I tend to agree.

The move to maven makes package relocation very easy, but we should be careful not to abuse it if thatís a direction we decide to take.

IMHO, users having to modify the contents of $STORM_HOME/lib is really bad and should only be done as a last resort. If someone asks for help with an issue after theyíve modified the contents of $STORM_HOM/lib, all bets are off.

I also agree that we need to keep a close watch on our dependencies, and that some might warrant re-evaluation.

Iíd love to others opinions.

- Taylor

On Feb 6, 2014, at 9:28 PM, Adam Lewis <mail@adamlewis.com> wrote:

My $0.02 on this subject:

Without going down the path of class loader or OSGi mania and becoming a full container, I'd definitely be in favor of storm relocating its own dependencies.  In this way edge cases around things like reflection can be handled once within storm rather than burdening every topology builder with those details.  Part of the problem seems to be that storm makes extensive use (directly or transitively) of a lot of go-to utility libraries like guava, thrift, jodatime, json-simple, snakeyaml, commons-io, etc... I'm sure that leveraging these libraries allowed storm's development to proceed rapidly, but from a maturity perspective, it is problematic to impose these version choices on users.  And while I might want Storm to, say, try to track the latest Guava version, that same policy could be very problematic for others.

If storm can relocate even some of its own dependencies, I think that would be a great help to me at least.  Longer term, I wonder how much of some of these libraries are really being used.  For example, is clj-time (and by extension joda-time) really needed? Or just a small fraction of the functionality in that library?  I can probably pitch in some of the effort required to do this, if this is the direction people want to go in.




On Thu, Feb 6, 2014 at 8:44 PM, P. Taylor Goetz <ptgoetz@gmail.com> wrote:
Iím glad the shader plugin worked for you. 

Updating dependencies can be tricky as it can easily introduce regressions. 

Ultimately we need to figure out the best solution to avoiding conflicts between user code (i.e. dependencies in topology jar files) and Stormís libraries.

The classloader approach has been attempted, but IMO Stormís use of serialization complicates things significantly. Package relocation seems to be a relatively lightweight solution.

If thatís a direction we pursue, then it introduces the question of whether Storm should relocate its dependencies, or if that should be left up to the user (topology developer).

Elastic Search has gone down the path of relocating some of their dependencies [1] (not necessarily an endorsement, just an observation).

Iíve CCíd dev@ since this is all related to the infamous issue #115, which is now STORM-129 [2].

- Taylor






On Feb 6, 2014, at 7:25 PM, Vinay Pothnis <vinay.pothnis@gmail.com> wrote:

Thank you all for replies! The shader-plugin solution seems to work for us. 

I wonder if we can create a JIRA ticket for storm to upgrade the http-client library as part of their next release.

-Vinay


On Thu, Feb 6, 2014 at 2:38 PM, Michael Rose <michael@fullcontact.com> wrote:
We've done this with SLF4j and Guava as well without issues.

Michael Rose (@Xorlev)
Senior Platform Engineer, FullContact
michael@fullcontact.com



On Thu, Feb 6, 2014 at 3:03 PM, Mark Greene <mark@evertrue.com> wrote:
We had this problem as well. We modified our chef cookbook to just replace the older version with the newer one and storm didn't complain or have any other issues as a result.


On Wed, Feb 5, 2014 at 10:31 AM, P. Taylor Goetz <ptgoetz@gmail.com> wrote:
Your best bet is probably  to use the shade plugin to relocate the http-client package so it doesnít conflict with the version storm uses.

Storm does this with the libtrhift dependency in storm-core:

https://github.com/apache/incubator-storm/blob/master/storm-core/pom.xml#L220

(You can ignore the clojure transformer in that config, unless you have non-AOT clojure code that uses the http-client library).

More information on using the shade plugin to do package relocations can be found here:

http://maven.apache.org/plugins/maven-shade-plugin/examples/class-relocation.html

- Taylor

On Feb 4, 2014, at 4:27 PM, Vinay Pothnis <vinay.pothnis@gmail.com> wrote:

> Hello,
>
> I am using storm version 0.9.0.1.
> My application depends on apache http-client version 4.3.2 - but storm depends on http-client version 4.1.1.
>
> What is the best way to override this dependency?
>
> Thanks
> Vinay