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<== Date ==> <== Thread ==>

Subject: Re: dm / medm applet?
From: Chip Watson <[email protected]>
To: [email protected] (William Lupton)
Cc: [email protected], Chip Watson <[email protected]>
Date: Tue, 25 Mar 1997 07:57:53 -0500
[email protected] said:
>   A couple of months ago it was mentioned that John Winans wrote an 
> OPI Java applet. Can anyone provide more details on this, e.g. which 
> OPI it emulates, which version of which .adl format it reads, how it 
> handles network connections (direct CA to IOC? or not?)), security 
> implications, availability?

John wrote an applet which parsed the medm ascii file and drew a subset
of the graphics (no I/O to a control system).  Patrick, a student here at 
Jefferson Lab, has ported cdev to java, and modified Winan's code to use 
the java cdev to communicate with a gateway program to animate medm screens.
An alpha version of this currently runs, with a larger subset of medm
than John did, but still not all capabilities.

This development effort is still underway, and is called jdm (java display
manager).  Because of the interpreted nature of java, the performance is
currently low.  As JITs become available, this will markedly improve.
Note that it (of course) runs on PC's, MAC's, and Unix machines without
recompiling (java evangelist speaking).

We are also working on "compiled screens" -- take an ascii file, translate
it into java code, and compile it.  The compiled screen is actually smaller
than the ascii file, so loads faster.  Execution speed is comparable.
You may also use the same class libraries to write custom graphical
displays (no ascii file, same graphical functionality, a la DataViews).

We hope to have some demo screens on our web site within a month, and
a beta (alpha?) version ready by the collaboration meeting.  We hope to
enlist others to extend the java widget set -- it is MUCH easier in java
for people to add display classes which can automatically be recognized
by the main program without code changes because of java's ability to
invoke new code by class name without recompiling.  Who want's to
contribute?  We'll get you an early release of what we've done.

Chip




References:
dm / medm applet? William Lupton

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