Hi Jeff,

Thank you for your detailed reply ! I will go through the mail carefully and 
come back with more questions if needed.

Best regards,
Shenny

From: [email protected] [mailto:[email protected]] On Behalf 
Of Jeff McAffer
Sent: Friday, September 24, 2010 4:36 AM
To: P2 developer discussions
Subject: Re: [p2-dev] Product publishing and product update

There are a couple sides to this.  One is that if you have Product X v 
1.2.3.20100923, that should mean something. If you allow ranges as described, 
then two users installing X 1.2.3.20100923 may not get the same actual software 
installed. Variation is introduced for example, if user 1 has access to a 
different set of repos than user 2 or there is a network error for user 1 but 
not user 2 or the single repo changed between when user 1 and user 2 did their 
install.


Of course, these behaviours *could* also be exactly what you want but certainly 
some folks free at this non-determinism as a support nightmare.

Anyway, looking at features, they allow for things to be *included* or 
*required*.  Included things have exact version ranges while required things 
have, generally, wider ranges. Traditionally the notion was that on install, 
the things *included* by the feature were installed whereas the things 
*required* merely had to be there. Early update manager didn't even help you 
find/get/install the required things.  That was goofy so we provided a means 
for users to say "yeah, get the required stuff also".  Now with p2 we do this 
automatically without involving the user.  So much for context...

It would be reasonable to allow ranges on product content but it would also 
force the product designer to be very aware of the consequences pointed out at 
the beginning of this message. I honestly don't know what people would do 
naturally or what guidance we could/should give them (e.g., what's the 
default?).

Back to your original topic, there is also the possibility of producing new 
versions of your product that identify the new versions of the components. 
Product production and distribution in p2 is very light weight and users would 
see this as incoming new versions of the product (that they know about) vs 
changes to random components (that they may well not even know exist).  What 
would you say as the user of some banking product if told that there was a new 
version of EMF?  "WFT?!"

Scenarios vary.  If that does not work for you, you can insulate your product 
by making it consist of one feature. In that feature, *require* everything that 
you want to be updatable, include the stuff you want to be fixed (or put this 
stuff directly in the product).  The product will be bound to the one version 
of your container feature and the container feature can use ranges.  Beware the 
problems outlined above with non-determinism.  Note that you can also usethe 
p2.inf file to do this.  Andew Niefer did a couple blog posts on this a while 
ago
            
http://aniefer.blogspot.com/2009/07/composing-and-updating-custom-eclipse.html
            
http://aniefer.blogspot.com/2009/07/composing-and-updating-custom-eclipse.html

Good luck
Jeff


On 2010-09-23, at 12:13 PM, Yousouf, Shenol wrote:


Hi all,

I noticed that product publishing always sets requirements for a fixed version 
of the contained bundles/features, i.e. the defined range has its lower and 
upper boundaries equal like this:
<required namespace="org.eclipse.equinox.p2.iu" 
name="TestBundle"range="[1.0.0.201009171510,1.0.0.201009171510]" />
while I need something like this:
<required namespace="org.eclipse.equinox.p2.iu" 
name="TestBundle"range="[1.0.0.201009171510,2.0.0)" />
or even this:
<required namespace="org.eclipse.equinox.p2.iu" name="TestBundle" 
range="1.0.0.201009171510" /> (which means "any version > 1.0.0.201009171510")


The .product file format does not support a way to specify a range for its 
components, only an attribute for a fixed version. The product publisher also 
has no notion how to generate version ranges - it simply sets the range 
boundaries equal to the component version (see method 
AbstractPublisherAction.createIURequirements() for reference). So far, I cannot 
find a way how to workaround this issue and in my opinion it as a limitation of 
the product definition concept.

Why is this so important ? The use case is like this:
I am developing a product consisting of several components which is getting 
published on an update site on a regular basis. The components receive frequent 
updates in the p2 repository and their versions are incremented which is 
reflected in the requirements of the published product. However, once I install 
this product, I cannot apply updates to the system any more. The updates are 
refused because version ranges of the requirements for the installed and the 
updated products do not intersect which seems to make them incompatible.

This wouldn't be the case if it was possible to define open ranges in the 
product file. For example, the installed product would require a specific 
component in version range [1.0.0, 2.0.0) while its new version would require 
it in the range [1.1.0, 2.0.0). This would allow the update to pass because 
obviously range [1.1.0, 2.0.0) is compatible with (falls into) range [1.0.0, 
2.0.0). The way they are generated now is [1.0.0, 1.0.0] for the old product 
and [1.1.0,1.1.0] for the new one. Since these two ranges do not intersect, the 
update is not possible.

In short, I have two issues and hope to receive some advice from you how to 
address them:

 *   Is it possible to define a product with extended version ranges of its 
components ?
 *   What makes product versions compatible for update ? Why changed version 
requirements, which come as a natural result of the publishing process, do not 
allow the product to get updated to the higher version of its included 
components ?


Best regards,
Shenny

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