将外部库集成到OSGI

Question

I have been trying to fix this issue for several days now, but i seem stuck somehow. I want to develop a OSGi bundle, and my implementation requires an external library (that has some more dependencies). The situation is as follows: My project is using gradle and i got a simple code snippet to compile, but it crashes at runtime when the bundle is launched ( i am using apache felix), giving me an exception complaining about unmet dependencies. But all libraries are present in the jar bundle, and i added them into the classpath. The missing package org.ethereum.facade is listed within Private-Packages. I read a lot of questions with similar problems, but none of the silutions proposed seems to solve my problem.

I am posting my gradle.build files

// ETHEREUM NODE
configurations.create('embed')
repositories {
  mavenLocal()
    mavenCentral()
    maven {
        url "http://dl.bintray.com/ethereum/maven"
     }
}
dependencies {
 // This will compile the openMuc Framework and place the result into the build classpath:
 compile project(':openmuc-core-api')
// This will place the etherum libraries into the classpath
    compile ("org.ethereum:ethereumj-core:latest.release")
    embed ("org.ethereum:ethereumj-core:latest.release")
}
jar {
    manifest {
        name = 'OpenMUC App - EthereumNode'
         instruction 'Bundle-ClassPath', 'lib/ethereumj-core-1.4.2-RELEASE.jar,.'
}
 into('lib') {
    from configurations.embed
  }
}

The resulting jar:

[MANIFEST openmuc-app-ethereumNode-0.16.0.jar]
Bnd-LastModified                         1490003658351                           
Bundle-ClassPath                         lib/ethereumj-core-1.4.2-RELEASE.jar,.  
Bundle-ManifestVersion                   2                                       
Bundle-Name                              OpenMUC App - EthereumNode              
Bundle-SymbolicName                      org.openmuc.framework.openmuc-app-ethereumNode
Bundle-Version                           0.16.0                                  
Created-By                               1.8.0_25 (Oracle Corporation)           
Export-Package                           org.openmuc.framework.app.ethereumNode;version="0.16.0";uses:="javax.xml.bind,org.osgi.service.component"
Import-Package                           javax.xml.bind,org.osgi.service.component;version="[1.2,2)",org.slf4j;version="[1.7,2)",org.ethereum.facade
Manifest-Version                         1.0                                     
Private-Package                          genesis,org.ethereum,org.ethereum.cli,org.ethereum.config,org.ethereum.config.blockchain,org.ethereum.config.net,org.ethereum.core,org.ethereum.core.genesis,org.ethereum.crypto,org.ethereum.crypto.cryptohash,org.ethereum.crypto.jce,org.ethereum.datasource,org.ethereum.datasource.inmem,org.ethereum.datasource.leveldb,org.ethereum.datasource.mapdb,org.ethereum.db,org.ethereum.db.index,org.ethereum.facade,org.ethereum.json,org.ethereum.jsonrpc,org.ethereum.listener,org.ethereum.manager,org.ethereum.mine,org.ethereum.net,org.ethereum.net.client,org.ethereum.net.dht,org.ethereum.net.eth,org.ethereum.net.eth.handler,org.ethereum.net.eth.message,org.ethereum.net.message,org.ethereum.net.p2p,org.ethereum.net.rlpx,org.ethereum.net.rlpx.discover,org.ethereum.net.rlpx.discover.table,org.ethereum.net.server,org.ethereum.net.shh,org.ethereum.net.submit,org.ethereum.net.swarm,org.ethereum.net.swarm.bzz,org.ethereum.samples,org.ethereum.solidity,org.ethereum.solidity.compiler,org.ethereum.sync,org.ethereum.trie,org.ethereum.util,org.ethereum.util.blockchain,org.ethereum.validator,org.ethereum.vm,org.ethereum.vm.program,org.ethereum.vm.program.invoke,org.ethereum.vm.program.listener,org.ethereum.vm.trace,lib
Require-Capability                       osgi.ee;filter:="(&(osgi.ee=JavaSE)(version=1.7))"
Service-Component                        OSGI-INF/org.openmuc.framework.app.ethereumNode.EthereumNode.xml
Tool                                     Bnd-3.0.0.201509101326                  

[IMPEXP]
Import-Package
  javax.xml.bind                         
  org.ethereum.facade                    
  org.osgi.service.component             {version=[1.2,2)}
  org.slf4j                              {version=[1.7,2)}
Export-Package
  org.openmuc.framework.app.ethereumNode {version=0.16.0}

[USES]
org.openmuc.framework.app.ethereumNode   java.lang
                                         javax.xml.bind
                                         org.ethereum.facade
                                         org.osgi.service.component
                                         org.slf4j

