P2P and the Web

In his first piece for Monkeyfist, noted XML pundit Edd Dumbill writes about the "new" world of Peer-to-Peer computing. Adapted from his presentation to the O'Reilly P2P Conference in February of 2001, this article addresses the fit between P2P and the original peer-to-peer platform, the worldwide web.

Despite what it says down there, Edd wrote this, not me ;)

P2P and the Web
By Niel Bornstein


    Introduction
    
   Some say that P2P is the future of the Internet, others that it's
   just a passing fad. In this article I will examine the relationship
   between P2P and the Web, and how both technologies might benefit
   each other.
   
    What is P2P?
    
   Before going further, it'll help to define what I'm talking about
   when I use the phrase "P2P". Several attempts have been made at
   drawing the boundary lines as to what constitutes a P2P application.
   One thing that has become immediately clear is that a strict
   technical definition is not appropriate -- most P2P applications
   currently make use of a central server at some point.
   
   Having earnestly studied the marketing materials for many
   applications, I've come to the opinion that the best definition of
   P2P is: "P2P is whoever says they're P2P." And it's quite likely
   that before that they were probably B2C, B2B and A2A!
   
   Seriously though, there's no doubt that there is a phenomenon known
   as P2P, driven by the need to communicate and collaborate, and with
   a strong element of decentralized control. It's this that I take as
   my starting point for P2P, and I doubt whether at this stage any
   stronger definition is viable.
   
   The purpose of this article is to examine this brave new world of
   user-level network applications, and compare it against the most
   popular user-level network application to-date, the Web.
   
    The Early Web
    
   Some of the defining characteristics of the early Web shed light on
   both why it was popular, and also on why P2P applications are
   achieving popularity. The early Web was easy: for the initial
   audience it was easy to read, easy to write and easy to implement.
   The ready availability of clients for multiple platforms, along with
   the "View Source" ethic, encouraged the rapid take-up of the new
   technology. Furthermore, the Web was a lot of fun! People revelled
   in the extra ability to express themselves and share information.
   
   Think here about the ease-of-use of instant messaging, or the
   instant satisfaction factor of Napster. There's a short and direct
   feedback loop, based on interaction with our fellow network users.
   
    As the Web Grew
    
   As the Web grew in popularity and adoption, its characteristics have
   necessarily changed. It hit upon several problems, connected with
   the increase in number of users, and the level of expertise of those
   new users. Web-based collaboration became less usable, network
   congestion became an issue, media outlets talked of the "World Wide
   Wait".
   
   Whereas in the first instance you might well have classified the Web
   as peer-to-peer in the sense that nearly everyone who wielded a
   browser also published their own web pages, that ratio changed too.
   Less expert users, on sporadically-connected client-only platforms
   (mostly personal computers), grew to be the majority. For those
   users there was less control, less immediacy and little of the
   positive feedback that Web early adopters drew. Sure, the Web was
   still great with its large and diverse content, but the excitement
   just wasn't the same.
   
   One major source of disappointment for web users is the
   ineffectiveness of search. The web's simple-minded and free-spirited
   approach to markup was simultaneously the key to widespread adoption
   and the death knell for structured searching. Even the most advanced
   search engine technology of today is remarkably basic, and the user
   still has to do a lot of the walking. Two factors contribute to this
   information noise: poor information quality, due to the lack of any
   reputation management, and poor page classification.
   
   So, with all these faults, is the Web in decline? No way. The Web
   has established certain baselines that benefit everyone and which
   ensures its place as a foundation of Internet information systems.
   These can be divided into technical factors and human factors.
   Technical factors include:
     * Universality. The ubiquity of HTML and HTTP in implementation
       ensures that Web technology is a basic level of communication
       that practically all platforms support -- even some microwave
       ovens!
     * Internationalization. Although still immature, the Web
       infrastructure is designed to support international content on a
       platform independent basis. Standards like XML and Unicode are
       encouraging this, and browser technology has increasingly good
       internationalization support.
     * Openness. The Web is based on open standards, with an increasing
       commitment to those standards from vendors. This promotes
       participation from software creators as well as the benefits of
       open scrutiny for the protocols and technologies.
     * Integration. Largely due to the ubiquity of Web software
       components, we're now seeing the Web integrated into many other
       applications. A basic example is the delivery of software
       updates over the web. Further on, most if not all modern desktop
       environments feature Web integration.
       
   More human factors include:
     * Content. The breadth, depth and extraordinary diversity of
       content on the Web means it is an important cornerstone of
       information systems. Anything that might replace it must exceed
       the Web's usefulness and challenge for the accessiblility crown.
       Notwithstanding my comments about web authors being
       proportionally on the decline, it's still sufficiently easy to
       publish on the Web that its primacy for content is not yet
       challenged.
     * Understanding. It's important that users of a system understand
       how it works, and what its limitations are. Albeit increasing
       slowly, there is an increasing awareness of what the Web is, and
       what it is not. URLs are sufficiently commonplace that most
       people have a basic understanding of the technology.
       
