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A data service provides a Web service interface to access data that is stored in relational databases, CSV files, Microsoft Excel sheets, Google spreadsheets, and more. The following sections describe how you can use WSO2 EI Tooling to work with data services' artifacts. 

Prerequisites

  • Install WSO2 EI tooling using the instructions in Installing Enterprise Integrator Tooling.

  • To demonstrate how data services work, we will use a MySQL database as the datasource. Follow the steps given below to set up a MySQL database:

    1. Install the MySQL server.

    2. Download the JDBC driver for MySQL from here and copy it to your <EI_HOME>/lib directory.

      If the driver class does not exist in the relevant folders when you create the datasource, you will get an exception such as 'Cannot load JDBC driver class com.mysql.jdbc.Driver'.

    3. Create a database named Employees.

      CREATE DATABASE Employees;

    4. Create the Employee table inside the Employees database:

      USE Employees;
CREATE TABLE Employees (EmployeeNumber int(11) NOT NULL, FirstName varchar(255) NOT NULL, LastName varchar(255) DEFAULT NULL, Email varchar(255) DEFAULT NULL, Salary varchar(255));

Creating a data service

Follow the steps given below to create a new data service.

Step 1: Creating a data service project

All the data services' artifacts that you create should be stored in a Data Service project. Follow the steps given below to create a project:

  1. Open the Developer Studio Dashboard (click Developer Studio > Open Dashboard) and click Data Service Project.
  2. Enter a name for the project and click Next.
  3. If required, change the Maven information about the project.
  4. Click Finish. The new project will be listed in the project explorer.

Step 2: Creating the datasource connection

Follow the steps given below to create the data service file:

  1. You can start creating a new data service in two ways:
    1. Open the dashboard (click Developer Studio -> Open Dashboard) and click Data Service.  
    2. Select the already created Data Service Project in the navigator, right click and go to New -> Data Service. 
    The New Data Service window will open as shown below.

  2. To start creating a data service from scratch, select Create New Data Service and click Next.

  3. Enter a name for the data service:

    Data Service NameRDBMSDataService

  4. Click Next and start adding the datasource connection details given below.

    Datasource IDDatasource
    Datasource TypeRDBMS
    Datasource Type (Default/External)Leave Default selected.
    Database EngineMySQL
    Driver Classcom.mysql.jdbc.Driver
    URLjdbc:mysql://localhost:3306/Employees
    User Nameroot
  5. Save the data service.

A data service file (DBS file) will now be created in your data service project. Shown below is the project directory.

Step 3: Creating a query

Let's write an SQL query to GET data from the MySQL datasource that you configured in the previous step:

  1. Select the data service you created in the previous step.
  2. Right-click and click Add Query.

  3. Enter the following query details:

    Query IDGetEmployeeDetails
    DatasourceDatasource
  4. Save the query. The query element is now added to the data service:

  5. Right-click the GetEmployeeDetails query and click Add SQL to add the following SQL statement:

    select EmployeeNumber, FirstName, LastName, Email from Employees where EmployeeNumber=:EmployeeNumber
  6. Save the SQL statement.

  7. Right-click the query again and click Add Input Mapping. 

  8. Enter the following input mapping details:

    Mapping NameEmployeeNumber
    Parameter TypeSCALAR
    SQL TypeSTRING
  9. Save the input mapping.

  10. Right-click the query again and click Add Output Mapping.

  11. Enter the following value to group the output mapping:

    Grouped by ElementEmployees

  12. Save the output mapping.

  13. Right-click the output mapping and go to Add Output Mapping → Add Element to create an element.

  14. Enter the following element details.

    Datasource Typecolumn
    Output Field NameEmployeeNumber
    Datasource Column NameEmployeeNumber
    Schema TypeString
  15. Save the element.

  16. Follow the same steps to create the following output elements:

    Datasource TypeOutput Field NameDatasource Column NameSchema Type
    columnFirstNameFirstNamestring
    columnLastNameLastNamestring
    columnEmailEmailstring
  17. Save the output elements.

The data service should now have the query element added as shown below.

Step 4: Creating a resource to invoke the query

Now, let's create a REST resource that can be used to invoke the query.

  1. Right-click the data service and click Add Resource. Add the following resource details.

    Resource MethodGET
    Resource PathEmployee/{EmployeeNumber}

  2. Expand the GET resource, and click the GetEmployeeDetails (call-query). Connect the query to the resource by adding the following:

    Query IDGetEmployeeDetails
  3. Save the resource.

The data service should now have the resource added as shown below.

Step 5: Testing the data service

You can test the data service artifacts by following the steps given below.

  1. Package the data service file (.dbs file) into a Composite Application (CApp). See the instructions in Packaging Artifacts into Composite Applications.
  2. Add your WSO2 EI product instance to the Tooling environment and deploy the CApp in the server. See the instructions in Deploying Composite Applications in the Server.
  3. Start the ESB profile. The data service is now deployed in WSO2 EI.

