Open Data Protocol (OData) is an OASIS standard that defines the best practice for building and consuming RESTful APIs. OData helps you to focus on your business logic, while building RESTful APIs, without having to worry about the approaches to define request and response headers, status codes, HTTP methods, URL conventions, media types, payload formats, query options, and so on. It is an open standard that is defined by the OASIS consortium.
OData also guides you in tracking changes, defining functions or actions for reusable procedures, sending asynchronous or batch requests, and so on. Additionally, OData provides a facility for extension to fulfill any custom needs of your RESTful APIs.
OData RESTful APIs are easy to consume. The OData metadata, a machine-readable description of the data model of the APIs, enables the creation of powerful generic client proxies and tools. Some of these can help you interact with OData, even without knowing anything about the protocol.
OData currently supports two formats for representing the resources it exposes:
- The XML-based AtomPub
- The JSON formats
Each OData service is represented by a URI, called the service root URI. A URI (Uniform Resource Identifier) is a uniform resource identifier, which is a string of characters used to identify a resource. More precisely, each resource can be accessed using a URL (Uniform Resource Locator), a uniform resource locator, describing how to access the resource. This type of identification enables interaction with representations of the resource across a network using specific protocols like OData.
Types of Documents associated with each OData service
OData and CAP
In a CAP-based application, services are usually articulated through Core Data Services (CDS) models and are managed by the CAP runtime environment. In the CAP framework, every functional component is viewed as a service. These services represent the interactive characteristics of a domain, including the entities they expose, the actions they enable, and the events they trigger.
You now have a more profound understanding of the OData protocol and you can describe its key concept. You also learned about OData in CAP and have heard about the possibility to use different protocols through protocol adapters.