!(SHUTDOWN_REQUESTED)

Chart:

CO_CLIENT

State:

AUTHENTICATION

Description:

Process authentication verification.

Activities Throughout:

VERIFY_AUTH

Chart:

CO_CLIENT

State:

CALL

Description:

Processing a remote procedure call request.

Chart:

CO_CLIENT

State:

CALL_IDLE

Description:

Initial remote procedure call state.

Reactions
Trigger	Action
en(CALL_IDLE)	RT_CANCEL_COUNT:=0; RT_RCV_CANCEL_COUNT:=0; tr!(RT_DID_NOT_EXECUTE)

Chart:

CO_CLIENT

State:

CANCEL

Description:

Processing of requests to terminate call in progress.

Reactions
Trigger	Action
tm(CLIENT_CANCEL, TIMEOUT_CANCEL)	RT_EXCEPTION_STATUS:= CONST_RPC_S_CANCEL_TIMEOUT; st!(EXCEPTION)
tm(CLIENT_CANCEL, TIMEOUT_CANCEL)[in(STUB_WAIT)]	DEALLOC_ASSOC
tm(CLIENT_CANCEL, TIMEOUT_CANCEL)[in(REQ_WAIT)]	DEALLOC_ASSOC; ORPHANED_CALL; st!(ABORT_SEND)
tm(CLIENT_CANCEL, TIMEOUT_CANCEL)[in(CONFIRMATION)]	DEALLOC_ASSOC; ORPHANED_CALL; st!(ABORT_RECEIVE)

Chart:

CO_CLIENT

State:

CAN_IDLE

Description:

Waits for cancel requests and handles cancel timeouts if pending cancel request.

Reactions
Trigger	Action
en(CAN_IDLE)	IF CURRENT_PENDING_CANCEL THEN tr!(RT_PENDING_CANCEL) ELSE fs!(RT_PENDING_CANCEL) END IF

Chart:

CO_CLIENT

State:

CNTL_IDLE

Description:

Waits for incoming control PDUs.

Reactions
Trigger	Action
en(CNTL_IDLE)	fs!(FAULT_PDU); fs!(BIND_ACK_PDU); fs!(BIND_NAK_PDU); fs!(SHUTDOWN_PDU); fs!(VERSION_MISMATCH_PDU); fs!(LAST_OUT_FRAG); fs!(ALTER_CONTEXT_RESP_PDU);;
RECEIVE_PDU[PDU_TYPE=FAULT and VALID_PDU_HEADER]	tr!(FAULT_PDU); RT_RCV_CANCEL_COUNT:= PDU_CANCEL_COUNT IF PDU_PENDING_CANCEL THEN tr!(RT_RCV_PENDING_CANCEL) ELSE fs!(RT_RCV_PENDING_CANCEL) END IF
RECEIVE_PDU[PDU_TYPE=BIND_ACK and VALID_PDU_HEADER and not LAST_OUT_FRAG]	DO_CNTL_RESP; RCV_FRAG_CNTL_PDU;;
RECEIVE_PDU[PDU_TYPE=BIND_ACK and VALID_PDU_HEADER and LAST_OUT_FRAG]	tr!(BIND_ACK_PDU);;
exiting	IF AUTH THEN RT_AUTH_VERIFIER_CNTL:= PDU_AUTH_VERIFIER; RT_AUTH_LENGTH_CNTL:= PDU_AUTH_SPEC END IF;;
RECEIVE_PDU[PDU_TYPE=BIND_NAK and VALID_PDU_HEADER and VERSION_MISMATCH]	tr!(VERSION_MISMATCH_PDU);;
RECEIVE_PDU[PDU_TYPE=BIND_NAK and VALID_PDU_HEADER]	tr!(BIND_NAK_PDU);;
RECEIVE_PDU[PDU_TYPE=SHUTDOWN and VALID_PDU_HEADER]	tr!(SHUTDOWN_PDU);;
RECEIVE_PDU[PDU_TYPE= ALTER_CONTEXT_RESP and VALID_PDU_HEADER and not LAST_OUT_FRAG]	DO_CNTL_RESP RCV_FRAG_CNTL_PDU
RECEIVE_PDU[PDU_TYPE= ALTER_CONTEXT_RESP and VALID_PDU_HEADER and LAST_OUT_FRAG]	tr!(ALTER_CONTEXT_RESP_PDU);;
RECEIVE_PDU[CNTL_PDU and VALID_PDU_HEADER]	RCV_CNTL_PDU;;
RECEIVE_PDU[CNTL_PDU and not VALID_FRAG_SIZE]	RCV_FRAG_SIZE_TOO_LARGE

Chart:

CO_CLIENT

State:

CONFIRMATION

Description:

Processing response data (out params) for remote procedure call.

Reactions
Trigger	Action
en(CONFIRMATION)	fs!(RESPONSE_ACTIVE); RT_OUT_PARAMS:=NULL
en(CONFIRMATION)[MAYBE]	DEALLOC_ASSOC

Chart:

CO_CLIENT

State:

CONF_IDLE

Description:

Receive response data from server (possibly fragmented).

Reactions
Trigger	Action
RECEIVE_PDU[PDU_TYPE=RESPONSE and VALID_PDU_HEADER and not AUTH]	tr!(RESPONSE_ACTIVE); DO_RESP; RCV_FRAG_PDU;;
RECEIVE_PDU[PDU_TYPE=RESPONSE and VALID_PDU_HEADER and AUTH]	tr!(RESPONSE_ACTIVE); DO_RESP; RCV_FRAG_PDU_A;;
RECEIVE_PDU[PDU_TYPE=RESPONSE and not VALID_FRAG_SIZE]	RCV_FRAG_SIZE_TOO_LARGE;;
en(CONF_IDLE)[RESPONSE_ACTIVE and LAST_OUT_FRAG]	RCV_LAST_OUT_FRAG;;
en(CONF_IDLE)[RESPONSE_ACTIVE]	DO_OUT_PKT; st!(HANDLE_OUT_FRAG)

Chart:

CO_CLIENT

State:

CONN_WAIT

Description:

Request transport connection and wait for response.

Reactions
Trigger	Action
en(CONN_WAIT)	IF VERSION_MISMATCH_PDU THEN PDU_VERSION_NUM_MINOR:=PDU_CN_VERS_COMPAT; END IF;; REQUEST_CONN

Chart:

CO_CLIENT

State:

CONTROL

Description:

Processing received control PDUs.

Chart:

CO_CLIENT

State:

CO_CLIENT

Description:

Main state for client association and call.

The CO_CLIENT_ALLOC machine creates this state by generating the CREATE_ASSOCIATION event.

Chart:

CO_CLIENT

State:

DATA

Description:

Processing RPC call data.

Reactions
Trigger	Action
en(DATA)	fs!(REQUEST_ACTIVE)

Chart:

CO_CLIENT

State:

FAULT

Description:

Handling fault PDU responses.

Reactions
Trigger	Action
en(FAULT)	DEALLOC_ASSOC; IF PDU_DID_NOT_EXECUTE THEN tr!(RT_DID_NOT_EXECUTE) END IF; RT_RCV_CANCEL_COUNT:=PDU_CANCEL_COUNT; RT_EXCEPTION_STATUS:=PDU_FAULT_STATUS; st!(EXCEPTION); IF in(REQ_WAIT) THEN st!(ABORT_SEND) END IF; IF in(CONFIRMATION) THEN st!(ABORT_RECEIVE) END IF

Chart:

CO_CLIENT

State:

INIT

Description:

Initial state for new association. Initialise state variables.

Reactions
Trigger	Action
en(INIT)	fs!(SHUTDOWN_REQUESTED); fs!(WAIT_FOR_GROUP); IF GROUP_EXISTS THEN SND_ASSOC_GROUP_ID:=RT_ASSOC_GROUP_ID ELSE SND_ASSOC_GROUP_ID:=NULL END IF

Chart:

CO_CLIENT

State:

INIT_WAIT

Description:

Wait for server's response to bind request.

Reactions
Trigger	Action
RCV_BIND_ACK[not GROUP_EXISTS]	CREATE_GROUP; tr!(WAIT_FOR_GROUP)

Chart:

CO_CLIENT

State:

REQ_WAIT

Description:

Handles fragmented requests to server.

Reactions
Trigger	Action
en(REQ_WAIT)[not REQUEST_ACTIVE]	FIRST_REQ
ex(REQ_WAIT)[not LAST_IN_FRAG]	fs!(SND_FIRST_FRAG)

Chart:

CO_CLIENT

State:

SND_CAN

Description:

Processes cancel requests. Sends cancel PDU.

Reactions
Trigger	Action
en(SND_CAN) or CLIENT_CANCEL	CAN_CALL; RT_CANCEL_COUNT:=RT_CANCEL_COUNT+1

Chart:

CO_CLIENT

State:

STUB_WAIT

Description:

Wait until stub calls with first fragment.

Chart:

CO_CLIENT

State:

WORKING

Description:

Main working state for call instance.

CO_CLIENT Events

The CO_CLIENT statechart defines the following events:

Chart:

CO_CLIENT

Event:

ABORT_ASSOC_REQ

Description:

Client run-time system requested termination of association (typically local error).

Chart:

CO_CLIENT

Event:

ADD_TO_GROUP

Description:

Signal group to add this association. Generated by an association in this group.

Association must check that the instance of the CO_CLIENT_ALLOC machine which initiated this association has not terminated. If it has terminated, then the ASSOCIATION machine must lock the group before issuing this event to avoid possible race conditions.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

Chart:

CO_CLIENT

Event:

ALLOC_ASSOC_ACK

Description:

Association allocated and may be used for call.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT

Event:

ALLOC_ASSOC_NAK

Description:

Unable to allocate association because requested context not supported.

Generated in chart CO_CLIENT and sensed in CO_CLIENT_ALLOC.

Chart:

CO_CLIENT

Event:

ALLOC_REQ

Description:

A client requested allocation of an association.

For efficiency, choose the association which has either or both a presentation context and a security context matching those requested for the call.

Event is generated by CO_CLIENT_ALLOC and sensed by CO_CLIENT.

Chart:

CO_CLIENT

Event:

ALTER_CONTEXT_REQ

Description:

The run-time system has requested an additional presentation context negotiation. The AUTH conditional flag is updated by the run-time system to reflect the requested security context.

Chart:

CO_CLIENT

Event:

AUTHENTICATED

Description:

Authentication processing completed successfully.

Chart:

CO_CLIENT

Event:

CHECK_CONTEXT

Description:

Check whether desired context is supported. Internally generated.

Chart:

CO_CLIENT

Event:

CLIENT_CANCEL

Description:

The client has issued an RPC cancel request call.

Generated by the Cancel service primitive.

Chart:

CO_CLIENT

Event:

CLOSE

Description:

Compound events to terminate association.

Definition:

ABORT_ASSOC_REQ or CONN_NAK or
NO_CONNECTION[not in(DATA)] or
RCV_BIND_NAK or RCV_ALTER_CONTEXT_REJECT
or DEALLOC_ASSOC[in(ASSOC_DONE) or
SHUTDOWN_OK and SHUTDOWN_REQUESTED] or
(RCV_SHUTDOWN or
RESOURCES_SCARCE)[SHUTDOWN_OK] or
RCV_FRAG_SIZE_TOO_LARGE[not in(DATA)] or
[in(ASSOC_DONE) and in(CALL_IDLE)] or
DENIED[in(INIT_WAIT)]

Chart:

CO_CLIENT

Event:

COMPLETE

Description:

RPC call completed (with success or fault).

Definition:

(RCV_LAST_OUT_FRAG or DEALLOC_ASSOC or
DENIED[not SHUTDOWN_PDU] or NO_CONNECTION
or RCV_FRAG_SIZE_TOO_LARGE) and not
RCV_FAULT

Chart:

CO_CLIENT

Event:

CONN_ACK

Description:

Transport connection was established. Generated by underlying transport.

Chart:

CO_CLIENT

Event:

CONN_NAK

Description:

Transport connection request failed. Generated by transport service.

Chart:

CO_CLIENT

Event:

CREATE_ASSOCIATION

Description:

This event, generated internally, creates the CO_CLIENT machine. The presentation context and security context are passed to the association along with this event. The AUTH conditional flag is initialised by the run-time system to reflect the requested security context.

Event is generated by CO_CLIENT_ALLOC and sensed by CO_CLIENT.

Chart:

CO_CLIENT

Event:

CREATE_FAILED

Description:

Failed to create a new association.

Event is generated by CO_CLIENT or CO_CLIENT_ALLOC and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT

Event:

CREATE_GROUP

Description:

Triggers creation of the association group. If this event is issued to a group that already exists, then it has no effect.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

Chart:

CO_CLIENT

Event:

CREATE_SUCCESS

Description:

A new association was successfully created.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT

Event:

DEALLOC_ASSOC

Description:

Deallocation of association requested. Generated internally.

Chart:

CO_CLIENT

Event:

DENIED

Description:

Authentication failure detected.

The VERIFY_AUTH activity generates this event if either the integrity check failed or the requested protection level for authentication services does not match.

Chart:

CO_CLIENT

Event:

DISCONN_REQ

Description:

Request termination of transport/session connection. Generated internally.

Chart:

CO_CLIENT

Event:

LAST_IN_PKT

Description:

Statechart internal event: last packet of fragmented request.

Definition:

[TRANSMIT_REQ and LAST_IN_FRAG and
REQUEST_ACTIVE]

Chart:

CO_CLIENT

Event:

MARK_ASSOC

Description:

Save status of association for RPC user and/or update presentation context set.

