http://www-306.ibm.com/software/webservers/appserv/Doc/v51/ec/infocenter-zh/edge/concepts.htm# HDrWhat_is
WebSphere Application Server Edge Components Introduction
WebSphere is the Internet infrastructure software that allows company to develop, deploy, and integrate next-generation e-commerce applications, such as those merchants' e-trading for merchants. WebSphere middleware supports business applications from simple Web to enterprise-wide transactions.
As the foundation of the WebSphere platform, WebSphere Application Server provides a comprehensive intermediate set, enables users to design, implement, deploy, and manage business applications. These applications include the entire version of the computational infrastructure for the front desk of the simple Web site to the organization.
The functional components of the processor (such as personalization) provide competitive advantages for each e-commerce. However, it is habit to entrust these features to the central server to prevent important functions from extending to the Internet. Therefore, with the increase in new web applications, merchants' Internet infrastructure must also increase their scope and influence. In addition, reliability and security are also important to e-commerce. Even if the minimum service is damaged, it will also cause loss of business.
Edge Components (previously Edge Server) is now part of the WebSphere Application Server product. Edge Components can be used in conjunction with WebSphere Application Server to control access to web servers, and allow business companies to provide better services for web content-based users through the Internet or company internal network. Use Edge Components to reduce web server blocking, increase content availability and improve web server performance. If the name is indicated, Edge Components typically runs near (in the network configuration sense) on the machine's internal network and the inter-Internet boundaries.
WebSphere Application Server contains a cache proxy and Load Balancer Edge Components.
Cache agent
The cache agent reduces the use of bandwidth and improves the speed and reliability of the web site by providing a rendering point node of one or more backend content servers. Cache proxy can cache and serve static content and WebSphere Application Server dynamically generated content and provide them with services.
The proxy server intercepts data requests from the client, retrieves the requested information from the machine of the managed content and sends this content back to the client. The most common case is that the request is for a document stored on a web server (also known as source server or content host), and sends a request using Hypertext Transfer Protocol (HTTP). However, you can configure proxy servers to process other protocols such as File Transfer Protocol (FTP) and Gopher.
The proxy server stores these contents into the local cache before sending the cache content to the requester. Examples of cache content include static web pages and dynamically generated but very few JavaServer Page files. By sending the above content directly from the local cache, the cache enables the proxy server to meet the subsequent request for the same content, and the speed is much faster than retrieving these content from the content host again.
The cache agent's plugin adds some features to the proxy server.
ICP plug-in, which enables the proxy server to query the Cache Cache Protocol (ICP) in the HTML page and other cache resources. Tivoli (R) Access Manager (previously known as Policy Director) plug-in enables the proxy server to use the Access Manager's integrated or authentication service. PAC-LDAP authentication module, which allows proxy servers to access the LDAP server when performing an authorization or authentication routine. WebSphere Transcoding Publisher plug-in, which allows the proxy server to use the WebSphere Transcoding Publisher in combination with a variety of conversion code versions of the content of the mobile device. You can further extend the functionality of the cache agent by writing a custom plug-in module to the application programming interface (API). The API is flexible, easy to use and platform-independent. The agent performs a series of steps for each client to process. The plug-in application will modify or replace a request to process one of the steps in the workflow, such as client authentication or request filtering. Powerful conversion interface, for example, providing access to HTTP data and allows alternatives or transform URLs and web content. The plugin can modify or replace the specified processing step, and you can call multiple plugins for a particular step.
