Re: [DISCUSS] Containerisms

[Richard S. Hall]

 On 10/11/10 10:05, Guillaume Nodet wrote:
On Mon, Oct 11, 2010 at 15:38, Richard S. Hall<he...@ungoverned.org>  wrote:
  On 10/11/10 3:32, Guillaume Nodet wrote:

What I don't get is why we don't get rid of the existing containerims in
Felix:
   * the reference: and inputstream: url protocol for installing bundles

There is no inputstream: URL for installing bundles. The reference: URL is
there largely because Equinox has it and it was created specifically to
match their containerism.

Right, the inputstream stuff seems like an internal way to pass a parameter.
  I may be wrong, but I guess it could be removed alltogether by simply
checking if the input stream parameter is null  in
BundleArchive#createRevisionFromLocation ...

Yeah, possibly. I'd have to look at it.

    * the pluggable cache
We could. I'm not aware of anyone using it. But in reality, I'd like to
find a completely different way to handle the cache. Making it pluggable is
only good design, since it allows us to change our own implementation too.


    * implicit boot delegation
This isn't really a containerism as much as it is trying to faithfully
implement the spec. It tries to workaround stupid assumptions in the JRE.

Out of curiosity, why can it be disabled then if the purpose is to be close
to the spec?

We added the ability to disable it not that long ago, but we 
affectionately refer to as the "magic hack" has existed for many years. 
We allow you to disable it because it is a best effort to approximate 
the spec, but it is not 100% correct, therefore you can disable it if it 
is causing you some difficulty. However, we've tried to constantly 
evolve it over time to incorporate more failing use cases as we uncover 
them. So, I'd expect the need to disable it continues to shrink.


  I suppose there are some more hidden throughout the code.
Probably, but given this list, it looks like we're doing a pretty good job.

As I said in another message, we look at everything on a case-by-case
basis. There is no blanket answer, but typically things that break
abstractions or encapsulation will be frowned upon.

Certainly there are places were we have container-specific behavior, but it
is often due to leeway in the spec. In other cases, I can almost assure you
that I discuss them with Tom Watson to make sure we can align such areas if
possible.

Yeah, I can see the purpose of trying to not introduce containerism, but
can't at the same time oppose to any change in the spec and oppose to any
containerism.   Users have some needs and there must be a way for Felix to
fullfill those.

What I don't get is why can't Felix Framework be a source of innovation for
solving real problems in OSGi, like AOP or such.   You can't certainly
believe the OSGi spec is perfect and that all use cases have been addressed,
else it would not evolve anymore.  Having to wait 2 years for the OSGi
alliance for publish an update to the spec, then 6 months for Felix to
implement and release it  isn't really a good solution for Felix users.

Again, we are willing to look at anything. Where do you think the 
standard launching and embedding API came from in R4.2? You should've 
seen the Virtual Bundle stuff I was cooking up before it was shelved. If 
you have a proposal for some great way to do AOP in a modular way, I'd 
definitely like to hear it. (Especially given the not so great byte code 
weaving RFC.)

I assume you are not equating getting real URLs with innovation, because 
to me it is just a hack even if/when it becomes standardized.

My original problem isn't really solved by the jarurl dir (if implemented as
drafted, meaning that Bundle#getResource.
I've been pointed to the Wiring#listResources() in the 4.3 draft which is
closer to my needs actually, but that looks like a much bigger work.

Yeah, tell me about it. I'm not looking forward to it. Originally, that 
was planned to be outside the framework, which I thought was a great 
idea. ;-)

-> richard





->  richard


  On Fri, Oct 8, 2010 at 20:17, Richard S. Hall<he...@ungoverned.org>
  wrote:

   On 10/8/10 14:08, Guillaume Nodet wrote:
  On Fri, Oct 8, 2010 at 18:43, Felix Meschberger<fmesc...@gmail.com>
  wrote:

  Hi,

First of all: I agree with Richard in that we should at all cost
prevent
containerisms.

