Example of using the name/token services

The following example shows how an application uses the name/token callable services. The application, called a server application, offers services to users. The application resides within a single address space, the server address space. The application offers services to users that reside in address spaces outside the server address space. The example assumes the server application has already set up the cross-memory environment that allows the users to connect to the server address space.

The server application uses name/token callable service twice during its initialization:

The first use is to make important information available to the users. Before users can invoke the services of the server application, they need to know the Program Call (PC) number that they use to switch program processing from their primary address spaces to the server's address space. Through IEANTCR, the server, in supervisor state, creates a system-level name/token pair. With a system-level pair, programs running in any address space can retrieve the token, in this case the PC number the user must have to call the server. The invocation that creates the name/token pair is as follows:
```
CALL IEANTCR,(SYSLEV,NAME,TOKEN,NOPERSIST,RETURNCODE)
```
The name/token pair is not marked as persistent; users cannot retrieve the token (that is, the PC number) if the server has terminated. If the server is terminated or in the process of restarting, the user will have to wait until the server is restarted before successfully retrieving the PC number.
A user retrieves the PC number through the following invocation:
```
CALL IEANTRT,(SYSLEV,NAME,TOKEN,RETURNCODE)
```
The server also uses IEANTCR to create a primary-address-space-level name/token pair. With this name/token pair, any program running in the server's address space can use the name to retrieve the associated token. In this case, the token contains a pointer to the application's main data area. The invocation that creates the name/token pair is as follows:
```
CALL IEANTCR,(PRIMLEV,NAME2,TOKEN2,NOPERSIST,RETURNCODE)
```
If the server abnormally terminates, its recovery routine might use the following invocation to retrieve the address of the main data area. Note that if the recovery routine gets control before the address space terminates, the recovery routine can retry; the name/token pair is still retrievable until the address space completes termination.
```
CALL IEANTRT,(PRIMLEV,NAME2,TOKEN2,RETURNCODE)
```