Let's say I have something named/identified with a URI, like myself, now everytime that's mentioned anywhere on the web I'd like to know about it (okay not all the time, but it should at least be possible) - insert multiple scenario's here, conclude that any notification solution needs to be as generalized as possible.

So, I simply propose 3 basic things:

NOTIFY - a new HTTP verb

Why a new verb? to prevent collisions with usage of POST and to leverage the already existing design of HTTP, especially things like Accept and OPTIONS. (will need to have properties similar to POST)

notify - a new link relation

To be used in html, and with the Link header, this allows resources to specify where notifications should be sent to.

x:notify - a URI identifying the new link relation

it's just the rel, but using a full URI for compatibility with the semantic web.

That's it, quite sure one can build a lot of things on top of that.

a) The web is currently converging around web applications and mobile devices, a lot of focus is being placed on sensor networks, internet of things, and augmented reality to display information. Simply, how can these applications make use of published data readily from multiple sources if that data is not in a uniform standard?

b) The core web which people use on a daily basis is ever more silo focussed, and the size of those silo's is ever increasing - the social sector is a great example of this, and whilst there are core movements to create a more federated and distributed social web, a key blockage in the way is a lack of uniform data, often new formats are being developed, or poorly modelled application (rather than domain) specific models are making it out on to the web, and interoperability is several times harder than it could be, given the presence of uniform data. This has significant social and economic repercussions.

c) Time, a significant amount of time is invested daily by thousands (if not millions) in to re-solving the same old problems, creating a schema for this, a model for that, learning the same lessons countless people have learned before them, often the learning curve spans several years. A standard way to publish and share reusable model specific schemas (/not/ format specific like XML schema and JSON schema) would save vast amounts of developer time per annum. In addition to having significant economic impacts this would also lend to far more innovation (since more time free to innovate!) within an already important and innovative sector.

Why not "plain" RDF?

RDF has failed to be understood, adopted or loved by the general masses of the web, even many who use RDF often do not fully understand it and have many issues. Adoption has been... let's just say not good.

There are 3196 APIs on ProgrammableWeb, out of those:

• 2152 produce XML
• 1255 produce JSON
• 36 produce RDF

Perhaps more indicative though, is that those 36 are spread over 6 years, with only 1 updated so far this year, meanwhile there have been 58 new JSON based APIs in the last month alone.

Over on stack overflow, there have been 1,569,512 questions asked, 273 that's 0.017% of them, are RDF related.

The numbers are pretty clear, for all RDF's merits, and the countless benefits of the uniformity of RDF, it's just not being adopted.

To use RDF correctly requires RDF tooling, and not just tooling to parse the data (like JSON, and common usage of XML), but to use the data, to handle triples and graphs and queries, all of which requires significant investment in skills, time, and deployable technologies.

Further more, RDF data published using multiple different ontologies is difficult for people to use, the infrastructure and tooling simply doesn't exist to follow ones nose around the web and make practical use of several thousand different ontologies, that level of understanding is a good generation away, and for now all it does is serve as a blockage to adoption, and primarily as a blockage to people actually using or presenting the data. Time and time again we have seen a rallying around core ontologies, with successful mixing and matching happening more at the ontology level, than the data level. For now applications will be looking for mentions of Classes and Properties they "understand" (have a hard coded usage for).

Additionally, these difficulties in usage have lead to a second layer of centralization on the web, one which was borne from RDF, and rather ironically many of the architectural benefits of uniformity and universality are being lost. That is SPARQL, we are seeing a huge increase in SPARQL enabled datastores on the web, each of which holds a specific set of data, and each of which has key resource limitations. Practically this means that:
- clients are tightly coupled to servers
- all processing and storage weight is being handled by the servers
- data on the wire is non uniform
- clients are not using the web of data, rather they are using a datasource on the web, a datasilo.
This is a pattern which is not optimized for anybody, servers, clients, developers, data, the web, the network.

The core benefits of a web of linked data have not realized, RDF has failed to deliver them, primarily due to complexity and tooling requirements. SPARQL (positioned on the server/silo) is only compounding matters. That's not to say it cannot deliver them, or that these technologies are bad, only that they have not delivered the core benefits, yet.