  4. Send a GET request to invoke the service. You can use curl as shown below.

    curl -X GET http://localhost:8280/services/RDBMSDataService.HTTPEndpoint/Employee/3

    You will receive the employee's details in the response.

Importing a data service

Follow these steps to import an existing data service descriptor file (DBS file) to a Data Service project in Tooling. Alternatively, you can create a new data service.

  1. You can either use the Data Service link on the dashboard (click Developer Studio -> Open Dashboard) or right-click the Data Service project in the project explorer and click New -> Data Service. 
  2. Select Import Data Service and click Next.

  3. Specify the data service descriptor (DBS) file by typing its full pathname or by clicking Browse and navigating to the file.

    You can test this using the sample data service file.

  4. Optionally, specify the location and working sets for this project. 
  5. A Maven POM file will be generated automatically for this project. If you want to customize the Maven options (such as including parent POM information in the file from another project in this workspace), click Next and specify the options.
  6. Click Finish. The data service is added and is open in the editor. You can now right-click the data service in the outline and add queries, operations, additional data sources, and so on.

Applying security to a data service

WSO2 supports WS-Security, WS-Policy, and WS-Security Policy specifications. These specifications define a behavioral model for Web services. To enable a security policy for a data service, you need to first create a security policy file, and then add it to the data service.

Step 1: Creating a registry resource project

Registry artifacts (such as security policy files) should be stored in a Registry Resource project. Follow the steps given below to create a project:

  1. Open the Developer Studio Dashboard (click Developer Studio > Open Dashboard) and click Registry Resource Project.
  2. Enter a name for the project and click Next.
  3. If required, change the Maven information about the project.
  4. Click Finish. The new project will be listed in the project explorer.

Step 2: Creating a security policy as a registry resource

  1. You can start creating a registry resource in two ways:
    1. Open the dashboard (click Developer Studio -> Open Dashboard) and click Registry Resource.  
    2. Select the already created Registry Resource Project in the navigator, right click and go to New -> Registry Resource. 
    The New Registry Resource window will open as shown below.

  2. Select From existing template and click Next.

  3. Enter the following details:

    Resource NameSample_Policy
    Artifact NameSample_Policy
    TemplateWS-Policy
    Registrygov
    Registry pathws-policy/
  4. Click Finish and the policy file will be listed in the navigator.

    1. Let's use the Design View to enable the required security scenario. For example, enable the Sign and Encyrpt security scenario as shown below.

      Click the icon next to the scenario to get details of the scenario.


    2. You can also provide encryption properties, signature properties, and advanced rampart configurations as shown below.

      Using role-based permissions?

      For certain scenarios, you can specify user roles. After you select the scenario, scroll to the right to see the User Roles button.

      Either define the user roles inline or retrieve the user roles from the server.

  5. Save the policy file.

Step 3: Adding the security policy to the data service

Once you have configured the policy file, you can add the security policy to the data service as explained below. 

  1. If you have already created a data service using Tooling, select the file from the Project Explorer. Alternatively, you can download this sample data service file and import it to your Tooling environment. 

  2. Once you have select the data service file, click the browse icon for the Policy field.

  3. Click workspace, to add the security policy from the current workspace. You can select the path to the sample_policy.xml file that you created in the previous steps.
  4. Click OK, and the security policy will be added to the data service.
  5. Save the data service.

Step 4: Testing the data service with the security policy

Follow the steps given below.

  1. Package the data service file (.dbs file) and the security policy file into a Composite Application (CApp). See the instructions in Packaging Artifacts into Composite Applications.

    Once you create the CApp project, note that the information about each of the projects and artifacts that you packaged into the CApp will be listed (under Dependencies in the Composite Application Project POM Editor).

    Be sure to set the server role to Enterprise Service Bus for the security policy file as shown below

  2. Add your WSO2 EI product instance to the Tooling environment and deploy the CApp in the server. See the instructions in Deploying Composite Applications in the Server.

  3. Start the ESB profile. The data service and the security policy is now deployed in WSO2 EI.

Filtering content by user role (Optional)

When you work with data services, you can control access to sensitive data for specific user roles. This facility is called Role-based content filtering. It filters data where specific data sections are only accessible to a given type of users. Follow the instructions given below to add role-based filtering for output elements in your data service. 

  1. Open the data service file in WSO2 EI tooling.
  2. Add an output element to your data service:
    1. Right-click the data service and click Add Query to add a new query.
    2. Right-click the query and click Add Output Mapping to add an output mapping.
    3. Right-click the output mapping and go to Add Output Mapping → Add Element to add an element.
  3. Add the user roles as a comma-separated list in the Allowed User Roles field for the output element as shown below.

