Despite armchair opinions that SPDY should have been leveraged with IP – could it have been?
We wanted to make sure the protocol was as widely deployable as possible. We knew that patents are encumbrances on technology adoption, so of course we didn't want patents at all. Further, we knew the rules of the standards bodies, and that if the protocol ever were to be adopted, patents are just a headache and a barrier.
Given these goals - patenting SPDY or holding back the IP would have been a horrific mistake.
As an example, consider the FAST TCP Congestion Avoidance protocol for TCP . It's generally well regarded as a promising and potentially better algorithm than what is used today. But it's patented. So nobody uses it. It's not "better enough" to overcome the obstacles of the restricted IP.
Those patents long predate SPDY, so the question of "aggressively or defensively" is moot. I think Microsoft, as a participant in the IETF standards process, is simply following it's duty in disclosing any patents they own that might have a bearing on this protocol. Given how broadly the claims are written up, it seems difficult for most application protocols to not infringe these patents.
So, to answer your questions in the title, there is some broad prior art, but the specific optimizations of SPDY could still have been patentable. By now, however, I'd guess the bar date to apply is long gone.
Your "historical multiplexing IP" patent has almost nothing to do with the Microsoft patents. The historical patent relates to "Inverse Multiplexing", which is achieving higher bandwidth transfers by splitting up and sending data over multiple lower-bandwidth channels in parallel. This is, of course, different from the multiplexing in SPDY and the Microsoft patents, which is combining multiple response objects into a single data connection.
Well, Akamai recently bought FastSoft, the company commercializing FAST TCP, so apparently, no; one of the largest CDNs ever will probably be using it.
The moral of the story, I guess, is that with any innovation your choices are mainly:
Either is a valid choice, and there certainly are lots of variations in between.
I will attempt to answer in brief.
First-off on protocols. Protocols as such cannot be patented [good reference required], just like the case of standards. Standards cannot be patented, but the catch is, technologies used in a standard could be patented. An example is the MPEG-2 standard that incorporates many patents. So, SPDY protocol as such cannot be patented, but the implementation (software) of the protocol can be (considering, we are talking about the US here).
Sure it could have been leveraged as a proprietary IP, say like a tradesecret, may be in the form of encrypted or obfuscated code. The article says, the protocol should have been kept proprietary. I think there is subtle difference between proprietary and patented. As said earlier, proprietary could mean a trade secret, e.g., the famous Coca Cola formula or even for that matter Google's search algoritms, and proprietary may not necessarily mean a patent. The information pertaining to a patent becomes publicly available (so not essentially proprietary), only restraint is that you cannot implement it without the permission of the patent owner before it expires.
Also, I must say that in my opinion making it open source was more beneficial. And beneficial to us, the public, since I feel the open source community has some pretty darn good developers and open source software comes free to the user.
Honestly, I don't know. Somebody else has to take this up.