OData Sample

Exposing a database as an OData service eliminates the need to define queries, operation etc. to access the information in the database. OData (Open Data Protocol) is an OASIS standard that defines the best practice for building and consuming RESTful APIs. You can easily expose databases as an OData service using WSO2 Enterprise Integrator (WSO2 EI).

About the sample

This OData sample was generated to work with the default h2 database (DATA_SERV_SAMP.h2.db), which is used for samples in the WSO2 EI product. This database is stored in the <EI_HOME>/samples/data-services/dbs/odata directory. The details of this database are as follows:

Driver class: org.h2.Driver
JDBC URL: jdbc:h2:file:./samples/database/DATA_SERV_SAMP 

Tables in the DB:

• CUSTOMERS
• ACCOUNTS
• PAYMENTS
• ORDERS
• PRODUCTLINES
• FILES
• PRODUCTS
• FILERECORDS
• EMPLOYEES
• OFFICES
• DEPARTMENT
• ORDERDETAILS

You can find the DDL of these sql tables in the <EI_HOME>/samples/data-services/sql/h2 directory.

Prerequisites

To demonstrate the functionality of reading detail from database views, let's add a view called 'USACustomers' to the H2 database that is used by this sample: Update the CreateTables.sql file (located in the <EI_HOME>/samples/data-services/sql/h2/ directory) with the SQL command shown below. 

CREATE VIEW USACustomers AS SELECT * FROM Customers WHERE country = 'USA';

Building the sample

The sample data service named ODataSampleService should be deployed, and the server should be started using the instructions in Samples Setup.

Executing the sample

You can easily invoke the service using HTTP requests. See the following examples.

• To get the service document:
  

  GET http://localhost:8280/odata/ODataSampleService/default 
  Accept : application/json

• To get the meta data of the service:
  

  GET http://localhost:8280/odata/ODataSampleService/default/$metadata
  Accept : application/xml

• To read customer details:
  

  GET http://localhost:8280/odata/ODataSampleService/default/CUSTOMERS
  Accept : application/json

• To read customer details from the 'USACUSTOMERS' view in the database, send the GET request as shown below. 

  Note the following:

  • This option is available only as a WUM update for WSO2 EI 6.1.1. See the prerequisites for details.
  • Database views can only be used with GET requests.

  GET http://localhost:8280/odata/ODataSampleService/default/USACUSTOMERS
  Accept : application/json

• To add accounts details, send the HTTP request as shown below. In this example, we will be creating an account ID named "1".
  

  POST http://localhost:8280/odata/ODataSampleService/default/ACCOUNTS
  Accept: application/json
  Content-Type: application/json
  Prefer : return=representation
  { "BALANCE" : 12.22 ,"ACCOUNTID" : 1 }

• To delete account details, send the HTTP request as shown below. In this example, we will be deleting the account ID "1".

  DELETE http://localhost:8280/odata/ODataSampleService/default/ACCOUNTS(1)
  Accept: application/json

• To update account details:

  PUT http://localhost:8280/odata/ODataSampleService/default/ACCOUNTS(1)
  Accept: application/json
  { "BALANCE" : 12.22 }

• To invoke a particular query, send the HTTP request as shown below. In this example, we will receive the city and phone numbers of customers.

  GET http://localhost:8280/odata/ODataSampleService/default/CUSTOMERS?$select=CITY,PHONE
  Accept: application/json

• To filter information based on a query, send the HTTP request as shown below. In this example, we will receive the employee details connected to the 'Nantes' city.

  GET http://localhost:8280/odata/ODataSampleService/default/CUSTOMERS?$filter=CITY eq 'Nantes'
  Accept: application/json