Perhaps another way to put it, is that if you break things like RDBMS and Classes and Objects down you can get to triples of some sort (EAV, RDF, or to atomic relations / predicate based logic), and RDF did just this, however it was done in such a way that the data format (RDF) required a full new stack of technologies to /use/ the data, rather than being a uniform data format acting as a bridge between say classes and objects and RDBMS, a webized data model; that is to say, you can't really use "it" (RDF, the model people don't really speak of) with 95% of the deployed technology out there, you can provide an RDF view of the data from that technology, map it to RDF, but you cannot easily pull it back in and use it, and unusable data, isn't much use. There are many shades of grey between, but it's certainly more at the unusable end of the spectrum.

What can we do?

If we look at what people already do, a large proportion of web developers (most) continue to publish data via web services as XML and JSON, the common process is simple, create a schema, document it somewhere out of band (perhaps call it API documentation), publish data using that schema in some arbitrary way as XML and JSON. On the client side the same process continues, find a new API, get an XML or JSON parser, map the data as described by the API to some classes and start using it. All of this is needless work, they are showing us what works, what they can do, and how they can work with data easily. Tersely, they are missing the benefits of Uniform Data.

We can bring the benefits of uniform data to the current web 2.0, class and objects, rdbms, xml and json focussed web.

We can not only address these core issues, and bring the benefits of linked data and the semantic web to the general developer population, but we can also:
- ensure it's RDF and traditional semantic web compatible (giving "us" mountains of useful every-day data)
- provide that clear migration path to the "full" semantic web that's missing now.
- increase semantic web adoption exponentially, bringing big benefits without the high cost.

Approaches

There are two key approaches I can personally see to this:

1. Webize Classes and Objects (Java style POJOs, Data Objects, subset of UML)
2. Provide a Classes and Objects view over RDF

The first of these approaches - providing an abstract syntax for classes and objects and then defining mappings for that to XML and JSON - would bring the benefits of OWL 2 and XSD to schemas, and the benefits of "linked data" to both the schemas (/class blueprints) and instance data. It would allow data validation rules to be augmented on from sources external to the schema, it could be codified in libraries across multiple languages, it could also serve as a translation layer between Classes and Objects, NoSQL, and RDBMS, and other formats such as CSV. Additionally it would lend each schema openly being mapped to vendor specific databases, as well as vendor neutral schemas such as ANSI SQL. Furthermore, it would also lend to innovation in each layer, for example standardized queries for each kind of data could be created, with translations of those to each specific vendor or to well defined standardized languages, and even codified to work in memory in libraries (for example within instance methods or to run on GPU enabled hardware and languages). Many benefits could come from webizing what the masses already do. Other examples include providing an opportunity to refine the core datatypes on the web in a serialization agnostic way (think xsd types merged with webidl types), ensuring the correct entailments for equality are baked in to the core, providing first level support for things like lists and sets, providing a foundation upon which diff, patch, versioning can all be accomplished, providing canonicalized forms so that encryption and a data signing can be accomplished... and more I'm sure.

The second of these approaches has less wide scale benefits, but would provide a more usable abstraction layer on top of RDF, which is currently (dare I say painfully) missing. This would ultimately make working with data more familiar, a codified example could be:

var person = new Class('foaf:Person');      // external class definitions loaded from the web
person.load('http://example.org/bob#me');   // instance data loaded
print(person.name);                         // simple access to pre-known properties
person.validate();                          // in built validation from OWL 2
                                            // and XSD data type restrictions

// work with a schema class at a time..

var man = new Class('gender:Male');         // different class for different data
man.load('http://example.org/bob#me');      // same data
print(man.wife);                            // different, domain specific properties
man.expand();                               // full entailment regimes support to get
                                            // the most from schema definitions 

The best approach will become clear as time progresses, for now I'm keen and happy to work on either or both.

Just some musings..

To do:
Update rdfa-api to align with the RDF API, add full Graph Literal support, add RDFa 1.1 Core parser + profile support, finish generic HTTP based CRUD clients, merge with JS3.

Upgrade to support full N3, work on rule, reasoning and inference methods with OWL and rdfs support + sl/ql/fol based approaches, basic and improving understanding of ontologies, including restriction and owl based data validation.

