Hi, 

I'll refrain from technical comments since I'm not that good in p2 internals, 
but will comment on the problem description . 

I think Pascal is right that ability to replace a part of base installation 
without affecting other parts would benefit Linux package managers. However, I 
think the actual user group for this feature is wider, and includes anybody 
willing to version-control parts of Eclipse. This is pretty much the case for 
any centrally managed installation, even on Windows. 

Right now it is only possible to version control Eclipse installation as a 
whole (i.e., "single package"), so one has to create a new installation for 
each new bundle version. However this approach does not scale because each 
complete installation is quite large, and due to a large number of bundles, new 
installations have to be created too often. Therefore, one is forced to 
fallback to using dropins (i.e., one "base package" + several "bundle 
packages"), which are very fragile and the use of which is discouraged. 


Kind regards, 
Mikhail Kalkov 

----- Ursprungligt meddelande -----

Från: "Pascal Rapicault" <[email protected]> 
Till: "P2 developer discussions" <[email protected]> 
Skickat: onsdag, 31 jul 2013 11:50:11 
Ämne: [p2-dev] 3rd party installers, droplets, etc 

(this is response to the threads on 3rd party installers ( 
http://dev.eclipse.org/mhonarc/lists/p2-dev/msg05226.html ) and droplets) 

Hi, 

Sorry for taking so long getting back to you. I have been away and did not feel 
like dealing with this issue as soon as I got back because this is likely to be 
long discussion :) 

First let's start by comments on the wiki page ( 
http://wiki.eclipse.org/Equinox/p2/Plan/3rd_party_installers ) 
- I think this page should be renamed to be "3 party installers on linux" as 
other systems generally have no issue invoking the p2 director. 
- It would be good to give a description of the problem you are running into 
with the current solution. You are mentioning the pb about "uniqueness" of 
libraries, but iirc there are other problems. Having all the problems listed 
will make sure that the solution we are creating will address them all, rather 
than discovering the problems piece meal and shoehorning a solution afterward. 
- Why should feature.xml contain ranges? what do you define as "external 
dependencies"? 
- I find the processing of droplets to be too complex. I think that a droplets 
needs to be a runnable repo plus something that identifies the feature(s) that 
must be installed. This way the work to be done by the droplet becomes easier. 
Wdyt? 

More generally, when we met at EclipseCon France, we blue-skied the concept of 
droplets as a potential solution and it is great to see that you are making 
progress. However, given the other requirements that I gather from some of your 
comments on the wiki page, I'm wondering if the droplet approach is the way to 
go. For example, we could also decide to go with an approach that generates a 
profile on the fly (or start from a stub profile) or structure the metadata 
differently to make it easier for you to patch, etc. 

Finally, a minor point, in the mail [1], you are saying 
"The rationale is quite trivial: in the devops times centralized 
deployment is something that completes common build infrastructure. One 
has to have the possibility to quickly build and deploy Eclipse and 
Eclipse components to developers. It's just too expensive to let them 
download each new version :-)." 

and this is misleading. Indeed, since its inception p2 has always supported a 
model where Eclipse can be completely updated from one build to another. This 
is not just a feature on paper. This is automatically tested but more 
importantly this is actively being used everyday by the development team which 
updates from one I-build to the next using p2, or by the EPP package 
maintainers when they verify that the SR0 package can be updated to SR1, and 
even to the next release. And, finally this is even works on Linux when Eclipse 
is installed by the user (downloading the eclipse archive). 
What you are describing is a situation specific to the way Eclipse is 
distributed on Linux by the package managers. 

Pascal 

[1] http://dev.eclipse.org/mhonarc/lists/p2-dev/msg05226.html 

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