Second: I do not really understand what the problem is, that must be
solved with this containerism and which cannot be solved with regular
OSGi API.

  The real problem is to be able to discover resources in the bundle
class

space. For example, i want to know all resources in foo/bar/**/*.xml The
OSGi API does not provide any way to do that atm and a lot of libraries
use
  some custom things based on jars / file urls to actually iterate and
discover those resources.

The problem is just about a way to actually do things.  It seems in the
enterprise world (JEE, middleware),  we're more keen on bending the
purity
a
bit to the benfit of being able to achieve our goals and we're also more
keen on doing that for third party libraries.

It's true that if you write the whole osgi application from scratch, you
don't really care about supporting third party libraries.
  Unfortunately,
people just won't rewrite a third party product they already use just
because they want to play nicely in OSGi.  That's my use case, and it
seems
it doesn't fit well with Felix goals, so I guess i'll have to support a
custom felix version in order to do that or only support equinox.

I think I'll revert my commit as if the plan is to ditch it in the next
felix version, there's really no point in even using such a hack from my
pov.

  Which is precisely the point from my perspective. Not only do you want
the
hack, but you want it maintained forever. That's precisely what I think
we
should avoid.

If you are keen on having your own custom version of Felix, we can always
start a new subproject so you can work on one that you think is better.
It
doesn't bother me to have two framework impls...as I've said many times,
the
framework is just a subproject like any other. Just create a fork and
call
it something completely different so there is no confusion.

->   richard



   Third: For us outsiders of the specification process it is very hard to
understand what insiders are talking of with respect to upcoming
specifications (I only learned 5 minutes ago, that there is a public
draft for 4.3). This issue must probably be solved by OSGi...

Regards
Felix

On 08.10.2010 16:37, Guillaume Nodet wrote:

  I was planning to start a discussion around that, so let's do that
now.

I'm not convinced we should remove this hack when classpath scanning
is
implemented, mostly because even if then ultimately try to solve the
same
problem, they will certainly do it in a different way.  What I mean is

  that
  AFAIK, the classpath scanning stuff will result in a new api on the
  bundle
  or bundleContext to iterate through resources, which means that in
order

  to
  support existing libraries, you kinda have to rewrite the whole thing
in
order to accomodate those apis (especially if they are written so that

  they
  work outside of osgi).
I think the hack i've written allows a smoother integration of those
libraries, with the drawback that you know it can break in certain
conditions.

Also, your comment says "Do not make containerisms public."
In that case, it's not really public because the public face of the
Felix
Framework is the OSGi api.
I guess the question comes down to wether we want Felix to remain pure
(without containerisms) or make it easier for people to use it (by

  bending
  the edges when it makes sense to allow people to deploy their existing
libraries without rewriting the whole thing).
Imho, Felix is not a research prototype, nor supposed to be the
cleaneest
reference implementation of OSGi, so adapting to the users makes sense

  imho,
  provided that it's done conciensouly by the user by activating a flag
or
accessing a non public api (we fall in that case here imho).

Thoughts?

On Fri, Oct 8, 2010 at 16:22,<rickh...@apache.org>    wrote:

  Author: rickhall

Date: Fri Oct  8 14:22:39 2010
New Revision: 1005843

URL: http://svn.apache.org/viewvc?rev=1005843&view=rev
Log:
Do not make containerisms public. (FELIX-2645)

Modified:



  
felix/trunk/framework/src/main/java/org/apache/felix/framework/ExtensionManager.java

  felix/trunk/framework/src/main/java/org/apache/felix/framework/ModuleImpl.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/URLHandlersBundleURLConnection.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/ContentDirectoryContent.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/DirectoryContent.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/JarContent.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Content.java

  
felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Module.java

Modified:

felix/trunk/framework/src/main/java/org/apache/felix/framework/ExtensionManager.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/ExtensionManager.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/ExtensionManager.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/ExtensionManager.java

