Using CORBA To Bridge C and JMS

1
Using CORBA To Bridge C and JMS

• Niall Stapley, CERN
• email niall.stapley_at_cern.ch
• http//stapley.web.cern.ch/stapley/CORBAtoJMS/doc/

2
Overview

• Alarms
• Message Oriented Middleware
• Architecture
• MessageStruct
• Bridge Description
• The C client
• Current Status

3
Alarms

• Part of CERN SL/CO.
• Gather, analyze, distribute fault states.
• Sources from any part of CERN
• heterogeneous platforms
• Servers
• PCs
• VME computers
• and languages
• C, C
• Java

4
Message Oriented Middleware

• What is it?
• Queue-based asynchronous message exchange
• Provides reliability, flexibility, portability
• Allows many-to-many communication
• Good for event-driven communication
• Java Message Service is the Java standard
• Includes publish and subscribe
• CMW project defined a MOM API
• which simplifies JMS
• but only implemented in Java

5
Architecture
6
MessageStruct
union BodyFormatUnion switch (BodyFormatEnum)
case BYTES_FORMAT OctetSeq octetSeqV
case TEXT_FORMAT string stringV case
MAP_FORMAT MapSeq mapSeqV case
STREAM_FORMAT DataTypeUnionSeq
dataTypeUnionSeqV case ANY_FORMAT
any anyV struct MessageStruct HeaderSeq
headers PropertySeq properties
BodyFormatUnion body
7
Bridge Description
8
Publish Example

• include ltinclude_the_world.hgt
• using namespace everything
• int main (int argc, char argv)
• Publisher the_publisher Publisherinit(
  argc, argv )
• TextMessage message()
• message.setStringProperty( "the_name",
  "the_value" )
• message ltlt "This is inserted into the body"
• the_publisher.publish( "CERN.TEST", message
  )
• return (EXIT_SUCCESS)
• // main

9
Subscribe Example

• include ltinclude_the_world.hgt
• using namespace everything
• void messageHandler (Message message)
• int main (int argc, char argv)
• Subscriber the_subscriber Subscriberinit(
  argc, argv )
• long long handle the_subscriber.subscribe(
  jms_topic, "",
• 
  messageHandler )
• // do other stuff
• the_subscriber.unsubscribe( handle )
• return (EXIT_SUCCESS)
• //main

10
Current Status

• Provides Publish / Subscribe MOM API as shown.
• Uses JacORB and Orbix/E
• Potential attention areas
• Increase security
• The long descriptor.
• Add user / password protection.
• Add JMS Message Headers.
• Dynamic Object/IDL conversion handler.
• extern C client library
• Start testing it with alarms

11
And Finally...

• Thanks for your attention!
• Any questions?