Because the association may terminate, the status, such as reason for termination, must be preserved for return to RPC user by the stub. This event is generated internally to CO_CLIENT.

Chart:

CO_CLIENT

Event:

NEXT_IN_PKT

Description:

Statechart internal event: intermediate packet of fragmented request.

Definition:

[TRANSMIT_REQ and not LAST_IN_FRAG and
REQUEST_ACTIVE]

Chart:

CO_CLIENT

Event:

NO_CONNECTION

Description:

Notification that the underlying transport connection terminated.

Generated externally by the underlying transport service.

Chart:

CO_CLIENT

Event:

OPEN_ASSOC

Description:

Open the association for use by a call.

Definition:

RCV_BIND_ACK[GROUP_EXISTS] or
[GROUP_EXISTS and WAIT_FOR_GROUP]

Chart:

CO_CLIENT

Event:

RCV_ALTER_CONTEXT_REJECT

Description:

Received an alter_context_resp PDU marking a security integrity failure.

This failure is indicated by the data item PDU_AUTH_VALUE_SUB_TYPE set to CONST_SUB_TYPE_INVALID_CHECKSUM. This event is generated in the CNTL_CALL action (CO_CLIENT chart).

Chart:

CO_CLIENT

Event:

RCV_ALTER_CONTEXT_RESP

Description:

Received an alter_context_resp PDU. Generated in CNTL_CALL action.

Chart:

CO_CLIENT

Event:

RCV_BIND_ACK

Description:

Receive a bind_ack PDU. Generated in CNTL_CALL action.

Chart:

CO_CLIENT

Event:

RCV_BIND_NAK

Description:

Received a bind_nak PDU. Generated in CNTL_CALL action (CO_CLIENT chart).

Chart:

CO_CLIENT

Event:

RCV_CNTL_PDU

Description:

Received one of the control PDUs with valid header.

Chart:

CO_CLIENT

Event:

RCV_FAULT

Description:

Received a valid fault PDU. Generated in CNTL_CALL action.

Chart:

CO_CLIENT

Event:

RCV_FRAG_CNTL_PDU

Description:

Received a fragmented control PDU.

Chart:

CO_CLIENT

Event:

RCV_FRAG_PDU

Description:

Received a response PDU for a non-authenticated call.

Chart:

CO_CLIENT

Event:

RCV_FRAG_PDU_A

Description:

Received a response PDU for an authenticated call.

Chart:

CO_CLIENT

Event:

RCV_FRAG_SIZE_TOO_LARGE

Description:

The received PDU exceeded the maximum allowed fragment size.

Chart:

CO_CLIENT

Event:

RCV_LAST_OUT_FRAG

Description:

Received last fragment response PDU. Signal completion to stub.

The last fragment of a multi-fragmented response or a single packet response was received. RCV_LAST_OUT_FRAG signals that the complete response data is available to the stub for unmarshaling.

Chart:

CO_CLIENT

Event:

RCV_SHUTDOWN

Description:

Shutdown indication was received from the server. Generated in CNTL_CALL action.

Chart:

CO_CLIENT

Event:

RECEIVE_PDU

Description:

Received a PDU from server.

Chart:

CO_CLIENT

Event:

REMOVE_FROM_GROUP

Description:

Remove association from this group.

To avoid a race condition which could result from multiple simultaneous events, the association machine must lock the group before generating the REMOVE_FROM_GROUP event and release the lock only after the event has been processed by the group machine.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

Chart:

CO_CLIENT

Event:

REQUEST_CONN

Description:

Request a new transport connection. If not null, use secondary address.

Chart:

CO_CLIENT

Event:

RESOURCES_SCARCE

Description:

Requests shutdown of association. Externally generated.

Resource management is implementation-specific. This event is generated by the implementation resource management policy when it is necessary to reclaim idle associations. It is recommended that idle associations be maintained for better performance.

CO_CLIENT Actions

The CO_CLIENT statechart defines the following actions:

Chart:

CO_CLIENT

Action:

CAN_CALL

Description:

Set up the cancel PDU to be sent.

Definition:

SND_REQUEST_TYPE:=CANCEL;
st!(SEND_PKT)

Chart:

CO_CLIENT

Action:

CNTL_CALL

Description:

Reactions on received control PDUs. Generates respective RCV_* events.

Definition:

IF
FAULT_PDU
THEN
RCV_FAULT;
IF
RT_CANCEL_COUNT/=RT_RCV_CANCEL_COUNT
THEN
tr!(RT_PENDING_CANCEL)
ELSE
IF
RT_RCV_PENDING_CANCEL
THEN
tr!(RT_PENDING_CANCEL)
ELSE
fs!(RT_PENDING_CANCEL)
END IF
END IF
END IF;
IF
BIND_ACK_PDU
THEN
RCV_BIND_ACK;
RT_SERVER_PRES_CONTEXT_LIST:=PDU_P_RESULT_LIST;
st!(SET_PRES_CONTEXT);
IF
PDU_MAX_RCV_FRAG_SIZE/=0
THEN
SND_MAX_XMIT_FRAG_SIZE:=PDU_MAX_RCV_FRAG_SIZE
END IF;
IF
PDU_MAX_XMIT_FRAG_SIZE/=0
THEN
SND_MAX_RCV_FRAG_SIZE:=PDU_MAX_XMIT_FRAG_SIZE
END IF
END IF;
IF
ALTER_CONTEXT_RESP_PDU
THEN
IF
PDU_AUTH_VALUE_SUB_TYPE=
CONST_SUB_TYPE_INVALID_CHECKSUM
THEN
RCV_ALTER_CONTEXT_REJECT
ELSE
RCV_ALTER_CONTEXT_RESP;
RT_SERVER_PRES_CONTEXT_LIST:=
RT_SERVER_PRES_CONTEXT_LIST
+PDU_P_RESULT_LIST;
st!(SET_PRES_CONTEXT)
END IF
END IF;
IF
BIND_NAK_PDU
THEN
RCV_BIND_NAK
END IF;
IF
SHUTDOWN_PDU
THEN
RCV_SHUTDOWN
END IF

Chart:

CO_CLIENT

Action:

DO_CNTL_RESP

Description:

Evaluate control PDU header.

Definition:

RT_HEADER:=RT_HEADER+PDU_HEADER;
IF
PDU_LAST_FRAG
THEN
tr!(LAST_OUT_FRAG);
END IF

Chart:

CO_CLIENT

Action:

DO_OUT_PKT

Description:

Append received response PDU body bgcolor="#FFFFFF" data to internal buffer.

Definition:

RT_OUT_PARAMS:=RT_OUT_PARAMS+RT_BODY

Chart:

CO_CLIENT

Action:

DO_RESP

Description:

Evaluate response PDU header.

Definition:

RT_BODY:=PDU_BODY;
IF
AUTH
THEN
RT_AUTH_VERIFIER_CALL:=PDU_AUTH_VERIFIER;
RT_AUTH_LENGTH_CALL:=PDU_AUTH_SPEC
END IF;
IF
PDU_LAST_FRAG
THEN
tr!(LAST_OUT_FRAG);
IF
PDU_CANCEL_COUNT/=RT_CANCEL_COUNT
THEN
tr!(RT_PENDING_CANCEL)
ELSE
IF
PDU_PENDING_CANCEL
THEN
tr!(RT_PENDING_CANCEL)
ELSE
fs!(RT_PENDING_CANCEL)
END IF
END IF;
RT_RCV_CANCEL_COUNT:=PDU_CANCEL_COUNT
END IF

Chart:

CO_CLIENT

Action:

END_ASSOC

Description:

Notification that association has been closed.

Definition:

MARK_ASSOC;
IF
in(INIT)
THEN
CREATE_FAILED
END IF;
WHEN
not NO_CONNECTION
THEN
DISCONN_REQ
END WHEN;
IF
in(ASSOC_OPEN) or in(ALLOCATED)
THEN
REMOVE_FROM_GROUP
END IF

Chart:

CO_CLIENT

Action:

FINAL

Description:

Perform final actions for RPC call.

Definition:

st!(DEQUEUE_CANCEL);
WHEN
RCV_LAST_OUT_FRAG
THEN
DEALLOC_ASSOC
END WHEN;
WHEN
DENIED
THEN
RT_EXCEPTION_STATUS:=CONST_NCA_S_INVALID_CHKSUM
END WHEN;
WHEN
NO_CONNECTION
THEN
RT_EXCEPTION_STATUS:=CONST_RPC_S_COMM_FAILURE;
DEALLOC_ASSOC
END WHEN;
WHEN
RCV_FRAG_SIZE_TOO_LARGE
THEN
RT_EXCEPTION_STATUS:=RT_NCA_S_PROTO_ERROR
END WHEN;
WHEN
DENIED or NO_CONNECTION or
RCV_FRAG_SIZE_TOO_LARGE
THEN
st!(EXCEPTION);
IF
not in(STUB_WAIT)
THEN
IF
in(REQ_WAIT)
THEN
st!(ABORT_SEND)
ELSE
st!(ABORT_RECEIVE)
END IF
END IF
END WHEN

Chart:

CO_CLIENT

Action:

FIRST_REQ

Description:

Set up and send first request PDU.

If the request is non-fragmented (single PDU), the actual send activity will be performed through the LAST_REQ action.

Definition:

tr!(REQUEST_ACTIVE);
tr!(SND_FIRST_FRAG);
RT_IN_FRAG:=RT_IN_PARAMS;
SND_IN_PARAMS:=RT_IN_PARAMS;
SND_PRES_CONTEXT_ID:=RT_PRES_CONTEXT_ID;
IF
RT_OBJ_ID/=NULL
THEN
SND_OBJ_ID:=RT_OBJ_ID
ENDIF;
SND_CALL_ID:=RT_CALL_ID;
SND_OP_NUM:=RT_OP_NUM;
IF
not LAST_IN_FRAG
THEN
fs!(TRANSMIT_REQ);
fs!(RT_DID_NOT_EXECUTE);
fs!(SND_LAST_FRAG);
SND_REQUEST_TYPE:=REQUEST;
st!(SEND_PKT)
END IF

Chart:

CO_CLIENT

Action:

INIT_ASSOC

Description:

Initiate an association. Create bind PDU and send it.

Definition:

SND_PRES_CONTEXT_LIST:=DESIRED_CONTEXT_LIST;
SND_IF_ID:=RT_IF_ID;
SND_IF_VERSION:=RT_IF_VERSION;
SND_MAX_RCV_FRAG_SIZE:=RT_MAX_RCV_FRAG_SIZE;
SND_MAX_XMIT_FRAG_SIZE:=RT_MAX_XMIT_FRAG_SIZE;
SND_REQUEST_TYPE:=BIND;
st!(SEND_PKT)

Chart:

CO_CLIENT

Action:

LAST_REQ

Description:

Send last in fragment to server.

Definition:

fs!(TRANSMIT_REQ);
fs!(RT_DID_NOT_EXECUTE);
tr!(SND_LAST_FRAG);
SND_IN_PARAMS:=RT_IN_FRAG;
SND_REQUEST_TYPE:=REQUEST;
st!(SEND_PKT)

Chart:

CO_CLIENT

Action:

MAKE_AVAIL

Description:

Make the association available for a call.

Definition:

CREATE_SUCCESS;
ADD_TO_GROUP

Chart:

CO_CLIENT

Action:

NEXT_REQ

Description:

Send next in fragment to server.

Definition:

fs!(TRANSMIT_REQ);
SND_IN_PARAMS:=RT_IN_FRAG;
SND_REQUEST_TYPE:=REQUEST;
st!(SEND_PKT)

Chart:

CO_CLIENT

Action:

ORPHANED_CALL

Description:

Set up orphaned PDU to be sent.

Definition:

SND_REQUEST_TYPE:=ORPHANED;
st!(SEND_PKT)

CO_CLIENT Conditions

The CO_CLIENT statechart defines the following conditions:

Chart:

CO_CLIENT

Condition:

ALTER_CONTEXT_RESP_PDU

Description:

Statechart internal flag: received PDU type alter_context_resp.

Chart:

CO_CLIENT

Condition:

AUTH

Description:

Statechart internal flag: indicates that call is authenticated.

Chart:

CO_CLIENT

Condition:

BIND_ACK_PDU

Description:

Statechart internal flag: received PDU type bind_ack.

Chart:

CO_CLIENT

Condition:

BIND_NAK_PDU

Description:

Statechart internal flag: received PDU type bind_nak.

Chart:

CO_CLIENT

Condition:

CHECK_AUTH

Description:

Verify authentication if requested (not required for shutdown and bind_nak PDUs).

Definition:

AUTH and (not PDU_TYPE=SHUTDOWN and not
PDU_TYPE=BIND_NAK)

Chart:

CO_CLIENT

Condition:

CNTL_PDU

Description:

Statechart internal flag: to be received control PDUs.

Definition:

PDU_TYPE=FAULT or PDU_TYPE=BIND_ACK or
PDU_TYPE=BIND_NAK or PDU_TYPE=SHUTDOWN or
PDU_TYPE=ALTER_CONTEXT_RESP

Chart:

CO_CLIENT

Condition:

CURRENT_PENDING_CANCEL

Description:

Cancel pending state passed from stub during initialisation of call.

Chart:

CO_CLIENT

Condition:

FAULT_PDU

Description:

Statechart internal flag: received PDU type fault.

Chart:

CO_CLIENT

Condition:

GROUP_EXISTS

Description:

The group to which this association belongs exists.

Definition:

in(CO_CLIENT_GROUP:CO_CLIENT_GROUP)

Chart:

CO_CLIENT

Condition:

LAST_IN_FRAG

Description:

Statechart internal flag: last in fragment or non-frag in packet ready to send.