Spec and upgrade to RDF Object View, spec and implement bi-direction oo-friendly tree views of RDF.

N3 Paths, RDF Selectors (and maybe SPARQL implementation?).

Create hook-in predicate, class and rule based agent framework for data streams and graphs, on top of aforementioned tooling - agents which listen for specific types of data / sets of statements and then do what's needed - to handle simple reflex, model-based reflex, goal-based and utility based intelligent agents.

Combine intelligent agent framework with data wiki support to create intelligent cloud storage agents, personal data streams and helper agents. (agent per uri, each agent has a task, collection of semi-dumb agents in to a data space makes a semi-intelligent agent).

Work on double-agent based auth/ident protocol - four-party, decentralized, temporally valid, webid-like protocol, with built in foothold for trust - details soon.

Leverage HTTP POST for storage / triple accepting agents in a "document which accepts annotations" style. Implement + compare and contrast SPARQL update vs Diff/Path approach.

Web Socket based triple & rdf object streams for personal data streams, filtered data streams, data synchronization and updates.

Generic linked data client side agents for specific tasks - basic social clients (messaging, friend adding, personal data management), and generic apps (like good-relations based client side basket which works on any site), shift of web application state to client side w/ stateless protocols and semi-intelligent agents at both sides.

side topics:
- micropayments via payswarm, open transactions, bitcoin.
- convergence of RDF libs and tooling for interoperability based on standardizing apis.
- p2p web / web architecture & movements on persistent domains, alternative approaches to resolvability/dns, bidirectional/back links.
- More amaya-like browsers/user agents, desktop based http client+cache+server in one efforts.
- RDF serializations (Turtle+Graph Literals ala AMORD in RDF, JSON based serializations / json-ld).

primary long term focus being the convergence of:
- read write acl enabled web of data
- "intelligent" / semantic agents
- internet of things
- augmented reality and innovations/improvements in device + human interface sectors.

A JSON compatible serialization of RDF

JSON is a lightweight text-based open standard designed for human-readable data interchange.

That's not what we need.

We need a lightweight text-based JSON-compatible open standard designed for machine optimized RDF data interchange.

We need it to be JSON compatible because JSON tooling is widely implemented, JSON is well supported, embraced by most web development communities, and of course it's fast and simple.

Stress: It won't be JSON, it'll be JSON-compatible, and to avoid any confusion or indicating that it may be human friendly, we probably would be wise not to put the term "json" in it's name, although we will need to put it in the media type identifier "+json".

We need to standardize because there are numerous competing and differing JSON serializations at the minute, so when somebody asks for a JSON serialization on the web, they get back different results in different places - that's unexpected behaviour, and it's not interoperability - so we need to standardize a JSON-compatible serialization of RDF, with an IANA registered mediatype.

The serialization needs to be machine optimized and usable in multiple different scenarios, else there's no point standardizing it, because other JSON compatible serializations will still be needed and therefore created. Thus we need to define the various use-cases and create a JSON-compatible serialization which caters for them.

An RDF API

There's been a lot of call for cool RDF tooling, specifically in javascript, mentions of a jquery extension and a jquery-like library - I agree that would be nice, but also say why just one? I like and want choice, freedom and to see innovation in the marketplace, I don't just use jquery, I use more libraries and modules than I could name - however..

A library is not an API, and that's not what we need to standardize.

We need to enable interoperability between libraries, and where multiple libraries may or do have overlapping and conflicting functionality, we need to align and standardize it, but only when it produces unexpected behaviour or limits interoperability.

Primarily, this means standardizing interfaces for the RDF Concepts (literals, references, triple and graph) - as soon as we do that, all libraries which implement these interfaces will immediately become interoperable. Web Developers will be able to throw data between libraries, cherry picking the features they want or the coding styles they prefer, library implementers will be able to focus on areas they specialize in, others will be able to stun us with innovative new approaches and tools we'd never have thought of ourselves, and we'll have an open and ever growing truly cool suite of interoperable classes, libraries and tools.

Next up we can standardize interfaces for things like RDF Parsers, because as soon as we do that, all libraries on each specific platform can share parsers, and these can be developed, maintained and improved independent of any specific library - it will also allow the same libraries to be used with specialist low memory parsers optimized for mobile devices, thus broadening their potential user base and giving the end users + developers the best experience possible.

