Remote Instance and Mount Configuration Details

WSO2 Carbon-based products support the concept of federating the directory structure of the repository across multiple servers. Therefore, the structure of collections does not necessarily need to exist in a single instance of the server. You can mount/un-mount each remote registry instance through a configuration, which defines how to connect to it. The Remote Registry API is used to communicate between such remote instances.

In order to mount an external registry, you have to define the remote registry instance. This can use the JDBC-based configuration, the Atom-based configuration model or the WebService-based configuration model.

JDBC-Based Remote Instance Configuration

• url - The URL of the remote instance.
• id - Remote instance id.
• dbConfig - The database configuration to use. 

• readOnly - Whether the instance is read-only.
• enableCache - Whether caching is enabled for this instance.
• registryRoot - The root of the registry instance.

Below is an example configuration of a remote instance.

<remoteInstance url="https://host:port/registry">
    <id>instanceId</id>
    <dbConfig>h2-db</dbConfig>
    <readOnly>false</readOnly>
    <registryRoot>/</registryRoot>
</remoteInstance>

For specific configuration details on mounting a remote WSO2 Governance Registry (G-Reg) instance using the JDBC-based configuration model, refer to Sharing Registry Space Among Multiple Products.

Atom-Based Remote Instance Configuration

• url - The URL of the remote instance.
• id - Remote instance id.
• username - Username of the remote registry login.
• password - Password of the remote registry login.
• cacheId - The identifier used in computing cache keys.

Below is an example configuration of a remote instance.

<remoteInstance url="https://host:port/registry">
    <id>instanceId</id>
    <username>username</username>
    <password>password</password>
</remoteInstance>

More than one remote instance can be attached to a given WSO2 product by adding the relevant configuration details as seen above. Each remote instance must be given an identifier along with valid credentials that have sufficient privileges to perform the desired registry operations (requires at least read-privileges to the registry along with permission to log-in to the server). The URL of the remote instance can be deduced as follows:

Let the URL of the destination server be https://localhost:9443/services. Then the URL of the remote instance will be https://localhost:9443/registry. Let the URL of the destination server be https://10.20.30.40:9445/webcontext/services. Then the URL of the remote instance will be https://10.20.30.40:9445/webcontext/registry.

The cache id is an optional parameter and should be used only if multi-node replicated caching is enabled. The cache id should be in the format of databaseUser@databaseURL. For example, the cache id for a remote instance running with the default embedded H2 database will be wso2carbon@jdbc:h2:repository/database/WSO2CARBON_DB.

WebService-Based Remote Instance Configuration

• url - The URL of the remote instance.
• id - Remote instance id.
• username - Username of the remote registry login.
• password - Password of the remote registry login.
• type - Set the type to ws.
• cacheId - The identifier used in computing cache keys.

Below is an example configuration of a remote instance.

<remoteInstance url="https://host:port/registry">
    <id>instanceId</id>
    <username>username</username>
    <password>password</password>
    <type>ws</type>
</remoteInstance>

More than one remote instance can be attached to a given WSO2 product by adding the relevant configuration details as seen above. Each remote instance must be given an identifier along with valid credentials that have sufficient privileges to perform the desired registry operations (requires at least read-privileges to the registry along with permission to log-in to the server). The URL of the remote instance can be deduced as follows:

Let the URL of the destination server be https://localhost:9443/services. Then the URL of the remote instance will be https://localhost:9443/registry. Let the URL of the destination server be https://10.20.30.40:9445/webcontext/services. Then the URL of the remote instance will be https://10.20.30.40:9445/webcontext/registry.

The cache id is an optional parameter and should be used only if multi-node replicated caching is enabled. The cache id should be in the format of databaseUser@databaseURL. For example, the cache id for a remote instance running with the default embedded H2 database would be, wso2carbon@jdbc:h2:repository/database/WSO2CARBON_DB.

Mount Configurations

Once a remote instance has been defined a collection on the remote registry can be mounted to the local instance.

• path - The path to which the mount will be added to.
• overwrite- Optional. Defines whether an existing collection at the given path will be overwritten or not.
• instanceId - Remote instance id.
• targetPath - The path on the remote registry.

Here is an example configuration of a mount.

<mount path="/_system/config" overwrite="true|false|virtual">
    <instanceId>instanceId</instanceId>
    <targetPath>/_system/nodes</targetPath>
</mount>

<mount path="/_system/config" overwrite="true">
    <instanceId>instanceId</instanceId>
    <targetPath>/_system/governance/mounting/config</targetPath>
</mount>
<mount path="/_system/config" overwrite="true">
    <instanceId>instanceId</instanceId>
    <targetPath>/_system/governance/mounting/governance</targetPath>
</mount>

Enable Clustering 

To enable clustering for a node, the enable attribute of the configuration in $GREG_HOME/repository/conf/axis2/axis2.xml should be set to true as follows:

<clustering class="org.apache.axis2.clustering.tribes.TribesClusteringAgent" enable="true">

This configuration is responsible for the initialization of a node in the cluster and getting this node to join the cluster.