Here is my configuration:
We are developing an OSGi application and want to include logging. I decided to use slf4j + logback.
We are using Eclipse as an IDE and Tycho to benefit from the Eclipse IDE like Manifest Editor and so on.
So I have tried the following:
Created a new plugin with the following Manifest.mf:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Createcommand
Bundle-SymbolicName: de.hswt.oms.ws.wsr.createcommand
Bundle-Version: 1.0.0.qualifier
Bundle-RequiredExecutionEnvironment: JavaSE-1.7
Import-Package: de.hswt.oms.ws.command.wsr,
de.hswt.oms.ws.ds.core.data.impl,
org.slf4j
Service-Component: OSGI-INF/component.xml
Now when i move to Run -> Run Configurations -> OSGi Framework and select my Bundle and click "Add Required plugins" more than 100 Bundles will be selected and I get a lot of errors and exceptions.
So I came up with a new plugin from existing Jars which include the following three jars:
logback-classic-1.0.7
logback-core-1.0.7
com.springsource.slf4j.api-1.6.1 (I dont believe this is a good idea, but hey...)
If I create a new run configuration manually (not clicking "add required bundles" it works as expected but as far as I click "add required bundles" I come back to the more then 100 Bundles with a lot of errors (some Jetty stuff for example...)
So my Question is: How can I enable logback and slf4j in my OSGi application and use it within eclipse and configure it properly?
If you need more information please feel free to ask.
AFAIK there are some issues in the bundle manifest header in the current official Logback/SLF4J jars. However, you only need the following three jars/bundles. No other are required for the basic functionality.
SLF4J API
Logback Core
Logback Classic
At Eclipse we put the bundles in Orbit for re-use across projects. We apply some modifications to the manifest header that we think are beneficial. For example, we deliver the actual SLF4J binding as a fragment to avoid the circular dependency of the original SLF4J API jar.
Here are the download links to the bundles:
org.slf4j.api
ch.qos.logback.core
ch.qos.logback.classic
ch.qos.logback.slf4j
You may also want:
org.slf4j.ext
org.slf4j.jcl (Commons Logging via SLF4J)
org.slf4j.jul (Java Logging Bridge)
org.slf4j.log4j (LOG4J via SLF4J)
Please note that "Add Required plugins" is not smart enough. It may select too many or too few plug-ins. Sometimes service API is delivered in one bundle but the actual service implementation is delivered in a second bundle. It may not select that bundle.
There is a checkbox saying something like 'Resolve optional imports'. It's on by default, but that pretty much always results in the behaviour you describe, that it wants to add everything.
Switching that off should help. also, PDE tends to add a lot of fragments that are not needed.
All in all, I rarely trust Eclipse with adding the 'right' bundles for runtime. I just use 'validate' and add whatever is needed manually, and check again. It might take a few minutes but figuring out what went wrong when you leave it to PDE can take hours.
Not sure about logback but you may also want to try pax logging. Just install pax logging api and pax logging service and it should work. There is also a documentation how to set it up in eclipse.
If you want it to use with Eclipse Equinox, you could try the Eclipse-BuddyPolicy. This enables one plugin to load all classes from another plugin without importing it explicitly.
This may solve your problem.
Add to your Manifest from the bundle with the jars:
Eclipse-BuddyPolicy: dependent
and to the bundle using the logging
Eclipse-RegisterBuddy: com.other.plugin
see http://help.eclipse.org/juno/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fmisc%2Fbundle_manifest.html
Related
I have an OSGi application (Eclipse plugin) that contains several bundles.
I have a com.domain.dependencies bundle that, as the name suggests, contains dependencies. There is NO code in this bundle. The concept is that all 3rd-party dependencies used by 1+ other bundles are contained in this bundle and made available to other bundles within the plugin. This has always worked for the past decade or so that this plugin has evolved.
The above bundle 'pulls in' log4j - an older log4j version 1.x. So, log4j has always been exposed as an available library to other bundles that use com.domain.dependencies.
Due to the recent security issues with log4j2, a company security directive/edict has stated that all use of log4j or log4j2 must be upgraded to log4j2 v2.16.0
Initially I thought I'd just change the declaration in the build.gradle file for com.domain.dependencies to pull in that newer log4j2 but discovered that log4j2 is split in to 'core' and 'api' jars. OK so I tried to use those instead. I then followed the Apache migration steps for moving from log4j 1.x to 2.x, updated all the code etc.
