3.2.5 Server Details

This section gives details specific to an implementation of a server. The state machine shown in the following figure specifies the states and the transitions between them for the server. Which event causes which transition is specified in sections 3.2.5.4 and 3.2.5.5.

Figure 29: Server state machine

The server state machine is used when the server is processing messages and PDUs coming from the network. The following description of the state machine is provided as an aid to understanding the overall work of the state machines. This description is not a substitute for the processing specifications in section 3.2.5.5.

The connection open state machine is used during connection opening. Once a transition to the opened state of that state machine is made, the IN channel and OUT channel state machines are started from the opened state. The IN channel and OUT channel have independent state machines that run in parallel.

When a new TCP connection to the server is established, the server implementation does not yet know whether this connection will be used to establish a new virtual connection or to recycle an IN channel or an OUT channel. This is why, at this stage, the state machine is in Open_Start state. Once an RTS PDU is received, an implementation of this protocol can inspect the RTS PDU and determine which state machine it will use.