This document describes the concept and the architecture of the Natural Development Server (product code NDV) which is designed for use under z/OS (Com-plete).
The following topics are covered:
A Natural Development Server is a multi-user, multi-tasking application. It can host Natural sessions for multiple users and execute their requests concurrently.
The concept is based on the "serverized" Natural runtime
system. Its architecture comprises a server front-end stub (development server
stub NATRDEVS) that uses the Natural front-end to dispatch Natural
sessions and to execute functionality within these sessions.
The Natural remote development server architecture basically consists of:
The stub NATRDEVS is launched to initialize a Natural
Development Server. It listens for incoming transactions and dispatches the
appropriate Natural session for executing the transaction.
The module NATGWSTG provides for interaction between the
Natural runtime system and the front-end stub. NATGWSTG is already
included in the Natural nucleus and is called by the Natural runtime system to
exchange the necessary request data.
Transaction processors are called by the front-end stub. The application logic of each individual transaction is implemented within a transaction processor.
Natural Driver
Natural is driven by the Natural Com-plete interface
NCF-SERV.
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 NATRDEVS is
launched to initialize a Natural Development 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
remote development client (Natural Studio). 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 command issued by the user on the client
side (in the menu of Natural Studio) 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 processes the request (indeed initializes a new
Natural session if the client sends a CONNECT request) and replies
to the client.
After the reply, TWork listens on that connection for
successive requests of that particular client. TWork remains
active until the user on the client (Natural Studio) side switches the focus to
a different environment (the local or a different mapped environment).
If the user activates the environment again, TMain
launches a new TWork subtask that resumes the existing Natural
session from the previous TWork.
That is, each client owns one subtask TWork on the Natural
Development Server and multiple remote Natural sessions (one for each mapped
environment). This subtask remains active as long as the mapped environment on
Natural Studio is the currently active environment. Each remote Natural session
remains active until the user disconnects/unmaps the corresponding environment
on the client side. Consequently, a Natural session can be executed under
different subtasks if the user switches among multiple environments.
Within a Natural Development Server session, the following Natural system variables are used:
*TPSYS contains
SERVSTUB,
*DEVICE contains VIDEO,
*SERVER-TYPE contains
DEVELOP.
The Natural runtime system allows I/O execution in the same way as in an online environment:
A Natural Development Server intercepts the I/O and sends the 3270 data stream to Natural Studio.
Natural Studio internally starts a terminal emulation window and passes the 3270 stream to that window.
After I/O execution, the I/O data is sent back to the server.
The front-end stub invokes the front-end to continue processing after I/O.
The Natural front-end required for a Natural
Development Server is the Natural Com-plete driver NCFNUC that is
delivered with the corresponding Natural Version for Mainframes.
The transaction processors are Natural programs in the library
SYSLIB that process transactions (for example, "save
source", "get library list") requested
by the remote development client. The transaction processors are invoked by the
front-end stub.
The gateway module NATGWSTG is already included in the
Natural nucleus.
To enable the administrator to monitor the status of the Natural Development 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 Development Server.
The following figure illustrates the interaction of Natural Studio used as a remote development client with a Natural Development Server.
Natural Studio (the client) sends a remote development request to the
Natural Development Server (NDV) using the port number specified with the NDV
configuration parameter PORT_NUMBER.
The Natural Development Server dispatches the Natural session using
the Natural front-end you have specified with the NDV configuration parameter
FRONTEND_NAME (NCFSERV in this example).