Deployment Synchronizer provides capability to synchronize deployment artifacts across the nodes of a product cluster. The artifact repository typically contains user-uploaded service archives, modules, service metadata, scheduled tasks etc. which are shared across the nodes of a cluster. Therefore, in a clustered environment, the artifact repository of WSO2 products (by default, it is <product-home>/repository/deployment/server) should be in sync between all the cluster nodes, in order to maintain consistency. This is synchronization functionality is provided by the following feature in the WSO2 feature repository:
Name: WSO2 Carbon - Deployment Synchronizer Feature
Identifier: org.wso2.carbon.deployment.synchronizer.feature.group
If it is not included in your product by default, you can add by installing the above feature using the instructions given in section, Feature Management.
In summary, the WSO2 deployment synchronizer has a number of use cases:
- Maintaining an up-to-date backup of the artifact repository.
- Sharing a single artifact repository among multiple servers in a cluster.
- Enforcing artifact updates to be deployed on a server at runtime.
Currently, The WSO2 Deployment Synchronizer feature (DepSync) uses an SVN-based repository for storing shared deployment artifacts. The Subversion repository is used to sync the contents in the sync directory (the axis2 repo directory, <PRODUCT_HOME>/repository/deployment/server, by default). This method is efficient and high-performant. The synchronization process is as follows:
- When changes to the contents of axis2 repo directory are present, the Read-Write nodes commit those to the Subversion repository.
- Then, this node sends a cluster message to all other (slave) nodes specifying the repo is updated.
- When the slave nodes receive the message, they update their axis2 repo directory with what's in the svn repository.
For instructions on configuring the SVN-based Deployment Synchronizer, refer to Configuring the SVN-Based Deployment Synchronizer.