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Package com.opencms.flex.cache

Provides the JSP funtionality for OpenCms, with some additional utility functions.

See:
          Description

Class Summary
CmsFlexCache	This class implements the FlexCache.
CmsFlexCacheEntry	Contains the contents of a cached resource.
CmsFlexCacheKey	Implements the CmsFlexCacheKey, which is a key used to describe the caching behaviour of a specific resource.
CmsFlexController	Controller for getting access to the CmsObject, should be used as a request attribute.
CmsFlexRequest	Wrapper class for a HttpServletRequest.
CmsFlexRequestDispatcher	Implementation of the javax.servlet.RequestDispatcher interface to allow JSPs to be loaded from OpenCms.
CmsFlexResponse	Wrapper class for a HttpServletResponse.

 

Package com.opencms.flex.cache Description

Provides the JSP funtionality for OpenCms, with some additional utility functions.

How the JSP integration is done:

The issue for JSP integration was this: In OpenCms all resources are residing in the OpenCms Database, the so called "Virtual File System" or VFS. However, all JSP engines available read the JSP code from a file in the local file system. The option to re-write a JSP engine so that it can read from the VFS would limit OpenCms to running with this JSP engine only, which was not a choice. So the approach that was taken is to dump the contents of the OpenCms JSP page from the VFS to the "real" file system and then dispatch to the standard JSP engine.

Here is a top-level description of how this works:

1. OpenCms gets the request through the com.opencms.core.OpenCmsHttpServlet
2. The requested resource is identified as a JSP page (resource type com.opencms.file.CmsResourceTypeJsp)
3. The JSP launcher is started up with the laucher manager com.opencms.launcher.CmsLauncherManager
4. The JSP launcher implements an additional interface: com.opencms.flex.I_CmsResourceLoader
5. A resource loader is a new interface that was introduced with the FLEX release. The main difference is that the original request / response is wrapped using a Servlet standard javax.servlet.http.HttpServletRequestWrapper / javax.servlet.http.HttpServletResponseWrapper.
6. On the first call to a page, the file contents of the JSP page are read from the OpenCms VFS using the com.opencms.file.CmsObject
7. The contents of the page are written to the "real" file system of the server, in the default configuration to the directories {WEBAPP-PATH}/opencms/WEB-INF/jsp/online or {WEBAPP-PATH}/opencms/WEB-INF/jsp/offline (depending if the request was for the online or the offline version of the page). The directory used can be configured in opencms.properties.
8. After the page is written to the "real" FS, the loader dispatches to the standard JSP mechanism with a simple include() call, this happens in com.opencms.flex.CmsJspLoader#service(CmsObject cms, CmsResource file, CmsFlexRequest req, CmsFlexResponse res).
9. The standard JSP mechanim will handle the JSP and deliver the output through the wrapped request / response back to OpenCms.
10. OpenCms will then deliver the contents back to the user.

Note: The FLEX package was originally developed to add only JSP functionality to OpenCms, but has since then grown to include other methods and functionality.

Since:

FLEX alpha 1

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Overview   Package  Class  Use  Deprecated  Index
Home >> All >> com >> opencms >> flex >> [ cache overview ]	PREV PACKAGE  NEXT PACKAGE

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