By Matt Rosoff [bio]
Posted: Jun. 16, 2008

The following is a chart accompanying an article published by Directions on Microsoft, an independent research firm focused exclusively on Microsoft strategy & technology. More samples of our content, as well as a list of upcoming articles and reports are also available.

For developers, currently available online services fall into three categories based on the type of benefit they provide: access to valuable data that a developer would have a difficult time collecting; a chance to capitalize on the large base of users for Microsoft Web sites by letting those users access their Microsoft data on a third-party site or service; and the ability to save money by using Microsoft's online infrastructure for certain tasks.

The Methods of Access column describes the specific technologies that developers can use to access a service; in many cases, multiple methods of access are available for a single service. Representational State Transfer (REST) APIs present a service as a computer-readable Web site; applications use the service by reading and writing URL-accessible resources in Web formats such as XML or JavaScript Object Notation (JSON). Simple Object Access Protocol (SOAP) and XML-RPC APIs present a service as a message box; applications use the service by sending and receiving messages in XML. Both types of APIs use the Hypertext Transfer Protocol, the standard Web protocol, for communication but require different programming techniques and technologies.

The Cost column describes prices for developers as of June 2008, which are subject to change. Specifically, Microsoft may begin charging for some services that are currently free.

Microsoft has also made available APIs that let developers interact with or modify Windows Live desktop applications, such as Messenger and Writer. However, because these are applications instead of services, they are not covered here.