Changing the Default Broker Database

When you use the Message Broker profile in WSO2 EI, a separate database is required for storing data specific to the broker. This is in addition to the default Carbon database. By default, the EI Message Broker is shipped with an embedded H2 database (WSO2MB_DB.ht.db) for this purpose. These databases are stored in the <EI_HOME>/wso2/broker/repository/database directory.

For instructions on changing the default Carbon database, see Changing the Carbon Database in the WSO2 Product Administration Guide.

Given below are the steps you need to follow in order to change the default broker-specific database.

Setting up the database

You can set up one of the following databases for storing broker-specific data:

Creating the datasource connection

A datasource is used to establish the connection to a database. By default, the WSO2_MB_STORE_DB datasource is configured in the master-datasources.xml file for the purpose of connecting to the default H2 database that stores MB-specific data.

After setting up the MySQL database to replace the default H2 database, either change the default configurations of the WSO2_MB_STORE_DB datasource, or configure a new datasource to point it to the new database as explained below.

Follow the steps below.

Open the <EI_HOME>/wso2/broker/conf/datasources/m aster-datasources.xml file and locate the <datasource> configuration element.
You simply have to update the url pointing to your database, the username and password required to access the database and the driver details as shown below. Further, be sure to set the <defaultAutoCommit> element to false for the MB database.

Optionally, you can update the configuration elements given below for your database connection.

Element	Description
maxActive	The maximum number of active connections that can be allocated at the same time from this pool. Enter any negative value to denote an unlimited number of active connections.
maxWait	The maximum number of milliseconds that the pool will wait (when there are no available connections) for a connection to be returned before throwing an exception. You can enter zero or a negative value to wait indefinitely.
minIdle	The minimum number of active connections that can remain idle in the pool without extra ones being created, or enter zero to create none.
testOnBorrow	The indication of whether objects will be validated before being borrowed from the pool. If the object fails to validate, it will be dropped from the pool, and another attempt will be made to borrow another.
validationQuery	The SQL query that will be used to validate connections from this pool before returning them to the caller.
validationInterval	The indication to avoid excess validation, and only run validation at the most, at this frequency (time in milliseconds). If a connection is due for validation but has been validated previously within this interval, it will not be validated again.
defaultAutoCommit	It is required to disable auto committing by setting this property to `false` for the MB database. This means that multiple SQL statements will be committed to the database as one transaction, as opposed to committing each SQL statement as an individual transaction.

For more information on other parameters that can be defined in the <EI_HOME>/wso2/broker/conf/datasources/ master-datasources.xml file, see Tomcat JDBC Connection Pool.

Updating other configuration files

Open the <EI_HOME>/wso2/broker/conf/broker.xml file. This is the root configuration file of the EI Message Broker profile. The changes made to this file must be done in all the broker nodes.
In the broker.xml file we need to use the Oracle message store and Andes context store. To do this, uncomment or add the following configuration.
```
...
<messageStore class="org.wso2.andes.store.rdbms.RDBMSMessageStoreImpl">
           <property name="dataSource">WSO2MBStoreDB</property>
</messageStore>

<andescontextStore class="org.wso2.andes.store.rdbms.RDBMSAndesContextStoreImpl">
           <property name="dataSource">WSO2MBStoreDB</property>
</andescontextStore>
```
The elements in the above configuration are described below.
- The fully qualified name of the respective implementation class should be defined under the class attributes of messageStore and andesContextStore elements. This implementation class will be used by the broker to persist relevant information.
- The <property> elements are used to define different properties for each store. The minimal property for starting each store is the dataSource property. Depending on the implementation, the required properties may differ.

Creating database tables

To create the database tables, connect to the database that you created earlier and run the following scripts: