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From Greg Trasuk <tras...@stratuscom.com>
Subject Re: [Discuss] Drop support for Activation?
Date Fri, 13 Nov 2015 20:11:18 GMT

> On Nov 13, 2015, at 2:21 PM, Bryan Thompson <bryan@systap.com> wrote:
> I was trying to remember precisely what is in "activation".  I found this
> [1]. From [1]:
> "Distributed object systems are designed to support long-lived persistent
> objects. Given that these systems will be made up of many thousands
> (perhaps millions) of such objects, it would be unreasonable for object
> implementations to become active and remain active, taking up valuable
> system resources for indefinite periods of time. In addition, clients need
> the ability to store persistent references to objects so that communication
> among objects can be re-established after a system crash, since typically a
> reference to a distributed object is valid only while the object is active."
> So the concept here was long lived object references and robustness of
> those references.
> This all seems very appropriate for IoT, but perhaps the goal of such
> durable / robust / on demand (re-)activation of services is now met through
> other mechanisms?  Something that does not need to be part of River?

“Long-lived persistent objects” reminds me of the Entity EJBs in EJB 1 and 2.  The metaphor
there was that every entity (e.g. a User) was represented by a persistent object, identified
by a primary key, and you interacted with the entity by making remote method calls on the
entity’s proxy.  The problem was that the typical interaction would be ‘getName()’,
‘getEmail()’, 'getUserId()’, ‘getPhoneNumber()’, etc.  By the time you had any useful
interaction you might have made 10-15 remote method calls.  Put twenty entities on a web page,
and you might need to make hundreds of remote calls to display the page.  In other words,
the distributed objects were at the wrong level of granularity.

If we have distributed services, on the other hand, we can readily accommodate the right granularity
in the service design.  In that case, though, activation only makes sense if we have so many
services that it isn’t practical to keep them all alive at the same time.  Typically you
have a reasonable number of services in any given virtual machine instance.  I suspect that
if you really did have that many services that needed activation, you’d end up with a really
slow system because the overhead of activating and passivating services would far outweigh
the time spend in actual service calls.

So, I don’t see much of a use case for Activation.  I’m interested to see if anyone else


Greg Trasuk

> Thanks,
> Bryan
> [1]
> http://www.javaworld.com/article/2076173/soa/activatable-jini-services--part-1--implement-rmi-activation.html
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> On Fri, Nov 13, 2015 at 10:21 AM, Greg Trasuk <trasukg@trasuk.com> wrote:
>> Hello all:
>> Last week I asked about removing activation from River, both the 2.2 and
>> 3.0 branches.  There didn’t seem to be a lot of anti-removal feeling, so
>> I’d like to formally propose removing Activation.  There are a couple of
>> other things that we could possibly remove, like JRMP support (i.e.
>> pre-compiled proxy classes), but we should probably discuss those
>> separately.
>> The main reason for this is that unused code still requires maintenance
>> and increases the chance of bugs.  Also I think that as we go forward with
>> refactoring, renaming, restructuring the build and so on, it seems wasteful
>> to do that work on code that isn’t actually in use.
>> Obviously, the code remains in Subversion and in the 2.2.2 release, so if
>> someone wants to get it back, we (or they) could package it into a
>> different deliverable.  But I wouldn’t plan on doing that unless there’s
>> actual demand for it.
>> My thought is to put this out there for discussion - If there is consensus
>> after a few days I’ll call a lazy-consensus vote.   I’ll be happy to do the
>> work in the 2.2 branch.
>> So, I propose to drop support for the following:
>> Activation -
>>        com.sun.jini.phoenix.*
>>        com.sun.jini.phoenix.resources.*
>>        net.jini.activation.*
>> Norm / LeaseRenewalService - is pretty much unneeded without activation
>>        com.sun.jini.norm.**
>> Activatable implementation of the infrastructure services
>>        com.sun.jini.fiddler.ActivatableFiddlerImpl
>>        com.sun.jini.mahalo.ActivatableMahaloImpl
>>        com.sun.jini.mercury.ActivatableMercuryImpl
>>        com.sun.jini.reggie.PersistentRegistrarImpl
>> Starter for Activatable Services
>>        com.sun.jini.start.ActivateWrapper
>>        com.sun.jini.start.SharedActivatableServiceDescriptor
>>        com.sun.jini.start.SharedGroupImpl
>> QA Harness classes that test any of the above.
>> Cheers,
>> Greg Trasuk

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