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Exposing an RDBMS Datasource¶

This example demonstrates how RDBMS data (stored in a MySQL database) can be exposed as a data service.

Prerequisites¶

Let's create a MySQL database with the required data.

Install the MySQL server.
Create a database named Employees .
```
CREATE DATABASE Employees;
```

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));

Synapse configuration¶

Given below is the data service configuration you need to build. See the instructions on how to build and run this example.

<data enableBatchRequests="true" name="RDBMSDataService" serviceGroup="" serviceNamespace="">
    <description/>
    <query id="GetEmployeeDetails" useConfig="Datasource">
        <sql>select EmployeeNumber, FirstName, LastName, Email, Salary from Employees where EmployeeNumber=:EmployeeNumber</sql>
        <param name="EmployeeNumber" paramType="SCALAR" sqlType="STRING"/>
        <result element="Employees" rowName="Employee">
            <element column="EmployeeNumber" name="EmployeeNumber" xsdType="xs:string"/>
            <element column="FirstName" name="FirstName" xsdType="xs:string"/>
            <element column="LastName" name="LastName" xsdType="xs:string"/>
            <element column="Email" name="Email" xsdType="xs:string"/>
            <element column="Salary" name="Salary" xsdType="xs:string"/>
        </result>
    </query>
  <config id="Datasource">
    <property name="driverClassName">com.mysql.jdbc.Driver</property>
    <property name="url">jdbc:mysql://localhost:3306/Employees</property>
    <property name="username">root</property>
    <property name="password"></property>
    <property name="dynamicUserAuthClass">com.mysql.jdbc.Driver</property>
  </config>
    <query id="AddEmployeeDetails" useConfig="Datasource">
        <sql>insert into Employees (EmployeeNumber, FirstName, LastName, Email, Salary) values(:EmployeeNumber,:FirstName,:LastName,:Email,:Salary)</sql>
        <param name="EmployeeNumber" paramType="SCALAR" sqlType="STRING"/>
        <param name="FirstName" paramType="SCALAR" sqlType="STRING"/>
        <param name="LastName" paramType="SCALAR" sqlType="STRING"/>
        <param name="Email" paramType="SCALAR" sqlType="STRING"/>
        <param name="Salary" paramType="SCALAR" sqlType="STRING"/>
    </query>
    <query id="UpdateEmployeeDetails" useConfig="Datasource">
        <param name="EmployeeNumber" paramType="SCALAR" sqlType="STRING"/>
        <sql>update Employees set FirstName=:FirstName, LastName=:LastName, Email=:Email, Salary=:Salary where EmployeeNumber=:EmployeeNumber</sql>
        <param name="FirstName" paramType="SCALAR" sqlType="STRING"/>
        <param name="LastName" paramType="SCALAR" sqlType="STRING"/>
        <param name="Email" paramType="SCALAR" sqlType="STRING"/>
        <param name="Salary" paramType="SCALAR" sqlType="STRING"/>
    </query>
    <resource method="GET" path="Employee/{EmployeeNumber}">
        <call-query href="GetEmployeeDetails">
            <with-param name="EmployeeNumber" query-param="EmployeeNumber"/>
        </call-query>
    </resource>
    <resource method="POST" path="Employee">
        <call-query href="AddEmployeeDetails">
            <with-param name="EmployeeNumber" query-param="EmployeeNumber"/>
            <with-param name="FirstName" query-param="FirstName"/>
            <with-param name="LastName" query-param="LastName"/>
            <with-param name="Email" query-param="Email"/>
            <with-param name="Salary" query-param="Salary"/>
        </call-query>
    </resource>
    <resource method="PUT" path="Employee">
        <call-query href="UpdateEmployeeDetails">
            <with-param name="EmployeeNumber" query-param="EmployeeNumber"/>
            <with-param name="FirstName" query-param="FirstName"/>
            <with-param name="LastName" query-param="LastName"/>
            <with-param name="Email" query-param="Email"/>
            <with-param name="Salary" query-param="Salary"/>
        </call-query>
    </resource>
</data>

Tip

If you use External instead of the Default as the datasource type, your datasource should be supported by an external provider class, such as com.mysql.jdbc.jdbc2.optional.MysqlXADataSource.

After an external datasource is created, it can be used as another datasource in queries. See the example on handling distributed transactions for more information on using external datasources.

Build and run¶

Create the artifacts:

Set up ESB Integration Studio. The path to this folder is referred to as MI_TOOLING_HOME throughout this tutorial.
Download the JDBC driver for MySQL from here and copy it to the MI_TOOLING_HOME/Contents/Eclipse/runtime/microesb/lib/ (for MacOS) or MI_TOOLING_HOME/runtime/microesb/lib/ (for Windows) directory.

Note

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.
Create a Data Service project.
Create the data service with the configurations given above.
Deploy the artifacts in your Micro Integrator.

Let's take a look at the curl commands that are used to send the HTTP requests for each of the resources:

Post new data¶

Create a file called employee-payload.xml file, and define the XML payload for posting new data as shown below.

<_postemployee>
    <EmployeeNumber>3</EmployeeNumber>
    <FirstName>Will</FirstName>
    <LastName>Smith</LastName>
    <Email>will@google.com</Email>
    <Salary>15500.0</Salary>
</_postemployee>

Send the following HTTP request from the location where the employee-payload.xml file is stored:

curl -X POST -H 'Accept: application/xml'  -H 'Content-Type: application/xml' --data "@employee-payload.xml" http://localhost:8290/services/RDBMSDataService/employee

Get data¶

The service can be invoked in REST-style via curl ( http://curl.haxx.se ). Shown below is the curl command to invoke the GET resource:

curl -X GET http://localhost:8290/services/RDBMSDataService.HTTPEndpoint/Employee/3

This generates a response as follows.

<Entries xmlns="http://ws.wso2.org/dataservice"><Entry><EmployeeNumber>3</EmployeeNumber><FirstName>Will</FirstName><LastName>Smith</LastName><Email>will@google.com</Email><Salary>15500.0</Salary></Entry><Entry><EmployeeNumber>3</EmployeeNumber><FirstName>Will</FirstName><LastName>Smith</LastName><Email>will@google.com</Email><Salary>15500.0</Salary></Entry><Entry><EmployeeNumber>3</EmployeeNumber><FirstName>Will</FirstName><LastName>Smith</LastName><Email>will@google.com</Email><Salary>15500.0</Salary></Entry></Entries>

Update data¶

Create a file called employee-update-payload.xml file, and define the XML payload for updating an existing employee record as shown below.

<_putemployee>
    <EmployeeNumber>3</EmployeeNumber>
    <LastName>Smith</LastName>
    <FirstName>Will</FirstName>
    <Email>will@google.com</Email>
    <Salary>30000.0</Salary>
</_putemployee>

Send the following HTTP request from the location where the employee-update-payload.xml file is stored:

curl -X PUT -H 'Accept: application/xml'  -H 'Content-Type: application/xml' --data "@employee-update-payload.xml" http://localhost:8290/services/RDBMSDataService/employee

Get Swagger definition¶

Copy the following URL to your browser to get the Swagger definition in JSON format:
```
http://localhost:8290/services/RDBMSDataService?swagger.json
```
Copy the following URL to your browser to get the Swagger definition in YAML format:
```
http://localhost:8290/services/RDBMSDataService?swagger.yaml
```

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