Creating a custom validator

An input validator allows a data service to validate the input parameters in a request and stop the execution of the request if the input doesn’t meet the required criteria. In addition to the default validators provided, you can create your own custom validators by creating a Java class that implements the org.wso2.carbon.dataservices.core.validation.Validator interface. You can create a new custom validator or import an existing validator project.  

Creating a new custom validator

Follow these steps to create a new custom validator. Alternatively, you can import an existing validator project.

  1. You can either use the Data Services Validator Project link on the dashboard (click Developer Studio -> Open Dashboard) or click File-> New -> Other -> Data Services Validator Project option. 
  2. Select Create New Data Services Validator Project and click Next.
  3. Type a unique name for the project and specify the package and class name for this validator.
  4. Optionally, specify the location and working set for this project.
  5. A Maven POM file will be generated automatically for this project. If you want to customize the Maven options (such as including parent POM information in the file from another project in this workspace), click Next and specify the options.
  6. Click Finish. The project is created, and the new validator class is open in the editor where you can add your validation logic.  

Importing a validator project

Follow these steps to import an existing custom validator project. Alternatively, you can create a new custom validator.

  1. You can either use the Data Services Validator Project link on the dashboard (click Developer Studio -> Open Dashboard) or click File-> New -> Other -> Data Services Validator Project option. 
  2. Select Import Project From Workspace and click Next.
  3. Select the existing validator project, and optionally specify the location and working sets for the new project. 
  4. A Maven POM file will be generated automatically for this project. If you want to customize the Maven options (such as including parent POM information in the file from another project in this workspace), click Next and specify the options.
  5. Click Finish. The project is imported, and the validator class is open in the editor, where you can modify the validation logic as needed.

Using an encrypted datasource password

When you create a data service for an RDBMS datasource, you have the option of encrypting the datasource connection password. This ensures that the password is encrypted in the configuration file (.dbs file) of the data service.

Step 1: Encrypting the datasource password

Any plain text password can be encrypted using the Cipher Tool that is shipped with your WSO2 product. This tool uses the secure vault implementation in the product to perform the encryption.

  1. Start by initiating the Cipher Tool. Execute the following command from the <EI_HOME>/bin directory.
    • Linux: sh ciphertool.sh -Dconfigure
    • Windows: ciphertool.bat -Dconfigure
  2. To encrypt your password, execute the same command without -Dconfigure as shown below. 
    • Linux: sh ciphertool.sh 
    • Windows: ciphertool.bat
    This command will prompt you to enter the KeyStore Password of the running Carbon instance. The default is wso2carbon.

  3. Specify the plain text password that is used to log in to your database and execute the command. The encrypted password will be returned.

    Be sure to use the password to the RDBMS that is used in your data service.

  4. Add the encrypted password and an alias to the cipher-text.properties file (stored in the <PRODUCT_HOME>/repository/conf/security/ directory) as shown below. Note that you can use a name of your preference for the password alias. In this example, we have used DB_Password_Alias.

    DB_Password_Alias=<encrypted_value>
  5. Save the file.

Step 2: Using the encrypted password in the data service

Once you have encrypted the datasource password, you can update the data service as explained below.

  1. Select the data service from the project explorer, right click and go to -> Open With -> Text Editor. This will open the data service in text form.

    If you don't have an already created data service in your Tooling environment, you can create a new data service or import an existing data service file.

  2. Update the datasource configuration by adding the secret alias of the password. See the example given below.

    <config id="Datasource">
        <property name="org.wso2.ws.dataservice.user">root</property>
        <property name="org.wso2.ws.dataservice.password" svns:secretAlias="DB_Password_Alias"></property>
        <property name="org.wso2.ws.dataservice.protocol">jdbc:mysql://localhost:3306/Employees</property>
        <property name="org.wso2.ws.dataservice.driver">com.mysql.jdbc.Driver</property>
        <property name="org.wso2.ws.dataservice.minpoolsize"/>
        <property name="org.wso2.ws.dataservice.maxpoolsize"/>
        <property name="org.wso2.ws.dataservice.validation_query"/>
</config>

  3. Add the "http://org.wso2.securevault/configuration" namespace configuration to the datasource as follows:

    <data enableBatchRequests="true" name="RDBMSDataService" serviceNamespace="http://org.wso2.securevault/configuration">

  4. Save the data service file.

Step 5: Testing the data service

You can test the data service artifacts by following the steps given below.

  1. Package the data service file (.dbs file) into a Composite Application (CApp). See the instructions in Packaging Artifacts into Composite Applications.
  2. Add your WSO2 EI product instance to the Tooling environment and deploy the CApp in the server. See the instructions in Deploying Composite Applications in the Server.
  3. Start the ESB profile. The data service is now deployed in WSO2 EI.
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