Excel Services – Architecture
Before I continue to drill down on the features of Excel Services, I would like to explain the architecture at a high level and touch on configuration possibilities.
Excel Services is built on the SharePoint products and technologies platform. There are three core components of Excel Services
Excel Calculation Service
Excel Web Access
Excel Web Service
Here is what each of these components do.
Excel Web Access – This is a web-part in SharePoint that performs the “rendering” (development team speak for “creating the HTML”) of Excel Workbooks on a web page. This is perhaps the most visible component for the end user. For those of you familiar with SharePoint, you can use it like any other web part in SharePoint to create a wide range of web pages.
Excel网络存取——SharePoint平台网络功能的一部分，负责”编译”(开发团队说这是”生成HTML “)Excel工作簿成为一个网页. 对于最终用户来说这也许是最显而易见的部分. 对于熟悉SharePoint的你,你可以用它像SharePoint其他网络功能一样来建立包括很多行的网页.
Excel Web Services – This component provides the programmatic access that I talked about yesterday. It is a web service hosted in SharePoint. You can use methods in this web service to develop applications that incorporate calculations done by Excel Services and to automate the update of Excel spreadsheets.
Excel网络服务——这个组件提供目录的存取，如同我昨天说的. 这是在SharePoint上的网络服务. 你可以使用这个方法来开发服务网络应用服务,将Excel表格的计算自动更新.
Excel Calculation Service – This is the component that loads the spreadsheets, calculates them, refreshes external data, and maintains session state for interactivity. This is the heart of Excel Services.
Additionally, there is also a proxy that is used internally to handle the communication between the components on the web front end and the application server in multiple-server configurations. It also handles the load balancing in case there are multiple application servers in your installation.
These three components are divided in two major groups – those that live on a front-end server (which we refer to as a “web front end”), and those that live on a back-end application server. In the simplest of the configurations, all these components could be running on the same machine (we call this a “single box” installation). In a typical production environment with significant number of users, the components on the web front end and the application server would be on different machines. It is possible to scale (up or out) these components independently.
这三个组件分为两大类,前台服务器(我们称为”网络前台”)组件,后端应用服务器组件. 在简单的配置中,这些组件可以运行在同机器(我们称之为”单盒”安装). 在有大量不同用户的典型环境中,前台后台组件可以运行在不同的机器上。也就是说在将来这些组件有可能都是独立的。.
Excel Services leverages the security infrastructure provided by SharePoint. Excel services uses SharePoint for authentication (who can log into the server) as well as authorization (who has access to which spreadsheet and the type of access; read, write, view only etc.). This provides a robust security environment for protecting your spreadsheets.
凭借SharePoint安全基础设施Excel服务同样安全. Excel使用SharePoint的认证服务, (登陆服务器)以及授权(获取表格的类型和使用; 读、写、浏览等等). 这个环境为你的表格提供了有力的安全保障.
Performance and Scalability
Excel Services are optimized for scenarios in which multiple users access the same spreadsheets. We have done a lot of work to optimize for this scenario – for example, caching at multiple levels so that collective performance for a group of users is improved by caching spreadsheets as well as external data queried by the spreadsheets. All this is transparent to the end user except for the good response time. (Anticipating a question, we only share cached results between users that have the same rights.)
Excel服务优化了多用户使用同一表格工作. 为优化这种状况我们已经做了大量工作,例如在多层次上的高速缓冲存贮使用户组可以在不同的时间里集体编辑同张表格. 在最终用户希望有很快的反映时间这个问题上所有的一切都是可见的. (预计到了这个问题,对于有相同权限的用户之间我们仅仅共享缓存上的结果).
Excel Services can be scaled up by adding additional CPUs or memory to the server it runs on. It will take full advantage of multiple CPUs to handle multiple requests concurrently. It also supports 64bit CPUs. And it is possible to scale out the web front end and application server components independently, so you can adjust either based on server load and performance requirements. For example, if there is a bottleneck in rendering spreadsheets with Excel Web Access, then you can add more web front ends, and if there is a bottleneck is in calculations, then you can add more application servers to the farm. A lot will depend on the type, size of the workbooks and external data connections in the workbooks you are planning to use with Excel Services. For large deployments, some planning will need to go into the number of users as well as the anticipated workbook mix for the installation. The architecture is designed to meet the needs of a spectrum of deployments from a departmental to enterprise. The multi-tiered approach also allows for better security and isolation of services, for example in extranet scenarios.
Excel服务可相应增加中央处理器或内存以升级的服务器. 它将充分利用多个中央处理器同时处理多个请求. 它也支持64bit中央处理器. 并可以将运行的网络应用服务器前台后台独立分开,可以调整基于服务器负载的性能要求. 举例来说,如果在Excel编译上存在瓶颈, 你可以增加编译网页的资源,如果有一个瓶颈是计算,则可以增加应用服务器的资源. 针对不少取决于类型、规模的电子工作簿,你可以考虑使用Excel服务. 对于大规模的部署你要计划需进入用户数并预期的考虑如何分配安装. Excel服务完全可以满足一系列部署,从企业部门到多层次的安全，还可以更好地隔离服务,例如外联网的情况.
Next time, more detail on publishing a spreadsheet to the server and viewing it in the browser.
Published Thursday, November 10, 2005 9:26 AM by David Gainer
Filed Under: Excel Server