[USEDBY]
java.lang                                org.openmuc.framework.app.ethereumNode
javax.xml.bind                           org.openmuc.framework.app.ethereumNode
org.ethereum.facade                      org.openmuc.framework.app.ethereumNode
org.osgi.service.component               org.openmuc.framework.app.ethereumNode
org.slf4j                                org.openmuc.framework.app.ethereumNode

[COMPONENTS]
OSGI-INF/org.openmuc.framework.app.ethereumNode.EthereumNode.xml
<?xml version="1.0" encoding="UTF-8"?>
<component name="org.openmuc.framework.app.ethereumNode.EthereumNode">
  <implementation class="org.openmuc.framework.app.ethereumNode.EthereumNode"/>
</component>


[LIST]
META-INF
  MANIFEST.MF extra='\uFFFD\uFFFD\u0000\u0000'
OSGI-INF
  org.openmuc.framework.app.ethereumNode.EthereumNode.xml
lib
  aopalliance-1.0.jar
  commons-codec-1.10.jar
  commons-collections4-4.0.jar
  commons-lang3-3.4.jar
  commons-logging-1.2.jar
  config-1.2.1.jar
  core-1.53.0.0.jar
  ethereumj-core-1.4.2-RELEASE.jar
  guava-16.0.1.jar
  jackson-annotations-2.5.0.jar
  jackson-core-2.5.1.jar
  jackson-core-asl-1.9.13.jar
  jackson-databind-2.5.1.jar
  jackson-mapper-asl-1.9.13.jar
  java-util-1.8.0.jar
  javassist-3.15.0-GA.jar
  json-io-2.4.1.jar
  json-simple-1.1.1.jar
  jsr305-3.0.0.jar
  leveldb-0.7.jar
  leveldb-api-0.7.jar
  leveldbjni-all-1.18.3.jar
  logback-classic-1.1.7.jar
  logback-core-1.1.7.jar
  mapdb-2.0-beta12.jar
  netty-all-4.0.30.Final.jar
  prov-1.53.0.0.jar
  slf4j-api-1.7.20.jar
  solcJ-all-0.4.8.jar
  spring-aop-4.2.0.RELEASE.jar
  spring-beans-4.2.0.RELEASE.jar
  spring-context-4.2.0.RELEASE.jar
  spring-core-4.2.0.RELEASE.jar
  spring-expression-4.2.0.RELEASE.jar
  spring-jdbc-4.2.0.RELEASE.jar
  spring-orm-4.2.0.RELEASE.jar
  spring-tx-4.2.0.RELEASE.jar
org
org/openmuc
org/openmuc/framework
org/openmuc/framework/app
org/openmuc/framework/app/ethereumNode
  EthereumNode.class

The exception i encounter when the bundle is loaded:

ERROR: Bundle org.openmuc.framework.openmuc-app-ethereumNode [3] Error starting file:/Volumes/UserData/Documents/FH/MasterThesis_MatthiasPosch/java/openmuc/framework/bundle/openmuc-app-ethereumNode-0.16.0.jar (org.osgi.framework.BundleException: Unable to resolve org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0): missing requirement [org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0)] osgi.wiring.package; (osgi.wiring.package=org.ethereum.facade) Unresolved requirements: [[org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0)] osgi.wiring.package; (osgi.wiring.package=org.ethereum.facade)])
org.osgi.framework.BundleException: Unable to resolve org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0): missing requirement [org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0)] osgi.wiring.package; (osgi.wiring.package=org.ethereum.facade) Unresolved requirements: [[org.openmuc.framework.openmuc-app-ethereumNode [3](R 3.0)] osgi.wiring.package; (osgi.wiring.package=org.ethereum.facade)]
    at org.apache.felix.framework.Felix.resolveBundleRevision(Felix.java:4112)
    at org.apache.felix.framework.Felix.startBundle(Felix.java:2118)
    at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1372)
    at org.apache.felix.framework.FrameworkStartLevelImpl.run(FrameworkStartLevelImpl.java:308)
    at java.lang.Thread.run(Thread.java:745)

So it seems all libraries are in place in the lib folder, but still the bundle does not work. I tried to play with the code, but any reference to the included libraries (eg. spring) will lead to a similar exception. Why?

Answer 1

My solution was to use the osgi-run plugin for gradle instead of the original osgi plugin. Declaring my dependencies as SystemLibrary systemLib ("org.ethereum:ethereumj-core:1.2.0-RELEASE") resolved the issues and i am able to use the library without exceptions and errors.

Answer 2

In your Manifest you import the package org.ethereum.facade . This can only work if there is also a bundle that exports this package. If the package is purely internal then you should set it as private package and not import it.

If the package might be needed from the outside then make sure you have an import and an export for it in your bundle. If you have not configured the import manually then for some reason the build seems to think you need it and it is not present locally in your bundle.

How do you create the Manifest? Do you use bnd for this? If yes then maybe the manual change in bundle classpath is not recognized by it.