This flag is set if the transmit queue contains the last fragment (see also Connection-oriented Protocol ).

Chart:

CO_CLIENT

Condition:

LAST_OUT_FRAG

Description:

Statechart internal flag: last out fragment or non-frag out packet received.

Chart:

CO_CLIENT

Condition:

MAYBE

Description:

Statechart internal flag: maybe call.

Chart:

CO_CLIENT

Condition:

PDU_DID_NOT_EXECUTE

Description:

fault PDU header flag PFC_DID_NOT_EXECUTE.

Chart:

CO_CLIENT

Condition:

PDU_LAST_FRAG

Description:

Header flag PFC_LAST_FRAG.

Chart:

CO_CLIENT

Condition:

PDU_PENDING_CANCEL

Description:

Header flag PFC_PENDING_CANCEL in received response or fault PDU.

Chart:

CO_CLIENT

Condition:

PRES_SEC_CONTEXT_SUPPORTED

Description:

The presentation and security contexts for the call are in the negotiated set.

Both the negotiated presentation context and the security credentials are saved by the SET_PRES_SEC_CONTEXT activity.

Chart:

CO_CLIENT

Condition:

REQUEST_ACTIVE

Description:

Statechart internal flag: send request has started.

Chart:

CO_CLIENT

Condition:

RESPONSE_ACTIVE

Description:

Statechart internal flag: indicates availability of response data.

Chart:

CO_CLIENT

Condition:

RT_DID_NOT_EXECUTE

Description:

Run time internal: the call has not been executed yet by the server manager.

This flag is common state shared between the stub and the run-time system. The stub must initialise this to true. The run-time system updates this flag. If a call fails, the stub may check this flag to ascertain whether it may safely retry the call when exactly-once semantics were requested.

Chart:

CO_CLIENT

Condition:

RT_PENDING_CANCEL

Description:

Statechart internal flag: cancel pending state at server.

Chart:

CO_CLIENT

Condition:

RT_RCV_PENDING_CANCEL

Description:

Statechart internal: holds received pending cancel state.

Chart:

CO_CLIENT

Condition:

SHUTDOWN_OK

Description:

Shutdown of association allowed.

Association must lock group when checking these state variables.

Definition:

ASSOC_COUNT>1 or ACTIVE_CONTEXT_COUNT=0

Chart:

CO_CLIENT

Condition:

SHUTDOWN_PDU

Description:

Statechart internal flag: received PDU type shutdown.

Chart:

CO_CLIENT

Condition:

SHUTDOWN_REQUESTED

Description:

Orderly shutdown of association requested.

Chart:

CO_CLIENT

Condition:

SND_FIRST_FRAG

Description:

Statechart internal flag: header flag (PFC_FIRST_FRAG) of next frag to be sent.

Chart:

CO_CLIENT

Condition:

SND_LAST_FRAG

Description:

Statechart internal flag: header flag (PFC_LAST_FRAG) of next buffered fragment.

Chart:

CO_CLIENT

Condition:

TRANSMIT_REQ

Description:

One or more fragments are queued for transmission of request data.

This flag indicates that one or more request fragment(s) are queued in a run-time internal buffer and ready to be transmitted.

The run-time system internally sets this flag (true) after the stub initially provides data in the transmit queue, sufficient for at least the first PDU fragment to be transmitted. The protocol machine resets this flag if it has detected and taken an event for sending the next fragment in the queue. The run-time system sets this flag again after completion of a SEND_PKT activity if the transmit queue contains enough data for the next PDU fragment to be transmitted.

Chart:

CO_CLIENT

Condition:

VALID_FRAG_SIZE

Description:

Evaluation whether received PDU exceeds size limit.

Definition:

PDU_FRAG_LENGTH<=RT_MAX_RCV_FRAG_SIZE

Chart:

CO_CLIENT

Condition:

VALID_PDU_HEADER

Description:

Pre-evaluation of PDU header (before authentication processing).

Definition:

PDU_CALL_ID=RT_CALL_ID
and PDU_VERSION_NUM=CO_VERSION_NUM_V20
and PDU_VERSION_NUM_MINOR=CO_VERSION_NUM_V20_MINOR
or PDU_VERSION_NUM_MINOR=PDU_CN_VERS_COMPAT
and VALID_FRAG_SIZE

Chart:

CO_CLIENT

Condition:

VERSION_MISMATCH

Description:

Version mismatch. Version .1 client access version .0 server.

Definition:

PDU_FAULT_STATUS=RPC_S_VERSION_MISMATCH

Chart:

CO_CLIENT

Condition:

VERSION_MISMATCH_PDU

Description:

Statechart internal flag: Received a bind_nak with a VERSION_MISMATCH.

Chart:

CO_CLIENT

Condition:

WAIT_FOR_GROUP

Description:

Indicates association is waiting for group to be created.

CO_CLIENT Data-Items

The CO_CLIENT statechart defines the following data items:

Chart:

CO_CLIENT

Data Item:

ACTIVE_CONTEXT_COUNT

Description:

Number of active context handles for group. State variable of CO_CLIENT_GROUP.

Chart:

CO_CLIENT

Data Item:

ALTER_CONTEXT

Description:

Constant: PDU type alter_context.

Definition:

14

Chart:

CO_CLIENT

Data Item:

ALTER_CONTEXT_RESP

Description:

Constant: PDU type alter_context_resp.

Definition:

15

Chart:

CO_CLIENT

Data Item:

ASSOC_COUNT

Description:

Number of associations in group. State variable of CO_CLIENT_GROUP.

Must lock group before accessing this state variable to avoid race conditions.

Chart:

CO_CLIENT

Data Item:

BIND

Description:

Constant: PDU type bind.

Definition:

11

Chart:

CO_CLIENT

Data Item:

BIND_ACK

Description:

Constant: PDU type bind_ack.

Definition:

12

Chart:

CO_CLIENT

Data Item:

BIND_NAK

Description:

Constant: PDU type bind_nak.

Definition:

13

Chart:

CO_CLIENT

Data Item:

CANCEL

Description:

Constant: PDU type cancel.

Definition:

18

Chart:

CO_CLIENT

Data Item:

CONST_NCA_S_INVALID_CHKSUM

Description:

Constant: fault status code nca_s_invalid_chksum.

Chart:

CO_CLIENT

Data Item:

CONST_RPC_S_CANCEL_TIMEOUT

Description:

Constant: fault status code rpc_s_cancel_timeout.

Chart:

CO_CLIENT

Data Item:

CONST_RPC_S_COMM_FAILURE

Description:

Constant: fault status code rpc_s_comm_failure.

Chart:

CO_CLIENT

Data Item:

CONST_SUB_TYPE_INVALID_CHECKSUM

Description:

Value indicating a security integrity failure (invalid checksum).

The value dce_c_cn_dce_sub_type_invalid_checksum, which is encoded in the sub_type field of the auth_value member of the authentication verifier. (See Security .)

Definition:

2

Chart:

CO_CLIENT

Data Item:

CO_VERSION_NUM_V20

Description:

Constant: RPC protocol version 2.0 major version number.

Definition:

5

Chart:

CO_CLIENT

Data Item:

CO_VERSION_NUM_V20_MINOR

Description:

Constant: RPC protocol minor version number.

Chart:

CO_CLIENT

Data Item:

DESIRED_CONTEXT_LIST

Description:

Presentation context determined by stub.

This is the presentation context required for the call. Its value is determined by the stub from the interface definition and transfer syntaxes. See the section on PDU encodings for details of this context.

Chart:

CO_CLIENT

Data Item:

FAULT

Description:

Constant: PDU type fault.

Definition:

3

Chart:

CO_CLIENT

Data Item:

ORPHANED

Description:

Constant: PDU type orphaned.

Definition:

19

Chart:

CO_CLIENT

Data Item:

PDU_AUTH_SPEC

Description:

PDU header field auth_length.

Chart:

CO_CLIENT

Data Item:

PDU_AUTH_VALUE_SUB_TYPE

Description:

The value of the sub_type field of the auth_value member of the authentication verifier as received in an alter_context_resp PDU. (See Security .)

Chart:

CO_CLIENT

Data Item:

PDU_AUTH_VERIFIER

Description:

PDU trailer: authentication verifier (authentication protocol-specific).

Chart:

CO_CLIENT

Data Item:

PDU_BODY

Description:

Array of PDU body bgcolor="#FFFFFF" data.

Chart:

CO_CLIENT

Data Item:

PDU_CALL_ID

Description:

PDU header field call_id.

Chart:

CO_CLIENT

Data Item:

PDU_CANCEL_COUNT

Description:

Received cancel_count value in response or fault PDU header.

Chart:

CO_CLIENT

Data Item:

PDU_CN_VERS_COMPAT

Description:

Constant: Protocol minor version compatible number.

Definition:

0

Chart:

CO_CLIENT

Data Item:

PDU_FAULT_STATUS

Description:

Constant: fault status code.

Chart:

CO_CLIENT

Data Item:

PDU_FRAG_LENGTH

Description:

PDU header field frag_length.

Chart:

CO_CLIENT

Data Item:

PDU_HEADER

Description:

Array of PDU header data.

Chart:

CO_CLIENT

Data Item:

PDU_MAX_RCV_FRAG_SIZE

Description:

PDU header field max_recv_frag.

Chart:

CO_CLIENT

Data Item:

PDU_MAX_XMIT_FRAG_SIZE

Description:

PDU header field max_xmit_frag.

Chart:

CO_CLIENT

Data Item:

PDU_P_RESULT_LIST

Description:

PDU header field: p_result_list in bind_ack and alter_context_resp PDUs.

Chart:

CO_CLIENT

Data Item:

PDU_TYPE

Description:

PDU header field PTYPE.

Chart:

CO_CLIENT

Data Item:

PDU_VERSION_NUM

Description:

PDU header field rpc_vers.

Chart:

CO_CLIENT

Data Item:

PDU_VERSION_NUM_MINOR

Description:

PDU header field rpc_vers_minor.

Chart:

CO_CLIENT

Data Item:

REQUEST

Description:

Constant: PDU type request.

Definition:

0

Chart:

CO_CLIENT

Data Item:

RESPONSE

Description:

Constant: PDU type response.

Definition:

2

Chart:

CO_CLIENT

Data Item:

RPC_S_VERSION_MISMATCH

Description:

Constant: fault status code rpc_s_rpc_prot_version_mismatch.

Chart:

CO_CLIENT

Data Item:

RT_ASSOC_GROUP_ID

Description:

Group ID for newly created association. Defined in CO_CLIENT_GROUP.

Chart:

CO_CLIENT

Data Item:

RT_AUTH_LENGTH_CALL

Description:

Statechart internal: authentication length field received in CALL state.

Chart:

CO_CLIENT

Data Item:

RT_AUTH_LENGTH_CNTL

Description:

Statechart internal: authentication length field received in CONTROL state.

Chart:

CO_CLIENT

Data Item:

RT_AUTH_VERIFIER_CALL

Description:

Received authentication trailer (verifier) for request PDU.

Chart:

CO_CLIENT

Data Item:

RT_AUTH_VERIFIER_CNTL

Description:

Received authentication trailer (verifier) for control PDU.

Chart:

CO_CLIENT

Data Item:

RT_BODY

Description:

Statechart internal: temporarily buffered response PDU body bgcolor="#FFFFFF" data.

Chart:

CO_CLIENT

Data Item:

RT_CALL_ID

Description:

Statechart internal: call identifier of current RPC call.

Chart:

CO_CLIENT

Data Item:

RT_CANCEL_COUNT

Description:

Statechart internal counter: number of cancel requests sent.

Chart:

CO_CLIENT

Data Item:

RT_EXCEPTION_STATUS

Description:

Statechart internal: status value passed to exception handler.

Chart:

CO_CLIENT

Data Item:

RT_HEADER

Description:

Statechart internal: temporarily buffered response PDU header data.

Chart:

CO_CLIENT

Data Item:

RT_IF_ID

Description:

Statechart internal: received interface UUID of call.

Chart:

CO_CLIENT

Data Item:

RT_IF_VERSION

Description:

Statechart internal: received interface version number.

Chart:

CO_CLIENT

Data Item:

RT_IN_FRAG

Description:

Statechart internal pointer to data to be sent in next request PDU.

The SEND_PKT activity increments this pointer after a request PDU is sent.

Chart:

CO_CLIENT

Data Item:

RT_IN_PARAMS

Description:

Statechart internal: buffered array of reassembled input data.

RT_IN_PARAMS is the queue of transmit data provided by the stub. A possible segmentation of this queue is not equivalent to the sizes of PDU fragments sent by the run-time system (SEND_PKT) activity.

The RT_IN_FRAG variable is a pointer data type that points to the to be transmitted data fragment within this RT_IN_PARAMS queue.

Chart:

CO_CLIENT

Data Item:

RT_MAX_RCV_FRAG_SIZE

Description:

Maximum size of a fragment the receiver is able to handle.

The minimum value of this fragment size is determined by the architected value MustRcvFragSize (refer to Fragmentation and Reassembly ).

Implementations may support larger fragment sizes that are subject to negotiation with the server. This value is set internally by run-time implementations.

Chart:

CO_CLIENT

Data Item:

RT_MAX_XMIT_FRAG_SIZE

Description:

Maximum size of a fragment the sender is able to handle.

The minimum value of this fragment size is determined by the architected value MustRcvFragSize (refer to Fragmentation and Reassembly ).

Implementations may support larger fragment sizes that are subject to negotiation with the server. This value is set internally by run-time implementations.

