InstantdbSync Perspectives
Syncing From the "Front End" Perspective
To replicate data using InstantdbSync:
1. Verify that you already have a CONNX Data Dictionary (CDD) containing the Adabas file definitions for the source files.
2. Add a link that points to the desired target database to the data dictionary.
3. Start the InstantdbSync Administrator and select the CDD.
The first time you open the CDD, you will be prompted to enter the location of the replication server components (Event Consumer), and specify any port overrides for communicating to the message queue.
4. Select the source tables to replicate, and the target database.
InstantdbSync assumes a one-for-one column mapping between the source and the target tables. Use the InstantdbSync Administrator to change the source column to target column mapping.
You can map SQL expressions to target columns. This provides a powerful transformation capability.
5. Add replication filters by using the built-in features of the CONNX SQL Engine. Using the Data Dictionary manager, a SQL based filter can be applied to any table in the "SQL View Clause" field.
6. Press Deploy - real-time event replication begins.
Syncing From the "Back End" Perspective
When you deploy a replication:
1. The Replication Administrator uses the "front end" information to create a new replication CDD and sends it to the Controller.
2. The Controller quiesces any active Event Consumers (EC).
3. The Controller deploys the new replication CDD in the proper location.
4. After reading the instructions from the new replication CDD, new event filters are sent to the Event Producer (EP) through the Message Queue (MQ). The EP captures only events for the replicated tables, and ignores all other events.
5. The Controller starts up one or more EC engines depending on the work to be done. An EC is started for every source DBID/target database combination in the new replication CDD.
6. The Controller determines whether an "initial state" is required based on persistent state information stored in a memory mapped file. If an initial state is required, the Controller instructs the EC to start the initial state processing.
Initial states are performed by reading the source data using the CONNX SQL Engine, and inserting it into the target database using a standard INSERT/SELECT SQL statement. During initial state processing, changes to the source Adabas file are kept in the Message Queue for future playback after initial state processing is complete.
7. After any initial state processing, the EP captures changes to the selected tables and places them on the MQ. The EC reads the MQ and uses the CONNX SQL Engine Target Adaptor to place changes in the target database. This continues in real time until replication is stopped.