After the above, compilation fails. None of the other bundles 'see' log4j2 as they saw log4j. A bit of Googling and I see people talk about creating OSGi Fragments. What's a Fragment? I've read a bit about them and feel none the wiser when it comes to my issue.
I should point out that my plugin also has a dedicated bundle com.domain.log, which depends on com.domain.dependencies and it's the com.domain.log bundle that contains the log4j.properties file (which also needs tweaking for log4j2). This logging bundle wrapped log4j (and soon to be log4j2) to expose logging features to the other bundles within the plugin.
So when it comes to using fragments, I am confused. I see some articles on the internet suggest at least 2 bundles are required. I don't know if these have to be new, or if I can re-use my existing arrangement of bundles. I struggle to relate those articles to how things are currently set up in my plugin, but I wish to maintain the idea that com.domain.dependencies supplies dependencies to other bundles and has no code of itself, while also having the com.domain.log continue to expose the same logging functionality to the other bundles that need it.
My instinctive feelings are that com.domain.log which exposes logging functionality to my other bundles, should use log4j-api, while com.domain.dependencies should obtain log4j-core (implementation) and expose it to com.domain.log. However, I can imagine too many different ways to try and set this up, and all will fail unless I am doing it the right way. Basically, I need help from somebody who knows how to in an OSGi environment.
So, how should I wire-in log4j2 to mimic the traditional behaviour/functionality in my OSGi environment?
I am learning AOP with Spring framework and I want to set the javadoc for AOP in eclipse. So what I did I downloaded aspectj-1.8.10.jar from eclipse web site https://eclipse.org/aspectj/downloads.php#install then I installed that jar and got 4 new jar files: aspectjrt.jar, aspectjtools.jar, aspectjweaver.jar, org.aspectj.matcher.jar which I added to my class path in eclipse. Now what I want is to add source files for these jars so, for example, when I hover over #Aspect I want to be able to see what this annotation represents. Unfortunately I can not find the source files for these jars, on the eclipse website mentioned above there is a file aspectj-1.8.10-src.jar but I'm not sure what to do with it, I tried to attach this file directly in the build path for each of the jars mentioned above but it didn't do the trick. Also I thought that maybe I had to install aspectj-1.8.10-src.jar the way I installed aspectj-1.8.10.jar so I would get 4 source files, but I'm not sure how (if possible) to install it, when I double click aspectj-1.8.10-src.jar, installation does not get triggered.
So can you please help me out to add javadoc for AspectJ 1.8.10 in Eclipse?
Select the library in your Eclipse project explorer window, click right button, select properties, select javasource attachment or javadoc location and enter the path to the source or javadoc file.
But I would suggest to use maven to maintain the dependencies of your project. It makes getting javadoc much easier, because libraries, source code and javadoc are fetch from a central repository. You just add the library you need in your project configuration (pom.xml file) and the other files are fetched for you.
You do not need all those libraries. Please first learn which one serves which purpose. E.g. aspectjrt is the runtime. When using Spring AOP you actually do not really use AspectJ, only a subset of its syntax. Thus, the runtime is needed for identifying some of the annotation classes. However, aspectjweaver is only needed if you want to use full AspectJ in a load-time weaving (LTW) scenario, with or without Spring. The weaver lib is a superset of the runtime, so you only need one of them. Last, but not least, aspectjtools again is a superset of the weaver lib and contains the AspectJ compiler (among other tools). This is only needed for compile-time weaving as part of your toolchain.
I do not think that source code and Javadoc will help you much in learning AspectJ. I suggest you read the Spring manual's AOP chapter describing both proxy-based Spring AOP and full AspectJ integration via LTW. If you want to learn AspectJ basics and maybe just use AspectJ without Spring (which is what I do), read the AspectJ documentation.
If you are still not convinced and want to add source and JavaDoc to your Eclipse project, why don't you follow jaysee's advice and use Maven? Then you get all the source/javadoc libs for free. But anyway, you can also load those JARs directly from Maven Central, e.g. the source and javadoc for AspectJ runtime 1.8.10. Good luck! But I assume you will be disappointed because the AspectJ JavaDoc is really bad for learning purposes and not suited to understanding how to actually use AspectJ.
