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RE: Multiple Servers and Shared Editing Contexts



Thanks David, I have downloaded it and I will take a look.

Karl

-----Original Message-----
From: email@hidden
[mailto:email@hidden] On Behalf Of David Aspinall
Sent: November 18, 2003 12:07 PM
To: Karl
Cc: Apple Webobjects List List
Subject: Re: Multiple Servers and Shared Editing Contexts

I had some of difficulty with the JMS kit also.  I wanted multiple 
messages (data changes, forecast request, and eventually session 
events)  I ended up rewriting the kit.

My classes ended up as

JMSCoordinator.java
JMSClient.java
+ -- JMSChangeNotificationClient
+ -- + -- JMSChangePublisher
+ -- + -- JMSChangeSubscriber
+ -- JMSForecastClient
+ -- + -- JMSForecastRequester
+ -- + -- JMSForecastProcessor

The forecast request is initiated much like the change notification, in 
that it listens for interesting EO changes, then requests the 
forecaster tool to recompute the client's plan automatically, which 
then updates cached forecast values in the database, which the client 
apps pick up as change notification.

For the notification I also altered it to check the current database 
context to see if the updated object was even loaded and only re-fault 
it if it was already in memory.

I have also been thinking about only passing global ID's around, rather 
than snapshots.    Although it seems efficient to send the snapshot, I 
found large objects could really hit the JMS server.  So if I passed 
just the ID and made the object into a fault, then it is re-fetched 
only if it is still being accessed.

I also had difficulty with the Java Class Loader.  The JMS jar's were 
loading in one framework, but it was being initialized by a different 
class loader than the frameworks.  I was constantly getting class not 
found errors for things that I knew were loaded.  I ended up having to 
create a JAR's framework to merge all the 3rd party jars and allow them 
to be loaded by the same loader that the application was using.

Oh, and I had more trouble using RMI on windows, so I switched to TCP 
for everything.

I submitted some of the early stuff (before I started rewriting) to 
wonder, but I didn't notice if they used any of it.

If you are interested I have placed the JMS and change notification 
stuff on my .Mac directory (heh, as a jaguar archive).
http://homepage.mac.com/daspinall

David


On 18-Nov-03, at 10:40 AM, Karl wrote:

> Did you ever try using one of the notification frameworks?  I am 
> playing with the Wonder JMS-based framework but can't seem to get it 
> working just yet.
>
> I would like to propagate updates individual rather than having to 
> reload all of the data.  The number of updates is small compared with 
> the total amount of data.
>
> Karl
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References: 
 >Re: Multiple Servers and Shared Editing Contexts (From: David Aspinall <email@hidden>)



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