Goal.We wish to demonstrate that it is possible toaccount for the putative transition between aWeb of document towards a Web ofapplications strictly from an architectural pointof view.
Web Architecture:Three (?) main concepts URIs HTTP HTML /RDFREST
Assumption: Blogic isright 1/1."<can-of-worms> Note, this is about what URIs refer towhen used as logical names, not what they "identify" whenused by HTTP. These are two quite distinct ideas. Typically(not always) a URI identiﬁes some (source of) data aboutwhat it refers to. </can-of-worms>" (Pat Hayes)
Assumption: Blogic isright 2/2.Two visions. Blogic and RDF as it is (aka the Semantic Web?)- The Web comes first- We deal with HTTP URIs- Resources vs representations- RDF- We deal with URIs as proper names- Meaning of URIs
Two approaches, not twoWebs- The RDF is one take on the Web, a model, not as complex as reality.- "Death by layers": but look, we got those layers already so we should think about them! How they relate to the Web (theory of assemblages).
Resources (my - AM -take)- Resources arent things out there : you dont need to previously check a thing exists in the physical or scientific sense of the word to identify a resource.- Cannot be accessed, we all know that ("shadows", if that is not a means without an end what is it ! Anything at all...).- The resource is what bears on therepresentations, what explains why there werepicked up.
In REST (birthplace)Three things:1. Resource2. The states of a resource3. The representational states of the resource1. Rule2. Application of the rule3. Representation of that result
Resources are anything,but also..." (...) the semantics of what an author identfies".(Fielding and Taylor 2002)Just an author ?In Webarch this idea seems to come from Kripkes idea of baptism. There would lot to say but lets not discus this now.Lets rather find out if what we need is such a model of authorship.
Micro, meso, macro.The micro level focuses on the resource itself and its inner mechanisms.The meso level is about relations and interactions between computational resources.The macro level highlights the causal relations between an editorial policy of a publisher and the way he manages his web resources
Micro. More clients.Many more devices are becoming clients."Web servers were originally designed to propose "filesystem like" remoteservices. Since the common gateway interfaces (CGI) their structure havebecome increasingly complex. Nowadays, servers are able to negotiate withclients to adjust the response so that most of the content is generated on thefly. Any Web server is also compatible with at least one programing languagethat can trigger the processing of very sophisticated tasks that sometimesinvolve other remote services."
Micro. Break the causalrelation."One of the defined rationale behind documentary resources is that people have tried to preserve the causal relation between a reference and an informational content, because it was constitutive of all our "real world" documentary reference systems. The evolution from documentary resource to computational resource made more obvious that this artificially preserved causal relation had been broken."
Micro. Conclusion.The documentary location has been replaced by a locus of computation, a space of invocation.CGI and REST have turn URL into RPC passing parameters to scripts or web services. Now everything is (and has always been in a sense) URI which are identifying protean resources that can turn themselves in any format required by the client. Such are the computational resources.
Micro to macro.As said before, a resource is a formal translation of apublishing rule but these rules can change, theimplementation can evolve to match a new technologicalcontext, a bug can be fixed, a database can be updatedwith fresh data. There are many reasons for Webrepresentations to change and that is the truecommunication power of the Web, an editor can instantlyadapt the whole editorial chain synchronously with anyinformational/technological activity.
MesoThrough HTTP, any computational resource is likely to refer to other resources or to communicate with themE.g.:• Web services composition and orchestration• Web Data transformations and MashupMore than ever, resources are related to each other andcan be nested to create original compositions. Thus,qualifying the Web as an hypertext seems a little bitoutdated so we would rather talk about hyperprocess.
Macro. Many more roles!1/2This seems to become clearer everyday.The authorship model was maybe related to the "documentary Web". A Web of addresses and static documents. Not that it ever was like that but it is the way it looked like and was thought of and used.
Macro. Many more roles2/2Too many to mention but a few:• URI "minter"• Resource definer?• Resource publisher• Service provider• Information architects• etc.
Macro. Computationalcommitment.On the other hand, it is more and more difficult forpublishers to ensure a good quality of service throughoutthe processing chain. The technological stack and theprocesses involved in publishing a resource have becomeso complex and so distributed that it is becoming harderand harder to ensure a strict editorial commitment becauseas the Web grows in diversity, this commitment has turnedinto a computational one.
Macro. Many more rules(1/2).The resource is not the only rule : how individual resources are distinguished from one another depends on a publishing commitments. Other rules, more or less implicit.In other words, Web resources are often published as partof bigger resource sets, that have in common to be namedand managed by the same publisher.
Macro. Many more rules(2/2).We consider that an editorial policy can be summarized as a structured rule set. Some of these rules are generic, some others are specific and can inherit or be related to broader ones. From this, we assert that any Web resource formally expresses one of these publishing rules. In other words, a Web resource is situated at the intersection of a number of publishing rules.A URI then gives access to a representational state that is the result of this intersection and its closure, while it only identifies the most specific rule involved in generating the aforementioned representational state.
Macro: editorialcommitment.From the societal point of view, content publishers whosemain activity was to produce content and to guarantee thequality of information now have to deal with various newconstraints owing to the specificity of the medium.
Conclusion.The architecture of the Web of data and the models of the SemanticWeb may provide a way to match the diversity of online resources bymeans of a framework of metadata designed to annotate Webresources and exploit the semantics of their schemas to process themintelligently.Metadata and their schemas could be the keystone of the newresource-centric Web applications, their integration and interoperability.It is conceivable that tomorrow, he who controls metadata on the Web,controls Web resources, and through them a lot of things.