Chart:

CO_CLIENT

Data Item:

RT_NCA_S_PROTO_ERROR

Description:

Constant: fault status code nca_s_proto_error.

Chart:

CO_CLIENT

Data Item:

RT_OBJ_ID

Description:

Statechart internal: buffered object UUID of RPC call.

Chart:

CO_CLIENT

Data Item:

RT_OP_NUM

Description:

Statechart internal: buffered operation number of RPC call.

Chart:

CO_CLIENT

Data Item:

RT_OUT_PARAMS

Description:

Buffered array of unfragmented output data.

Chart:

CO_CLIENT

Data Item:

RT_PRES_CONTEXT_ID

Description:

Statechart internal: presentation context identifier of current call.

Selection of values for the context identifier is implementation-dependent. There must be a one-to-one mapping between each negotiated context and the identifiers within an association.

Chart:

CO_CLIENT

Data Item:

RT_RCV_CANCEL_COUNT

Description:

Statechart internal: received cancel count.

Chart:

CO_CLIENT

Data Item:

RT_SERVER_PRES_CONTEXT_LIST

Description:

Statechart internal: the received set of supported server presentation contexts.

Chart:

CO_CLIENT

Data Item:

SHUTDOWN

Description:

Constant: PDU type shutdown.

Definition:

17

Chart:

CO_CLIENT

Data Item:

SND_ASSOC_GROUP_ID

Description:

Association group ID sent in bind and alter_context PDUs.

Chart:

CO_CLIENT

Data Item:

SND_CALL_ID

Description:

Call ID of current RPC call.

Chart:

CO_CLIENT

Data Item:

SND_IF_ID

Description:

Interface UUID to be sent.

Chart:

CO_CLIENT

Data Item:

SND_IF_VERSION

Description:

Interface version number to be sent.

Chart:

CO_CLIENT

Data Item:

SND_IN_PARAMS

Description:

PDU body bgcolor="#FFFFFF" data promoted to SEND_PKT activity.

Chart:

CO_CLIENT

Data Item:

SND_MAX_RCV_FRAG_SIZE

Description:

Constant: Maximum receive fragment size. Sent in bind PDU.

Chart:

CO_CLIENT

Data Item:

SND_MAX_XMIT_FRAG_SIZE

Description:

Constant: Maximum transmit fragment size. Sent in bind PDU.

Chart:

CO_CLIENT

Data Item:

SND_OBJ_ID

Description:

Object UUID of current RPC call.

Chart:

CO_CLIENT

Data Item:

SND_OP_NUM

Description:

Operation number of current call.

Chart:

CO_CLIENT

Data Item:

SND_PRES_CONTEXT_ID

Description:

Determined by the presentation context in the binding information.

Chart:

CO_CLIENT

Data Item:

SND_PRES_CONTEXT_LIST

Description:

Presentation context list to be sent.

Chart:

CO_CLIENT

Data Item:

SND_REQUEST_TYPE

Description:

PDU type to be sent.

Chart:

CO_CLIENT

Data Item:

TIMEOUT_CANCEL

Description:

Timeout value for cancel requests.

Sets the lower bound on the time to wait before timing out after forwarding a cancel PDU to the server. The default of this timeout value is set to infinity (see Architected and Default Values for Protocol Machines ). Applications may set a different value via the rpc_mgmt_set_cancel_timeout RPC API.

CO_CLIENT_ALLOC Machine

CO_CLIENT_ALLOC Statechart shows the CO_CLIENT_ALLOC machine statechart. Figure: CO_CLIENT_ALLOC Statechart

CO_CLIENT_ALLOC Activities

The CO_CLIENT_ALLOC statechart defines the following activities:

Chart:

CO_CLIENT_ALLOC

Activity:

FETCH_TICKET

Description:

Obtains the security context for the RPC session from the security service (that is, kerberos ticket, if authentication service is rpc_c_authn_dce_secret).

The activity resets the conditional flag TICKET to false at the beginning, and sets TICKET to true before termination only if the fetch operation succeeded. FETCH_TICKET is a self-terminating activity.

CO_CLIENT_ALLOC States

The CO_CLIENT_ALLOC statechart defines the following states:

Chart:

CO_CLIENT_ALLOC

State:

ALLOC_ASSOC

Description:

Wait for association to be allocated.

Reactions
Trigger	Action
en(ALLOC_ASSOC)	ALLOC_REQ

Chart:

CO_CLIENT_ALLOC

State:

CO_CLIENT_ALLOC

Description:

Protocol machine for association allocation. Created by Invoke service primitive.

Chart:

CO_CLIENT_ALLOC

State:

CREATE_ASSOC

Description:

Create a new association.

Reactions
Trigger	Action
en(CREATE_ASSOC)	IF in(CO_CLIENT_GROUP:CO_CLIENT_GROUP) and RT_SECONDARY_ADDRESS=NULL THEN CREATE_FAILED ELSE CREATE_ASSOCIATION END IF

Chart:

CO_CLIENT_ALLOC

State:

GET_TICKET

Description:

Get authentication ticket from security server (security service-specific).

Activities Throughout:

FETCH_TICKET

Chart:

CO_CLIENT_ALLOC

State:

INIT

Description:

Initialise state for a call.

Reactions
Trigger	Action
en(INIT)[not AUTH or TICKET]	TIMEOUT_MAX_ALLOC_WAIT:=3; MAP_TO_GROUP_AND_LOCK; TIMEOUT_RANDOM:=RAND_UNIFORM(0,3)

Chart:

CO_CLIENT_ALLOC

State:

WAIT_RETRY

Description:

Wait and retry if resources for association currently not available.

Reactions
Trigger	Action
en(WAIT_RETRY)	UNLOCK_GROUP; TIMEOUT_RANDOM:= MIN(RAND_UNIFORM (0,TIMEOUT_MAX_ALLOC_WAIT), CONST_MAX_BACKOFF); TIMEOUT_MAX_ALLOC_WAIT:= 2*TIMEOUT_MAX_ALLOC_WAIT
tm(en(WAIT_RETRY), TIMEOUT_RANDOM)	MAP_TO_GROUP_AND_LOCK

CO_CLIENT_ALLOC Events

The CO_CLIENT_ALLOC statechart defines the following events:

Chart:

CO_CLIENT_ALLOC

Event:

ALLOC_ASSOC_ACK

Description:

Association allocated and may be used for call.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT_ALLOC

Event:

ALLOC_ASSOC_NAK

Description:

Unable to allocate association because requested context not supported.

Generated in chart CO_CLIENT and sensed in CO_CLIENT_ALLOC.

Chart:

CO_CLIENT_ALLOC

Event:

ALLOC_REQ

Description:

A client requested allocation of an association.

For efficiency, choose the association which has either or both a presentation context and a security context matching those requested for the call.

Event is generated by CO_CLIENT_ALLOC and sensed by CO_CLIENT.

Chart:

CO_CLIENT_ALLOC

Event:

ATTEMPT_DONE

Description:

Attempt to allocate association either completed successfully or failed.

Definition:

RCV_BIND_NAK or RCV_ALTER_CONTEXT_REJECT
or ALLOC_ASSOC_ACK or ALLOC_ASSOC_NAK or
tm(en(INIT),
CONST_MAX_RESOURCE_WAIT)[not
in(ALLOC_ASSOC)] or NO_COMMUNICATION or
sp(FETCH_TICKET)[not TICKET]

Chart:

CO_CLIENT_ALLOC

Event:

CREATE_ASSOCIATION

Description:

This event, generated internally, creates the CO_CLIENT machine.

The presentation context and security context are passed to the association along with this event.

Event is generated by CO_CLIENT_ALLOC and sensed by CO_CLIENT.

Chart:

CO_CLIENT_ALLOC

Event:

CREATE_FAILED

Description:

Failed to create a new association.

Event is generated by CO_CLIENT or CO_CLIENT_ALLOC and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT_ALLOC

Event:

CREATE_SUCCESS

Description:

A new association was successfully created.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_ALLOC.

Chart:

CO_CLIENT_ALLOC

Event:

FETCHED_TICKET

Description:

Client fetched a valid authentication ticket.

Definition:

sp(FETCH_TICKET)[TICKET]

Chart:

CO_CLIENT_ALLOC

Event:

LOCK_GRANTED

Description:

The request to lock access to the group was granted.

To guard against race conditions, the model assumes the existence of a centralised locking mechanism for each group. One lock is associated with each group. Requests for a lock are queued and serviced in FIFO order. At most one machine may be in possession of the lock for a particular group at any time.

Chart:

CO_CLIENT_ALLOC

Event:

MAP_TO_GROUP_AND_LOCK

Description:

Map the call to a group based upon the binding information and request lock.

Determine the group to which the binding information maps. Request a lock for this group. If the group does not exist, then possession of the lock indicates that this allocation machine is permitted to create the group.

Chart:

CO_CLIENT_ALLOC

Event:

NO_COMMUNICATION

Description:

An unrecoverable network error occurred. Generated by underlying transport.

This may occur either during an attempt to create a new association or during an attempt to allocate an existing association.

Chart:

CO_CLIENT_ALLOC

Event:

RCV_ALTER_CONTEXT_REJECT

Description:

Received an alter_context_resp PDU marking a security integrity failure.

This failure is indicated by data item PDU_AUTH_VALUE_SUB_TYPE set to CONST_SUB_TYPE_INVALID_CHECKSUM. This event is generated in the CNTL_CALL action (CO_CLIENT chart).

Chart:

CO_CLIENT_ALLOC

Event:

RCV_BIND_NAK

Description:

Received a bind_nak PDU. Generated in CNTL_CALL action (CO_CLIENT chart).

Chart:

CO_CLIENT_ALLOC

Event:

START_CALL

Description:

The client has initiated a remote procedure call (Invoke service primitive).

Chart:

CO_CLIENT_ALLOC

Event:

UNLOCK_GROUP

Description:

Release group lock or dequeue pending lock request. Generated internally.

If the machine has been granted the lock for the group, then release the lock. If the machine has queued a request for the lock, then dequeue the request.

CO_CLIENT_ALLOC Actions

The CO_CLIENT_ALLOC statechart defines the following actions:

Chart:

CO_CLIENT_ALLOC

Action:

RETURN_STATUS

Description:

Return status of allocation attempt to stub and unlock group.

The CO_CLIENT_ALLOC machine indicates to the stub whether an association was allocated. If an association was successfully allocated, then a the identity of the association is returned to the stub. If the allocation attempt failed, then the reason for the failure is returned to the stub.

Definition:

UNLOCK_GROUP

Chart:

CO_CLIENT_ALLOC

Action:

SETUP_CALL

Description:

Set up and initialise call data.

Definition:

tr!(RT_DID_NOT_EXECUTE)

CO_CLIENT_ALLOC Conditions

The CO_CLIENT_ALLOC statechart defines the following conditions:

Chart:

CO_CLIENT_ALLOC

Condition:

ASSOC_AVAIL

Description:

The group exists and at least one association in the group is available.

The group indicated by the binding information exists, and at least one association in that group is in the ASSOC_OPEN state.

Definition:

in(CO_CLIENT:ASSOC_OPEN)

Chart:

CO_CLIENT_ALLOC

Condition:

AUTH

Description:

Statechart internal flag: indicates that call is authenticated.

Chart:

CO_CLIENT_ALLOC

Condition:

RESOURCE_AVAIL

Description:

Policy and resources permit new association. Value determined externally.

The policy for allowing creation of new associations and the management of resources is implementation-dependent.

Chart:

CO_CLIENT_ALLOC

Condition:

RT_DID_NOT_EXECUTE

Description:

Run time internal: the call has not been executed yet by the server manager.

This flag is common state shared between the stub and the run-time system. The stub must initialise this to true. The run-time system updates this flag. If a call fails, the stub may check this flag to ascertain whether it may safely retry the call when exactly-once semantics were requested.

Chart:

CO_CLIENT_ALLOC

Condition:

TICKET

Description:

The authentication ticket is valid. Determined externally.

The authentication ticket from the call's client principal to the server's principal is valid. The particular ticket depends on the client/server pair of principals, and may be different for different RPCs.

Note that implementations may cache unexpired tickets, even across process invocations or system reboots. Therefore, this condition predicate may be maintained externally to the RPC run-time system.

CO_CLIENT_ALLOC Data-Items

The CO_CLIENT_ALLOC statechart defines the following data items:

Chart:

CO_CLIENT_ALLOC

Data Item:

CONST_MAX_BACKOFF

Description:

Upper bound in seconds for wait to retry allocation. Architectural constant.

Definition:

60

Chart:

CO_CLIENT_ALLOC

Data Item:

CONST_MAX_RESOURCE_WAIT

Description:

Maximum time in seconds to wait for association allocation. Architected value.

Definition:

300

Chart:

CO_CLIENT_ALLOC

Data Item:

RT_SECONDARY_ADDRESS

Description:

The secondary address for the group. Determined by CO_CLIENT_GROUP.

Chart:

CO_CLIENT_ALLOC

Data Item:

TIMEOUT_MAX_ALLOC_WAIT

Description:

Maximum wait before retrying association allocation. Internal variable.

Chart:

CO_CLIENT_ALLOC

Data Item:

TIMEOUT_RANDOM

Description:

Random time between 0 and TIMEOUT_MAX_ALLOC_WAIT. Internal variable.

CO_CLIENT_GROUP Machine

CO_CLIENT_GROUP Statechart shows the CO_CLIENT_GROUP machine statechart. Figure: CO_CLIENT_GROUP Statechart

CO_CLIENT_GROUP States

The CO_CLIENT_GROUP statechart defines the following states:

Chart:

CO_CLIENT_GROUP

State:

CO_CLIENT_GROUP

Description:

Client association group machine. Created by CO_CLIENT:CREATE_GROUP event.

