Chapter 2, Leveraging Platform Features, provided a good overview of the many platform APIs available to those integrating with your application from outside of the Force.com platform, from environments such as Java, .NET, PHP, and Ruby. It also provided the best practices to ensure that your application and developers using these APIs have the best experience.
As stated in that chapter, these APIs are mostly focused on record data manipulation and querying, often known as CRUD. Leveraging the Salesforce APIs means developers wishing to learn how to integrate with your application objects can leverage the standard Salesforce API documentation and websites such as https://developer.salesforce.com/.
Tip
Although the Enterprise API provides a strongly typed SOAP API for Java or .NET developers, its larger size can be problematic to load into development environments (as it includes all Custom Objects and fields present in the org). As such, more general Partner API is often a better recommendation to make to Developer X. Most developers are used to generic data access layers such as JDBC and ADO, and in essence to them the Partner API is similar and a lot smaller to embed in their applications. If however, you are recommending an API for mobile or JavaScript integration, the Salesforce REST APIs are even lighter, though come at the added responsibility of the developer to parse and form the correct JSON responses and requests without the aid of generated class types provided via the WSDLs of the SOAP APIs. Typically, languages that prefer more strongly typed programming principles prefer the SOAP variants over the REST variant.
For Java developers, Salesforce provides an excellent Web Service Connector (WSC) framework, which offers an efficient way to consume the SOAP and REST APIs without the need for any other web service stacks. They provide compiled versions of their popular Partner and Metadata APIs, with plenty of examples online. If you're familiar with it, the easiest way to download and start using this API is to use Apache Maven (https://mvnrepository.com/artifact/com.force.api/force-wsc). You can also download WSC from https://github.com/forcedotcom/wsc:
"The Force.com Web Service Connector (WSC) is a high performing web service client stack implemented using a streaming parser. WSC also makes it much easier to use the Force.com API (Web Services/SOAP or Asynchronous/BULK API)."
For .NET developers, Salesforce started an open source initiative to build precompiled assemblies providing access to their APIs, much in the same spirit as the WSC Java library described earlier. You can download the toolkit for .NET from https://github.com/developerforce/Force.com-Toolkit-for-NET:
"The Force.com Toolkits for .NET provides an easy way for .NET developers to interact with the Force.com & Chatter REST APIs using native libraries."
For NodeJS developers, Kevin O'Hara has contributed to the community a library known as nforce to the community. You can download this toolkit for NodeJS from https://github.com/kevinohara80/nforce:
"nforce is node.js a REST API wrapper for force.com, database.com, and salesforce.com."