Registering in the Initial Session

To initialize and register your process with the initial ToolTalk session, your application needs to obtain a process identifier (procid). You can then obtain the file descriptor (fd) that corresponds to the newly initialized ToolTalk process.

The following code sample first initializes and registers the sample program with the ToolTalk service, and then obtains the corresponding file descriptor.

int ttfd;
char   *my_procid;
/*
* Initialize ToolTalk, using the initial default session
*/
my_procid = tt_open();
/*
* obtain the file descriptor that will become active whenever
* ToolTalk has a message for this process.
*/
ttfd = tt_fd();

tt_open returns the procid for your process and sets it as the default procid; tt_fd returns a file descriptor for your current procid that will become active when a message arrives for your application.

	CAUTION: Your application must call tt_open before other tt_ calls are made; otherwise, errors may occur. There are, however, some exceptions, such as: tt_default_session_set, tt_default_procid, tt_X_session, tt_netfile_file, tt_file_netfile, tt_host_file_netfile, and tt_host_netfile_file.

	NOTE: Transparent to an application, the CDE action and data typing services use ToolTalk to execute message-type actions and to notify an application when the user has changed an action or data typing database. To do this, these services automatically register an application with a ToolTalk session if the application is not registered, or the service will reuse the procid if the application is already registered. In general, an application will only want to register with one ToolTalk session. Consequently, it is recommended that an application call tt_open before it uses libDtSvc service functions such as DtDbLoad, DtActionInvoke, or DtDbReloadNotify.

When tt_open is the first call made to the ToolTalk service, it sets the initial session as the default session. The default session identifier (sessid) is important to the delivery of ToolTalk messages. The ToolTalk service automatically fills in the default sessid if an application does not explicitly set the session message attribute. If the message is scoped to TT_SESSION, the message will be delivered to all applications in the default session that have registered interest in this type of message.