Installing Event Handlers

This example shows the gateway application installing an SRV_START event. An SRV_START event occurs once (when srv_run is called) and starts the Open Data Services server application. The SRV_START event invokes the init_server callback function defined in GATECBS.C to initialize the remote server. The init_server function installs the remaining events required to run the gateway application.

1. Add a prototype for the init_server function in the gateway callback program, GATECBS.C:

   int init_server (SRV_SERVER * server);
   

2. Install an SRV_START event using srv_handle to call the init_server function when an Open Data Services server application is first started:

   srv_handle (server, (DBINT)SRV_START, init_server);
   

   • The init_server function installs an SRV_CONNECT event for connecting to the remote server in the init_remote function:

     srv_handle (server, (DBINT)SRV_CONNECT, init_remote);
     

   • The init_server function installs an SRV_LANGUAGE event for sending SQL statements to the remote server in the lang_execute function:

     srv_handle (server, (DBINT)SRV_LANGUAGE, lang_execute);
     

   • The init_server function installs an SRV_RPC event for sending SQL statements to the remote server in the rpc_execute function:

     srv_handle (server, (DBINT)SRV_RPC , rpc_execute);
     

   • The init_server function installs an SRV_DISCONNECT event to close the connection to the remote database in the exit_remote function:

     srv_handle (server, (DBINT)SRV_DISCONNECT, exit_remote);
     

   • The init_server function installs an SRV_ATTENTION event to process a dbcancel function call from a client in the attn_handler function:

     srv_handle (server, (DBINT)SRV_ATTENTION, attn_handler);
     

3. Return the srv_continue constant to the Open Data Services server application to continue processing events:

   return (SRV_CONTINUE);