On Tue, Jun 23, 2009 at 8:03 AM, Craig Taverner <cr...@amanzi.com> wrote:
> Hi, > > This is my take on the problem - If we register a URL handler, it will > handle all cases. And it will not require any changes to JRuby itself. > Consider this scenario. The URL created looks like this: > > bundleresource://9/./some_script.rb > > This URL is being dealt with inside JRuby. When JRuby tries to access this > URL using the usual approach of url.openConnection() or url.getContents(), > the actual work is passed to the URL handler registered for the protocol > returned by url.getProtocol() which is 'bundleresource'. When not in > equinox, there will be no registered protocol handler, so these URL's are > invalid and will not work, which is correct behaviour, as JRuby should have > no knowledge of equinox. However, when inside equinox, the JVM search for a > protocol handler for 'bundleresource' should succeed if the classloaders are > correctly setup, as described in > http://wiki.eclipse.org/index.php/Context_Class_Loader_Enhancements. > Then what will happen is the JVM will pass the thread that called > url.openConnection() to the equinox bundle URL handler, which will be able > to understand what is meant by the '9'. So the trick here is: > > - Make sure that the 'bundleresource' protocol handler is in fact > registered in an equinox environment, as I believe it must be. (I did a > quick google search and found that the class should be * > org.eclipse.osgi.framework.internal.core.BundleURLConnection*) > - Make sure that code running in JRuby has the correct classloader > arrangement to ensure that the JVM actually does find this URL handler. > (This is probably the only trick here, and probably requires a combination > of setting the context classloader on the thread starting JRuby, as well as > appropriate buddy classloader settings on the plugins). > - Make sure that the URL handler does understand the path, including > the numerical references, like the '9' above. This should be the case, > since > this code should be part of equinox already (ie. * > org.eclipse.osgi.framework.internal.core.BundleURLConnection* should > just work). > > So, my theory here is that all the code already exists, and this is mainly > a classloader issue. A variation on the same classloader issue we have seen > repeatedly in using JRuby in eclipse. > > To learn more about protocol handlers, read > http://java.sun.com/developer/onlineTraining/protocolhandlers/. This > covers also how to write them, which I believe should not be necessary in > this case. Hopefully you can find here the information necessary to > investigate what protocol handlers exist in various contexts (different > plugins, inside and outside the JRuby runtime, etc.) Then you can work out > how to make sure the right handler does exist inside JRuby. > Does this make sense? Any comments? > We're working with pathnames here, not contents, so we don't actually go so far as to open the URL or get its contents, so I'm not sure that what you're describing will actually work. I'd consider it an enhancement at this point to make something like "IO.readlines('bundleresource://9/./some_script.rb')" actually do what you expect (though note that this isn't the same problem that the OP mentioned). Context classloader bugs in JRuby were fixed long ago, so I'm less suspect of that being the problem. /Nick
