Re: Class Server requests

Aha! that makes sense.

Altho a return of 404 for the '/' request, which is what i do, should then
prompt the registrar, or whoever is asking for the class, to ask for
individual class files.

BTW, when serving individual classes, the first request is for:

GET /META-INF/PREFERRED.LIST HTTP/1.1

To which i return 404, but was curious what jini was looking for.



----- Original Message -----
From: "Calum Shaw-Mackay" <[email protected]>
To: "Dave Brosius" <[email protected]>
Cc: <[email protected]>
Sent: Sunday, December 31, 2006 12:59 PM
Subject: Re: Class Server requests


>> Yup, and jini should do the same, it's no burden. If it really wants to
>> be
>> that persnickety, it should throw an
>> URISyntaxException or similar exception if it finds an unruly codebase
>> specification.
>
> May I make a small interjection here.....this is not a Jini issue,
> it's actually a URLClassLoader Issue (i.e J2SE) and there are a couple
> of good reasons for it....
>
> if the codebase (or if you are using a straight URLClassLoader outside
> of jini) has a trailing slash, the name of the class is appended to
> the URL request by the URL ClassLoader i.e. com.foo.Bar in
> http://localhost:8080/ would actually be expanded to.....
> http://localhost:8080/com/foo/Bar.class and each individual class
> would result in a request to the Class Servert
>
> However, if you don't add the trailing slash, URLClassLoader assumes
> that the request points to a Zip/Jar File that the classloader can
> download as a single entity then open a Jar Input Stream on which then
> retrieves com/foo/Bar.class, thus meaning that for all classes in that
> jar file, the download only has to occur once, and then can be
> resolved locally from the downloaded file from then on, thus jars are
> more efficient from a transport cost point of view.
>
> In your first post the URLClassLoader is trying to open a file as
> pointed to your codebase, which at the time had no trailing slash
> indicating that the URLClassLoader would expect a JarFile as a
> response, which is wasn't getting, thus causing your errors. By adding
> the trailign slash you placed the URL ClassLoader into what is
> commonly referred to as 'Directory Mode', and would thus append the
> actual classnames to the HTTP request, which then caused it to work.
>
> In fact if your classserver is running in verbose mode, you should see
> each class being requested separately.
>
> So to cut a very long story quite short; appending the trailing slash
> significantly affects the operation of URLClassLoader.
>
> Hope this clarifies the situation
>
> BTW, I'd like to wish everyone a happy and prosperous new year.
>
> --Calum

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