REST Web services

You already know that Web services are software systems designed to support interoperable machine-to-machine interaction over a network. In this section, we are going to talk about another type of Web service: REST Web services. This kind of service uses HTTP for communication and is based on the REST (REpresentational State Transfer) architectural style as protocol for exchanging messages.

Following the specification:

• The primary purpose of REST is to manipulate representations of Web resources using a uniform set of stateless operations.
• It does not require XML-based protocols (like SOAP and WSDL) to support its light-weight interfaces.
• It defines a set of operations using predefined HTTP verbs (GET, PUT, POST, or DELETE).
• The format of the information returned (representation) is typically HTML, XML or JSON, although it may be an image, plain text, or other format.

Just like SOAP, Denodo can publish any base/derived views and interfaces as REST Web services to enable external applications (or users using their browser) to retrieve data from the Data Virtualization layer.

Creating REST web services in Denodo

To create your first REST Service:

1. Open the Web Design tool and create a new folder called "REST".
2. Click on the option of the "2 - Data Services" and select New > Data service > REST Web service.
   
3. This will open the new REST Web service dialog. This dialog has similar tabs to the "Create SOAP Web service" dialog:
   • Resources: here you can define the REST service.
   • Settings: manages the configuration, representation formats and authentication.
   • Advanced: in this tab you can change the parameters of the connection between the Web service and Denodo server.
   

New operation

In the first tab, Resources, you can add views to the Web service. You only have to drag any view/stored procedure/interface into this dialog to add them.

1. First, drag the i_client_info interface into the workspace panel.
2. Rename the REST Service customer by clicking the web service name space at the top.
3. Since you are only going to search for clients with their ID, remove the rest of fields from input i_client_info in the dialog. Press + next to i_client_info, click on icon except client_id.
   

More settings

REST web services have more configurations available in the second tab (Settings).

In this tab you can complete the REST Web service definition by selecting the output representation format. By default, HTML, XML and JSON are made available.

Another important configuration is the authentication method. By default, created REST services don't have any authentication method and any connection could use it. In this example, simply select the HTTP Basic with VDP method (leaving the Accepted user(s) field empty) to delegate the authentication to the Denodo server.

Finally, click on Save, to create the REST Web service.

Now, you have created a SOAP and a REST web service in Denodo. In the next section, you are going to see how to deploy them with the Denodo Internal Web Container.