This section introduces the new Web API introduced in Microsoft Dynamics 365. Prior to Microsoft Dynamics 365, the following were the different services provided by Dynamics CRM for executing different operations:

• Organization service: This service has been available since Microsoft Dynamics CRM 2011 and is mainly used for server-side operations. Due to this, the service is tightly coupled with the tools and assemblies provided in the .NET framework. It uses WCF to SOAP endpoints. The request and response have a SOAP format and can return a maximum of 5,000 records in one request.
• Organization data service: This service has been available since Microsoft Dynamics CRM 2011 and is mainly used for client-side operations. It supports the JSON format for request and response and, thus, can easily be handled in client-side scripting. It uses REST endpoints and can return a maximum of 50 records in an operation. It has been deprecated with Microsoft Dynamics CRM 2016.

In Microsoft Dynamics 365, the organization data service has been deprecated and replaced with the Web API. The main purpose of the API is to provide parity with the organization service and try to reduce as many constraints as possible. The following are the main characteristics of the Web API:

• It implements OData version 4.0, which is the open standard for building and consuming RESTful APIs over rich data sources, such as DOC, HTML, and PDF.
• It supports a wide variety of devices, platforms, and programming languages, such as .NET and C++.
• The request and response have the JSON format. Therefore, we can easily work with it in JavaScript.

In upcoming sections, we will explore various Web APIs in further detail.