PageBox |
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| Mapper component Mapper is a facility embedded in the Application Server version of JSPservlet. The diagram above shows the problem that it addresses. Requestor 1 and 2 call a Presentation entry page. They know only its well-known URL, therefore they are routed to the same PageBox A, which is not the best one for Requestor 1 and 2. The difference can be significant. Let say PageBox A is at 300ms of Requestor 1 and at 200ms of Requestor 2, whereas PageBox B is at 25ms of Requestor 1 and PageBox C is at 30ms of Requestor 2. Mapper has recorded the location of all PageBoxes that have subscribed and therefore host the presentation. So when requestor 1 makes a subsequent request, it is routed to PageBox B. When requestor 2 makes a subsequent request, it is routed to PageBox C. Note that Mapper includes a load balancing facility. If requestor 3 - a neighbor of 1 makes a request, it can be routed to PageBox D, in the same area as PageBox B. With that facility, PageBox not only enhances the performance, it also provides a scalability only limited by backends systems that PageBoxes invoke. You can browse Mapper documentation for more information. Downloadable documentation Rationale
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