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RE: [eclipse-incubator-e4-dev] Re: Avoiding Bloat


The difference in policy between [2] and [4] is because those documents are written by different people for different audiences. [2] was written by me at the request of the Eclipse Project PMC to codify our guidelines (which had been around much longer but never written down). Those guidelines were only intended to be for the Eclipse top-level project. I don't know the history of document [4], but I suspect it was written by the Foundation with the intent to provide guidelines that all top-level projects could live with. I don't know what projects follow them, but I know some projects put provisional API in non-internal packages. There was never broad agreement across projects on this point which likely led to that compromise table with several different flavours of pseudo-API.

> [2] After the API freeze, there is really no such thing as "provisional API". Either it is complete and committed platform > API, or it is internal code.
> Hm... I know this passage and agree that it is not in line with my current
> thinking. Perhaps Boris, John or McQ could explain?


API is primarily a contract that implies long term support and a promise of compatibility across releases. If something is provisional and subject to change, then there is no implied support or compatibility, so it is not API. This doesn't mean it can't become API at some point in the future. We certainly do have packages with "*.internal.provisional.*" in one release, which is then validated and polished into real API in the next release. But, at the time the package is "internal.provisional", it is internal code and subject to change. I'm happy to clarify it, but I don't understand what is unclear or illogical about it.

John




"Oberhuber, Martin" <Martin.Oberhuber@xxxxxxxxxxxxx>
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10/21/2008 07:59 AM

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RE: [eclipse-incubator-e4-dev] Re: Avoiding Bloat





Hello Krzysztof,
 
[2] After the API freeze, there is really no such thing as "provisional API". Either it is complete and committed platform API, or it is internal code.
Hm... I know this passage and agree that it is not in line with my current
thinking. Perhaps Boris, John or McQ could explain? For me, it seems

OK to have provisional API live in "internal" packages even across multiple
releases.
Just assuming that some provisional API was proposed and just didn't get
ready in time. This can't be a reason for never ever working on promoting

it in the future? The passage cited does not seem logical, and I'm wondering
if it could be rewritten for clarification.
 
[2] Technically, a provisional API can change arbitrarily or be removed at any time without notice.
Yes, I agree that this doesn't sound friendly for provisional API adopters at
all, and does not help encouraging early adoption. I think that we should

consider more helpful policies, such as
  • Provisional API can be removed at any milestone build, provided that
    it has been marked @deprecated in the previous milestone build.
Discussing such policies for provisional API (making a recommendation for
all Eclipse projects to adopt them) would be a good topic for the Architecture

Council. The goal of the discussion should be increasing early adoption and
feedback for provisional API. I'd just like to get some initial feedback on this
idea before I file a bug on the Architecture Council component (well in fact
anybody can file such a bug).

 
Note the public package in the provisional API. It is contradictory to the [2]
 
I assume that in the cited table, the "public" means that the packages are
exported and publicly visible (which is recommended for EVERY package
including those that have an "internal" segment in their package name. In
this light, this isn't a contradiction.
 
new API is released as provisional in release X and then hardened into platform APIs in release X+1.
 
Well that also seems too blindly following a principle. The API is ready when
it is ready and shouldn't be promoted just because it's old. A better description
should be
  "We have a constant project plan item to work on hardening API that has
    been introduced as provisional in the previous release".

which says that it's an item to work on, regardless of to what extent the goal
is reached.
 
Provisional API should be in public packages and has clear javadoc that would:
But that's exactly what's happening. The packages are public today. They
just have some "internal" segment in their name. Perhaps what you're missing
is some clear indication in the package name that separates provisional API
from all the wade of other internal stuff. That's something worth discussing
and specifying. As far as I know, some projects have adopted a naming scheme
like
 
   org.eclipse.platform.internal.core.provisional.api
 
which is lengthy but does provide the requested separation. I'm against placing
provisional API into non-internal packages since it would way too easily be
taken for hardened. Although some API Tooling tags could perhaps help here.
 
