Back in 2002, Yahoo acquired Inktomi, a struggling software vendor whose fortunes had turned unpleasantly with the dot-com crash. While at the time of the acquisition, Inktomi had refocused its efforts upon search, its original flagship product — the one that really drove its early revenue growth — was something called Traffic Server.
Traffic Server was a Web proxy server — essentially, software for running big caches. It delivered significantly greater scalability, stability, and maintainability than did the most commonly-used alternative, the open-source Squid. It was a great piece of software; at one point in time, I was one of Inktomi’s largest customers (possibly the actual largest customer), with several hundred Traffic Servers deployed in production globally, so I speak from experience, here. (This was as ISP caches, as opposed to the way that Yahoo uses it, which is a front-end, “reverse proxy” cache.)
Now, as ghosts of the dot-com era resurface, Yahoo is open-sourcing Traffic Server. This is a boon not only to Web sites that need high scalability, but also to organizations who need inexpensive, high-performance proxies for their networks, as well as low-end CDNs whose technology is still Squid-based. There are now enterprise competitors in this space (such as Blue Coat Systems), but open-source remains a lure for many seeking low-cost alternatives. Moreover, service providers and content providers have different needs from the enterprise.
This open-sourcing is only to Yahoo’s benefit. It’s not a core piece of technology, there are plenty of technology alternatives available already, and by opening up the source code to the community, they’re reasonably likely to attract active development at a pace beyond what they could invest in internally.