| 摘要 |
The invention concerns the upper layers of the OSI 7-layer system interconnection model, and specifically the upper 3 layers (session, presentation, and application). The three layer state tables of the standard system are merged (amalgamated) into a single state table. Merged component state tables 28' are looked up by the message PDU (protocol data unit) in register 11' and the merged state in register 26' and the entries (predicate, actions, and next state combinations) are processed by an entry logic unit 31', a predicate logic unit 32', and a variable list 33'. In merging the state tables, the data phase services of the session and presentation layers have to be merged. The presentation layer service P-ALTER-CONTEXT requires 4 states for each of the supporting session states. The number of states of the merged tables concerned with this is divided by 4 by using a new variable, p-state, which represents the 4 session layer states associated with P-ALTER-CONTEXT. A set of new predicates are used in the state table entries to detect a variety of possible combinations of states of this variable p-state.
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