Fri Oct  8 14:22:39 2010

@@ -610,6 +610,7 @@ class ExtensionManager extends URLStream
         return null;
     }

+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     public URL getEntryAsURL(String name)
     {
         return null;
@@ -763,6 +764,7 @@ class ExtensionManager extends URLStream
             return
getClass().getClassLoader().getResourceAsStream(urlPath);
         }

+        // TODO: REMOVE - Remove when class path scanning is

  implemented.
         public URL getLocalURL(int index, String urlPath)

         {
             return getClass().getClassLoader().getResource(urlPath);

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/ModuleImpl.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/ModuleImpl.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/ModuleImpl.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/ModuleImpl.java

Fri Oct  8 14:22:39 2010

@@ -1091,6 +1091,7 @@ public class ModuleImpl implements Modul
         return getContentPath()[index - 1].getEntryAsStream(urlPath);
     }

+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     public URL getLocalURL(int index, String urlPath)
     {
         if (urlPath.startsWith("/"))

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/URLHandlersBundleURLConnection.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/URLHandlersBundleURLConnection.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/URLHandlersBundleURLConnection.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/URLHandlersBundleURLConnection.java

Fri Oct  8 14:22:39 2010

@@ -28,7 +28,7 @@ import org.apache.felix.framework.resolv

  import org.apache.felix.framework.util.Util;

-public class URLHandlersBundleURLConnection extends URLConnection
+class URLHandlersBundleURLConnection extends URLConnection
  {
     private Felix m_framework;
     private Module m_targetModule;
@@ -201,7 +201,8 @@ public class URLHandlersBundleURLConnect
      *
      * @return the local URL
      */
-    public URL getLocalURL()
+    // TODO: REMOVE - Remove when class path scanning is
implemented.
+    URL getLocalURL()
     {
         if ((m_targetModule == null) || (m_classPathIdx<    0))
         {

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/ContentDirectoryContent.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/ContentDirectoryContent.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/ContentDirectoryContent.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/ContentDirectoryContent.java

Fri Oct  8 14:22:39 2010

@@ -82,6 +82,7 @@ public class ContentDirectoryContent imp
         return m_content.getEntryAsStream(m_rootPath + name);
     }

+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     public URL getEntryAsURL(String name)
     {
         return m_content.getEntryAsURL(m_rootPath + name);

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/DirectoryContent.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/DirectoryContent.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/DirectoryContent.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/DirectoryContent.java

Fri Oct  8 14:22:39 2010

@@ -133,6 +133,7 @@ public class DirectoryContent implements
         return new FileInputStream(new File(m_dir, name));
     }

+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     public URL getEntryAsURL(String name)
     {
         if ((name.length()>    0)&&    (name.charAt(0) == '/'))

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/JarContent.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/JarContent.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/JarContent.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/cache/JarContent.java

Fri Oct  8 14:22:39 2010

@@ -192,6 +192,7 @@ public class JarContent implements Conte
         return is;
     }

+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     public URL getEntryAsURL(String name)
     {
         try

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Content.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Content.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Content.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Content.java

Fri Oct  8 14:22:39 2010

@@ -120,5 +120,6 @@ public interface Content
      * @return A URL using a standard protocol such as file, jar
      *           or null if not possible.
      */
+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     URL getEntryAsURL(String name);
  }
\ No newline at end of file

Modified:


felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Module.java

URL:


http://svn.apache.org/viewvc/felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Module.java?rev=1005843&r1=1005842&r2=1005843&view=diff

==============================================================================
---

felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Module.java

(original)

+++


felix/trunk/framework/src/main/java/org/apache/felix/framework/resolver/Module.java

Fri Oct  8 14:22:39 2010

@@ -72,5 +72,6 @@ public interface Module
         throws IOException;
     InputStream getInputStream(int index, String urlPath)
         throws IOException;
+    // TODO: REMOVE - Remove when class path scanning is
implemented.
     URL getLocalURL(int index, String urlPath);
  }
\ No newline at end of file