Example: Client-Library initialization and cleanup

The following code fragment, taken from the ctfirst.c migration example program, illustrates Client-Library initialization and cleanup.

The fragment installs error handlers for CS-Library and Client-Library, as well as a Client-Library server message callback. For examples of a Client-Library error handler and a server message handler, see the “Callbacks” topics page in the Open Client Client-Library/C Reference Manual. For an example CS-Library error handler, see the Open Client/Server Common Libraries Reference Manual.

#define NORMAL_EXIT (0)
#define ERROR_EXIT (-1)

CS_CONTEXT    *context = (CS_CONTEXT *) NULL;
CS_CONNECTION *conn;
CS_RETCODE    ret;

/*
** Step 1.
** Allocate a CS_CONTEXT structure and initialize Client-Libary. -- if (dbinit() == FAIL)
--   exit(ERREXIT);
*/

ret = cs_ctx_alloc(CS_VERSION_125, &context);
EXIT_ON_FAIL(context, ret, "Could not allocate context.");

ret = ct_init(context, CS_VERSION_125);
EXIT_ON_FAIL(context, ret, 
            "Client-Library initialization failed.");

/* 
** Step 2.
** Install callback handlers for CS-Library errors, Client-
** Library errors, and CS-Library errors.
**
-- dberrhandle(err_handler);
-- dbmsghandle(msg_handler);
*/

/*
** cs_config() installs a handler for CS-Library errors.
*/
ret = cs_config(context, CS_SET, CS_MESSAGE_CB, 
               (CS_VOID *) cserror_cb, CS_UNUSED, NULL);
EXIT_ON_FAIL(context, ret, 
            "Could not install CS-Library error handler.");

/*
** ct_callback() installs handlers for Client-Library errors and
** server messages. 
**
** ct_callback() lets you install handlers in the context or the
** connection. Here, we install them in the context so that they
** are inherited by connections that are allocated using this
** context.
*/
ret = ct_callback(context, NULL, CS_SET, CS_CLIENTMSG_CB, 
                  (CS_VOID *) clientmsg_cb);
EXIT_ON_FAIL(context,ret,
            "Could not install Client-Library error handler.");

ret = ct_callback(context, NULL, CS_SET, CS_SERVERMSG_CB, 
                  (CS_VOID *) servermsg_cb);
EXIT_ON_FAIL(context,ret,
            "Could not install server message handler.");

... deleted code that connects and interacts with the server ...

/*
** Clean up Client-Library.
** 
** ct_exit(context, CS_UNUSED) requests an "orderly" exit. 
** This call fails if we have open connections. If it fails, 
** EXIT_ON_FAIL() calls ct_exit(context, CS_FORCE_EXIT) to 
** force cleanup of Client-Library.
*/
ret = ct_exit(context, CS_UNUSED);
EXIT_ON_FAIL(context, ret, "ct_exit(CS_UNUSED) failed.");

/*
** Clean up CS-Library. cs_ctx_drop() always fails if ct_init()
** succeeded on the context but ct_exit() did not (or if
** ct_exit() was not called at all).
*/
(CS_VOID) cs_ctx_drop(context);
context = (CS_CONTEXT *) NULL;

exit(NORMAL_EXIT);