18.1.1 Types of transaction

The server is normally a passive object, which waits for a client object to tell it what to do. The client can communicate with the server in four ways:

• The client can issue a request transaction to the server. This means the client is asking for some information about the server application.
• The client can issue a poke transaction . This means the client is passing data to be stored by the server application.
• The client can issue an execute transaction . This means the client is asking the server to get the server application to run a command.
• The client can ask the service to set up an advise loop , or to close an existing advise loop. An advise loop causes the server to communicate with the client whenever a specified change occurs in the server application.