    So What is the Web Anyway?
    
   When defining the web, most people would probably still say "Well,
   it's HTTP and HTML." This may have been an original fact of the
   situation, but the philosophy of the Web is a lot broader. As seen
   by Tim Berners-Lee, the Web is in fact constituted of anything that
   can be named with a uniform resource identifier, URI. URIs include
   URLs as a subset, but also include those things which have names but
   cannot be retrieved directly via a protocol that forms part of that
   name. The other foundation stone of the Web is of course
   internationalization -- whose end, at least in the W3C's eyes, is
   Unicode everywhere.
   
   What does this expansion of the concept of the Web mean? Anything
   with a URI is part of the Web. If we look at things directly
   accessible, this might include:
     * USENET (news:)
     * Pages on a web server (http:)
     * Telephones (tel:)
     * Email (mailto:)
     * Freenet (freenet:)
       
   What you can notice here immediately is that some P2P applications,
   given a URI naming scheme, are automatically part of the Web's
   structure. It would be quite simple to create URIs for instant
   messaging, for instance, in addition. Ideally, we want P2P protocols
   to have some of the Web's other characteristics as mentioned above,
   as well as just a URI scheme.
   
    P2P Applications Scratch Itches
    
   Now we've established where the Web is, let's look again at some of
   its deficiencies. It's my opinion that several of the popular P2P
   trends address direct lacks in current web technology. These
   attributes of P2P apps include:
     * Ease of "publication". With file sharing clients, publication is
       as simple as dragging and dropping. While some web programs
       offer this, it either costs or results in unfortunate lockin to
       certain systems. The fact is that web publication is still
       harder than it should be, perhaps primarily due to configuration
       issues.
     * Everyone's a server. Supported by the increasing availability of
       always-on connectivity, P2P's everyone-a-server mentality gets
       back to how things were before the dialup explosion. It means,
       in effect, that sharing and publication involves fewer
       configuration and inconvenient upload/synchronization issues.
     * Better user interfaces. Perhaps this one's the killer point.
       Though there is definitely room for improvement in P2P app UIs,
       dedicated interfaces that are suited for the task make a life a
       lot easier than contorted web-forms interfaces. Many web-based
       communication and collaboration solutions lose heavily because
       of user interface issues.
     * Controlled communities. Dedicated P2P apps create communities
       with a certain amount of control, which is largely due to the
       use of a custom UI. This makes it a lot easier to introduce more
       structure either transparently, or with minimum fuss. For
       example, benefits can be drawn in the metadata (and thus
       searching) arena, and cryptographic transport (e.g. Groove).
       These are areas where on the Web it's difficult to persuade
       users their extra effort is worth it.
       
   P2P Needs to be Plugged in to the Web
   
   The itches that P2P scratch are all well and good, but what's the
   use of systems that aren't integrated into the ubiquitous protocols
   and software systems that we all use today? In today's environment,
   no technology can afford to stay an island. Remember "push"
   technology? Rather than reinventing from the ground up, P2P
   applications need to open up and embrace the open platform of the
   Web.
   
   One useful integration technique is proxying. A local HTTP gateway
   to another service can be run locally on a machine, providing an
   HTML/HTTP-based user interface. This technique has been used for
   Freenet, and for a telephony interface. There's even a project for
   Mozilla, called [1]Protozilla, to enable Mozilla to natively
   understand new URI schemes.
   
   Many P2P apps already use the Web as a bootstrapping point,
   underlining that integration is desirable. The alternative --
   fragmentation -- is in the long term neither in the vendor or the
   users' interest.
   
    Scratching the Web's Itches
    
   Proxying is just the first step. Web technologies are in rapid
   development that will help bring the missing pieces from P2P to the
   Web. Let's examine some of these.
     * User Interface. It's long been recognized that the Web's UI
       features are woeful. The W3C's [2]XForms activity is working on
       creating a new set of widgets and browser/server interaction
       model. These should go a long way to making the Web a more
       comfortable interface for performing interactive tasks.
     * Ease of publishing. Although it's been around a while, [3]WebDAV
       (HTTP extensions to support content authoring and management) is
       still in the startup stage as a technology, though it's great to
       see it in the latest versions of Microsoft operating systems and
       in GNOME's [4]Nautilus. Where it's really lacking is on the ISP
       side, though folk like FreeDrive, DriveSpace and XDrive are
       providing WebDAV access. Such access needs to get nearer to the
       user. When users sign up with an ISP they need to get a folder
       on their desktop, which is their web site via WebDAV.
     * Shared computation. This is an area in which web technologies
       are making leaps and bounds of late. Both Sun and Microsoft's
       future strategies appear to depend on distributed computing over
       the Web, using HTTP and XML as the foundation. RPC/messaging
       focused technologies such as SOAP, WSDL, UDDI and friends all
       provide an underpinning for web-distributed computation. Other,
       more minority interest, techniques like shared data spaces can
       also underpin web-distributed computation. Technologies such as
       RDF, essentially an interchange format for knowledge, are
       important in this area.
       
