Adding RDBMS Data Sources

Data source management capability is provided by the following feature in the WSO2 feature repository:

Name : WSO2 Carbon - Datasource Management Feature
Identifier : org.wso2.carbon.datasource.feature.group

If data source management capability is not included in your product by default, you can add it by installing the above feature using the instructions given in section, Feature Management. Follow the instructions below to add a new Data Source to a running Carbon instance.

1. Log on to the product's management console and select "Data Sources."

2. Click on the "Add Data Source" link in the "Data Sources" page.

3. Specify the required options in the "New Data Source" page. Depending on the data source type, the required fields may vary. Discussed below are the two types available.

RDBMS
Custom Data Source

RDBMS

If you select the "Data Source Type" as RDBMS, the following screen will appear.

This is the default RDBMS data source configuration provided by WSO2. Users can also write your own RDBMS configuration by selecting the Custom Data Source option. The following fields should be provided when defining the default RDBMS data source.

Data Source Type : RDBMS
Name : Name of the data source (This value should be unique.)
Data Source Provider : Discussed below.
Driver : The JDBC driver to be used.
URL : The connection URL to be passed to the JDBC driver to establish a connection.
User Name : The connection user name to be passed to the JDBC driver to establish a connection.
Password : The connection password to be passed to the JDBC driver to establish a connection.
Expose as a JNDI Data Source : Discussed below.
Data Source Configuration Parameters : Additional properties can be defined when creating an RDBMS data source. For more information on these properties, refer to section Properties of RDBMS Data Sources.

The meaning of many fields is similar to the DBCPconfiguration guide, to which you can refer for more information: http://commons.apache.org/dbcp/configuration.html

4. Once the values are entered, click "Save".

5. You have created a carbon data source. Also refer to edit and delete Data Sources.

Data Source Provider

There are two types of data source providers. You can use the default provider or link an external provider. For the 'default' Data Source Provider, given connection properties Driver, URL, User Name and Password need to be entered as follows:

If you need to add a data source supported by an external provider class such as "com.mysql.jdbc.jdbc2.optional.MysqlXADataSource", select the "external" option and enter the name and value of connection properties by clicking "Add Property". Given below is an example data source of External Data source Provider with entered values.

JNDI Data Source

Java Naming and Directory Interface (JNDI) is a Java application programming interface (API) providing naming and directory functionality for Java software clients to discover and look up data and objects via a name. It helps decouple object creation from the object look-up. When you have registered a data source with JNDI, others can discover it through a JNDI look-up and use it.

To expose a data source as a JNDI data source, select the "Expose as a JNDI Data Source".

Name : Name of the JNDI data source which will be visible to others in object look-up.

Use Data Source Factory : If the data source need to be accessed from an external environment Data Source Factory should be used. If this is selected, a Reference object will be created with defined data source properties. Then Data Source Factory will create the data source instancebased on the values of Reference object when accessing the data source from an external environment. In the configuration this is set as useDataSourceFactory="true".

JNDI Properties : Properties related to the jndi data source (Password etc). If Use Data Source Factory is selected, following properties should be specified.

java.naming.factory.initial -This property is used to select the registry service provider as the initial context.

java.naming.provider.url - This property specifies the location of the registry when the registry is being used as the initial context.

Custom Data Source

If you select the "Data Source Type" as Custom, the following screen will appear.

Data Source Type : Custom
Custom Data Source Type : Described below.
Name : Name of the data source (This value should be unique)
Description : Description of the data source
Configuration : XML configuration of the data source

Custom Data Source Type

The actual type of the custom data source can be either "DS_CUSTOM_TABULAR" or "DS_CUSTOM_QUERY". There are two options cover most of the common business use cases.

Custom Tabular Data Sources

Tabular data sources are used when there is a data source which represents its data using tables, where a set of named tables contains data rows that can be queried later.

To implement tabular data sources, the interface "org.wso2.carbon.dataservices.core.custom.datasource.TabularDataBasedDS" is used. A sample implementation of tabular custom data source can be found at InMemoryDataSource.

A tabular data source is typically associated with an SQL data services query. This is done by internally using our own SQL parser to execute SQL against the custom data source. A sample data service descriptor on how this is done can be found at InMemoryDSSample. Also, this is supported in Carbon data sources, with the data source reader implementation "org.wso2.carbon.dataservices.core.custom.datasource.CustomTabularDataSourceReader". A sample Carbon data source configuration file can be found at <CARBON_HOME>\repository\conf\datasources\custom-datasources.xml.

Custom Query Data Sources

Custom query based data sources are created when there is a data source which has some form of a query expression support.

To implement , the interface "org.wso2.carbon.dataservices.core.custom.datasource.CustomQueryBasedDS" is used. Any non-tabular data source can be created using the query-based approach. Even if the target data source does not have a query expression format, users can create their own and it. For example, any NoSQL type data source can be supported using this type of a data source.

A sample implementation of a query-based custom data source can be seen at EchoDataSource. A sample data service descriptor with custom query data sources can be found in action in InMemoryDSSample. This is supported in Carbon data sources, with the data source reader implementation org.wso2.carbon.dataservices.core.custom.datasource.CustomQueryDataSourceReader. A sample of a Carbon data source configuration file can be found at <CARBON_HOME>\repository\conf\datasources\custom-datasources.xml.

In the "init" methods of all custom data sources, user-supplied properties will be parsed to initialize the data source accordingly. Also, a property named "__DATASOURCE_ID__", which contains a UUID to uniquely identify the current data source, will be passed. This can be used by custom data source authors to identify the data sources accordingly. For example, scenarios like data source instances communicating within a server cluster for data synchronization.

Shown below is an example configuration of a custom data source of type 'DS_CUSTOM_TABULAR'.

4. Once the values are entered, click "Save".

5. You have created a carbon data source. Also refer to edit and delete Data Sources .