Excel Services consists of both the underlying services running on the server and a set of the Web Parts that are used to display them. In this section, you will look at each of the major components of Excel Services.
The Excel Calculation Services component is responsible for loading workbooks from Trusted File Locations, executing the calculations in the worksheet cells, and refreshing references to external data. Executing a calculation in a spreadsheet within Excel Calculation Services on the server produces exactly the same results as the same formulas executed in the Excel 2007 client. Excel Calculation Services manages security of the calculations in the workbooks, ensuring that no unauthorized external data source is called during recalculation. Excel Calculation Services is an application role that can be run on a separate server from the Web front-end components and can be load-balanced across multiple servers. The Excel Calculation Services component also manages caching of data related to workbooks for improved performance. The data cached includes the sheets and graphs, as well as the state of ongoing calculations and the results from external data queries.
Excel Web Access is the feature set that allows Excel 2007 workbooks to be rendered as HTML in a Web browser. Excel Web Access enables users to load entire workbooks in the browser and interact with them in much the same way as they could inside Excel, short of saving any changes to them. Excel Web Access requires no client installation beyond the browser and does not download any code to the user's workstation. The Excel Web Access Web Part is a standard Web Part that can be placed on any Web Part page and used to render all or part of an Excel workbook stored in a Trusted File Location.
Excel Web Services is the component of Excel Services that supports programmatic access to Excel workbooks stored on the server. Developers can write code to pass parameters to workbooks, refresh calculations, and retrieve results through Excel Web Services. This functionality allows organizations to remotely call server-side logic stored in workbooks in SharePoint for use in other applications without having to port or rewrite the code.
The Excel Calculation Service Proxy is responsible for coordinating requests for calculations from the Excel Web Access and Excel Web Services components to the Excel Calculation Services component. On a single-server machine, this is a simple hand-off operation. In a multiserver farm, the Excel Calculation Service Proxy is also responsible for load balancing requests between Microsoft Office SharePoint Server 2007 servers running the Excel Calculation Services component.
The Report Center template is the starting point for business intelligence portals in Office Server 2007. It provides a ready-to-use layout for organizing workbooks, reports, scorecards, data connections, and dashboards. A site based on the Report Center template can store multiple different sets of data focusing on distinct aspects of the organization or it can focus on displaying the progress results toward one specific goal.