This document describes the concept and the structure of the server for the Natural Web I/O Interface which is designed for use on z/OS.
The following topics are covered:
A Natural Web I/O Interface server is a multi-user, multi-tasking application. It can host Natural sessions for multiple users and execute their applications concurrently.
The concept is based on the "serverized" Natural runtime
system. Its architecture comprises a server front-end stub (Web I/O Interface
server stub NATRNWO) that uses the Natural front-end to dispatch
Natural sessions and to execute applications within these sessions.
The Natural Web I/O Interface server architecture basically consists of:
The stub NATRNWO is launched to initialize a Natural Web
I/O Interface server. It listens for incoming connection requests an launches a
Natural session for executing the application.
The front-end is called (together with the Natural runtime system) by the front-end stub for session initialization/termination, application execution and session roll-in/roll-out.
A monitor task allows the administrator to control the server activities, to cancel particular user sessions or to terminate the entire server, etc.
The multi-user, multi-tasking, front-end stub NATRNWO is
launched to initialize a Natural Web I/O Interface server.
The following topics are covered below:
The task executing the server initialization (TMain)
basically is the main listener which waits for incoming requests from the Web
I/O Interface client. It owns a session directory to manage multiple clients
(users) and their corresponding remote Natural sessions. TMain has
the task to accept all incoming requests and to dispatch them to other subtasks
(TWork). The process is as follows:
First, a server connection issued by the user on the client side (the
Login button of the Web I/O Interface client) connects to TMain to
establish a connection.
Next, TMain inserts the client into its session
directory, attaches a new TWork subtask and passes the connection
to TWork.
TWork initializes a new Natural session and starts the
specified Natural application program.
While the application performs I/O requests, TWork
intercepts the I/O data and passes them to the Web I/O Interface client for
processing the I/O. The I/O reply is sent back to the server and the server
continues the application.
If the application terminates (reaches the NEXT mode),
TWork terminates the Natural session and drops the connection to the Web I/O
Interface client.
That is, each client owns one subtask TWork on the Natural
Web I/O Interface server. This subtask runs a Natural session (and within the
Natural session, a Natural application) and remains active as long as the
application is running.
Within a Natural Web I/O Interface server session, the following Natural system variables are used:
*TPSYS
contains SERVSTUB,
*DEVICE
contains BROWSER,
*SERVER-TYPE
contains WEBIO.
Under z/OS, the Natural front-end required for a Natural Web I/O Interface server is a Natural batch front-end driver, which should be LE enabled. See sample installation jobs for details.
Under z/OS, the front-end is called (together with the Natural runtime system) by the front-end stub for session initialization/termination, request execution and session roll-in/roll-out.
The Natural front-end required for executing the Natural sessions under
control of CICS is the Natural remote front-end NATCSRFE that is
delivered with the Natural Web I/O Interface server. For more information,
refer to the Natural Web I/O Interface Server CICS Adapter
documentation.
To enable the administrator to monitor the status of the Natural Web I/O Interface server, a monitor task is provided which is initialized automatically at server startup. Using the monitor commands, the administrator can control the server activities, cancel particular user sessions, terminate the entire server, etc. See Operating the Web I/O Interface Server.