2012/10/17 Mark Thomas <ma...@apache.org>: > On 17/10/2012 15:07, Konstantin Kolinko wrote: > >> 1. Are <PreResource> and <PostResource> able to inject individual files? > > Not yet, but that should be relatively simple to implement. > >> 2. I am -1 on removal of VirtualWebappLoader. >> >> The feature of injecting additional classpath entries into >> WebappClassLoader.super.addURL() is an important one and I use it a >> lot to inject external dependent libraries into web applications. >> >> I do not like your approach as a replacement, because classpath >> entries handling (jars handling) in URLClassLoader and in >> WebappClassLoader is based on different requirements. I think that >> URLClassLoader serves better for external libraries > > Could you expand on this please. I'm struggling to see the difference > between using the VirtualWebappLoader and mapping JARs into WEB-INF/lib > and directories containing classes onto WEB-INF/classes >
There is a difference, but after thinking about it I am removing my veto. 1. If I consider the following two operations a. adding a library to the classpath b. maintaining it as a proper webapplication resource if "a." is all that I need, then having (a. + b.) will have an additional overhead. What VirtualWebappLoader does is essentially similar to putting a library into $CATALINA_BASE/shared. I know of the following overheads: 1.1.) An additional resource participates in resource lookups In my use case I insert a dozen of libraries into the classpath. I do not use VirtualWebappLoader directly, I am calling the API that it uses - WebappLoader.addRepository(). Looking at the example of Tomcat 7 aliases, if you have 100 aliases then every resource lookup will perform a linear search through all the aliases. Regarding my question of injecting individual files into resources - maybe it would be better to support collections of individual files rather than files themselves. E.g. wrap a dozen of libraries into single collection for "/WEB-INF/lib". This way the individual libraries will be enumerated only when one is searching for something with a prefix of "/WEB-INF/lib". Searching for any other prefix will skip the libraries. 1.2.) WebappClassLoader#closeJARs(..) WebappClassLoader closes unused JARs after some time of inactivity. Discussed here: https://issues.apache.org/bugzilla/show_bug.cgi?id=52448 I do not see much sense in this jar closing feature. Anyway, URLClassLoader keeps its jars open. (Not much of an issue, though. If it were a real nuisance, we can make it configurable). 2. There will be small difference with handling of VirtualWebappLoader#setSearchVirtualFirst( ) property. With VirtualWebappLoader and searchVirtualFirst=true the order of precedence when looking of a class is {external classes and libs, webapp classes, webapp libs}. With webresources I think the order will be different, because WEB-INF/classes takes precedence over WEB-INF/lib: {external classes, webapp classes, external libs, webapp libs}. It is a little nuance. I do not think there will be much confusion from it. Best regards, Konstantin Kolinko --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@tomcat.apache.org For additional commands, e-mail: dev-h...@tomcat.apache.org
