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Interoperable P2P: Jxta
Troy writes: "This article went up today (on developerWorks) about the Open Source project called Jxta, which is a community-run attempt to build a utility application substrate for peer-to-peer applications. Anything with an electronic heartbeat can become a Jxta peer." A nice high-level overview of how Jxta is supposed to work.
Ok. i'll take a dare and assert that i'm not the only one puzzled by wether or not we even need such a thing.
Anybody with an hour or two and a good book on Perl can write a client/server package, complete with a crude protocol that allows both sides to talk. I guess what i'm getting at is, what good is an "application substrate" in this situation? If peer-to-peer sharing is by definition a specialized application meant only to communicate (and deal with) an equally specialized scorresponding part, then why bother building a "one size fits all" version in the first place? Perhaps a common protocol for P2P would be a good idea, but then again, we already have that. Its called TFTP. Or NFS, for that mattter. I've always thought that publically exported NFS shares make the best platform-independant P2P solution.
Sometimes, especially for experienced coders, it becomes tempting to want to reinvent the wheel. If you're going to set out to make something as complicated into something thats now easier to handle, cool..Go for it. But don't try and over-do something that is already simple by its very design.
By the way, if you're one of the guys building such an app, feel free to swing by System 26 when you're ready and have a look around. You might find something useful to include in your code to make it a little more asthetically pleasing. Plus, its free.
Cheers,
Bowie J. Poag
Jxta seems to be a bit better at being a true P2P network without having to know the address of a node before-hand, but Freenet seems to handle bandwidth better by distributing popular files across multiple nodes as needed.
Sun is apparently trying to keep a "hands-off" posture with IP security on Jxta, while Freenet carries it one step further by making it difficult to find who posted or holds "bad" information at any given time.
So... which will ultimately be the better/prefered choice of users?
Sun are a strange bunch, a company where the vi v emacs wars can really kick off as two of the developers are there (Gosling for emacs, Joy for vi). JXTA is another of Bill Joy's babies, its meant to be a language/protocol independent offering for peer to peer solutions, which was originially what http://www.jini.org said they would do (Jim Waldo).
JXTA is a nice idea, and there are some good papers from JavaOne on the subject. But given that Sun's marketing might is behind J2EE will JXTA really be given a chance ?
IMO the answer is probably yes, JXTA and Java are part of a two pronged attack at next generation devices, this isn't really PC to PC type applications but device to device, most of the next generation mobiles will be running Java, some will not and most service provider cells will not, JXTA enables the bridge between the Java world of the device and the big bad world of networking to interact.
Strange how the best ideas come without marketing strategies. Java was an inhouse project which aimed for 10,000 downloads. Will the same explosion happen with JXTA in a wireless world ?
PCs suck, time to distribute.
An Eye for an Eye will make the whole world blind - Gandhi
The closeness operator sounds a bit like sorting, and anything that can be sorted can also have a closeness operator, however not everything that can have a closeness operator can be sorted. There is no reason why a more general query couldn't conform to these requirements. Generally speaking it would probably require some form of "fuzzy matching" of metadata to an SQL-style query. Of course this would require some constraints on the nature of the query, but it could still be much more flexible than Freenet's current lexographic search.
My point is that Jxta is making development decisions that are best left up to implementers. For instance, the Freenet developers are never going to allow broadcast anything, but if Freenet were made within the Jxta framework, they would have to live with broadcast node announcement (despite the fact that the experimental 0.4 Freenet is getting support for a uber-efficent node announcement that scales linearly).
Not a typewriter
You could have your coffee pot programmed to start by itself every morning, and then have it send a signal to your alarm clock when it's ready! Now that would be some useful technology!