Forward Replication Concept:
- Replicating content from author to publish instances (or dispatcher) is known as Forward Replication.
- Replication agents to all publish instances to which content should be replicated to, should first be configured on the author instance(s).
- When content is activated (for example a page is activated), the content is placed in the queue of all forward replication agents configured.
- The replication agents then package the content and forwards it to the appropriate Publish instance using the protocol configured on the replication agent (default is HTTP).
- A servlet in the Publish instance receives the request and it publishes the received content.
Examine the Default Agent:
- The Default Agent is configured out of the box and is already set-up when CQ is installed and started for the first time.
- The Default Agent is the Forward Replication Agent from author to a Publish Server and is configured with port 4503 (default port for Publish).
To examine the Default Agent:
- Navigate to http://localhost:4502/miscadmin#/etc/replication (assuming author is running on port 4502) and select "Agents on author" in the hierarchy tree on the left.
- Double Click on Default Agent from the list to open it.
- You can see that Replication request is being sent to "http://localhost:4503/bin/receive" - this is the servlet on the publish server that receives the replication request and publishes the content.
- Also you can observe from the above image, that the Agent status is shown - enabled or disabled. And the Queue status is shown as well - in this picture it says Queue is blocked as the Publish instance running on 4503 is not running and the content in the queue can not be activated until the publish server is running. Hence the 'Queue is blocked' message.
- A few other elements to note here are:
- the 'View log' link which gives insight into the replication activity
- the 'Test Connection' link which can perform a check to see if the author-publish connection is intact or not.
- For any Replication Agent, the Replication Queue shows the content that is pending activation to the Publish Server. You can perform a few actions on the Replication Queue such as - Refresh the queue to see if there is any new content in the queue since the last view, Clear the queue to remove all content, Force Retry to retry activating the content if the content is not being activated and is lying in the queue and Pause to pause activating content to the Publish Server.
Examine the Settings:
- To examine settings of a replication agent, click on the "Edit" link. This pops-up the Replication Agent's Settings. The Agent Settings pop-up window has five tabs. Let us examine each of these: