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

If a project produces a zipped p2 repository would that remove the need to produce the current zip format entirely?  That is, would anything not be possible with zipped p2 repositories that is possible with the traditional zips?

Steve Francisco

IBM Rational, Canada Lab, Toronto
IES Technical Lead
cisco@xxxxxxxxxx  905-413-3684  TL:969

John Arthorne/Ottawa/IBM@IBMCA
Sent by: cross-project-issues-dev-bounces@xxxxxxxxxxx

02/10/2009 09:48 AM

Please respond to
Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>

[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:


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