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Recommendation Q.772
TRANSACTION CAPABILITIES INFORMATION ELEMENT DEFINITIONS
1 General
This Recommendation describes the individual information elements and
parameters used within Transaction Capabilities messages. The encoding and
formatting of these elements are shown in Recommendation Q.773.
The meaning of each information element is described in general terms.
For TC based upon a connectionless network service, the current TC is
equivalent to the Transaction Capabilities Application Part (TCAP).
The TCAP message format consists of two parts, namely the transaction
portion and the component portion. Information in the component portion concerns
individual operations and their replies. The transaction portion contains
protocol control information for the transaction sub-layer.
For a more detailed analysis of the architecture, see Figure 3/Q.771, and
associated text.
2 Transaction portion
The transaction portion of a TC message may contain the following
information elements, viz:
2.1 Message type
Five types of messages are defined for the transaction portion as follows:
2.1.1 Unidirectional
This message is used when there is no need to establish a transaction with
another peer TR-User.
2.1.2 Begin
This message is used to initiate a transaction with another peer TR-User.
2.1.3 End
This message is used to terminate a transaction with another peer TR-User.
2.1.4 Continue
This message is used to complete the establishment of a transaction and to
continue an established transaction.
2.1.5 Abort
This message is used to terminate a transaction following an abnormal
situation detected by the transaction sub-layer (the service provider), or to
abort a transaction by the TR-User (the service user).
2.2 Transaction IDs
Transaction IDs are independently assigned by each of the two nodes
communicating via a transaction, enabling each node to uniquely identify the
transaction and associate the entire contents of the message with that particular
transaction. There are two types of Transaction IDs, viz:
Fascicle VI.9 - Rec. Q.722 PAGE33
2.2.1 Originating Transaction ID
The Originating Transaction ID is assigned by the node sending a message,
and is used to identify the transaction at that end.
2.2.2 Destination Transaction ID
The Destination Transaction ID identifies the transaction at the receiving
end. The first Originating Transaction ID value received is reflected as the
Destination Transaction ID value.
2.3 P-Abort Cause
This is used when the transaction sub-layer aborts a transaction.
P-Abort cause definitions are as follows:
2.3.1 Unrecognized Message Type
The message type is not one of those defined in SS 2.1.1 to 2.1.5 above.
2.3.2 Unrecognized transaction ID
A transaction ID has been received for which a transaction does not exist
at the receiving node.
2.3.3 Badly formatted transaction portion
The transaction portion of the received message does not conform to the
X.209 encoding rules as outlined in Recommendation Q.773, S 3.
2.3.4 Incorrect transaction portion
The elemental structure within the transaction portion of the received
message, does not conform to the rules for the transaction portion defined in
Recommendation Q.773 S 5.
2.3.5 Resource limitation
Sufficient resources are not available.
2.4 User abort information
This is used to pass User Specified Information by the TR-User when it
aborts a transaction.
2.5 Component portion
This contains the component portion. When the component portion is empty
this information element is not present.
3 Component Portion
The Component Portion contains the following types of information
elements. They are delivered to the user at the receiving end in the same order
in which they were received from the user at the originating end.
PAGE34 Fascicle VI.9 - Rec. Q.772
3.1 Component type
There are five types of component that may be present in the Component
Portion of a TC message. The four Protocol Data Units (PDUs) defined
inRecommendation X.229 are used, viz:
TCAP component X.229 PDU
Invoke ROIV
Return result (last) RORS
Return error ROER
Reject RORJ
The remaining component type - Return Result (Not Last) - is defined by
TCAP.
These component types are defined as follows:
3.1.1 Invoke
The invoke component requests that an operation be performed. It may be
linked to another operation invocation previously sent by the other end.
3.1.2 Return result (Not Last)
When TC uses a connectionless Network Service, it may be necessary for the
TC-User to segment the result of an operation. In this case this component is
used to convey each segment of the result except the last, which is conveyed in a
Return Result (Last) component.
3.1.3 Return result (Last)
The Return Result (Last) component reports successful completion of an
operation. It may contain the last/only segment of a result.
3.1.4 Return error
The Return Error component reports that an operation has not been
successfully completed.
3.1.5 Reject
The Reject component reports the receipt and rejection of an incorrect
component, other than a Reject component. The possible causes for rejecting a
component are defined by the Problem Code element in S 3.8.
3.2 Invoke ID
An Invoke ID is used as a reference number to identify uniquely a request
for an operation. It is present in any reply to an Invoke component (Return
Result, Return Error or Reject), enabling the reply to be correlated with the
invoke.
