[JAVA] I examined the flow of TCP communication with Spring Integration (server edition)

Continuing from the last time, in order to organize the flow of TCP communication with Spring Integration, I drew a sequence diagram on the client side, although it is complicated.

Last time: I checked the flow of TCP communication with Spring Integration (client edition)

Pre-stage

It is assumed that ʻautoStartUp is enabled, that is, ʻInbound Gateway and ConnectionFactory are started when the application is started. That made the starting point strange: confounded :.

1. ʻInbound Gateway calls the method that sets ConnectionFactory`.
2. ConnectionFactory registers ʻInbound Gateway in Sender, Listener as a sender / receiver (ʻInbound Gateway implements TcpSender, TcpListener).
3. Set the life cycle of ConnectionFactory to start.

TCP connection (preparation for reception from client)

1. Ask ServerSocketFactory to generate ServerSocket based on the specified port number.
2. Hold the received ServerSocket and make Socket wait for the connection to be accepted.
3. Issue TcpConnectionServerListeningEvent.
4. Build a TcpConnection based on the Socket.
5. TcpConnection registers ʻInbound Gateway as a sender / receiver via ConnectionFactory`.
6. ʻInbound Gateway holds TcpConnection`,
7. Issue TcpConnectionOpenEvent.

TCP connection (reply to client)

1. Receive a message from the client.
2. Pass messages and channels to MessagingTemplate, which is a template for telegram conversion and business processing.
3. Return the processing result to ʻInbound Gateway`.
4. Pass the message to reply to TcpConnection.
5. Pass the message to MessageMapper.
6. MessageMapper extracts and returns the message payload.
7. TcpConnection serializes the payload and returns it to the client.

Remarks: Although omitted in the figure, there are Channel and various endpoints between MessagingTemplate and ʻInbound Gateway`.

TCP connection (disconnect)

1. Issue a ConnectionExceptionEvent if any exception occurs while the TCP connection is being established.
2. Close Socket.
3. TcpConnection asks ʻInbound Gateway` to remove the connection to disconnect from the list.
4. Issue ConnectionCloseEvent.
5. Ask the Processor, which manages the LifeCycle, to stop at the ʻInbound Gateway`.
6. ʻInbound Gateway asks ConnectionFactory` to stop.
7. ConnectionFactory closes ServerSocket.
8. Close any TCP connections that still remain.
9. TcpConnection asks ʻInbound Gateway` to remove the connection to disconnect from the list. Also, if there are any remaining tasks, delete them as well.

Remarks: I mentioned that when some exception occurred in 1, but it refers to the case where Socket is closed. For more information [TcpNetConneciton # run](https://github.com/spring-projects/spring-integration/blob/master/spring-integration-ip/src/main/java/org/springframework/integration/ip/ See tcp / connection / TcpNetConnection.java # L169).

The service used to create the diagram

The figure above was created using a service called WebSequenceDiagrams, continuing from the previous time.