   To me, one of the most important things about P2P that I want to see
   brought back into the Web is giving back the user decent access to
   content creation facilities. Browser vendors have consistently
   failed to fulfill the original vision of the writeable web, and the
   flow of hypertext creation has become ever increasingly one-way.
   We've seen web applications like Blogger and EditThisPage.com become
   successful in filling this need, but there's no obvious business
   model there, and many of these companies are struggling. The
   authoring, publishing and interaction capability simply has to make
   its way back into the user agent. (There's an argument to be made
   that the Internet Service Provider should provide these types of
   services.) Those of us who determinedly use the Web as a research
   notebook, and as a means of keeping in touch with family and
   friends, as well as a business tool know the value of being able to
   create hypertext -- but we know how hard it is too.
   
   While the technologies I've mentioned above are to a certain extent
   works-in-progress, there are also aspects of the Web that are more
   established, which P2P itself will benefit from building on.
     * Data interoperability. The rise of interoperable data formats,
       due to the influence of XML, enables applications and developers
       to "do more" with data. We've seen some creative uses of other
       applications' data due to open file formats: these things often
       "just happen." Projects like [5]Jabber illustrate the potential
       of opening up applications and protocols like this.
     * Decentralization. Picked out as one of the strong features in
       P2P, the Web has always been a decentralized information
       resource. So there's already a philosophical compatibility
       between the Web and P2P, meaning that such things as the
       adoption of URI addressing schemes should be natural. It's hard
       to think of a good reason not to try and integrate P2P
       architectures with the Web.
       
    Some P2P-ish Ideas for the Web
    
   One advantage P2P applications have had is the opportunity to make a
   fresh start with several ideas unencumbered by web history. While
   this is both good and bad, there are some ideas from P2P apps that I
   think the Web would definitely benefit from.
   
   The first of these that attracted me was search by example, as
   employed by [6]OpenCOLA. The idea here is that a simple way of
   searching for quite a complex set of metadata matches is to throw
   out an example. This is a lot simpler for the user than defining
   separately each metadata facet and the relationships between them.
   As the Web heads towards exposing a larger amount of metadata,
   useful ways will be required to sift through this extra information.
   We already know that users of search engines only want one text-box
   and that's it -- how are they going to cope with the many dimensions
   of investigation created by decent web metadata? Therefore, the
   search by example technique seems a hopeful way to progress,
   although it will require some thought in order to implement.
   
   The second aspect of P2P applications that the Web could benefit
   from is a notification API. One of the most awkward things about the
   web is the need to continually check pages to see if they've
   changed. There's no general publish-subscribe system in order to
   notify me of updates, or the meeting of particular search criteria.
   Particular applications do implement this in a proprietary way --
   but there is no standard piece of web infrastructure to implement
   this. Perhaps this is another area in which it's hard to find a
   business model. This is a problem that needs to be solved by both
   web protocol engineers and user agent creators. WebDAV may be one
   way in which this problem can be attacked, especially if client-side
   servers were in use. The [7]ICE protocol has already implemented
   notifications, but it has a specialized application area.
   
    Conclusions
    
   Peer-to-peer applications, free from legacy issues, have started to
   fill needs where the web browser and web-based applications are
   failing. In particular communication and collaboration are needs
   which the Web isn't meeting properly. Ease-of-publication,
   configuration and search are advantages of P2P applications.
   However, the Web's ubiquity and openness contrast with the
   fragmented, control-seeking, nature of many P2P networks. If
   P2P-type apps aren't to die from fragmentation, or to collapse into
   corporation-controlled monopoly, then they need to embrace the
   technologies of the Web. The Web already has many technologies that
   are a suitable substrate for P2P applications, there's no need to
   start from scratch. On the other hand, Web software vendors -- and
   Internet service providers -- need to pay more attention to the
   desires of the user, and enable content creation, collaboration and
   searching to reach new levels of usability. "Just good enough" won't
   always be good enough.

References

   1. http://protozilla.mozdev.org/
   2. http://www.w3.org/MarkUp/Forms/
   3. http://www.webdav.org/
   4. http://nautilus.eazel.com/
   5. http://www.jabber.org/
   6. http://www.opencola.com/
   7. http://www.icestandard.org/


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Posted on Monkeyfist at http://monkeyfist.com/articles/754