Using the server push (applet) method
Note: The server push (applet) method is deprecated.
While this method is currently supported, support for this feature
may be removed in a future release. You are advised to use the client
pull (AJAX) method instead.
There are two functions performed by the server
push (applet) implementation method, also known as the asynchronous
update applet:
- Pushing asynchronous host updates to the browser:
- This enables the user to see host updates automatically without the user clicking the Refresh button
- Notification of browser close to ZIETrans server:
- This allows the ZIETrans server to clean up resources associated with the browser session and reduces the load on the server
When using the asynchronous update applet, in addition
to the connection used to send transformed terminal screens from the
ZIETrans server to the user's browser, a separate socket connection
is established between the applet running on the client and the ZIETrans
server. This separate socket connection is used to pass small messages,
between the client and server, relating to asynchronous screen refreshes
from the host and notification to the ZIETrans server that the browser
has been closed. Typically, the amount of traffic over this separate
socket connection is very small. The sequence of events which occurs
to set up this separate socket connection is as follows:
- The user enters the ZIETrans application URL in the browser (using a link or typing in the address bar).
- The ZIETrans server receives the request and sends a response to the browser, which includes the asynchronous update applet Java™ code.
- Once the applet is downloaded to the client, it attempts to communicate
directly back to the ZIETrans server by opening a separate socket
connection. The local port used on the client for making this socket
connection is chosen at random from the available unused ports on
the client, and is not configurable. The remote ZIETrans server IP
name and port information that the applet attempts to connect to are
supplied by the server when the applet is downloaded to the client.
If a value of 0 is specified for the server's port number in the ZIETrans
application configuration on the server, then one random, unused port
number above 1024 is chosen on the ZIETrans server and supplied to
the applet as a parameter. The port number that has been chosen by
the server can be seen by viewing the page source of the ZIETrans
transformation in the browser. Search the page source for the value
specified for
PARAM NAME="port"
. For more information about the applet parameter settings, see Server push (applet) settings.
In order to run the applet, a Java-enabled browser is needed.