[This documentation is preliminary and is subject to change.]
Excel Services was first introduced in Microsoft Office SharePoint Server 2007. Excel Services is a shared service that enables you to load, calculate, and display Microsoft Excel workbooks on Microsoft SharePoint Server 2010.
In Office SharePoint Server 2007, there are two primary interfaces for Excel Services:
An Excel Web Access Web Part, which enables you to view and interact with a live workbook by using a browser
Excel Web Services for programmatic access
In addition, you can extend Excel Calculation Services by using user-defined functions (UDFs).
In SharePoint Server 2010, the following abilities are added to Excel Services:
An ECMAScript (JavaScript, JScript) object model
A REST API
Additional methods and properties in Excel Web Services
Excel Services ECMAScript (JavaScript, JScript)
The ECMAScript object model in Excel Services enables syndication, mashups, automation, and extension of Excel Services. For example, a mashup enables you to combine functionality or data from multiple sources into a single, integrated service, application, or medium.
For more information about the ECMAScript object model, see Excel Services ECMAScript (JavaScript, JScript).
The REST API in Excel Services enables operations against Excel workbooks by using operations specified in the HTTP standard. This allows for a flexible, secure, and simpler mechanism to access and manipulate Excel Services content. For more information about the REST API in Excel Services, see Accessing Excel Services REST API.
Enhancements to Excel Web Services
Excel Web Services is expanded and enhanced in SharePoint Server 2010. You can edit and save a workbook programmatically, amongst other capabilities. For more information about Excel Web Services, see Excel Web Services.