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Re: Configuring ERChangeNotification/JMS Help needed
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Re: Configuring ERChangeNotification/JMS Help needed


  • Subject: Re: Configuring ERChangeNotification/JMS Help needed
  • From: Chuck Hill <email@hidden>
  • Date: Wed, 26 Oct 2005 08:06:50 -0700


On Oct 26, 2005, at 5:13 AM, Wolfram Stebel wrote:

Am 26.10.2005 12:11 Uhr schrieb "David Teran" unter
<email@hidden>:

Hi David,

Thanks for your hints.
1. The reason why i do this is, that i hopefully will have a site with high
traffic in the future, where i will need load balancing.
But thats a minor reason!

See David's comment, "If you ever use a lot of instances it will slow down everything". This might not be the best way to get you where you want to go.



2. I have 3 Applications working on the same database, i.e. they might
change the same data entries concurrently.

So deal with it. This framework will _not_ eliminate the need to handle concurrent editing issues. It will just _reduce_ the frequency of occurrence. ChangeNotification framework or not, you still have to code for these.



One of the applications is an administrators app, two others are customers
applications. The admin might change some values, that are very important
for the customers, i.e. client aliases, which are also used for directory
locations. When those change, the customer needs direct feedback of the
change.

What does direct feedback mean? They need a message to popup? An e- mail? Or just that they need to see fresh data.



3. I asked on this list how to handle this issue, and i was told to do what
i'm now implementing.


So, what other tips do you have?


1. Implement code to handle optimistic locking failures

2. Determine the data freshness requirements and implement refreshing fetches and new EC creation to meet those needs.

Chuck


Just a simple question:

why do you want to use this framework? Is it really important for
you? It cannot handle a lot of load, others mentioned to have strange
deadlocks when using it and the best approach is:

build your application in a way it does not need change notification
as its error prone (imho). If you ever use a lot of instances it will
slow down everything. If you ever have other applications which use
the database (non WO apps) it will break your WO apps. If you ever
use more than on EOF stack it will lead to unexpected results as
change notification framework is only for one EOF stack.

maybe there is another solution than using this framework. Explain a
little bit why you want to use it, whats the problem with your
current app?

regards, David


Am 26.10.2005 um 11:49 schrieb Wolfram Stebel:


Hi list,

i have three apps i want to talk between using ERChangeNotification
via jms.
i already got jms installed (0.7.6.1 on OSX 10.4.2) and linked the
framework
into my apps.
i have a startupitem and can do the administrative start/stop via
"sudo
SystemStarter start OpenJMS" etc. without any error messages in
console.
The service seems to run after machine restart too, so i expect
everything
is well at first glance!

Now i just wonder how to configure jms :-)
i tried googling but found no essentials on it.

My setup is:

1.

In "Properties" file of all applications i have (as recommended):

er.changenotification.entitiesNotToSynchronize = ()
er.changenotification.changeTypesToTrack = (inserted, updated,
deleted)
er.changenotification.jms.topicName = MyTopic
er.changenotification.jms.durableSubscribers = false


2.

In openjms.xml i have:

<Configuration>
  <ServerConfiguration host="localhost" embeddedJNDI="true" />
  <Connectors>
    <Connector scheme="rmi">
      <ConnectionFactories>
        <QueueConnectionFactory name="JmsQueueConnectionFactory" />
        <TopicConnectionFactory name="JmsTopicConnectionFactory" />
      </ConnectionFactories>
    </Connector>
  </Connectors>
  <!-- Required  -->
  <DatabaseConfiguration>
    <JdbmDatabaseConfiguration name="openjms.db" />
  </DatabaseConfiguration>
  <!-- Required -->

**** in the following line there was "startjms.sh" wich does not
exist and i
replaced it by "startup.sh"

  <AdminConfiguration script="${openjms.home}\bin\startup.sh" />

**** and i wonder if the following block is correct or required anyway
<AdministeredDestinations>
<AdministeredTopic name="MyTopic">
<Subscriber name="MyApp1" />
<Subscriber name="MyApp2" />
<Subscriber name="MyApp3" />
</AdministeredTopic>
<AdministeredQueue name="doINeedaQueue1?" />
<AdministeredQueue name="doINeedaQueue2?" />
<AdministeredQueue name="doINeedaQueue3?" />
</AdministeredDestinations>


**** and i wonder if i can delete the following block or does
someone need a
user?

  <Users>
    <User name="admin" password="openjms" />
  </Users>
</Configuration>


3.

In "rmi_jms_jdbm.xml" i have:

<Configuration>
  <!-- Required when using an RMI connector -->
  <Connectors>
    <Connector scheme="rmi">
      <ConnectionFactories>
        <QueueConnectionFactory name="JmsQueueConnectionFactory" />
        <TopicConnectionFactory name="JmsTopicConnectionFactory" />
      </ConnectionFactories>
    </Connector>
  </Connectors>
  <!-- Required  -->
  <DatabaseConfiguration>
    <JdbmDatabaseConfiguration name="openjms.db" />
  </DatabaseConfiguration>
  <!-- Required -->
  <AdminConfiguration

**** in the following line there was "startjms.sh" wich does not
exist and i
replaced it by "startup.sh"

    script="${openjms.home}/bin/startup.sh"
    config="${openjms.home}/config/rmi_jms_jdbm.xml" />
  <!-- Required: Add your own AdministeredTopics -->

**** and i wonder if the following block is correct
  <AdministeredDestinations>
    <AdministeredTopic name="MyTopic" />
  </AdministeredDestinations>
</Configuration>



I hope, you gurus can help me :-)

TIA




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