[jbosscache-dev] Let's make 3.0 backwards compatible

[Manik Surtani]

On 19 Aug 2008, at 06:53, Bela Ban wrote:

> First of all: I don't think there's a need to make 1.x compatible  
> with 2.x and/or 3.x. The need is there to make 2.x compatible with  
> 3.x.

I don't know about that.  There are still a lot of people who are on  
AS 4.x and who won't switch to AS 5.0 for a while to come.  Which  
means they will be stuck on 1.x APIs.  See the forum link that sparked  
off this thread.

> Inline
>
> Manik Surtani wrote:
>> After a good nights' sleep and a fresh mind, I've had a rethink and  
>> have a potential solution.  Tell me what you guys think, this will  
>> apply to both 3.x -> 2.x compat, 3.x -> 1.x compat and 3.x -> 2.x  
>> compat.
>>
>> 1.  For each release, create a "namespace-safe" package.  E.g., for  
>> 3.0.0, create jbosscache-core.jar as well as jbosscache-core- 
>> namespace-safe.jar. This would be constructed using jarjar, where  
>> org.jboss.cache.* is translated to org.jboss.cache.3.* (or  
>> org.jboss.cache.2.*).
>
> One additional JAR ? -1. jarjar ? -1. That's -2 ...

This won't be in the distro.  Jarjar is only needed by ant for the ant  
task - I'm expecting an equivalent Maven plugin.  So no extra jars in  
the distro, although one extra plugin dependency for a full build.

Why a -1 for jarjar?

> Sorry, but when I smell complexity, I turn negative... :-)

In relation to the other approach we were considering for an adapter  
(use a separate classloader to load 3.x classes) I think this is  
simpler.  :-)

> What about a single adapter, shipped with 3.x, which makes 3.x  
> compatible with 2.x ? I don't hope there will be a 4.x any time  
> soon, which break API compatibility again, so this should be a one- 
> time exercise.

We could but that would mean some sort of package renaming or class  
renaming (e.g., o.j.c.Cache -> o.j.c.Cache3 or o.j.c.3.Cache) and  
o.j.c.Cache remains 2.x compatible.  Either way, very ugly for anyone  
who wants to use 3.x APIs directly.

Specifically, interfaces that have changed include:

- Cache
- Fqn
- EvictionConfig
- Region/RegionManager
- EvictionAlgorithm

Cheers,
--
Manik Surtani
Lead, JBoss Cache
manik at jboss.org