Data Encoding for SDL in ITU-T Rec. Z.104

摘要

When SDL is used for the implementation, different parts of the system may be implemented by different tools. Data communicated between different parts needs to be encoded and decoded in the same way by each part if the information encoded by one part is to be seen as the same value by another part. The ITU-T Recommendation Z.104 'Encoding of SDL Data' that is currently being refined for approval, allows the data encoding to be specified for communication paths or for specific encoding and decoding expressions. This paper presents the Recommendation in a less formal way than the ITU-T document. The presentation adds examples illustrating uses. The use of the ASN.1 encoding and text encoding is shown. One principle of Z.104 is to introduce an implicit data type that represents all the signals that can be received on a path. The paper further extends SDL to introduce ways to use implicit data types associated with interfaces.