Remote Instance and Mount Configuration Details

The WSO2 Governance Registry supports the concept of federating the directory structure of the repository across multiple servers. Thus, the structure of collections need not necessarily be existent on a single instance of the server. Each remote instance can be mounted and un-mounted by the simple addition of a configuration describing how to connect to it. The WSO2 Governance Registry's Remote Registry API is used to communicate between such remote instances.

The configurations in this page are all found in the registry.xml file which is located in the <PRODUCT_HOME>/repository/conf folder.

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

JDBC-Based Remote Instance Configuration

Following 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>
    <enableCache>true</enableCache>
    <cacheId>wso2carbon@jdbc:h2:repository/database/WSO2CARBON_DB</cacheId>
</remoteInstance>

Elements of the configuration are explained below.

`url`	The URL of the remote instance.
`id`	Remote instance ID.
`dbConfig`	The database configuration to use, which should not be the currentDBConfig.
`readOnly`	Whether the instance is read-only.
`enableCache`	Whether caching is enabled for this instance.
`registryRoot`	The root of the registry instance.
`cacheID`	This is the cache id of the remote instance. Here the cache id should be in the format of $database_username@$database_url, where $database_username is the username of the remote instance database and $database_url is the remote instance database URL.

Infor

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

Atom-Based Remote Instance Configuration

Note

The Atom-based remote instance configuration is not recommended for use in a production deployment as it does not support transactions.

Following is an example configuration of a remote instance.

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

Elements of the configuration are explained below.

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

You can attach more than one remote instance to a given WSO2 product by adding relevant configuration details. Provide each remote instance 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. Use it 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 should be wso2carbon@jdbc:h2:repository/database/WSO2CARBON_DB.

Note

You cannot mount the same server as a remote instance to itself.

WebService-Based Remote Instance Configuration

Note

The WebService-based configuration is not recommended for use in a production deployment as it does not support transactions.

Following 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>

Elements of the configuration are explained below.

`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.

You can attach more than one remote instance to a given WSO2 product by adding the relevant configuration details as seen above. Provide each remote instance 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.

Note

You cannot mount the same server as a remote instance to itself.

Mount Configurations

Following is an example configuration of a mount.

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

Elements of the configuration are explained below.

`path`	The path to which the mount will be added.
`overwrite`	Defines whether an existing collection at the given path will be overwritten or not. This is an optional field.
`instanceId`	Remote instance ID.
`targetPath`	The path on the remote registry.

Once you have defined a remote instance, a collection on the remote registry can be mounted to the local instance.

Note

It is recommended to refrain from mounting a target path under "/_system/governance" of a remote registry to path "/_system/config". Similarly, refrain from mounting a target path under "/_system/config" of a remote registry to path "/_system/governance". Such configurations can produce unpredictable results.

For example, with the following mounting configurations, "/_system/governance" will be mounted to the correct path, which is "/_system/governance/mounting/governance" but "/_system/config" will be mounted to " /_system/governance/mounting/governance/ mounting/config".

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

Enable Clustering

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

<clustering class="org.wso2.carbon.core.clustering.hazelcast.HazelcastClusteringAgent" enable="true">

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