Is there a convenient way to find an Eclipse update sites? How do I proceed if I want to know the update site of org.eclipse.ui?
I had some difficulty finding some update sites while defining a target platform from scratch. I thought it might be useful to know about a straightforward way to find them.
I don't think that there is a general solution for this – I am not aware of any search engines for p2 repositories. So you will need to do manual steps.
I'll start with the second one: Let's assume you already have the URL of a p2 repository (aka update site) that may contain the package you are interested in. How do you find out what the repository contains?
One option is to try to read the p2 metadata files directly. These are located at <repositoryURL>/content.jar or /compositeContent.jar or /content.xml, or /compositeContent.xml. The metadata files are kind of human-readable:
content.xml lists all bundles and their exported packages, and you could do a string search for the package you are interested in.compositeContent.xml points to other repositories that are (logically) included in the repository at <repositoryURL>.Or, you just use Igor's p2 browswer to browse the p2 repository content.
But how do you find the right repository?
Probably the first p2 repository you should try out is the latest Eclipse release train p2 repository, e.g. http://download.eclipse.org/releases/kepler/ for the Kepler release. There, you would for example find the org.eclipse.ui bundle and packages.
If the package not there, there is no general rule where to look. Try to find the project providing the bundle or package and see if they offer a p2 repository/update site/software site, but if that doesn't help, you'd probably need to ask a new question here on SO ;-)