mpsrvr

        The multi-panel, line plotting server.  In the grand design of
        things, this server is intended to be the server for large
        range of line plotting services.  As a server, it listens on a
        well advertised UNIX socket port for requests from clients.
        Once a request is posted on this port and validated, it opens
        two more sockets per connection and transmits these port
        numbers to the client which in turn should connect to the
        first one for sending commands to the server and the second
        one to send the data.  Once these connections have been made,
        the original socket is closed by the server to allow further
        request to be served.

        However, as implemented now, the server can process only one
        request correctly at a time.

        The server is capable of (read this is "expected to") handle
        the arrival of data on the data port and the arrival of
        commands on the command port independent of each other.  A
        side effect of this is that it becomes the responsibility of
        the client to make sure that a command arrives at the command
        port BEFORE the arrival of the relevant data on the data port.
        The protocol for communication on both these ports have
        feature which will let the client synchorise between the two
        ports.

        The sever can be instructed to work in "scrolling" mode or in
        "static" mode and ultimately (ie. when all feature of this
        server are implemented) it will be possible to switch between
        these modes at anytime.



 Author

        Sanjay Bhatnagar (sanjay@ncra.tifr.res.in)



 Server Interface

        Yet to be written!


 The User Interface

        The plots can be controlled to a large extend using the GUI of
        the server.  

        The plots can be shown either as a grid of panels, each
        showing a different graph, or multiple plots plotted on the
        same surface.  The entire surface on which the grid of panels
        is drawn is a scroll-able surface.  Hence a large number of
        panels can be displayed and brought in view by the moving the
        scroll bar for the entire surface.

        Each of the panels also have a two scroll bars attached to
        them.  One control the upper limit of the y-axis while the
        other controls the lower limit of the y-axis.  Changing the
        scroll bars would dynamically change the y-range and the in
        turn the plotted graph.  

        The y-range scroll bars operate between the range defined by
        the plotted data, i.e., the upper limit can only be lowered
        while the lower limit can only be raised.  To change the
        limits defined by the data, one can use the up and down arrow
        keys.  The up-arrow key will increase the upper limit and
        down-arrow key will lower the lower limit.  The y-range scroll
        bars will then operate in the new limits.

        When the two y-range scroll bars come close to each other or
        when the y-range itself is very small, fine control of the
        y-range becomes difficult via the scroll bars.  Use the F1 key
        to set the limits between which the scroll bars operate to the
        current y-range.  Repeated use of changing the y-range and F1
        key effectively allows you to have fine control on the y-range
        irrespective of the difference between the ymax and ymin and
        would effectively allow you to "zoom-in" on the graph.  The F2
        key can be used to reset the y-range to the maximum range
        defined by the plotted data, use the F2 key.


        All the labels, and legend printed on the canvas can be moved
        by a drag-n-drop operation on them.  The individual panels
        themselves can also be moved around the canvas in a similar
        manner (however, this feature show be used carefully,
        particularly when there are large number of panels.  I really
        do not see much use of drag-n-drop operation of the panels
        themselves - that's a feature for later use, and is right now
        only a "side effect").