3.3 Linked ID
A Linked ID is included in an invoke component by a node when it responds
to an operation invocation with a linked operation invocation. The node receiving
the Linked ID uses it for correlation purposes, in the same way that it uses the
invoke ID in Return Result, Return Error and Reject components.
3.4 Operation code
The Operation Code element indicates the precise operation to be invoked,
and is present in an invoke component type. The operation may be a local
operation or a global operation. A local operation can be used in one ASE only.
The same global operation can be used in several different ASEs.
Fascicle VI.9 - Rec. Q.722 PAGE33
The actual operation codes, the definition of the operations and their
associated parameters, are defined in relevant ASE specifications. The component
sub-layer does not set or examine the operation code value, nor which parameters
are present, nor the parameter values.
3.5 Set (of parameters)
The Set element is used to contain a set of parameters accompanying a
component. It is required in the case of more than one parameter being included
in a component. The parameters themselves are defined in relevant ASE
specifications.
3.6 Sequence (of parameters)
The Sequence element is used similarly to the Set element, except that a
specific sequence of parameters is included in the component.
3.7 Error code
The Error Code element contains the reason why an operation cannot be
completed successfully. It is present only in a Return Error component. As with
operations, errors may be local or global.
These errors and associated parameters are defined in relevant ASE
specifications.
3.8 Problem code
The Problem code element contains the reason for the rejection of a
component, and one such element is present in a Reject component. Four problem
code elements are defined, viz:
3.8.1 General problem
This element contains one of the problem codes which apply to the
component sub-layer in general, and which do not relate to any specific component
type. All of these are generated by the component sub-layer. They are:
3.8.1.1 Unrecognized component
The component type is not recognized as being one of those defined in S
3.1.
3.8.1.2 Mistyped component
The elemental structure of a component does not conform to the structure
of that component as defined in Recommendation Q.773 S 6.
3.8.1.3 Badly structured component
The contents of the component do not conform to the encoding rules defined
in Recommendation Q.773 S 3.
3.8.2 Invoke problem
This element contains one of the problem codes which relate only to the
invoke component type. They are:
3.8.2.1 Duplicate invoke ID
The invoke ID is already in use by a previously invoked operation. This
code is generated by the TC-User.
3.8.2.2 Unrecognized operation
The operation code value is not one of those used by the ASE. This code is
generated only by the TC-User.
3.8.2.3 Mistyped parameter
A parameter tag is not one of those associated with the operation invoked.
This code is generated only by the TC-User.
PAGE34 Fascicle VI.9 - Rec. Q.772
3.8.2.4 Resource limitation
Sufficient resources are not available to perform the operation requested.
This code is generated by the TC-User.
3.8.2.5 Initiating release
The operation requested cannot be invoked as the dialogue is about to be
released. This code is generated only by the TC-User.
3.8.2.6 Unrecognized linked ID
The linked ID does not correspond to a previously invoked operation. This
code is generated only by the component sub-layer.
3.8.2.7 Linked response unexpected
The operation referred to by the linked ID is not an operation for which
linked invokes are allowed. This code is generated only by the TC-User.
3.8.2.8 Unexpected linked operation
The linked operation is not one of those that the operation referred to by
the linked ID allows. This code is generated only by the TC-User.
3.8.3 Return result problem
This element contains one of the problem codes which relate only to the
return result component type. They are:
3.8.3.1 Unrecognized invoke ID
No operation with the specified invoke ID is in progress. This code is
generated by the component sub-layer.
3.8.3.2 Return result unexpected
The invoked operation does not report success. This code is generated by
the component sub-layer.
3.8.3.3 Mistyped parameter
A parameter tag is not one of those associated with the outcome of the
operation. This code is generated only by the TC-User.
3.8.4 Return error problem
This element contains one of the problem codes which relate only to the
return error component type. They are:
3.8.4.1 Unrecognized invoke ID
No operation with the specified invoke ID is in progress. This code is
generated by the component sub-layer.
3.8.4.2 Return error unexpected
The invoked operation does not report failure. This code is generated by
the component sub-layer.
3.8.4.3 Unrecognized error
The reported error is not one of those defined for the ASE. This code is
generated by the TC-User.
3.8.4.4 Unexpected error
The received error is not one of those which the invoked operation may
report. This code is generated by the TC-User.
3.8.4.5 Mistyped parameter
A parameter tag is not one of those associated with the outcome of the
operation. This code is generated only by the TC-User.
Fascicle VI.9 - Rec. Q.722 PAGE33