I am stuck with a problem I can't solve for weaks now.
I have to create a modular JavaFX application, where each component defines a "domain unit" (with models+views+controllers). Each component can be loaded into a "shell application" (as a content of a tab view or multiple tab views) and the modules can depend on another module(s) (their content in tabs won't appear if their dependency is not loaded).
That's why I was planning to create an OSGi based JavaFX application and build it with Gradle as a multiproject.
I've already tried dozens of tutorials with no success and I experienced, that most of these tutorials:
are outdated, not reproducible (e.g. elcipse's interface, templates have changed, bndtools tutorials doesn't seem to work, equinox doesn't seem to to work without felix, javafx8+osgi generate different kind of problems... etc.)
are too complex for a beginner (I just started to learn OSGi and Gradle) and they skip important steps I am not aware of
contain too much "IDE magic" (I would rather type some code instead of filling forms in eclipse)
some solve the problem with different tools (maven/tycho, bndtools, e(fx)clipse), but I've got no time to learn them
I want my application to be independent from IDE's environment. I don't want to use e(fx)clipse or BndTools if possible (even if they can make the build process easier)..
I'm experimenting with OSGi implementations, that's why I would rather not to choose between Equinox, Felix or Karaf.
I've already programmed similar application in .NET world, but it seems to me impossible to do the same in Java world..
My main questions are:
is it possible to do what I have imagined?
how to create a gradle multiproject what is IDE/platform independent (if projects are not tied to eclipse environment, or equinox, but it's possible to use them)?
what are the best ways to initialize the application (shell application + modules) and load the independent modules/bundles/components?
how to separate my views into subprojects (what build.gradle files should contain)?
how to solve the javafx8 inpompatibility with osgi?
what is the correct way to apply javafx plugin in gradle?
what tutorials are the most relevant?
is there any working example, pattern or tutorial (without using additional tools) what solve the same problem (using only osgi+javafx+gradle)?
I could group your questions in differents topic:
OSGI
You just need to google around to find out that is a java specification that encourages modularization, provides hot-deploy feature, and so on. As I told you, is just an specification like Java Servlet API, so they are different providers or implementers of OSGI Specification such as Felix and Equinox. Karaf instead is a OSGI container based on Felix, so you get all felix benefits and in addiction karaf natives features. For that reason I encourage you to take Karaf into use.
Aquote BndTool
In order to satisfy the OSGI specification, you need that your modules contains a MANIFEST.MF which holds all dependency information so Karaf create the classloader required for your bundles.
Assuming that you don't want to create that MANIFEST.MF files by hand, you could take aqute/bndtool for that. Don't get mess with bndtool for eclipse plugin. That application can be used from command line, from a maven plugin, or from a gradle plugin. Basically scans your classes, check the imports, and create a MANIFEST.MF automatically.
Gradle
If you choose gradle as a build tool, then you can take into use: Bnd Gradle plugin. It's easy to set up, but follow the instruction for non-workspace plugin. If you don't want to use BndTool for eclipse. IDE independent solution, you mentioned in your question.
MultiProject Layout
How the project layout should look like, depends on your modularization, but you can have a look on this layout example that uses gradle+osgi+karaf for a multiproject. Perhaps inspires you.
https://github.com/antoniomaria/gradle-karaf-bnd-project
I have an Eclipse RAP product, I like to export as a web app for use inside Tomcat. For this I use the warproduct exporter in Eclipse, which until now have worked fine.
I have a problem with compilation of one of the OSGi bundles in the product as this refers to a set of external jars using a variable substitution. This is shown in the following fragment from a MANIFEST.MF:
Bundle-Name: ...
Bundle-SymbolicName: ...
Bundle-ClassPath2: external:/A/test1/jakarta-tomcat/shared/lib/a_base.jar
Bundle-ClassPath: external:$A_HOME$/jakarta-tomcat/shared/lib/a_base.jar
If I use the first classpath instead and have the correct /A/test1/jakarta-tomcat/shared/lib/a_base.jar in place, then everything is fine during the compilation... And I can even manually change the MANIFEST.MF afterwards to the correct version with the substitution.
But, I would really like to avoid this extra step, if at all possible!