The group is created when the CO_CLIENT receives a valid bind_ack PDU and the group did not already exist. Note that once the CO_CLIENT_GROUP is terminated, the group ID, RT_ASSOC_GROUP_ID, is no longer valid. If the run-time system or stub was maintaining this value with other state (for example, it may be stored with other binding data pointed to by a binding handle) then the value must be invalidated appropriately.

Chart:

CO_CLIENT_GROUP

State:

GROUP_ACTIVE

Description:

Associations belong to this group.

Reactions
Trigger	Action
REMOVE_FROM_GROUP [ASSOC_COUNT>1]	ASSOC_COUNT:=ASSOC_COUNT-1
ADD_TO_GROUP	ASSOC_COUNT:=ASSOC_COUNT+1
CONTEXT_ACTIVE	ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT+1
CONTEXT_INACTIVE	ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT-1

Chart:

CO_CLIENT_GROUP

State:

GROUP_OPEN

Description:

Open a new associations group.

Reactions
Trigger	Action
en(GROUP_OPEN)	ACTIVE_CONTEXT_COUNT:=0; ASSOC_COUNT:=0; RT_ASSOC_GROUP_ID:=PDU_ASSOC_GROUP_ID; RT_SECONDARY_ADDRESS:=PDU_SEC_ADDR

CO_CLIENT_GROUP Events

The CO_CLIENT_GROUP statechart defines the following events:

Chart:

CO_CLIENT_GROUP

Event:

ADD_TO_GROUP

Description:

Signal group to add this association. Generated by an association in this group.

Association must check that the instance of the CO_CLIENT_ALLOC machine which initiated this association has not terminated. If it has terminated, then the ASSOCIATION machine must lock the group before issuing this event to avoid possible race conditions.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

Chart:

CO_CLIENT_GROUP

Event:

CONTEXT_ACTIVE

Description:

A context handle was activated. Generated by the client stub.

The stub generates this event for each context handle which makes a transition from inactive to active. To avoid a race condition which could result from multiple simultaneous events, the stub must lock the group before generating the CONTEXT_ACTIVE event and release the lock only after the event has been processed by the group machine.

Chart:

CO_CLIENT_GROUP

Event:

CONTEXT_INACTIVE

Description:

Context handle deactivated. Generated by the client stub.

The stub generates this event for each context handle which makes a transition from active to inactive. To avoid a race condition which could result from multiple simultaneous events, the stub must lock the group before generating the CONTEXT_INACTIVE event and release the lock only after the event has been processed by the group machine.

Chart:

CO_CLIENT_GROUP

Event:

CREATE_GROUP

Description:

Triggers creation of the association group. If this event is issued to a group that already exists, then it has no effect.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

Chart:

CO_CLIENT_GROUP

Event:

REMOVE_FROM_GROUP

Description:

Remove association from this group.

To avoid a race condition which could result from multiple simultaneous events, the association machine must lock the group before generating the REMOVE_FROM_GROUP event and release the lock only after the event has been processed by the group machine.

Event is generated by CO_CLIENT and sensed by CO_CLIENT_GROUP.

CO_CLIENT_GROUP Data-Items

The CO_CLIENT_GROUP statechart defines the following data items:

Chart:

CO_CLIENT_GROUP

Data Item:

ACTIVE_CONTEXT_COUNT

Description:

Number of active context handles for group. State variable of CO_CLIENT_GROUP.

Chart:

CO_CLIENT_GROUP

Data Item:

ASSOC_COUNT

Description:

Number of associations in group. State variable of CO_CLIENT_GROUP.

Must lock group before accessing this state variable to avoid race conditions.

Chart:

CO_CLIENT_GROUP

Data Item:

PDU_ASSOC_GROUP_ID

Description:

The association group ID (header field assoc_group_id) from the bind_ack PDU.

Chart:

CO_CLIENT_GROUP

Data Item:

PDU_SEC_ADDR

Description:

The optional secondary address (header field sec_addr) from the bind_ack PDU.

Chart:

CO_CLIENT_GROUP

Data Item:

RT_ASSOC_GROUP_ID

Description:

Group ID for newly created association. Defined in CO_CLIENT_GROUP.

Chart:

CO_CLIENT_GROUP

Data Item:

RT_SECONDARY_ADDRESS

Description:

The secondary address for the group. Determined by CO_CLIENT_GROUP.

CO_SERVER Machine

CO_SERVER Statechart shows the CO_SERVER machine statechart.

CO_SERVER Activities

The CO_SERVER statechart defines the following activities:

Chart:

CO_SERVER

Activity:

ABORT_RECEIVE

Description:

Flush and discard any further received packets for this call. There may be numerous additional packets in the pipeline. The flush may be lazy, upon subsequent receive processing. Also, notify the run-time system and stub to reclaim any resources for this call.

Chart:

CO_SERVER

Activity:

ABORT_SEND

Description:

Discontinue any further transmission of response data for the current call, to the best extent possible. Some error condition has caused a fault.

Chart:

CO_SERVER

Activity:

CANCEL_NOTIFY_APP

Description:

This activity notifies the manager routine of the RPC application about the cancel request issued by the client.

CANCEL_NOTIFY_APP activity terminates after acknowledgement from the stub. The stub sets the RETURN_PENDING_CANCEL flag appropriately.

Chart:

CO_SERVER

Activity:

HANDLE_IN_FRAG

Description:

This activity is invoked at each received fragment evaluation of in parameters for multi-fragmented RPC requests.

The HANDLE_IN_FRAG activity makes received data of the next fragment available to the stub for unmarshalling and passes the object UUID (RT_OBJ_ID) to the manager routine. This does not require a transfer of control from the run-time system to the stub for each fragment; implementation policy determines when control is transferred.

Chart:

CO_SERVER

Activity:

SEND_PKT

Description:

Prepare a PDU to send to the client, adding the appropriate header information as necessary. If security services were requested (conditional flag AUTH is true), apply per-message security services. Send the PDU.

The conditional flags and data items set in the run-time system (with prefix SND_) provide the appropriate input for generating the PDU data. Note that actions within the same execution step that started this activity may have assigned values to the SND_* variables which have to be taken by this instance of the activity.

After sending a response PDU, the RT_OUT_FRAG pointer is incremented accordingly, to point to the remaining data in the transmit queue.

Note:

The SEND_PKT activity may be invoked simultaneously by several orthogonal states (WORKING, CONTROL, CANCEL, and so on). The run-time system must catch these send requests, buffer these and the associated data, and perform the sends in sequential order.

Chart:

CO_SERVER

Activity:

STOP_ORPHAN

Description:

Tell the stub that the client orphaned the call and allow the manager routine to run down gracefully. If it is executing (that is, it is still receiving for a pipe), cancel it. Otherwise, discard the input and/or output data. If possible (not required), ensure that neither response nor fault PDU is returned for the orphaned call.

Chart:

CO_SERVER

Activity:

VERIFY_AUTH

Description:

Verify the authentication trailer of PDU and decrypt message if necessary.

This activity takes as input values the PDU header field auth_proto and the authentication verifier.

Depending on the result of the verification, the activity VERIFY_AUTH generates either the event AUTHENTICATED (success) or DENIED (authentication failure).

The algorithm applied to this activity is dependent on the security service in use (determined by RT_AUTH_SPEC). The general evaluation steps for authentication service rpc_c_authn_dce_secret are as follows (for more details see Security ):

• Check the protection level applied to the PDU (parameter in RT_AUTH_VERIFIER) against the protection level for the call (negotiated security context). If matching, proceed with verification, otherwise raise DENIED.

Note that bind and alter_context PDUs are used for negotiating the security context. Therefore, the protection level will not be verified for these PDUs; this verification takes only place for actual call PDUs.

• Decrypt the cyphertext portion of the verifier and verify PDUs integrity. If discrepancies are found, raise DENIED, otherwise raise AUTHENTICATED and proceed (if privacy protected).
• If privacy protection is requested, decrypt PDU body bgcolor="#FFFFFF" data.

Note:

The VERIFY_AUTH activity may be invoked simultaneously by several orthogonal states (WORKING, CONTROL and CANCEL). VERIFY_AUTH must not generate the event AUTHENTICATED unless the entire requested authentication processing is completed. If VERIFY_AUTH detects an authentication failure and generates the event DENIED, the protocol machine rejects the RPC call and no further processing is required.

CO_SERVER States

The CO_SERVER statechart defines the following states:

Chart:

CO_SERVER

State:

ASSOCIATION

Description:

Main state for active association.

Chart:

CO_SERVER

State:

ASSOC_OPEN

Description:

Association available for call.

Reactions
Trigger	Action
RCV_ALTER_CONTEXT	DO_ALTER_CONTEXT_RESP
RESOURCES_SCARCE	SND_REPLY_TYPE:=SHUTDOWN; st!(SEND_PKT)
DENIED[ALTER_CONTEXT_PDU]	SND_AUTH_VALUE_SUB_TYPE:= CONST_SUB_TYPE_INVALID_CHECKSUM; SND_REPLY_TYPE:=ALTER_CONTEXT_RESP; st!(SEND_PKT)

Chart:

CO_SERVER

State:

ASSOC_REQ

Description:

Wait for decision on whether to accept association.

Reactions
Trigger	Action
DENIED[BIND_PDU]	SND_REJECT_REASON:= CONST_REASON_INVALID_CHECKSUM SND_REPLY_TYPE:=BIND_NAK st!(SEND_PKT)
ACCEPT_BIND[not GROUP_EXISTS]	tr!(WAIT_FOR_GROUP)
entering	RT_GROUP_ID:=PDU_ASSOC_GROUP_ID
ASSOC_REJECT	SND_REJECT_REASON:=RT_REJECT_REASON SND_REPLY_TYPE:=BIND_NAK st!(SEND_PKT)

Chart:

CO_SERVER

State:

ASSOC_WAIT

Description:

Wait for all bind packets containing EPAC information.

Chart:

CO_SERVER

State:

AUTHENTICATION

Description:

Process authentication verification.

Activities Throughout:

VERIFY_AUTH

Chart:

CO_SERVER

State:

CALL

Description:

Processing a remote procedure call request.

Chart:

CO_SERVER

State:

CANCEL

Description:

Processing of client requests to terminate call in progress.

The reaction within this state senses the termination of the CANCEL_NOTIFY_APP activity as cancel acknowledgement from the server manager routine. The manager routine also sets the RETURN_PENDING_CANCEL flag appropriately.

Reactions
Trigger	Action
sp(CANCEL_NOTIFY_APP)	IF RETURN_PENDING_CANCEL THEN tr!(SND_PENDING_CANCEL) END IF

Chart:

CO_SERVER

State:

CAN_IDLE

Description:

Waits for cancel requests.

Reactions
Trigger	Action
exiting	IF AUTH THEN RT_AUTH_VERIFIER_CAN:=PDU_AUTH_VERIFIER; RT_AUTH_LENGTH_CAN:=PDU_AUTH_SPEC END IF

Chart:

CO_SERVER

State:

CLOSED

Description:

Association waiting to receive bind request.

Reactions
Trigger	Action
en(CLOSED)	fs!(WAIT_FOR_GROUP)
DENIED[BIND_PDU]	SND_REJECT_REASON:= CONST_REASON_INVALID_CHECKSUM; SND_REPLY_TYPE:=BIND_NAK; st!(SEND_PKT)

Chart:

CO_SERVER

State:

CNTL_IDLE

Description:

Waits for incoming control PDUs.

Reactions
Trigger	Action
en(CNTL_IDLE)	fs!(ORPHANED_PDU) fs!(LAST_IN_FRAG) fs!(BIND_PDU) fs!(ALTER_CONTEXT_PDU)
RECEIVE_PDU[PDU_TYPE=ORPHANED and VALID_PDU_HEADER]	tr!(ORPHANED_PDU)
exiting	IF AUTH THEN RT_AUTH_VERIFIER_CNTL:= PDU_AUTH_VERIFIER RT_AUTH_LENGTH_CNTL:= PDU_AUTH_SPEC END IF
RECEIVE_PDU[PDU_TYPE=BIND and VALID_PDU_HEADER and not LAST_IN_FRAG]	DO_CNTL_RESP RCV_CNTL_FRAG_PDU
RECEIVE_PDU[PDU_TYPE=BIND and VALID_PDU_HEADER and LAST_IN_FRAG]	tr!(BIND_PDU)
RECEIVE_PDU[PDU_TYPE= ALTER_CONTEXT and VALID_PDU_HEADER and not LAST_IN_FRAG]	DO_CNTL_RESP RCV_CNTL_FRAG_PDU
RECEIVE_PDU[PDU_TYPE= ALTER_CONTEXT and VALID_PDU_HEADER and LAST_IN_FRAG]	tr!(ALTER_CONTEXT_PDU)
RECEIVE_PDU[CNTL_PDU and not VALID_FRAG_SIZE]	RCV_FRAG_SIZE_TOO_LARGE
RECEIVE_PDU[CNTL_PDU and VALID_PDU_HEADER]	RCV_CNTL_PDU

Chart:

CO_SERVER

State:

CONTROL

Description:

Processing received control PDUs.

Chart:

CO_SERVER

State:

CO_SERVER

Description:

Main state for call and association; created by CONNECT_ESTABLISHED event.

The CO_SERVER state is created when a connection to a server is established, using the primary or secondary address for an association group.

Chart:

CO_SERVER

State:

DATA

Description:

Processing RPC call data.

