Book Image

IBM InfoSphere Replication Server and Data Event Publisher

By : Pav Kumar-Chatterjee, Pav Kumar Chatterjee
Book Image

IBM InfoSphere Replication Server and Data Event Publisher

By: Pav Kumar-Chatterjee, Pav Kumar Chatterjee

Overview of this book

Business planning is no longer just about defining goals, analyzing critical issues, and then creating strategies. You must aid business integration by linking changed-data events in DB2 databases on Linux, UNIX, and Windows with EAI solutions , message brokers, data transformation tools, and more. Investing in this book will save you many hours of work (and heartache) as it guides you around the many potential pitfalls to a successful conclusion. This book will accompany you throughout your Q replication journey. Compiled from many of author's successful projects, the book will bring you some of the best practices to implement your project smoothly and within time scales. The book has in-depth coverage of Event Publisher, which publishes changed-data events that can run updated data into crucial applications, assisting your business integration processes. Event Publisher also eliminates the hand coding typically required to detect DB2 data changes that are made by operational applications. We start with a brief discussion on what replication is and the Q replication release currently available in the market. We then go on to explore the world of Q replication in more depth. The latter chapters cover all the Q replication components and then talk about the different layers that need to be implemented—the DB2 database layer, the WebSphere MQ layer, and the Q replication layer. We conclude with a chapter on how to troubleshoot a problem. The Appendix (available online) demonstrates the implementation of 13 Q replication scenarios with step-by-step instructions.
Table of Contents (12 chapters)
IBM InfoSphere Replication Server and Data Event Publisher
Credits
About the Author
About the Reviewer
Preface

The Q Capture and Q Apply programs


It is the Q Capture and Q Apply programs, which form the heart of Q replication as it is these two programs, which read transactions from the source system and apply them to the target table.

The Q replication constituent components section from Chapter 1, gave a brief introduction to the Q Capture and Q Apply programs. What we will do in this section is examine at a deeper level how these programs work and communicate with each other.

Q Capture internals

Let’s review what Q Capture does. Essentially, Q Capture reads transactions for tables that it is interested in from the DB2 log by its transaction thread calling the DB2 log interface API db2ReadLog. It builds complete transactions in memory until it detects a commit or rollback statement in the log. If it detects a rollback statement, then the transaction is flushed from memory. If it detects a commit statement, then Q Capture places the transaction in compressed XML format onto a WebSphere MQ queue called...