Another set of interfaces which need standardized, are those which are to be implemented by multiple different vendors on the same platform, i.e. the web browsers, i.e. anything near the DOM or HTML, i.e. the RDFa API - which is already being worked on.

Finally, an interface which will make linked data and RDF easier to work with by developers (carrying on from my previous post) is a "Data Object" interface, that is a simple object which holds the description of a single subject, where the properties are keys and the values are native values. I was wrong in my previous post, serving up simple JSON objects will help, but isn't perfect, because we don't know and can't determine whether people will want to use URIs, CURIEs or terms to access properties, thus an interface will be needed to handle this.

This isn't an exhaustive list, and each paragraph above can be considered to handle a different layer in the stack, but standardizing anything substantially more than that will stifle innovation and be counter productive, people need and want different libraries with different coding styles, features and different ways to access and query data. Different tools for different jobs, and for different people doing the same job.

If you disagree, please do share and let me know!

Clarification

Earlier this week I was quoted as follows:

Nathan’s recent post on Opening Linked Data, which is worth reading in its entirety, captures the essence of the issue:

You can’t shoe horn RDF in to JSON, no matter how hard you try - well, you can, but you loose all the benefits of JSON in the first place, because the data is RDF, triples and not objects, rdf nodes and not simple values

In other words, using JSON as the basis for an RDF syntax doesn’t actually win you anything in terms of the ease of processing of that RDF. In fact, I’ll go further and say it has exactly the same bad qualities as RDF/XML.

However I have to point out that I probably didn't make the context clear, I was referring specifically to making a human friendly/optimized JSON serialization of RDF, you can however, very easily, create a machine optimized JSON-compatible serialization of RDF, without the drawbacks of XML (you just don't pin it as being human friendly JSON as outlined above) because unlike XML which requires a full XML stack, and RDF/XML which can be serialized in any one of a billion ways, we have a chance here to make a clean lightweight unambiguous serialization of RDF, one which is based on a lightweight data interchange format and not on a heavy extensible document interchange format.

Hope that clarifies :)

Why? well the sem web community is packed full of the most technically skilled and decent people I've come across so far, so it can't be that, the tooling is pretty damn good, there's loads of data, most of the data's of a high quality, wanted by developers, and certainly more than usable. The concepts, theory and technical aspects are all solid as a rock. In short it's all good, apart from one rather important detail.

Our Linked Open Data isn't really open data, not in the eyes of the common web developer at least. To most web developers on the planet, open data is something they can get access to and use easily.

A good example of 'open data' for most developers, is the Twitter API.

Here's how a developer accesses it in PHP:

  $uri = 'http://api.twitter.com/1/statuses/show/7907258268647424.json';
  $tweet = json_decode(file_get_contents($uri));
  echo $tweet->user->description;

Here's how they access it in Javascript:

  uri = 'http://api.twitter.com/1/statuses/show/7907258268647424.json';
  $.getJSON(uri, function(tweet) {
    write( tweet.user.description );
  });

The reality of the matter is that you can't do this with Linked Open Data, and that's because you can't do it with RDF - and really, honestly, if it's not that simple, the masses won't use it, because, if it's not that simple, they can't use it.

The problems with the RDF formats

They're not perfect, and they are a very mixed bunch, for a change, let's look at the negatives.

RDF/XML
- Requires full XML tooling
- Can't read or write by hand
- butt ugly

Let's be honest, unless you have a full XML and RDF stack and you know what you're doing, RDF/XML is simply a no go zone.

RDFa
- Requires HTML/DOM/XML tooling
- An extension to a markup language, designed to augment annotated documents.

RDFa is great, but not for the general data use case, it's not a simple data interchange format like JSON, and you can't publish or consume it without specialist tooling, in fact it requires an even bigger, more complicated, stack than RDF/XML.

Turtle
- Requires a custom parser
- It's not yet seen as a data format by the masses.
- Doesn't have a registered media type.

If we're all honest, Turtle is the king of RDF serializations, it's small, powerful, easy to write and read, requires minimal tooling to parse. In fact, I'd quite happily say that Turtle is the best all round data format, period.

