While Chapter 1, is the foundation chapter for the rest of this book, Chapter 2 is the blue print chapter. In this chapter, we went over the major design considerations to take into account when designing your distributed environment.

We discussed the who, what, when, where, why, and how factors to consider for your replicated system. Why are you replicating? What are you replicating? Who will use the data and how? Where are you replicating to and from? How will you propagate the data between sites and when? How will you handle the data divergence between sites? Taken on-board together, this all helps you to determine the most efficient tools and functionality to employ in your design. It also helps you predict the time and effort needed to implement the environment, and subsequently maintain the environment.

The number one goal of a successful Streamed environment is to avoid data divergence. Data divergence leads to data conflicts, and data conflicts lead to unsynchronized data mayhem in a distributed environment. Establishing overall business rules for data ownership and change flow is the precursor to understanding what your conflict resolution design will require.

We also looked at additional considerations that you will want to take into account. These included network connectivity, propagation volume (transaction size and queue growth), database security and user privileges, database platform and version compatibility, additional hardware resource requirements, administration and maintenance costs, and the flexibility-to-complexity factor (using the best tool for the job).

The Streams Site Matrix was introduced and demonstrated to show us how to succinctly organize and visualize the sites and components needed to build your distributed environment using Oracle Streams technology.

Now that we have plotted our course, we next turn our attention to the vehicles we will use to get there. In Chapter 3, Prepare the Rafts and Secure Your Gear: The pre-work before configuring Oracle 11g Streams, we will properly set up the database and make the necessary configuration changes to support a Streams environment. We will go over the changes and provide the reasons for those changes. We won't go into all the minute details and bore you with too much analysis of mundane configurations. If you wish additional information, please refer to the Oracle Streams Concepts and Administration Manual and the Oracle Streams Replication Administrator's Guide.

We now know what we need to build and the tools we have available to us for building it, so let's start configuring the database! (Ok, maybe take a quick bio-break first.)