It's not just the groupId/artifactId that changed between Jackson 1 and Jackson 2. It's the Java package, too. Simply excluding Flume's dependency on 1.x and introducing a dependency on 2.x doesn't work. Flume classes literally don't load due to NoClassDefFound errors.
N On May 16, 2013, at 1:04 PM, Ralph Goers wrote: > The master log4j pom.xml should have a version for jackson in the dependency > management section. That version should replace any transitive dependencies. > However, if the groupId has changed then that doesn't work. You would have to > add the Jackson 2 dependencies to flume-ng's pom.xml and exclude the old > artifact/groupId. > > Note that required transitive dependencies are never obvious just by looking > at a pom. > > Ralph > > > On May 16, 2013, at 10:17 AM, Nick Williams wrote: > >> So this is all kinds of fun... >> >> log4j-core depends on: >> ....jackson 1.9.11 (optional) >> log4j-flume-ng depends on: >> ....flume-ng-sdk 1.3.1 depends on: >> ........avro 1.7.2 depends on: >> ............jackson 1.8.8 >> flume-embedded (sample) depends on: >> ....flume-ng-sdk 1.3.1 depends on: >> ........avro 1.7.2 depends on: >> ............jackson 1.8.8 >> ....flume-ng-node 1.3.1 depends on: >> ........jackson 1.9.3 >> >> So, we already had three different versions of Jackson in the build: 1.8.8, >> 1.9.3, and 1.9.11 ... yuck! >> >> I took the following steps: >> >> 1) I upgraded log4j-core's dependency from 1.9.11 to 2.2.1 without any >> negative consequences. Everything compiled and all the tests passed. At this >> point the dependencies were now 1.8.8, 1.9.3, and 2.2.1. >> 2) I used dependency exclusions to exclude 1.8.8 and got it down to just >> 1.9.3 and 2.2.1. Everything compiled and all the tests passed. >> 3) I tried to eliminate 1.9.3 through a further dependency exclusion, but >> log4j-flume-ng classes didn't load anymore. This indicated that Jackson is >> NOT an optional dependency of log4j-flume-ng, but instead is a mandatory >> dependency, which wasn't obvious the way it was set up. >> 4) I kept the 1.9.3 dependency exclusion but added a mandatory 1.9.11 >> /runtime/ dependency for log4j-flume-ng. Now everything compiles and all >> tests pass again, and the Jackson dependencies are limited to the latest >> minor.patch versions of each major version: 1.9.11 (log4j-flume-ng only, >> runtime) and 2.2.1 (log4j-core only, compile). >> >> Ralph said below "I have no problem upgrading to 2.x so long as it works for >> both the JSON configuration and Flume." It doesn't work with Flume; Flume >> requires 1.x. So as a next step we can either: >> >> 1) Revert my changes to configuration so that it relies on Jackson 1.9.11 as >> well and not on 2.2.1. >> 2) Apply my earlier suggestion that we support both 1.9.11 /and/ 2.2.1 or >> configuration. >> 3) Stick with what we have: 1.9.11 for Flume, 2.2.1 for JSON configuration, >> and no more dependency on 1.8.8. >> >> Nick >> >> On May 15, 2013, at 7:33 PM, Ralph Goers wrote: >> >>> I wrote the JSON support just after the ApacheCon in Vancouver, which I >>> believe was in 2011. If 2.x was available then it was brand new and the >>> documentation was slim. I have no problem upgrading to 2.x so long as it >>> works for both the JSON configuration and Flume (I don't think Flume >>> actually uses JSON but Avro probably does). Like you, I would prefer not >>> to have two versions of Jackson in out build. >>> >>> Ralph >>> >>> >>> On May 15, 2013, at 11:16 AM, Gary Gregory wrote: >>> >>>> I would only support the current version: 2.x. >>>> >>>> Gary >>>> >>>> >>>> On Wed, May 15, 2013 at 2:00 PM, Nick Williams >>>> <nicho...@nicholaswilliams.net> wrote: >>>> Guys, >>>> >>>> Background: Since I'm the lead developer on a Jackson Mapper module >>>> (https://github.com/FasterXML/jackson-datatype-jsr310), I'm actively >>>> involved on their development mailing list. >>>> >>>> Jackson 1.9 is, well, old. Specifically, 1.9.0 is two years old. 1.9 is >>>> the last minor version of the 1.x family. There will continue to be bug >>>> fixe releases—for now—about every 4-6 months. The last patch release was >>>> in January. >>>> >>>> Jackson 2.x is the current version with rapid release periods. 2.0 Is >>>> about a year old, 2.1 was released in October and 2.2 was released last >>>> month. Only major bugs will be fixed in 1.9.x. Minor bug fixes and all new >>>> features will go in 2.x. >>>> >>>> Jackson 1.x and 2.x use different Java packages. This has both advantages >>>> and disadvantages. One advantage is that frameworks and libraries, like >>>> Spring Framework, can easily support both versions because they can >>>> coexist on the same class path during compilation and testing. One >>>> disadvantage is that if some library is using 1.x and some other library >>>> is using 2.x and you create an application that depends on both libraries, >>>> you'll have to pull BOTH versions of Jackson on to your class path. Ugh. >>>> >>>> Log4j 2 is "brand new" (it's not even released yet). Typically, I would >>>> argue that new projects should not use old versions of their dependencies. >>>> In Log4j 2's case, I tend to lean the same direction. It doesn't seem wise >>>> to tie ourselves to Jackson 1.x so late in its life when Jackson 2.x is >>>> already mature and Log4j 2 isn't even released yet. As a Java 8, Spring 4, >>>> Jackson 2 user, I know I wouldn't love having to also have Jackson 1 on my >>>> class path (if I were using JSON configuration). >>>> >>>> I would suggest that we should either support both or we should only >>>> support 2.x, but only supporting 1.x feels wrong to me. >>>> >>>> Supporting both wouldn't be a major challenge. The way Spring does it is >>>> to have two Jackson* classes and Jackson2* classes with identical APIs. >>>> Depending on which version you are already using, you use the appropriate >>>> class. In this case, I would approach it like this: >>>> >>>> - Rename JSONConfiguration to Jackson1JSONConfiguration, and (using >>>> CheckStyle's import control) ensure that only this class imports Jackson >>>> 1.x >>>> - Create a similar class named Jackson2JSONConfiguration, and ensure that >>>> only this class imports Jackson 2.x >>>> - Alter JSONConfigurationFactory to detect which version is on the class >>>> path and return the appropriate JSON configuration, preferring 2.x if both >>>> are on the class path >>>> >>>> Thoughts? >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org >>>> For additional commands, e-mail: log4j-dev-h...@logging.apache.org >>>> >>>> >>>> >>>> >>>> -- >>>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org >>>> Java Persistence with Hibernate, Second Edition >>>> JUnit in Action, Second Edition >>>> Spring Batch in Action >>>> Blog: http://garygregory.wordpress.com >>>> Home: http://garygregory.com/ >>>> Tweet! http://twitter.com/GaryGregory >>> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org >> For additional commands, e-mail: log4j-dev-h...@logging.apache.org >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org > For additional commands, e-mail: log4j-dev-h...@logging.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: log4j-dev-unsubscr...@logging.apache.org For additional commands, e-mail: log4j-dev-h...@logging.apache.org