RDF/JSON and JSON-LD
- Square peg, round hole

You can't shoe horn RDF in to JSON, no matter how hard you try - well, you can, but you loose all the benefits of JSON in the first place, because the data is RDF, triples and not objects, rdf nodes and not simple values - I fear I'd better explain, quickly:

The benefit of JSON is that you can do the following:

  var u = tweet.user;                                // nested, simple objects
  write(u.message);                                  // simply "a string of text"
  if(u.geo_enabled) {                                // a boolean true
    var d = u.statuses_count * u.favourites_count;   // numbers..
  }

Anything more complicated than that and you've lost 95% of the benefits of JSON.

Here's the code to do that if(u.geo_enabled) with JSON/RDF:

  var tweet = rdf['http://example.org/tweet/12343'];
  var user = rdf[tweet['http://example.org/property/userid']];
  var geoenabled = user['http://example.org/property/geo_enabled'];
  if( Boolean(geoenabled.value) ) {

and JSON-LD:

  var tweet, user;
  for(o in jsonld) {
    if(jsonld[o]["@"] == 'http://example.org/tweet/12343') tweet = jsonld[o];
  }
  for(o in jsonld) {
    if(jsonld[o]["@"] == tweet['twit:userid']) user = jsonld[o];
  }
  if(user['twit:geo_enabled']) {

Remember, those two examples are only for the simple if line from the benefits of JSON example, can you even imagine all four lines?

Clearly, RDF in JSON is of little to no use to anybody, you can see plainly yourself, 95% of the benefits are lost and it's just another RDF serialization that's pretty much unusable without tooling. The only benefit JSON serializations of RDF have, are that you don't require an XML stack, which is quite a large benefit tbh.

The problem with RDF

I've been a little unfair there, you see the problem isn't with the serializations, we can't make a "better" serialization of RDF for general web developers, because the real problem is that the data's RDF, it's triples not simple objects, URIs rather than simple terms, RDF Nodes with a language or type, and not just simple values.

An array of RDF triples, or a structure of RDF, just simply isn't usable in most (all?) programming languages, by a typical web developer, without specialist tooling and libraries or APIs.

Am I saying RDF is bad? no of course not, it's awesomely brilliant in every way, it powers a paradigm shift and will have huge positive effects on the web and the human race. You know the score :)

What I am saying, is that we're not backwards compatible, we're not making our data open in formats which are usable by normal developers, developers who need and want the data, want the links, but not the semwebbery. Hell even most of us who are heavy sem web users only consider the ontology+reasoning side enabled by properties-with-uris some of the time, most of the time <http://xmlns.com/foaf/0.1/name> might as well just be "name".

Opening Linked Data

So, here's what we need to do, we need to just accept that although we publish linked data as RDF, we also need to publish the data as simple objects so the world can use the data.

Given the linked data:

  @prefix : <http://webr3.org/nathan#> .
  @prefix foaf: <http://xmlns.com/foaf/0.1/> .
  @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

  :me a foaf:Person;
    foaf:age 29;
    foaf:holdsAccount [ foaf:accountName "webr3";
        foaf:homepage <http://twitter.com/webr3>;
        rdfs:label "Nathan's twitter account"@en ];
    foaf:homepage <http://webr3.org>;
    foaf:knows <http://example.com/bob#me>;
    foaf:name "Nathan";
    foaf:nick "webr3", "nath" .

  <http://example.com/bob#me> a foaf:Person;
    foaf:name "Bob" .

We also need to publish it like this:

{
  "http://webr3.org/nathan#me": {
    "a": "http://xmlns.com/foaf/0.1/Person",
    "age": 29,
    "holdsAccount": {
      "accountName": "webr3",
      "homepage": "http://twitter.com/webr3",
      "label": "Nathan's twitter account"
    },
    "homepage": "http://webr3.org",
    "knows": "http://example.com/bob#me",
    "name": "Nathan",
    "nick": [ "webr3", "nath" ]
  },
  "http://example.com/bob#me": {
    "a": "http://xmlns.com/foaf/0.1/Person",
    "name": "Bob"
  }
}

and now one can do: me.holdsAccount.label and get back a string, in any language.