I think the question is how to pass in a proper value for A_HOME during the compilation?
(Why do this? Above, I just shown a single jar file, but we have a larger number of jar files we want to share between our older Tomcat applications and the newer RAP based application. We know, there are other ways of sharing jars in this situation - e.g. via an OSGi framework extender or the extendedFrameworkExports initialization parameter in web.xml - but we need the chosen method as we use EMF and therefore cannot share the EMF meta data between Tomcat and Eclipse... And thus not the class objects...)
this feature is currently not support within the WAR Products Tooling. I recommend to open a bug against Eclipse Libra and to define the feature request their. Anyway, we have created an example how to build a RAP application with tycho which is pretty easy, maybe you want to take a look: https://github.com/eclipsesource/rap-mobile-demos
Cheers Holger
example:
For logging, my code uses log4j. but other jars my code is dependent upon, uses slf4j instead. So both jars must be in the build path. Unfortunately, its possible for my code to directly use (depend on) slf4j now, either by context-assist, or some other developers changes. I would like any use of slf4j to show up as an error, but my application (and tests) will still need it in the classpath when running.
explanation:
I'd like to find out if this is possible in eclipse. This scenario happens often for me. I'll have a large project, that uses alot of 3rd party libraries. And of course those 3rd party jars have their own dependencies as well. So I have to include all dependencies in the classpath ("build path" in eclipse) for the application and its tests to compile and run (from within eclipse).
But I don't want my code to use all of those jars, just the few direct dependencies I've decided upon myself. So if my code accidentally uses a dependency of a dependency, I want it to show up as a compilation error. Ideally, as class not found, but any error would do.
I know I can manually configure the classpath when running outside of eclipse, and even within eclipse I can modify the classpath for a specific class I'm running (in the run configurations), but thats not manageable if you run alot of individual test cases, or have alot of main() classes.
It sounds like your project has enough dependency relationships that you might consider structuring it with OSGi bundles (plug-ins). Each bundle gets its own classloader and gets to specify what bundles (and optionally what version ranges, etc.) it depends on, what packages it exports, whether it re-exports stuff from its dependencies, etc.
Eclipse itself is structured out of Eclipse plug-ins and fragments, which are just OSGi bundles with an optional tiny bit of additional Eclipse wiring (plugin.xml, which is used to declare Eclipse "extension points" and "extensions") attached. Eclipse thus has fairly good tooling for creating and managing bundles built-in (via the Plug-in Development Environment). Much of what you find out there may lead you to conflate "OSGi bundle" with "plug-in that extends the Eclipse IDE", but the two concepts are quite separable.
The Eclipse tooling does distinguish rather clearly (and sometimes annoyingly, but in the "helpful medicine" way) between the bundles in your build environment vs. the bundles that a particular run configuration includes.
After a few years of living in OSGi land, the default Java "flat classpath" feels weird and even kind of broken to me, largely because (as you've experienced) it throws all JARs into one giant arena and hopes they can sort of work things out. The OSGi environment gives me a lot more control over dependency relationships, and as a "side effect" also naturally demands clarification of those relationships. Between these clear declarations and the tooling's enforcement of them, the project's structure is more obvious to everyone on the team.
if my code accidentally uses a dependency of a dependency, I want it to show up as a compilation error. Ideally, as class not found, but any error would do.
Put your code in one plug-in, your direct dependencies in other plug-ins, their dependencies in other plug-ins, etc. and declare each plug-in's dependencies. Eclipse will immediately do exactly what you want. You won't be offered dependencies' dependencies' contents in autocompletes; you'll get red squiggles and build errors; etc.
Why not use access rules to keep your code clean?
It looks like it would better be managed with maven, integrated in eclipse with m2eclipse.
That way, you can only execute part of the maven build lifecycle, and you can manage separate set of dependencies per build steps.
In my experience it helps to be more resrictive, I made the team filling out (paper) forms why this jar is needed and what license...
and they did rather type in a few lines of code instead of drag along 20 jars to open a file using only one line of code, or another fancy 'feature'.
Using maven could help for a while, but when you first spot jars having names like nightly-build or snapshot, you will know you're in jar-hell.
conclusion: Choose dependencies well
Would using the slf4j-over-log4j jar be useful? That allows using slf4j with actual logging going to log4j.