Friday, January 24, 2003

TLD listeners and context initialization

Updated and reformated:

JSP spec allows TLDs in any .jar file and in WEB-INF. TLD may contain application listeners. That means tomcat must scan all the .jars, as well as all .TLDs. Even if the app has no JSP or taglib - we still must can all .jars.

This is a pretty expensive operation ( some small test show 2/3 of the startup time on some apps with a lot of jars going in .tld processing ). If you have a lot of .jars or tags - it will be visible.

The simple solution that I checked in will just cache the result in a .ser file in work, and avoid re-scaning if no .jar or .tld has changed. It's "ant-like" ( setters and exec) so it could be used in the deploy tool ( if we had one :-).

Someone could also add a flag to turn off tld scanning - for example if no JSPs are

used ( cocoon, velocity, etc ).

In future this should be extended to include a cache of the extension list ( scanned by the classloader ) and packages ( used to optimize loading ).


This is one of the big errors in the JSP spec (IMO) - other java APIs use META-INF/services or the manifest so at least you read a single entry in a JAR. In JSP - you have to scan the entire META-INF dir, and look for all files with .tld extension. It is nice idea from developer perspective to be able to just drop jars - how you specify the descriptors is a problem.

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