Developer X, using languages such as Java, .NET, Node.js, or Ruby, uses the HTTP protocol to connect between the two platforms. Salesforce provides APIs to log in and authorize access for you, as well as APIs to manipulate the data in your Custom Objects, much like using Apex DML. Salesforce currently chooses to expose both SOAP- and REST-based variants of its HTTP-based APIs. So, again, you need not develop your own APIs for this type of data integration.

When it comes to exposing application APIs, in order to support SOAP and REST, you will need to develop separate Apex classes in each case for each API that you want to expose. This is because the definition and design of these types are different, though the functionality you're exposing is the same. We will discuss this further later in this chapter.