RE: serving multiple shape files with Linklayer

> -----Original Message-----
> From: James Edward Marca [mailto:jmarca@translab.its.uci.edu]
> Sent: Monday, May 14, 2001 8:43 AM
> To: openmap-users@bbn.com
> Subject: Re: serving multiple shape files with Linklayer
>
>
> Hi,
>
> I am running multiple ShapeLinkServers to serve up multiple shape
> files. I am not so clued in on sockets and servers, and I was
> wondering what happens when lots of applets start hitting the same
> servers. Right now I am lucky enough that only one person is using
> my applet to process data, but that may change in the future.
>

Openmap handles multiple clients just fine; each applet client get's it's
own socket and thread.

The only potential drawback is that once a client thread is started, I
don't think it ever stops. As I read the code, the shape server blocks
in the link, waiting for the next request from the client. So I think
you theoretically could run into a situation where all the sockets
(62,000??) could be exhausted on the shape file port.

I would expect that when the applet closes, the link layer client should
let the shape server know it's ok to close that socket. Based on my
previous experience with OpenMap code, this is probably happening; I
just not looking in the right place!

> I wrote another layer server for my own GPS/database data source
> that works via a Java client implementation of
> XML-RPC---mostly to get
> around the applet same-server requirement (the xmlrpc server
> is on the
> same machine, but it routes calls for services to other machines (my
> database server)). The other advantage is the client just has to know
> one socket, one function name, but I can move the actual
> client elsehwere
> If I need to.
>
> I am a little more confident about multiple hits on the
> XML-RPC server,
> and so I was wondering if it would be worth it to wrap the
> ShapeLinkServer
> in xml-rpc server calls. Any thoughts?
>
> James
>
> From Donald F. Dietrick, received Mon, May 14, 2001 at
> 12:51:45PM -0400:
> > Hi Rajesh,
> >
> > The current ShapeLinkServer only provides a way to serve up a single
> > shape file at a time, so if you want multiple shape files displayed,
> > you'll have to set up multiple layers and multiple servers.
> >
> > You could create your own ShapeLinkServer to use multiple
> SpatialIndex
> > objects to access more than one shape file at a time. The protocol
> > doesn't limit you in terms of how your server is
> constructed and what
> > data it accesses.
> >
> > Cheers,
> >
> > Don
> >
> > "Rajesh.M" wrote:
> > >
> > > Hi Don,
> > >
> > > >The LinkLayer, as part of an OpenMap Application or
> Applet using the
> > > >MapBean, is the client. The LinkLayer has been written
> to use the
> > > >protocol to talk to a server as needed.
> > > ** succesfully did the Linklayer - linkserver
> communication and popped
> > > up the applet with shapefiles..that was cool stuff..
> > > However i need to support multiple shape files. Should i
> start Linkserver
> > > on multiple socket ports each serving different shape
> files or is there any
> > > other better way there in the code for serving multiple
> shape files?
> > > cheers
> > > rajesh.m
> > >
> > > --
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> --
> james e. marca
> jmarca@translab.its.uci.edu
> http://www.its.uci.edu/~jmarca
>
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