95-843 Service Oriented Architecture

Homework 2 Due Wednesday, November 3, 2010

JBoss Exploration

    In this homework you will explore the samples that are provided with
the JBoss Enterprise Service Bus (JBossESB). Download and unzip the 
JBoss ESB from http://jboss.org/jbossesb. Read the documentation to
the extent that you are able to get the JBossesb quickstarts running.

    Your main task is to report to me on your success or failure. If
you are successful your homework 2 submission will consist of a single
text file with your name and a list of those samples that you were able
to run. Dumps from your console screens are encouraged. English descriptions (in your own words) of what is going on in the samples are also highly valued. Post your results to Blackboard.

    Quality of submissions will be valued more highly than quantity. In
other words, if you report that you were able to make various modifications
to the source code of services and explain the services well, that will be 
more highly valued than simply reporting that you were able to run all of 
the services.

    If you run into difficulty let me know immediately. I will either help
you through the difficulty or grant you an exemption from this work. Depending on how far you have gotten and how much time remains, the exemption may include a less technical assignment related to ESB's.

    Below are some notes that I have compiled on the JBoss ESB.

Notes from the JBOSS ESB Programer's Guide
==========================================

What is an ESB

   - Next generation of EAI
   - Business logic left to higher levels
   - It's about infrastructure logic
   - Needed when we map abstract SOA to a concrete implementation

To ensure loose coupling

   - Use one-way messages rather than request-response style
   - Do not expose service back-end implementation choices
   - use an extensible message structure so that it may
     be versioned over time, for backward compatibility
   - do not use the distributed object approach of fine
     grained services
   - One way message delivery requires that we encode 
     return address information in the message

JBOSS ESB Components

  - The Message Store Service
    A pluggable persistence service designed for audit tracking
  - Data Transformation Service
    Often clients and services will use the same vocabulary.
    If not, on the fly transformation is provided.
    JBoss uses Smooks and XSLT
  - Content based routing
    JBossESB can route messages based on arbitrarily complex rules
    Uses XPath and JBoss Rules (Drools) notation
  - Registry Service is at the heart of JBossESB
    services can self-publish their endpoint references (EPRs) into the    
    Registry when they are activated, and remove them when they are 
    taken out of service. Consumers can introspect over the Registry 
    to determine the EPR for the right service for the work at hand.
 

Running some of the samples:
============================

    - See 
      http://docs.jboss.org/jbossesb/docs/4.8/manuals/html/GettingStarted.html

    - Start server
      cd 95-843/JBossESB/jbossesb-server-4.8/bin
      sh run.sh on unix run.bat under dos
      mine starts in 47 seconds

    - open a new command shell
      cd 95-843/JBossESB/jbossesb-server-4.8/samples/quickstarts

      cd helloworld
      read readme.txt
      ant deploy
      ant runtest
      explain

    - Modify the source code 
      ant compile
      ant deploy
      ant runtest
      explain

    - Run the example that goes straight to the esb with
      no adapter.
      ant sendesb

    - Open a new command shell on the http_gateway quickstart
      ant compile
      ant deploy
      with a browser visit 
      http://localhost:8080/Quickstart_http_gateway/http/sales/a/b/c
      The user id is "kermit" and the password is "thefrog".
      Explain