Hello all,
I am a researcher and software engineering lecturer at University of West
Bohemia, Czech Republic. In my team we have been researching component
compatibility methods and their applications to industrial technologies,
in particular OSGi.
Some time ago I came to know the Apache ACE project, through Marcel
Offermans.
During our discussions, the idea came up that an automated mechanism of
assigning version numbers to bundles and their exported packages, which we
came up with, could be useful for ACE. To cut a long story short, we
are now able
to reliably generate semantic versions (as per the recent OSGi Technical
Whitepaper)
when a bundle is newly stored in ACE repository. The versions are
stored/updated in
the appropriate bundle manifest headers.
This effectively ensures version-implementation consistency across all
bundles managed
by the given ACE repo instance, in other words, no nasty runtime errors
/ exceptions due
to type mismatches in wired bundles obtained from such a repository.
Also, it means
the bundle programmer can be lazy and leave versioning chores to the
repository ;-)
Now then, I have a couple of questions to the community here:
- First, is the explanation clear enough?
- Does this sound interesting? (To me, it certainly does :-) Why yes/no?
- [if yes] How would you imagine/suggest such a thing should be integrated
into ACE?
We of course have an implementation, it extends the plain
org.apache.ace.obr.storage.BundleStore interface to include versioning --
see the attached pieces of code to get an idea how it works (there is
about 0.5MB of libraries hidden behind this small interface). However,
this is our first cut and by no means an ideal solution.
I would be therefore very much interested in any thoughts and ideas
you may have about this versioning ACE repository.
Best,
Premek
PS: A sort of advertisement: we have a bundle versioning service at
http://osgi.kiv.zcu.cz/obvs/ <http://osgi.kiv.zcu.cz/obvs/index.html> -
you are invited to give it a try, I would be interested in any feedback.
--
Premek Brada (Ing et MSc, PhD)
Lecturer in Software enginering, Erasmus coordinator, Webmaster
Department of Computer Science and Engineering
University of West Bohemia, Pilsen, CZ
<< brada at kiv.zcu.cz | www.kiv.zcu.cz/~brada/ | +420-377-63-2435>>
/**
* This is OSGi Bundle Compatibility Checker (OBCC) -- a toolset to verify
* bundle compatibility using type checking on exported and imported
* features.
*
* Copyright (c) 2007-2010 Department of Computer Science and Engineering,
* University of West Bohemia, Pilsen, CZ
*
* This software and this file is available under the Creative Commons
* Attribution-Noncommercial-Share Alike license. You may obtain a copy
* of the License at http://creativecommons.org/licenses/ .
*
* This software is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR
* CONDITIONS OF ANY KIND, either express or implied. See the License
* for the specific language governing permissions and limitations.
*/
package org.apache.ace.obr.storage.versioning;
import java.io.IOException;
import java.io.InputStream;
import org.apache.ace.obr.storage.BundleStore;
/**
* Extends the @see BundleStore by ability to store a bundle that is versioned
along the way.
*
* @author Premek Brada <[email protected]>
*
*/
public interface VersionedBundleStore extends BundleStore {
/**
* Take the bundle from the provided data, update its version metadata
by
* comparing it with the latest revision of equally-named bundle in the
repository,
* create correct filename (symbolic name + updated bundle version),
store result
* in the repository via BundleStore.put(). Leaves and uses bundle
version untouched
* if this is the first revision of the bundle.
*
* @see org.apache.ace.obr.storage.BundleStore
*
* @param bundleData
* Stream with the bundle content
* @return The filename given to the bundle by the repository, null if
not stored
*
* @throws IllegalArgumentException
* When the data provided is not a valid bundle archive
*/
public String put(InputStream bundleData) throws IOException,
IllegalArgumentException;
}
import org.apache.ace.obr.storage.versioning.VersionedBundleStore;
/**
* A simple standalone command line app to demonstrate the versioning interface
* to ACE OBR file repository.
*
* @author Premek Brada <[email protected]>
*
*/
public class Demo {
static String REPO_DIR_NAME = "repo";
private static int BUFFER_SIZE = 8 * 1024;
@SuppressWarnings("deprecation")
public static void main(String[] args) throws Exception {
/*
* repo needs data as InputStream, so create this from bundle .jar and
then
* work with it as if it was provided by higher level layer
*/
InputStream data = createBundleDataStream(args[0]);
/*
* versioned bundle store initialized manually (instead of properties
injection)
* for demonstration purposes, so BundleFileStore was modified by
adding setters
*/
VersionedBundleStore store = setupBundleStore("." + File.separator +
REPO_DIR_NAME);
// store in the versioning repo
String generatedFileName = null;
try {
generatedFileName = store.put(data); // argument is
InputStream data;
}
catch (IllegalArgumentException e) {
System.err.println("Exception on storing: " + e);
}
// observe the result
if (generatedFileName != null) {
System.out.println("File successfully stored with name '" +
generatedFileName + "'");
} else {
System.out.println("Error while storing file '" + args[0] + "'");
}
}
/*
* ... private helper methods omitted
*/
}
