6 Using Target-Initiated Distribution Paths

Learn about target-initiated distribution paths in MA, the need to set it up, and various use cases where it is helpful to use target-initiated distribution paths.

Topics:

• Overview of Target-Initiated Paths
  
• How Do Target-Initiated Distribution Paths Work?
  

6.1 Overview of Target-Initiated Paths

Target-initiated paths for microservices enable the Receiver Server to initiate a path to the Distribution Service on the target deployment and pull trail files. This feature allows the Receiver Server to create a target initiated path for environments such as Demilitarized Zone Paths (DMZ) or Cloud to on-premise, where the Distribution Server in the source Oracle GoldenGate deployment cannot open network connections in the target environment to the Receiver Server due to network security policies.

If the Distribution Server cannot initiate connections to the Receiver Server, but Receiver Server can initiate a connection to the machine running the Distribution Server, then the Receiver Server establishes a secure or non-secure target initiated path to the Distribution Server through a firewall or Demilitarized (DMZ) zone using Oracle GoldenGate and pull the requested trail files.

The Receiver Server end-points display that the retrieval of the trail files was initiated by the Receiver Server, see Quick Tour of the Receiver Server Home Page.

You can enable this option from the Configuration Assistant wizard Security options, see How to Create Deployments. For steps to create a target-initiated distribution path, see How to Add a Target-Initiated Distrbution Path in Using the Oracle GoldenGate Microservices Architecture.

6.2 How Do Target-Initiated Distribution Paths Work?

Oracle GoldenGate has been using the passive alias configuration to initiate passive and alias connection between source and target systems. With MA, this functionality has been enhanced and is not available with target-initiated distribution paths, which can be managed from the Receiver and Distribution server and the Admin Client commands.

The path is created from the Receiver Server of the target deployment and has the property TARGET_INITIATED. This is read-only. This path is accessible from the Distribution Server also. The path information is stored on the target system.

If the communication is lost, then the Receiver Server on the target host needs the path definition to restart the connection. This information is shared with the Distribution Server when the path is running.

The path is ephemeral on the source deployment. Ephemeral paths help with consolidation of path configuration and with reinforcement of target-to-source connection initiation.

When the path is stopped or disconnected, the Distribution Server removes all the path information including the path definition. However, the checkpoint file is retained because the checkpoint is used to decide whether old trails can be purged or not. It is recommended that old trails are not purged unless the path is intentionally deleted.

Security Configuration between Secure and Non-Secure Source and Target Deployments

The communication channel can optionally be secured using SSL and the same authentication mechanisms. See the Security Options in How to Create Deployments.