Project hosting sites move in and out of popularity in much the same way that programming languages do. They become suddenly popular, the place to host for cool new projects; then they mature into wide but less enthusiastic use; and finally, they begin a long decline in which they increasingly are associated with legacy projects.
Because the highest visibility hosts today -- GitHub and its predecessor in the top position, SourceForge -- both are offshoots of companies that sell code-hosting services, it's easy to forget that most hosts did not and do not have material commercial benefits to derive from hosting open source.
In fact, in the early days, such hosting was seen more as a service to a community than a profitable activity. Often, the hosts were created as the centerpieces of developer communities. The Apache Software Foundation is one such community and is still very active. Another is Codehaus, a site purpose-designed by a group of hackers (Bob McWhirter, Jason van Zyl, and later Ben Walding) to host their projects and those of like-minded developers. Codehaus, in particular, provided more than just code hosting: email support, continuous integration, and other services. By offering what was then a very rare compliment of services completely free, it was able to attract top projects, including Drools, Groovy, Maven, and others.
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