Transaction Capabilities Application Part
Encyclopedia
Transaction Capabilities Application Part, from ITU-T
recommendations Q.771-Q.775 or ANSI
T1.114 is a protocol for Signalling System 7
networks. Its primary purpose is to facilitate multiple concurrent dialogs between the same sub-systems on the same machines, using Transaction IDs to differentiate these, similar to the way TCP
ports facilitate multiplexing connections between the same IP address
es on the Internet
.
TCAP is used to transport INAP
in Intelligent Network
s and MAP
in mobile phone networks.
TCAP messages are sent over the wire between machines. TCAP primitives are sent between the application and the local TCAP stack, all TCAP messages are primitives but there are primitives that are not messages, i.e. some are only transferred inside the local machine. A TCAP primitive is made up of one or more TCAP components.
An ITU-T TCAP primitive may be one of the following types:
A Begin primitive has an Originating Transaction ID (up to 4 bytes). Continues have an Originating Transaction ID and a Destination Transaction ID. Ends and Aborts only have a Destination Transaction ID. Each primitive has both an optional component and (required) dialogue portions. The component portion for the unidirectional primitive is mandatory.
The dialogue portion carries dialogue or unidialogue control PDUs. For MAP and INAP, dialogue PDU is used which performs establishment and release of dialogues for the application context provided in the primitives. Following primitives are defined for the dialogue PDU:
Each ITU-T TCAP component may be one of the following types:
Invoke components have a signed 7 bit InvokeID which is present in all the other components to identify which invoke they relate to.
TCAP is based on the OSI defined ROSE
, Remote Operations Services Element protocol.
As the TCAP dialog goes on each Continue message includes the Transaction ID of the destination machine as the Destination Transaction ID and the Transaction ID of the originating machine as the Originating Transaction ID. When any of the machines wants to close the dialog it sends an End message or an Abort message to the other machine. This message contains the Destination Transaction ID only.
62 74 48 04 00 02 00 30 6B 1A 28 18 06 07 00 11 86 05 01 01 01 A0 0D 60 0B A1 09 06 07 04 00 00
01 00 19 02 6C 50 A1 4E 02 01 01 02 01 2E 30 46 80 05 70 31 42 44 44 84 06 A1 70 91 92 55 55 04
35 2F 09 00 70 97 92 62 23 04 00 90 20 11 80 01 24 00 27 43 50 7A 0E A2 A3 CB 20 71 79 4E 07 B1
C3 EE 73 3D 7C 2E 83 D2 20 74 D8 5E 06 95 ED 65 39 68 5E 2E BB 01 00
According to tag length values, this can be decoded as below.
|
'--> 62|74 <- Start of Tcap begin message
|
'--> 48|04:00 02 00 30 <- Transaction ID
|
'--> 6B|1A <- Start of Dialog portion
|
'--> 28|18
|
'--> 06|07:00 11 86 05 01 01 01
|
'--> A0|0D
|
'--> 60|0B
|
'--> A1|09
|
'--> 06|07:04 00 00 01 00 19 02 <- Application context
|
'--> 6C|50 <- Start of component portion
|
'--> A1|4E
|
'--> 02|01:01 <- Component Id (invoke id)
|
'--> 02|01:2E <- Operation Code
|
'--> 30|46 <- Start of parameter buffer
|
'--> 80|05:70 31 42 44 44 <- SM-RP-DA(BCD)
|
'--> 84|06:A1 70 91 92 55 55 <- SM-RP-OA(BCD)
|
'--> 04|35:2F 09 00 70 97 92 62 23 04 00 90 20 11 80 01 24 00 27 43 50 7A 0E A2 A3 CB 20 71 79 4E 07 B1 C3 EE 73 3D 7C 2E 83 D2 20 74 D8 5E 06 95 ED 65 39 68 5E 2E BB 01 <- SM-RP-UI
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
recommendations Q.771-Q.775 or ANSI
Ansi
Ansi is a village in Kaarma Parish, Saare County, on the island of Saaremaa, Estonia....
T1.114 is a protocol for Signalling System 7
Signalling System 7
Signalling System No. 7 is a set of telephony signaling protocols which are used to set up most of the world's public switched telephone network telephone calls. The main purpose is to set up and tear down telephone calls...
networks. Its primary purpose is to facilitate multiple concurrent dialogs between the same sub-systems on the same machines, using Transaction IDs to differentiate these, similar to the way TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
ports facilitate multiplexing connections between the same IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es on the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
.
TCAP is used to transport INAP
INAP
The Intelligent Network Application Part is a signalling protocol used in the intelligent network architecture. It is part of the SS7 protocol suite, typically layered on top of TCAP.It can also be termed as logic for controlling telecommunication services migrated from traditional switching...
in Intelligent Network
Intelligent network
The Intelligent Network , is the standard network architecture specified in the . It is intended for fixed as well as mobile telecom networks...
s and MAP
Mobile Application Part
The Mobile Application Part is an SS7 protocol which provides an application layer for the various nodes in GSM and UMTS mobile core networks and GPRS core networks to communicate with each other in order to provide services to mobile phone users...
in mobile phone networks.