Chart:

CO_SERVER

State:

FAULT

Description:

Handles processing faults and sends fault PDU.

Reactions
Trigger	Action
en(FAULT)	DEALLOC_REQ

Chart:

CO_SERVER

State:

INDICATION

Description:

Handles incoming RPC request fragments.

Reactions
Trigger	Action
en(INDICATION) [not LAST_IN_FRAG]	DO_IN_PKT; st!(HANDLE_IN_FRAG)
en(INDICATION) [LAST_IN_FRAG]	DO_IN_PKT; st!(HANDLE_IN_FRAG); RCV_LAST_IN_FRAG
RECEIVE_PDU[PDU_TYPE=REQUEST and not VALID_FRAG_SIZE]	RCV_FRAG_SIZE_TOO_LARGE
RECEIVE_PDU[PDU_TYPE=REQUEST and VALID_PDU_HEADER and not AUTH]	DO_REQ; RCV_FRAG_PDU
RECEIVE_PDU[PDU_TYPE=REQUEST and VALID_PDU_HEADER and AUTH]	DO_REQ; RCV_FRAG_PDU_A

Chart:

CO_SERVER

State:

INIT

Description:

Initial RPC call state. Waits for request from client.

Reactions
Trigger	Action
en(INIT)	fs!(MAYBE); fs!(LAST_IN_FRAG); SND_CANCEL_COUNT:=0; fs!(SND_PENDING_CANCEL)
RECEIVE_PDU[PDU_TYPE=REQUEST and not VALID_FRAG_SIZE]	RCV_FRAG_SIZE_TOO_LARGE
tm(en(INIT), TIMEOUT_SERVER_DISCONNECT)	SND_REPLY_TYPE:=SHUTDOWN; st!(SEND_PKT)
exiting	IF PDU_MAYBE THEN tr!(MAYBE) END IF
exiting	IF PDU_PENDING_CANCEL THEN tr!(SND_PENDING_CANCEL) END IF
exiting	SETUP_CALL

Chart:

CO_SERVER

State:

PROCESS_REQ

Description:

Promotes completely received request to manager routine

Reactions
Trigger	Action
entering	RT_OUT_PARAMS:=NULL

Chart:

CO_SERVER

State:

REPLIED

Description:

Terminal state for calls.

Reactions
Trigger	Action
en(REPLIED)	DEALLOC_REQ

Chart:

CO_SERVER

State:

REPLYING

Description:

Handles fragmented reply to client.

Reactions
Trigger	Action
en(REPLYING)	fs!(SND_FIRST_FRAG)

Chart:

CO_SERVER

State:

WORKING

Description:

Main working state for call instance.

CO_SERVER Events

The CO_SERVER statechart defines the following events:

Chart:

CO_SERVER

Event:

ABORT_ASSOC_REQ

Description:

Abrupt termination of the association requested. Generated externally.

Chart:

CO_SERVER

Event:

ABORT_CONNECTION

Description:

Signal transport to abort connection. Generated internally.

Chart:

CO_SERVER

Event:

ACCEPT_BIND

Description:

Generated by the ACCEPT_ASSOC_POLICY activity.

The local policy permits establishment of the requested association. The mechanism for deciding whether to accept or reject a bind request is implementation and policy-dependent.

Chart:

CO_SERVER

Event:

ADD_ALTER_CONTEXT

Description:

Update the set of presentation contexts for this association.

Select the set of matching presentations contexts based on the received presentation context list (p_context_elem field) of the alter_context PDU and the contexts supported by the server. Generate the structure p_result_list to be sent to the client in the alter_context_response PDU.

Chart:

CO_SERVER

Event:

ADD_PRES_CONTEXT

Description:

Update the presentation context set for this association.

Select the set of matching presentations contexts based on the received presentation context list (p_context_elem field) of the bind PDU and the contexts supported by the server. Generate the structure p_result_list to be sent to the client in the bind_ack PDU.

Chart:

CO_SERVER

Event:

ADD_TO_GROUP

Description:

Signal group to add this association.

To avoid race conditions, the ASSOCIATION must lock the group before issuing this event and unlock the group only after the event has been processed by the group machine instance.

Event is generated by CO_SERVER and sensed by CO_SERVER_GROUP.

Chart:

CO_SERVER

Event:

ASSOC_ACCEPT

Description:

The server accepted the association.

Definition:

ACCEPT_BIND[GROUP_EXISTS] or
[GROUP_EXISTS and WAIT_FOR_GROUP]

Chart:

CO_SERVER

Event:

ASSOC_REJECT

Description:

Generated by the ACCEPT_ASSOC_POLICY activity.

The local policy rejected the request for a new association. The mechanism for deciding whether to accept or reject a bind request is implementation and policy-dependent.

Chart:

CO_SERVER

Event:

AUTHENTICATED

Description:

Authentication processing completed successfully.

Chart:

CO_SERVER

Event:

CANCEL_CALL

Description:

Generate local cancel request for the call currently using the association.

Chart:

CO_SERVER

Event:

CLOSE

Description:

Compound events to terminate association.

Definition:

NO_CONNECTION or ABORT_ASSOC_REQ

Chart:

CO_SERVER

Event:

COMPLETE

Description:

RPC call completed (with success or fault).

Definition:

DEALLOC_REQ or DENIED[not ORPHANED_PDU] or
[AUTH and TICKET_EXP] or
RCV_FRAG_SIZE_TOO_LARGE

Chart:

CO_SERVER

Event:

CONNECT_ESTABLISHED

Description:

A connection to server has been established. Generated externally by transport.

The address used to establish the connection may be either the primary or, if one exists, secondary address for the server.

Chart:

CO_SERVER

Event:

DEALLOC_REQ

Description:

Call completed or failed. Service provider requests the deallocation of assoc.

Chart:

CO_SERVER

Event:

DENIED

Description:

Authentication failure detected.

The VERIFY_AUTH activity generates this event if either the integrity check failed or the requested protection level for authentication services does not match (not for bind or alter_context PDUs).

Chart:

CO_SERVER

Event:

LAST_OUT_PKT

Description:

Statechart internal event: last fragment of fragmented response.

Definition:

[TRANSMIT_RESP and LAST_OUT_FRAG]

Chart:

CO_SERVER

Event:

MARK_ASSOC

Description:

Mark association with termination status and related information.

Chart:

CO_SERVER

Event:

NEXT_OUT_PKT

Description:

Statechart internal event: intermediate fragment of fragmented response.

Definition:

[TRANSMIT_RESP and not LAST_OUT_FRAG]

Chart:

CO_SERVER

Event:

NO_CONNECTION

Description:

Notification that the underlying connection terminated. Generated externally.

Chart:

CO_SERVER

Event:

PROCESSING_FAULT

Description:

Execution of procedure failed. Returned from called procedure (stub).

Chart:

CO_SERVER

Event:

PROCESSING_FDNE

Description:

Stub (manager routine) or run-time system rejected RPC request.

The call did not execute.

Chart:

CO_SERVER

Event:

PROC_FAULT

Description:

Execution of call failed.

Definition:

PROCESSING_FAULT or PROCESSING_FDNE

Chart:

CO_SERVER

Event:

PROC_RESPONSE

Description:

Call returned from called procedure (server manager routine).

This event indicates that the called application procedure is ready to respond to the RPC request and has provided out parameter data in the RT_OUT_PARAMS queue. The processing of the application procedure may not have been completed and more out parameter data may to be queued (sensed by the TRANSMIT_RESP and LAST_OUT_FRAG condition flags).

Chart:

CO_SERVER

Event:

RCV_ALTER_CONTEXT

Description:

Received valid alter_context PDU. Generated in CNTL_CALL action.

Chart:

CO_SERVER

Event:

RCV_BIND

Description:

Received valid bind PDU on this association's transport connection.

Generated in CNTL_CALL action.

Chart:

CO_SERVER

Event:

RCV_CAN_PDU

Description:

Received cancel PDU with valid header.

Definition:

RECEIVE_PDU[PDU_TYPE=CANCEL and
VALID_PDU_HEADER and in(DATA) and not
in(REPLYING) and not in(REPLIED)]

Chart:

CO_SERVER

Event:

RCV_CNTL_FRAG_PDU

Description:

Receive incoming control PDU fragment.

Chart:

CO_SERVER

Event:

RCV_CNTL_PDU

Description:

Received one of the control PDUs with valid header.

Chart:

CO_SERVER

Event:

RCV_FRAG_PDU

Description:

Received PDU for non-authenticated fragmented requests with valid header.

Chart:

CO_SERVER

Event:

RCV_FRAG_PDU_A

Description:

Received PDU for authenticated fragmented request with valid header.

Chart:

CO_SERVER

Event:

RCV_FRAG_SIZE_TOO_LARGE

Description:

The received PDU exceeded the maximum allowed fragment size.

Chart:

CO_SERVER

Event:

RCV_LAST_IN_FRAG

Description:

Received last fragment request PDU. Signal completion to stub.

The last fragment of a multi-fragmented request or a single packet request was received. RCV_LAST_IN_FRAG signals that the complete request data is available to the stub for unmarshalling, and it transfers the control from the run-time system to the stub for processing the RPC request.

Chart:

CO_SERVER

Event:

RCV_REQ_PDU

Description:

Received request PDU (first packet for fragmented requests) with valid header.

Definition:

RECEIVE_PDU[PDU_TYPE=REQUEST and
in(ASSOC_OPEN) and PDU_FIRST_FRAG and
VALID_VERSION]

Chart:

CO_SERVER

Event:

RECEIVE_PDU

Description:

Received a PDU from client.

Chart:

CO_SERVER

Event:

REMOVE_FROM_GROUP

Description:

Signal association group to remove this association.

To avoid race conditions, the ASSOCIATION must lock the group before issuing this event and unlock the group only after the event has been processed by the group machine instance.

Event is generated by CO_SERVER and sensed by CO_SERVER_GROUP.

Chart:

CO_SERVER

Event:

RESOURCES_SCARCE

Description:

Request to reclaim resources. Externally generated.

Resource management is implementation-specific. This event is generated by the implementation resource management policy when it is necessary to reclaim idle associations. It is recommended that at least one idle association per client-server pair be maintained for better performance. This may be tuned for different style applications.

Chart:

CO_SERVER

Event:

SEND_RESPONSE

Description:

Called procedure provided out parameters to be sent.

Definition:

PROC_RESPONSE[not MAYBE]

CO_SERVER Actions

The CO_SERVER statechart defines the following actions:

Chart:

CO_SERVER

Action:

CLEAN_UP

Description:

Termination actions.

Definition:

MARK_ASSOC;
IF
in(ASSOC_OPEN)
THEN
REMOVE_FROM_GROUP;
CANCEL_CALL
END IF;
WHEN
ABORT_ASSOC_REQ
THEN
ABORT_CONNECTION
END WHEN

Chart:

CO_SERVER

Action:

CNTL_CALL

Description:

Reactions on received control PDUs. Generate respective RCV_* events.

Definition:

IF
ORPHANED_PDU
THEN
st!(STOP_ORPHAN);
DEALLOC_REQ
END IF;
IF
BIND_PDU
THEN
RCV_BIND
END IF;
IF
ALTER_CONTEXT_PDU
THEN
RCV_ALTER_CONTEXT
END IF

Chart:

CO_SERVER

Action:

DO_ALTER_CONTEXT_RESP

Description:

Process the alter context negotiation request and send response back.

Note that the activities ADD_ALTER_CONTEXT and SEND_PKT must be synchronised to assure that the alter_context_resp PDU contains the negotiated context.

Definition:

RT_CLIENT_PRES_CONTEXT_LIST:=PDU_P_CONT_LIST;
RT_IF_ID:=PDU_IF_ID;
RT_IF_VERSION:=PDU_IF_VERSION;
IF
PDU_AUTH_SPEC=0
THEN
fs!(AUTH)
ELSE
tr!(AUTH)
END IF
ADD_ALTER_CONTEXT;
SND_REPLY_TYPE:=ALTER_CONTEXT_RESP;
st!(SEND_PKT)

Chart:

CO_SERVER

Action:

DO_BIND_ACK

Description:

Signal CO_SERVER_GROUP to add group and send a bind_ack PDU.

Definition:

RT_IF_ID:=PDU_IF_ID;
RT_IF_VERSION:=PDU_IF_VERSION;
IF
PDU_AUTH_SPEC=0
THEN
fs!(AUTH)
ELSE
tr!(AUTH)
END IF
IF
PDU_MAX_XMIT_FRAG_SIZE>RT_MAX_RCV_FRAG_SIZE
or PDU_MAX_XMIT_FRAG_SIZE=0 and
RT_MAX_RCV_FRAG_SIZE<CONST_MUST_RCV_FRAG_SIZE
THEN
SND_MAX_RCV_FRAG_SIZE:=RT_MAX_RCV_FRAG_SIZE
ELSE
IF
PDU_MAX_XMIT_FRAG_SIZE=0
THEN
SND_MAX_RCV_FRAG_SIZE:=CONST_MUST_RCV_FRAG_SIZE
ELSE
SND_MAX_RCV_FRAG_SIZE:=PDU_MAX_XMIT_FRAG_SIZE
END IF
END IF;

IF
PDU_MAX_RCV_FRAG_SIZE>RT_MAX_XMIT_FRAG_SIZE
or PDU_MAX_RCV_FRAG_SIZE=0 and
RT_MAX_XMIT_FRAG_SIZE<CONST_MUST_RCV_FRAG_SIZE
THEN
SND_MAX_XMIT_FRAG_SIZE:=RT_MAX_XMIT_FRAG_SIZE
ELSE
IF
PDU_MAX_RCV_FRAG_SIZE=0
THEN
SND_MAX_XMIT_FRAG_SIZE:=CONST_MUST_RCV_FRAG_SIZE
ELSE
SND_MAX_XMIT_FRAG_SIZE:=PDU_MAX_RCV_FRAG_SIZE
END IF
END IF;
SND_GROUP_FIELD:=RT_GROUP_ID;
SND_SEC_ADDR:=RT_SECONDARY_ADDRESS;
RT_CLIENT_PRES_CONTEXT_LIST:=PDU_P_CONT_LIST;
ADD_TO_GROUP;
ADD_PRES_CONTEXT;
SND_REPLY_TYPE:=BIND_ACK;
st!(SEND_PKT)

Chart:

CO_SERVER

Action:

DO_CNTL_RESP

Description:

Append received header fragment to buffer. Check for last fragment flag.

