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connection.md

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Handling connections in cxxtools {#connection}

There are several classes, which implements higher level protocols on top of TCP/IP. They are:

  • cxxtools::http::Client
  • cxxtools::xmlrpc::HttpClient
  • cxxtools::json::RpcClient
  • cxxtools::json::HttpClient
  • cxxtools::bin::RpcClient

All classes handle the connection to the server the same way.

To connect to a server all need at least a IP address and a port. The classes all can be either default constructed or initialized with the constructor. When default constructed the user have to call the connect method before they are usable. For each connect variant there is a constructor, which calls connect on initialization.

By default the connect method do not actually do a network connection. Hence the method never fails (except on memory overflow). The method just stores the connection parameters for later use.

When a actual request is to be done, the class checks, whether it has already a network connection. When not, it connects to the remote site before sending the actual request. If the connection fails, the request throws an exception.

The connection is kept open until the class is destroyed or the connect method is called to change the connection parameters.

If it has already a connection, it just uses it. If the request fails, it tries to reconnect once.

All connect methods have a additional parameter of type bool named realConnect. It defaults to false but when explicitly set to true, the connect method already connects to the server. If the connection fails, a exception is thrown. That is a good way to check, if the server is available.

Note that the new connection parameters are still stored so to make the client usable you have to either change the connection parameters by calling the connect method or just fix the problem by e.g. starting the server.