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Re: [cross-project-issues-dev] Producing downloadable p2 repositories

What does p2 do when in encounters an unpacked p2 repo containing packed jars, dropped into the dropins folder? Does it unpack those jars, effectively doubling the disk footprint on the client' machine as it installs them into the eclipse root folder? Or does it *replace* the packed jars w/ normal jars, and keep them in dropins?

The last time I checked the numbers pack200 (using Java 5.0) reduced the size of sites' update jars by 30-40%. So, sure, you're only downloading 7M instead of 10M, but then on disk you've eaten up 17M instead of 10M. Save 30% bandwidth, but incur 170% disk usage.

I can see the benefit for mirrors, but this sounds like teh suck for the end user, especially since some of those unpacked jars still need to be unpacked again to be useful (eg., feature jars) - which means we've not got the same content three times on disk.

Or am I off-base here?


John Arthorne wrote:

Hi Anthony,

We're unfortunately not in a position to be able to tell people what they must do ;). We were hoping to provide sufficiently convincing arguments that you would *want* to provide zips of your repositories, since this makes it much easier for downstream components and products to consume your project's binaries and metadata (and a happier Eclipse Foundation due to reduced disk footprint and bandwidth use). And making life easier for your consumers is typically in projects' best interests...


*Anthony Hunter/Ottawa/IBM@IBMCA*
Sent by: cross-project-issues-dev-bounces@xxxxxxxxxxx

02/10/2009 12:16 PM
Please respond to
Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>

	Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>
	Re: [cross-project-issues-dev] Producing downloadable p2 repositories


Hi John,

Your email says "The p2 team is now recommending". It is not clear to me what you are asking of projects for Galileo, if anything.

Anthony Hunter _mailto:anthonyh@xxxxxx.com_
Software Development Manager: Eclipse Open Source Components
IBM Rational Software: Aurora / GEF / GMF / Modeling Tools
Phone: 613-270-4613

Inactive hide details for John Arthorne---02/10/2009 09:49:48 AM---If you are responsible for your project's builds and packagiJohn Arthorne---02/10/2009 09:49:48 AM---If you are responsible for your project's builds and packaging, please read on!

John Arthorne/Ottawa/IBM@IBMCA


02/10/2009 09:49 AM

[cross-project-issues-dev] Producing downloadable p2 repositories


If you are responsible for your project's builds and packaging, please read on!

As you all know, providing update sites that include p2 metadata is a "must do" for the Galileo release. Now that everyone is producing this metadata, the obvious question that arises is how do people building products and packages consume this metadata? Everyone is accustomed to consuming Eclipse project output in the convenient form of zip files:

* zips are easily replicated to company mirrors, which reduces bandwidth costs for both producers and consumers * zips are a reliable and consistent input for builds. If you keep the input zips around, you can reproduce an old build easily and reliably * power users can hack together applications by unzipping various zips into the Eclipse dropins folder

However, there are also numerous advantages to consuming project output in the form of p2 repositories:

* Repositories can use pack200 to drastically reduce transfer costs and disk footprint * Repositories contain p2 metadata that would otherwise need to be generated on the fly by p2 on first startup * As projects start to produce and exploit more advanced p2 metadata, it can no longer be generated on the fly (think chmod and sym-link metadata for example) * A project can produce a single repository containing all of their project's output. Consumers then have the flexibility to install only the portions they need. In the past this consumer flexibility was only possible by having the producer provide numerous zip files containing the different permutations of their project output. These large collections of zips are a maintenance nightmare for producers, and lead to slower builds and higher disk usage.

On the other hand, remote repositories don't make for a reliable build input. They expose builds to transient communication failures, they may change or be deleted, they are difficult to mirror, they add to bandwidth costs if they are consumed remotely on every build, etc.

So, how do projects offer all of the advantages of both zips and p2 repositories? The answer: zipped p2 repositories. Simply take the p2 repositories you are producing today, zip them up, and make them available on your project download page. Consumers can then download these repositories, and use them offline in all the same ways they use either zips or remote repositories today. The p2 team is now recommending this zipped repository format as the downloadable format of the future. For more details, see this wiki page:

The p2 team_______________________________________________
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Nick Boldt ::
Release Engineer :: Eclipse Modeling & Dash CBI

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