• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Tim Cooke
  • Devaka Cooray
  • Ron McLeod
  • Jeanne Boyarsky
Sheriffs:
  • Liutauras Vilda
  • paul wheaton
  • Junilu Lacar
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Piet Souris
  • Carey Brown
  • Tim Holloway
Bartenders:
  • Martijn Verburg
  • Frits Walraven
  • Himai Minh

Data Retrival in Clustered environment

 
Greenhorn
Posts: 15
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Hi

We have a Java process that pings the DB (mainframe DB2) at a predefined frequency. If Java process finds some data in DB it reads and processes that data and inserts the data in IBM MQ using JMS.

We are now planning to migrate it to WAS with support for Load Balancing and Clustering environments. We have decided to use Spring Batch Framework.

Problem:-

Now in a multi clustered environment, suppose if some data is there in DB2 and is updated in MQ by java program running in one cluster. How can we ensure that once data is retrieved from one cluster, it should not be repeated by other java program running in differnet cluster. Otheriwse it will lead to duplicate data in MQ by differnet clusters.

May be if we put some flag checks in java to comply to it. But in a multi clustered environment, how we can achieve this.

Regards,
Hitesh.
 
Bartender
Posts: 1638
IntelliJ IDE MySQL Database Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator


May be if we put some flag checks in java to comply to it. But in a multi clustered environment, how we can achieve this.


Put flags in DB and not in java.

An alternative is to put processed and unprocessed data in different tables.

Lets assume, you have a table T1 where new data is kept.
One process picks up the data ("select for update" insures that nobody else processes the data at the same time) from T1. On successful processing, it deletes the data from this table and adds it to the another table T2.
Since all your processes queries T1 and not T2, no data will be processed twice.
Make sure that you take a lock on the data using "Select for Update" so that no two processes process the same record concurrently.
[ July 03, 2008: Message edited by: Nitesh Kant ]
 
Hitesh Gupta
Greenhorn
Posts: 15
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Nitesh,

Thanks for your reply. The suggestion is remarkable but here all data is being provided by third party vendor and I can't change the design of data retrival in to new table.
So, I was looking if we make it happen through Java only.

Regards,
Hitesh.
 
author
Posts: 3892
5
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Would it be possible to add a trigger to the DB2 table that adds the data to MQ directly rather than polling for it in Java?
 
Hitesh Gupta
Greenhorn
Posts: 15
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Kyle,

How will I interact with MQ form DB2.
 
Ranch Hand
Posts: 2187
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

How can we ensure that once data is retrieved from one cluster, it should not be repeated by other java program running in differnet cluster. Otheriwse it will lead to duplicate data in MQ by differnet clusters.



You can develop a monitor that watches the activity of the cluster members and the queue via correlation ID. Once a set of data has been retrieved, the monitor ensures that no other cluster takes the data.
 
Nitesh Kant
Bartender
Posts: 1638
IntelliJ IDE MySQL Database Java
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

hitesh:
So, I was looking if we make it happen through Java only.



I think it will be difficult for you to do in a java app sitting on one of the nodes.
Moreover, the information that you have processed a record must be persisted so that even if the node that processed the data crashed, other nodes still know that it has been processed.

In my opinion you have 2 options:

1) Run a single instance of your java application i.e. as a separate process .
2) Write a process that copies data from the main table to a secondary database that you have a control on. The processing threads uses the table from this secondary database.
 
Don't listen to Steve. Just read this tiny ad:
the value of filler advertising in 2021
https://coderanch.com/t/730886/filler-advertising
reply
    Bookmark Topic Watch Topic
  • New Topic