Definition:

RT_HEADER:=RT_HEADER+PDU_HEADER;
IF
PDU_LAST_FRAG
THEN
tr!(LAST_IN_FRAG);
END IF;

Chart:

CO_SERVER

Action:

DO_IN_PDU_FRAG

Description:

Assemble incoming PDU header packets.

Chart:

CO_SERVER

Action:

DO_IN_PKT

Description:

Append received request PDU body bgcolor="#FFFFFF" data to internal buffer.

Definition:

RT_IN_PARAMS:=RT_IN_PARAMS+RT_BODY

Chart:

CO_SERVER

Action:

DO_REPLY

Description:

Send last out frag to requesting client.

Definition:

fs!(TRANSMIT_RESP);
IF
LAST_OUT_FRAG
THEN
tr!(SND_LAST_FRAG)
ELSE
fs!(SND_LAST_FRAG)
END IF;
SND_OUT_PARAMS:=RT_OUT_FRAG;
SND_REPLY_TYPE:=RESPONSE;
st!(SEND_PKT)

Chart:

CO_SERVER

Action:

DO_REQ

Description:

Evaluate request PDU header and signal allocation request.

Definition:

RT_PRES_CONTEXT_ID:=PDU_P_CONT_ID;
RT_BODY:=PDU_BODY;
IF
PDU_AUTH_SPEC/=0
THEN
RT_AUTH_VERIFIER_CALL:=PDU_AUTH_VERIFIER;
RT_AUTH_LENGTH_CALL:=PDU_AUTH_SPEC
END IF;
IF
PDU_LAST_FRAG
THEN
tr!(LAST_IN_FRAG)
END IF

Chart:

CO_SERVER

Action:

ERROR

Description:

Determine the type of failure.

Definition:

WHEN
PROCESSING_FDNE
THEN
tr!(SND_DID_NOT_EXECUTE)
ELSE
fs!(SND_DID_NOT_EXECUTE)
END WHEN;
FAULT_CALL

Chart:

CO_SERVER

Action:

FAULT_CALL

Description:

Send fault PDU.

Definition:

IF
not MAYBE
THEN
SND_REPLY_TYPE:=FAULT;
st!(SEND_PKT)
END IF;
IF
in(PROCESS_REQ) or in(REPLYING) or
in(REPLIED)
THEN
st!(ABORT_SEND)
ELSE
st!(ABORT_RECEIVE)
END IF

Chart:

CO_SERVER

Action:

FINAL

Description:

Perform final actions for RPC call.

Definition:

WHEN
DENIED[not BIND_PDU and not
ALTER_CONTEXT_PDU]
THEN
SND_OUT_PARAMS:=CONST_NCA_S_INVALID_CHKSUM;
FAULT_CALL;
DEALLOC_REQ
END WHEN;
WHEN
RCV_FRAG_SIZE_TOO_LARGE
THEN
SND_OUT_PARAMS:=CONST_NCA_S_PROTO_ERROR;
FAULT_CALL;
DEALLOC_REQ
END WHEN

Chart:

CO_SERVER

Action:

FIRST_REPLY

Description:

Initialise and send first response PDU.

Definition:

fs!(TRANSMIT_RESP);
IF
LAST_OUT_FRAG
THEN
tr!(SND_LAST_FRAG)
ELSE
fs!(SND_LAST_FRAG)
END IF;
tr!(SND_FIRST_FRAG);
SND_PRES_CONTEXT_ID:=RT_PRES_CONTEXT_ID;
SND_CALL_ID:=RT_CALL_ID;
RT_OUT_FRAG:=RT_OUT_PARAMS;
SND_OUT_PARAMS:=RT_OUT_PARAMS;
SND_REPLY_TYPE:=RESPONSE;
st!(SEND_PKT)

Chart:

CO_SERVER

Action:

PROCESS_CAN

Description:

Process cancel request (signal manager routine).

Definition:

SND_CANCEL_COUNT:=SND_CANCEL_COUNT+1;
st!(CANCEL_NOTIFY_APP)

Chart:

CO_SERVER

Action:

SETUP_CALL

Description:

Set up call data at first call's request PDU.

Definition:

RT_CALL_ID:=PDU_CALL_ID;
IF
PDU_OBJ_UUID
THEN
RT_OBJ_ID:=PDU_OBJ_ID
ELSE
RT_OBJ_ID:=NULL
ENDIF;
RT_OP_NUM:=PDU_OP_NUM

CO_SERVER Conditions

The CO_SERVER statechart defines the following conditions:

Chart:

CO_SERVER

Condition:

ALTER_CONTEXT_PDU

Description:

Statechart internal flag: received PDU type alter_context.

Chart:

CO_SERVER

Condition:

AUTH

Description:

Statechart internal flag: false if PDU field auth_length = 0; true otherwise.

Chart:

CO_SERVER

Condition:

BIND_PDU

Description:

Statechart internal flag: received PDU type bind.

Chart:

CO_SERVER

Condition:

CNTL_PDU

Description:

Statechart internal flag: to be received control PDUs.

Definition:

PDU_TYPE=ORPHANED or PDU_TYPE=BIND or
PDU_TYPE=ALTER_CONTEXT

Chart:

CO_SERVER

Condition:

GROUP_EXISTS

Description:

The group exists.

Definition:

in(CO_SERVER_GROUP:CO_SERVER_GROUP)

Chart:

CO_SERVER

Condition:

LAST_IN_FRAG

Description:

Statechart internal flag: last in fragment or non-frag in packet received.

Chart:

CO_SERVER

Condition:

LAST_OUT_FRAG

Description:

Statechart internal flag: last out fragment or non-frag out packet ready to send.

This flag is set by the run-time system if the transmit queue contains the last fragment (see also Connection-oriented Protocol ).

Chart:

CO_SERVER

Condition:

MAYBE

Description:

Statechart internal flag: maybe call.

Chart:

CO_SERVER

Condition:

ORPHANED_PDU

Description:

Statechart internal flag: received PDU type orphaned.

Chart:

CO_SERVER

Condition:

PDU_FIRST_FRAG

Description:

Header flag PFC_FIRST_FRAG.

Chart:

CO_SERVER

Condition:

PDU_LAST_FRAG

Description:

Header flag PFC_LAST_FRAG.

Chart:

CO_SERVER

Condition:

PDU_MAYBE

Description:

Header flag PFC_MAYBE.

Chart:

CO_SERVER

Condition:

PDU_OBJECT_UUID

Description:

Status if optional object field is present in received PDU (header flag PFC_OBJECT_UUID is set).

Chart:

CO_SERVER

Condition:

PDU_PENDING_CANCEL

Description:

Header flag PFC_PENDING_CANCEL in received request PDU.

Chart:

CO_SERVER

Condition:

PDU_VERSION_VALID

Description:

PDU contains valid most recent version.

Definition:

PDU_VERSION_NUMBER=CO_VERSION_NUM_V20
and PDU_VERSION_NUMBER_MINOR=1

Chart:

CO_SERVER

Condition:

RETURN_PENDING_CANCEL

Description:

Cancel pending state returned from stub after processing the cancel request.

Chart:

CO_SERVER

Condition:

SND_DID_NOT_EXECUTE

Description:

Statechart internal flag: send fault PDU with PFC_DID_NOT_EXECUTE header flag set.

Chart:

CO_SERVER

Condition:

SND_FIRST_FRAG

Description:

Statechart internal flag: send first out fragment.

Chart:

CO_SERVER

Condition:

SND_LAST_FRAG

Description:

Statechart internal flag: header flag PFC_LAST_FRAG for PDU to be sent.

Chart:

CO_SERVER

Condition:

SND_PENDING_CANCEL

Description:

Cancel pending state for current call at server.

The cancel pending state is set by the server manager routine via the CANCEL_NOTIFY_APP activity.

Chart:

CO_SERVER

Condition:

TICKET_EXP

Description:

Statechart internal flag: ticket expired.

Definition:

SYS_TIME>GRACE_PERIOD+PDU_EXP_TIME

Chart:

CO_SERVER

Condition:

TRANSMIT_RESP

Description:

One or more fragments queued for transmission of response data.

This flag indicates that one or more response fragment(s) are queued in a run-time internal buffer and ready to be transmitted.

The run-time system internally sets this flag (true) after the stub initially provides data in the transmit queue, sufficient for at least the first PDU fragment to be transmitted. The protocol machine resets this flag if it has detected and taken an event for sending the next fragment in the queue.

The run-time system sets this flag again after completion of a SEND_PKT if the transmit queue contains enough data for the next PDU fragment to be transmitted.

Chart:

CO_SERVER

Condition:

VALID_FRAG_SIZE

Description:

Evaluation whether received PDU exceeds size limit.

Definition:

not PDU_TYPE=BIND and
PDU_FRAG_LENGTH<=RT_MAX_RCV_FRAG_SIZE or
PDU_TYPE=BIND and
PDU_FRAG_LENGTH<=CONST_MUST_RCV_FRAG_SIZE

Chart:

CO_SERVER

Condition:

VALID_PDU_HEADER

Description:

Pre-evaluation of PDU header (before authentication processing).

Definition:

PDU_CALL_ID=RT_CALL_ID and VALID_VERSION
and VALID_FRAG_SIZE

Chart:

CO_SERVER

Condition:

VALID_VERSION

Description:

Evaluation of protocol version.

Definition:

PDU_VERSION_NUM=CO_VERSION_NUM_V20 and
PDU_VERSION_NUM_MINOR<=CO_VERSION_NUM_V20_MINOR

Chart:

CO_SERVER

Condition:

WAIT_FOR_GROUP

Description:

Association waits for group creation before opening.

CO_SERVER Data-Items

The CO_SERVER statechart defines the following data items:

Chart:

CO_SERVER

Data Item:

ALTER_CONTEXT

Description:

Constant: PDU type alter_context.

Definition:

14

Chart:

CO_SERVER

Data Item:

ALTER_CONTEXT_RESP

Description:

Constant: PDU type alter_context_resp.

Definition:

15

Chart:

CO_SERVER

Data Item:

BIND

Description:

Constant: PDU type bind.

Definition:

11

Chart:

CO_SERVER

Data Item:

BIND_ACK

Description:

Constant: PDU type bind_ack.

Definition:

12

Chart:

CO_SERVER

Data Item:

BIND_NAK

Description:

Constant: PDU type bind_nak.

Definition:

13

Chart:

CO_SERVER

Data Item:

CANCEL

Description:

Constant: PDU type cancel.

Definition:

18

Chart:

CO_SERVER

Data Item:

CONST_MUST_RCV_FRAG_SIZE

Description:

Constant: MustRecvFragSize value, indicating the lower bound of the fragment size.

Definition:

1432

Chart:

CO_SERVER

Data Item:

CONST_NCA_S_INVALID_CHKSUM

Description:

Constant: reject status code nca_s_invalid_chksum.

Chart:

CO_SERVER

Data Item:

CONST_NCA_S_PROTO_ERROR

Description:

Constant: reject status code nca_s_proto_error.

Chart:

CO_SERVER

Data Item:

CONST_REASON_INVALID_CHECKSUM

Description:

The value indicating a security integrity failure.

This value is the invalid_checksum member of the enumerated type p_reject_reason_t (see RPC PDU Encodings ). This is transmitted in the provider_reject_reason field of the bind_nak PDU.

Chart:

CO_SERVER

Data Item:

CONST_SUB_TYPE_INVALID_CHECKSUM

Description:

Value indicating a security integrity failure (invalid checksum).

The value dce_c_cn_dce_sub_type_invalid_checksum, which is encoded in the sub_type field of the auth_value member of the authentication verifier. (See Security .)

Definition:

2

Chart:

CO_SERVER

Data Item:

CO_VERSION_NUM_V20

Description:

Constant: RPC protocol version 2.0 major version number.

Definition:

5

Chart:

CO_SERVER

Data Item:

CO_VERSION_NUM_V20_MINOR

Description:

Constant: RPC protocol minor version number.

Chart:

CO_SERVER

Data Item:

FAULT

Description:

Constant: PDU type fault.

Definition:

3

Chart:

CO_SERVER

Data Item:

GRACE_PERIOD

Description:

Grace period on server after ticket expiration (implementation-specific).

Chart:

CO_SERVER

Data Item:

ORPHANED

Description:

Constant: PDU type orphaned.

Definition:

19

Chart:

CO_SERVER

Data Item:

PDU_ASSOC_GROUP_ID

Description:

The assoc_group_id field from the received bind PDU.

Chart:

CO_SERVER

Data Item:

PDU_AUTH_SPEC

Description:

PDU header field auth_length.

Chart:

CO_SERVER

Data Item:

PDU_AUTH_VERIFIER

Description:

PDU trailer: authentication verifier (authentication protocol-specific).