Coming up with a generally recommended naming scheme for provisional
API might be worth another bug on the Architecture Council component for
discussion.
 
Thanks for bringing up the issue and being persistent. I think that we're
touching on some important issues here, and I'm looking forward to the
followup discussions.
 
Cheers,
--
Martin Oberhuber, Senior Member of Technical Staff, Wind River
Target Management Project Lead, DSDP PMC Member
http://www.eclipse.org/dsdp/tm
 
 


From: eclipse-incubator-e4-dev-bounces@xxxxxxxxxxx [mailto:eclipse-incubator-e4-dev-bounces@xxxxxxxxxxx] On Behalf Of Krzysztof Daniel
Sent:
Tuesday, October 21, 2008 11:29 AM
To:
E4 developer list
Subject:
RE: [eclipse-incubator-e4-dev] Re: Avoiding Bloat



Hi Martin,


The sources you have mentioned also say:

[2]
After the API freeze, there is really no such thing as "provisional API". Either it is complete and committed platform API, or it is internal code.
Moreover it reads:

[2]
Technically, a provisional API can change arbitrarily or be removed at any time without notice.
I believe that this document indicates that there is strong "API"-"Internal" division after the release (and maybe this is only my interpretation).


In the [4] I have found interesting table:
Specification
Test Suite
Implementation
Clients
Support Promise
Package
Platform API
yes
yes
yes
yes
yes
public
Provisional
yes
yes
yes
yes
not quite
public



The table is bigger of course, but only those two cases are important for us. Note the public package in the provisional API. It is contradictory to the [2] unless provisional API becomes API after every release.


I am happy to see that someone is already using provisional API independent from release cycle, even happier that
The TPTP project uses Provisional APIs for all new API introductions: the new API is released as provisional in release X and then hardened into platform APIs in release X+1. (4)

Maybe it would be good to ask TPTP team how this approach works in real environment?


What I'd expect from Eclipse is to adopt  slightly modified TPTP strategy - harden provisional API when it has not changed for one development cycle. Provisional API should be in public packages and has clear javadoc that would:

* warn the user that the API *may* change.

* encourage the user to register to particular mailing list/watch some wiki pages


On the other hand we could think about support from API tools, that would throw warnings/errors when the client access provisional API, and about completely new tool that would ask the user to register on mailing list, display messages from developer etc.


[4]
http://wiki.eclipse.org/Eclipse_Quality

Example:

Commiter A creates:

package org.eclipse.component;

/**

* This is provisional API. It is believed to be stable, but still may change. For your own good subscribe to the list component-dev-provisional to be notified about changes.

* @provisional

* @since 3.5

*/

public interface IInterface{

       public void method1();

       public void method2();

}


Now some client implements that interface. It is warned (by API tools) and prompted to register to the newsgroup.  During the development cycle we may ask clients if they got what they expected and if we can do anything better.


Eclipse 3.5 is released. A lot of people uses that interface, and it appears that third method is necessary. So the commiter adds method3(), posts to concrete mailing list and all customers are informed about compatibility breaking change. Also steps necessary to adapt new method are described (and in the future maybe some more advanced refactoring scripts).


Eclipse 3.6 is released with that change, than 3.7 without change, so the @provisional tag should be deleted and... no refactoring at that point :-).


I hope that my vision is easier to understand now :-).

[1] EclipseCon 2008 Device Debugging (DD) Update
   
http://www.eclipsecon.org/2008/index.php?page=sub/&id=45
   
http://www.eclipsecon.org/2008/sub/attachments/Device_Debugging_Project_Update.pdf
 

[2]
http://wiki.eclipse.org/Provisional_API_Guidelines
 

[3]
http://wiki.eclipse.org/Export-Package
--
Christopher Daniel        
Technical Support Engineer
Eclipse Support Center    
IBM Software Group      
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