Comparison of TSS application layer protocols: TCAP (Q.771-775) and ROSE (X.219/X.229)

Two ITU-TSS (formerly CCITT) Recommendations Q.771-775 and X.219, define the communication between two application processes. The Recommendations Q.771-775 referred to as the Transaction Capabilities Application Part (TCAP), define the highest generic layer protocol of the signalling system number 7 (SS7) protocol for transaction processing. The X.219 defines the application layer protocol for Remote Operations in the OSI model. We will review the major issues in the two Recommendations and discuss the key differences between the two protocols. The major differences include the connectionless structure of Q.771-775 where the establishment of a pseudo association is provided by the transaction sublayer. We will discuss both the advantages of TCAP due to its connectionless structure, and its disadvantages in case of abnormal situations such as message loss, missequencing and corruption. Remote Operations on the other hand can handle these abnormal situations, but is not efficient for handling a large amount of transactions with potentially large number of nodes in a network. Also, we will address the differences between ANSI and TSS TCAP which encompass the variations in the transaction sublayer, the component sublayer and the encoding of messages.<
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