The Design And Implementation Of Encoder/Decoder In TTCN-3 Testing Platform

TTCN (Tree and Tabular Combined Notation) used for protocol conformance testing was constituted by ETSI, ITU-T, ISO in 1990's.Now,TTCN-3—version 3 of TTCN is published,which is a newly testing description language. TTCN-3 is not restricted to conformance testing,and the range of application is wider. By using TTCN-3 compiling system, the abstract testing suite is compiled into executable one, which can be carried out at the platform of TTCN-3. The architecture of TTCN-3 testing platform has great differences with the existing consistency testing platform. However, it is a blank work about compiling system and testing platform of TTCN-3 in our country.TTCN-3 testing platform is composed of multiple distributed subsystems.Encoder and decoder are used for communicating with System Under Test(SUT).By way of communicating with SUT,we must use a standard syntax format independenting of network. ASN.1 is established by ITU-T,according with this condition.The idea of designing encoder/decoder in the TTCN-3 testing platform is recommended firstly. Based on fully analyzing ASN.1 encoding rules, arithmetics of encoding/decoding for TTCN-3 basic types and structured types are designed.Finally,four encoder/decoders are implemented in WindowsXP/VC6.0, and the four methods are compared.