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.