Item 47. Catalog Common Resources

Many XML processes use system IDs (in practice, URLs) to locate the standard DTDs, schemas, stylesheets, and other supporting files for applications like DocBook, XHTML, and SVG. However, this can put quite a load on the central server, and it means your application may have to wait on a potentially slow remote server you don't control. You might not even be able to process your documents when the central server is down due to hardware failure, a system crash, or network outages. Alternatively, you can use XML catalogs to remap public IDs and URLs. A catalog can convert public IDs like -//OASIS//DTD DocBook XML V4.2//EN into absolute URLs like It can replace ...

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