TRANSACTION CAPABILITIES APPLICATION PART The transaction capabilities application part (TCAP) of signaling system , in conjunction with the signaling control connection part (SCCP) and the message transfer part (MTP) [l-3], enables application service elements (ASE) at two nodes (the TCAP term for signaling points) to conduct transact ions. | Signaling in Telecommunication Networks. John G. van Bosse Copyright 1998 John Wiley Sons Inc. ISBNs 0-471-57377-9 Hardback 0-471-22415-4 Electronic 15 TRANSACTION CAPABILITIES APPLICATION PART INTRODUCTION The transaction capabilities application part TCAP of signaling system in conjunction with the signaling control connection part SCCP and the message transfer part MTP 1-3 enables application service elements ASE at two nodes the TCAP term for signaling points to conduct transactions. TCAP is similar in many respects to the protocols defined by CCITT ITU-T for data communication networks which are documented in X-series recommendations. The first CCITT Recommendations on TCAP were published in 1989 4 and have been revised in 1993 by ITU-T 5-9 . The . version of TCAP has been specified by ANSI 10 . The work on this version started before the publication of the initial CCITT recommendations. As a consequence there are pronounced differences in terminology and some differences in coding between the two versions. Sections of this chapter follow the CCITT version. Section describes the main differences of the . version. Transactions and Remote Operations During a transaction one usually or more rarely remote operations are executed. The operation is requested by an ASE at one node and executed by an ASE at another node. Transaction ASEs are application-specific and involve peer ASEs dedicated to the same application at the two nodes. 417 418 TRANSACTION CAPABILITIES APPLICATION PART Some remote operations provide information to the requesting ASE. For example in the 800 number calling application an ASE at an exchange requests its peer to translate an 800 number into a routing number. Other remote operations provide instructions to the requesting ASE. In the chapters that follow we shall encounter operations of both types. Components and Messages Fig. shows the SS7 entities involved in a transaction between ASE-1 .
