Brain Dump #1
Marc Ernst Eddy van Woerkom
Thu Feb 6 15:34:51 CET 2003
> > http://luxor-xul.sourceforge.net/
> > http://luxor-xul.sourceforge.net/talk/vanx-jul-2002/slides.html
> Heh, cool. (:
The guy behind that page, Gerald Bauer, is working hard to promote the idea:
He also does an awful amount of work by going through the web based
discussion list for Java Web Start over at java.sun.com and distilling
the useful postings there into his unofficial JWS FAQ
and a quick news letter
Java Web Start is a very interesting technology, which might be interesting
as well for Erlang, if it ever becomes popular for clients.
It is kind of "setup.exe for the web".
One writes a piece of XML, called JNLP, which contains the information
of what jars the Java is made of. Those jars reside on some server.
One can even distinguish between Java versions and operating systems,
so a Windows version would consist of a jars with windows specific
native code and a Linux version would consist of a jar with Linux
The interesting bit is versioning. It is possible to put in
what version the different jars are. And also what version
of the Java VM has to be used.
A user will launch a JWS app by clicking on some link featured on
a web page. The browser notices that this is a special link by its
MIME type and passes the link to the JNLP client installed on the
user machine. This client grabs the JNLP descriptor featured
by the link and compares the app description with the contents
of the application cache it manages on the user system.
If stuff is newer in the JNLP, it fetches thoses new jars from
the net into the cache. Then the app is started (what method
to call is described in the JNLP as well) with the Java VM
stated in the JNLP.
The next time the user starts the app, it might exceute from
the cache if nothing has changed on the server.
This scheme save a lot of troubles with different incompatible
Java VM version, and saves bandwidth by caching and updating
only changed parts of the app.
It is the easiest way to install Java client apps I know of.
Microsoft's .NET framework seems to have a similiar gadget
in store. foo.exe is now called an "assembly", there is a
global assembly cache and it seems it is possible to
fetch assemblies from the network.
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