Chart:

CO_SERVER

Data Item:

PDU_BODY

Description:

Array of PDU body bgcolor="#FFFFFF" data.

Chart:

CO_SERVER

Data Item:

PDU_CALL_ID

Description:

PDU header field call_id.

Chart:

CO_SERVER

Data Item:

PDU_EXP_TIME

Description:

Ticket expiration time transmitted in the authentication verifier.

Chart:

CO_SERVER

Data Item:

PDU_FRAG_LENGTH

Description:

PDU header field frag_length.

Chart:

CO_SERVER

Data Item:

PDU_HEADER

Description:

Array of buffered PDU header data.

Chart:

CO_SERVER

Data Item:

PDU_IF_ID

Description:

PDU header field: interface identifier, encoded in the p_context_elem field of bind and alter_context PDUs.

Chart:

CO_SERVER

Data Item:

PDU_IF_VERSION

Description:

PDU header field: interface version, encoded in the p_context_elem field of bind and alter_context PDUs.

Chart:

CO_SERVER

Data Item:

PDU_MAX_RCV_FRAG_SIZE

Description:

PDU header field max_recv_frag.

Chart:

CO_SERVER

Data Item:

PDU_MAX_XMIT_FRAG_SIZE

Description:

PDU header field max_xmit_frag.

Chart:

CO_SERVER

Data Item:

PDU_OBJ_ID

Description:

PDU header field object.

Chart:

CO_SERVER

Data Item:

PDU_OP_NUM

Description:

PDU header field opnum.

Chart:

CO_SERVER

Data Item:

PDU_P_CONT_ID

Description:

PDU header field p_cont_id.

Chart:

CO_SERVER

Data Item:

PDU_P_CONT_LIST

Description:

PDU header field p_cont_elem in bind and alter_context PDUs.

Chart:

CO_SERVER

Data Item:

PDU_TYPE

Description:

PDU header field PTYPE.

Chart:

CO_SERVER

Data Item:

PDU_VERSION_NUM

Description:

PDU header field rpc_vers.

Chart:

CO_SERVER

Data Item:

PDU_VERSION_NUM_MINOR

Description:

PDU header field rpc_vers_minor.

Chart:

CO_SERVER

Data Item:

REQUEST

Description:

Constant: PDU type request.

Definition:

0

Chart:

CO_SERVER

Data Item:

RESPONSE

Description:

Constant: PDU type response.

Definition:

2

Chart:

CO_SERVER

Data Item:

RT_AUTH_LENGTH_CALL

Description:

Statechart internal: auth_length field received in CALL state.

Chart:

CO_SERVER

Data Item:

RT_AUTH_LENGTH_CAN

Description:

Statechart internal: auth_length field received in CANCEL state.

Chart:

CO_SERVER

Data Item:

RT_AUTH_LENGTH_CNTL

Description:

Statechart internal: auth_length field received in CONTROL state.

Chart:

CO_SERVER

Data Item:

RT_AUTH_VERIFIER_CALL

Description:

Received authentication trailer (verifier) for request PDU.

Chart:

CO_SERVER

Data Item:

RT_AUTH_VERIFIER_CAN

Description:

Received authentication trailer (verifier) for cancel PDU.

Chart:

CO_SERVER

Data Item:

RT_AUTH_VERIFIER_CNTL

Description:

Received authentication trailer (verifier) for control PDU.

Chart:

CO_SERVER

Data Item:

RT_BODY

Description:

Statechart internal: temporarily buffered request PDU body bgcolor="#FFFFFF" data.

Chart:

CO_SERVER

Data Item:

RT_CALL_ID

Description:

Statechart internal: call identifier of current RPC call.

Chart:

CO_SERVER

Data Item:

RT_CLIENT_PRES_CONTEXT_LIST

Description:

Statechart internal: presentation context as represented by the client.

Chart:

CO_SERVER

Data Item:

RT_GROUP_ID

Description:

The identifier of the association group of which this association is a member.

Chart:

CO_SERVER

Data Item:

RT_HEADER

Description:

Statechart internal: temporarily buffered PDU header data.

Chart:

CO_SERVER

Data Item:

RT_IF_ID

Description:

Statechart internal: received interface UUID.

Chart:

CO_SERVER

Data Item:

RT_IF_VERSION

Description:

Statechart internal: received interface version number.

Chart:

CO_SERVER

Data Item:

RT_IN_PARAMS

Description:

Statechart internal: buffered array of reassembled input data.

Chart:

CO_SERVER

Data Item:

RT_MAX_RCV_FRAG_SIZE

Description:

Maximum size of a fragment the receiver is able to handle.

The minimum value of this fragment size is determined by the architected value MustRcvFragSize (refer to RPC PDU Encodings ).

Implementations may support larger fragment sizes that are subject to negotiation with the client. This value is set internally by run-time implementations.

Chart:

CO_SERVER

Data Item:

RT_MAX_XMIT_FRAG_SIZE

Description:

Maximum size of a fragment the sender is able to handle.

The minimum value of this fragment size is determined by the architected value MustRcvFragSize (refer to RPC PDU Encodings ).

Implementations may support larger fragment sizes that are subject to negotiation with the client. This value is set internally by run-time implementations.

Chart:

CO_SERVER

Data Item:

RT_OBJ_ID

Description:

Statechart internal: buffered object UUID of RPC call.

Chart:

CO_SERVER

Data Item:

RT_OP_NUM

Description:

Statechart internal: buffered operation number of RPC call.

Chart:

CO_SERVER

Data Item:

RT_OUT_FRAG

Description:

Statechart internal pointer to data to be sent in next response PDU.

The SEND_PKT activity increments this pointer after a response PDU is sent.

Chart:

CO_SERVER

Data Item:

RT_OUT_PARAMS

Description:

Buffered array of unfragmented output data.

RT_OUT_PARAMS is the queue of transmit data provided by the stub. A possible segmentation of this queue is not equivalent to the sizes of PDU fragments sent by the run-time system (SEND_PKT) activity.

The RT_OUT_FRAG variable is a pointer data type that points to the to be transmitted data fragment within this RT_IN_PARAMS queue.

Chart:

CO_SERVER

Data Item:

RT_PRES_CONTEXT_ID

Description:

Statechart internal: presentation context identifier of current call.

Chart:

CO_SERVER

Data Item:

RT_REJECT_REASON

Description:

The reason the bind request was rejected.

The RPC run-time system sets this value according to the detected error (see also the p_reject_reason_t type definition in RPC PDU Encodings ).

Chart:

CO_SERVER

Data Item:

RT_SECONDARY_ADDRESS

Description:

Secondary address for this server.

Chart:

CO_SERVER

Data Item:

SHUTDOWN

Description:

Constant: PDU type shutdown.

Definition:

17

Chart:

CO_SERVER

Data Item:

SND_AUTH_VALUE_SUB_TYPE

Description:

The value of the sub_type field of the auth_value member of the authentication verifier sent in an alter_context_resp PDU. (See Security .)

Chart:

CO_SERVER

Data Item:

SND_CALL_ID

Description:

Call identifier to be sent.

Chart:

CO_SERVER

Data Item:

SND_CANCEL_COUNT

Description:

Counter of received cancel requests for current call.

Chart:

CO_SERVER

Data Item:

SND_GROUP_FIELD

Description:

The assoc_group_id field of a bind_ack PDU.

Chart:

CO_SERVER

Data Item:

SND_MAX_RCV_FRAG_SIZE

Description:

max_recv_frag header value to be sent.

Chart:

CO_SERVER

Data Item:

SND_MAX_XMIT_FRAG_SIZE

Description:

max_xmit_frag header field to be sent.

Chart:

CO_SERVER

Data Item:

SND_OUT_PARAMS

Description:

PDU body bgcolor="#FFFFFF" data promoted to SEND_PKT activity.

Chart:

CO_SERVER

Data Item:

SND_PRES_CONTEXT_ID

Description:

Presentation context identifier to be sent.

Chart:

CO_SERVER

Data Item:

SND_REJECT_REASON

Description:

The value sent for the reject reason in a bind_nak PDU.

Chart:

CO_SERVER

Data Item:

SND_REPLY_TYPE

Description:

PDU type to be sent.

Chart:

CO_SERVER

Data Item:

SND_SEC_ADDR

Description:

The sec_addr field of a bind_ack PDU to be sent.

Chart:

CO_SERVER

Data Item:

SYS_TIME

Description:

Secure reference time of local system.

Chart:

CO_SERVER

Data Item:

TIMEOUT_SERVER_DISCONNECT

Description:

Timeout value: DefaultServerDisconnectTimer.

CO_SERVER_GROUP Machine

CO_SERVER_GROUP Statechart shows the CO_SERVER_GROUP machine statechart. Figure: CO_SERVER_GROUP Statechart

CO_SERVER_GROUP States

The CO_SERVER_GROUP statechart defines the following states:

Chart:

CO_SERVER_GROUP

State:

CALL_WAIT

Description:

Wait for calls to complete before running down context handles.

Allows the server an opportunity to complete before attempting context rundown.

Reactions
Trigger	Action
exiting	IF ACTIVE_CONTEXT_COUNT>0 THEN RUNDOWN_CONTEXT_HANDLES END IF
CONTEXT_ACTIVE@T{ ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT+1
CONTEXT_INACTIVE	ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT-1

Chart:

CO_SERVER_GROUP

State:

CO_SERVER_GROUP

Description:

Main state for a server association group. Created by ACCEPT_BIND event.

Note that once the CO_SERVER_GROUP is terminated, the group ID associated with this group is no longer valid. Receipt of a PDU containing a PDU_ASSOC_GROUP_ID which does not match the group ID of any group is a client protocol error.

Chart:

CO_SERVER_GROUP

State:

GROUP_ACTIVE

Description:

Group contains associations not in CLOSED state.

Reactions
Trigger	Action
ADD_TO_GROUP	ASSOC_COUNT:=ASSOC_COUNT+1
REMOVE_FROM_GROUP[ASSOC_COUNT>1]	ASSOC_COUNT:=ASSOC_COUNT-1
CONTEXT_ACTIVE	ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT+1
CONTEXT_INACTIVE	ACTIVE_CONTEXT_COUNT:= ACTIVE_CONTEXT_COUNT-1

CO_SERVER_GROUP Events

The CO_SERVER_GROUP statechart defines the following events:

Chart:

CO_SERVER_GROUP

Event:

ACCEPT_BIND

Description:

Externally generated. Server accepts association. Same as in CO_SERVER.

Chart:

CO_SERVER_GROUP

Event:

ADD_TO_GROUP

Description:

Signal group to add this association.

To avoid race conditions, the ASSOCIATION must lock the group before issuing this event and unlock the group only after the event has been processed by the group machine instance.

Event is generated by CO_SERVER and sensed by CO_SERVER_GROUP.

Chart:

CO_SERVER_GROUP

Event:

CLOSE_GROUP

Description:

Close the group.

Definition:

NO_CALLS[in(CALL_WAIT)] or
REMOVE_FROM_GROUP[ACTIVE_CONTEXT_COUNT=0
and ASSOC_COUNT=1]

Chart:

CO_SERVER_GROUP

Event:

CONTEXT_ACTIVE

Description:

A context handle was activated. Generated by the server stub.

The stub must generate this event for each context handle which makes a transition from inactive to active. To avoid a race condition which could result from multiple simultaneous events, the stub must lock the group before generating the CONTEXT_ACTIVE event and release the lock only after the event has been processed by the group machine.

Chart:

CO_SERVER_GROUP

Event:

CONTEXT_INACTIVE

Description:

Context handle deactivated. Generated by the server stub.

The stub generates this event for each context handle which makes a transition from active to inactive. To avoid a race condition which could result from multiple simultaneous events, the stub must lock the group before generating the CONTEXT_INACTIVE event and release the lock only after the event has been processed by the group machine.

Chart:

CO_SERVER_GROUP

Event:

NO_CALLS

Description:

All calls using this association group have completed. Generated externally.

Chart:

CO_SERVER_GROUP

Event:

REMOVE_FROM_GROUP

Description:

Signal association group to remove this association.

To avoid race conditions, the ASSOCIATION must lock the group before issuing this event and unlock the group only after the event has been processed by the group machine instance.

Event is generated by CO_SERVER and sensed by CO_SERVER_GROUP.

Chart:

CO_SERVER_GROUP

Event:

RUNDOWN_CONTEXT_HANDLES

Description:

Signal stub to rundown all active context handles for this group.

The stub manages context handles and may associate them with rundown routines. An instance of the CO_SERVER_GROUP signals the stub to rundown any active context handles that were associated with this group.

CO_SERVER_GROUP Actions

The CO_SERVER_GROUP statechart defines the following actions:

Chart:

CO_SERVER_GROUP

Action:

INIT_GROUP

Description:

Initialise state for group and generate value for RT_GROUP_ID.

Definition:

ASSOC_COUNT:=0;
ACTIVE_CONTEXT_COUNT:=0

CO_SERVER_GROUP Data-Items

The CO_SERVER_GROUP statechart defines the following data items:

Chart:

CO_SERVER_GROUP

Data Item:

ACTIVE_CONTEXT_COUNT

Description:

Number of active context handles for this group. Internal variable.

Chart:

CO_SERVER_GROUP

Data Item:

ASSOC_COUNT

Description:

Number of associations in group. Internal variable.

Chart:

CO_SERVER_GROUP

Data Item:

PDU_ASSOC_GROUP_ID

Description:

The group id field from the received bind PDU.

Please note that the html version of this specification may contain formatting aberrations. The definitive version is available as an electronic publication on CD-ROM from The Open Group.