TCAP messages are sent over the wire between machines. TCAP primitives are sent between the application and the local TCAP stack, all TCAP messages are primitives but there are primitives that are not messages, i.e. some are only transferred inside the local machine. A TCAP primitive is made up of one or more TCAP components.
An ITU-T TCAP primitive may be one of the following types:
| Unidirectional | A single primitive with no subsequent primitives. Sometimes referred to as a Notice. |
| Begin | Start a dialog, further primitives will follow. |
| Continue | Send a subsequent primitive on an existing dialog, further primitives will follow. |
| End | The last primitive on an existing dialog, Close an existing dialog. |
| Abort | An error has caused the dialog to close. |
| Cancel | The invoke timer has expired without a response being received (this is a primitive but not a message) |
A Begin primitive has an Originating Transaction ID (up to 4 bytes). Continues have an Originating Transaction ID and a Destination Transaction ID. Ends and Aborts only have a Destination Transaction ID. Each primitive has both an optional component and (required) dialogue portions. The component portion for the unidirectional primitive is mandatory.
The dialogue portion carries dialogue or unidialogue control PDUs. For MAP and INAP, dialogue PDU is used which performs establishment and release of dialogues for the application context provided in the primitives. Following primitives are defined for the dialogue PDU:
| AARQ | Dialogue request. For MAP and INAP, AARQ is sent in the Begin primitive with the Invoke component in general, with the application context of MAP/INAP operation's package. |
| AARE | Dialogue response. Sent in response to AARQ in either Continue or End primitives. |
| ABRT | Dialogue abort. |
Each ITU-T TCAP component may be one of the following types:
| Invoke | A new operation is being requested, this may or may not solicit a response |
| Return Result Last | A final response to an Invoke |
| Return Result Not Last | A response to an Invoke, further responses will be sent |
| Return Error | An error occurred |
| Reject | Component is rejected for some reason like duplicate invocation, unrecognized linked id, unrecognized operation or mistyped argument |
Invoke components have a signed 7 bit InvokeID which is present in all the other components to identify which invoke they relate to.
TCAP is based on the OSI defined ROSE
Remote operations service element protocol
The Remote Operations Service Element is the OSI service interface, specified in , that provides remote operation capabilities, allows interaction between entities in a distributed application, and upon receiving a remote operations service request, allows the receiving entity to attempt the...
, Remote Operations Services Element protocol.
Transaction ID
The transaction ID is a TCAP reference for a set of TCAP operations that are performed within a single dialog. When machine A starts a TCAP dialog with another machine B, the machine A sends a Begin message to machine B. This Begin message contains an Originating Transaction ID, which is the Transaction ID reference for A. When the machine B replies to A with a Continue message it includes A's Transaction ID as the Destination Transaction ID. Furthermore B includes its own Transaction ID as the Originating Transaction ID.As the TCAP dialog goes on each Continue message includes the Transaction ID of the destination machine as the Destination Transaction ID and the Transaction ID of the originating machine as the Originating Transaction ID. When any of the machines wants to close the dialog it sends an End message or an Abort message to the other machine. This message contains the Destination Transaction ID only.
Decoded TCAP Message
This is a MO-SMS sent by a MAP layer and the hex stream is taken from TCAP layer.62 74 48 04 00 02 00 30 6B 1A 28 18 06 07 00 11 86 05 01 01 01 A0 0D 60 0B A1 09 06 07 04 00 00
01 00 19 02 6C 50 A1 4E 02 01 01 02 01 2E 30 46 80 05 70 31 42 44 44 84 06 A1 70 91 92 55 55 04
35 2F 09 00 70 97 92 62 23 04 00 90 20 11 80 01 24 00 27 43 50 7A 0E A2 A3 CB 20 71 79 4E 07 B1
C3 EE 73 3D 7C 2E 83 D2 20 74 D8 5E 06 95 ED 65 39 68 5E 2E BB 01 00
According to tag length values, this can be decoded as below.
|
'--> 62|74 <- Start of Tcap begin message
|
'--> 48|04:00 02 00 30 <- Transaction ID
|
'--> 6B|1A <- Start of Dialog portion
|
'--> 28|18
|
'--> 06|07:00 11 86 05 01 01 01
|
'--> A0|0D
|
'--> 60|0B
|
'--> A1|09
|
'--> 06|07:04 00 00 01 00 19 02 <- Application context
|
'--> 6C|50 <- Start of component portion
|
'--> A1|4E
|
'--> 02|01:01 <- Component Id (invoke id)
|
'--> 02|01:2E <- Operation Code
|
'--> 30|46 <- Start of parameter buffer
|
'--> 80|05:70 31 42 44 44 <- SM-RP-DA(BCD)
|
'--> 84|06:A1 70 91 92 55 55 <- SM-RP-OA(BCD)
|
'--> 04|35:2F 09 00 70 97 92 62 23 04 00 90 20 11 80 01 24 00 27 43 50 7A 0E A2 A3 CB 20 71 79 4E 07 B1 C3 EE 73 3D 7C 2E 83 D2 20 74 D8 5E 06 95 ED 65 39 68 5E 2E BB 01 <- SM-RP-UI
External links
- ITU-T Recommendation Q.773: Transaction capabilities formats and encoding
- TCAP ASN1 specification