What have we lost?
Well nothing in the grand scheme of things because we're still publishing the RDF in other formats via conneg, however in this specific serialization of the data: we've lost the properties, the .language and the .type, although basic types are still there, dates are detectable, numbers are supported, booleans are supported, everything else is just a PlainLiteral, a string.

What's still there?
The data, http names for things, follow your nose, rdf types ++usable-accessible-data in a web standard format. It's 3.5 if not 4.5 star data!

Other considerations
Probably be wise to allow direct access to a .json URI too, so people can simple-GET the data (in addition to exposing via conneg).

Should be an easy hit, any good reasons why not?

The other RDF Serializations

While we're here, there are a few other things that need tidied up, properly.

Turtle
Let's make it the standard RDF serialization, with a proper registered media types of application/turtle and text/turtle, fix any bugs in the spec (if any), and possibly allow an optional comma in those lists (1,2,3).

Let's just accept that RDFa is great, but sometimes you just want to embed a chunk of RDF in an HTML document, you know we all want to on occasion, people are shouting for it, it's easy to do, to deploy, doesn't break anything, and it's a really easy hit - so, in the Turtle standard spec pop a note that shows how to include it in an HTML document.

<script type="text/turtle">
  // turtle in here, as-is, no special encoding
</script>

RDF/XML
Leave it as is, let it run it's course naturally, and in many respects just forget it moving forwards, everybody supports it already, that won't change, but there's approximately zero need to keep pushing it.

RDFa
As awesome as it is, just see it for what it is, RDF in attributes, it's like the missing markup features of HTML, for annotating documents and describing the things described in the documents with annotations. It's not a simple data or RDF format, and it's not really suited to just dropping chunks of machine readable RDF in to an HTML document, Turtle in HTML will do that far better.

RDF/JSON and JSON-LD
Standardize a JSON serialization as a replacement / alternative to XML - but, admit and stipulate before hand that it's not usable as-is, or really writable and is arguably human readable. It simply needs to be a fast, unambiguous, optimized for the machine, RDF serialization - no bells and whistles for humans, no "12^^xsd:type" in a string - just something that you can JSON.parse and run circa 10-20 standardized lines of code over to get back an RDFGraph of RDFTriples.

Fin & end.

As we all know, one of the biggest hindrances to innovation in the various areas of computer science is the human brain, and specifically the tendency to think inside, rather than outside the box. There are things we never even consider or imagine because we just can't think outside of what we already know/presume - a small percentage of gifted individuals can, but on the whole, we as humans/geeks/programmers cannot.

To keep this short and simple, let's return to the aforementioned point, with javascript, any libraries you write can be used on both client and server. Great eh, write an AMF parser and it works on both client and server -wonderful.

Now, let's flip the example to a 'shopping basket', you see what we did there? now you've got an ecommerce application on the client side (think about that for a minute, you could put items from any 'website' in your basket, not one, any/all - oh and keep http stateless, and, and..) - here's another one, an authorization protocol like openid or webid - so a server could 'login' to a browser.. - how about an HTTP server in js, yes now it's on the client side and the server side - and when each side is both client and server isn't that just p2p?.

This universality breaks down the barriers of convention, it gets rid of that wall we have between server and client - can you imagine how many 'server side' technologies, libs, patterns and architectures nobody has ever even considered working with on the client side, can you imagine the implications and the period of innovation this will bring on?

Conversely, can you imagine how many client side technologies and libs nobody has thought about putting on a server? fancy using HTML as a data storage serialization and editing it via jquery on the server perhaps?

Maybe you can't imagine, maybe I can't - but fact is it will be possible, and people will start doing it, often just by lack of these assumptions and notions the current generation(s) of programmers have, they won't assume that something we've always used on the server side will be on the client, they'll just do it because it makes sense, and we, well we'll all be astounded.

Make sense?

There have been some nice examples of combining client and server side js recently, and node knockout is sure to provide many more real soon - if you don't know of node.js I'd recommend taking a look. Also worth noting the realtime client push service, Pusher (for HTML5 WebSockets) - of course there are also node implementations, and here's a nice article with some more details and examples.

I've also been playing with some of google's projects (radar check, you know about the ajax playground ya?), namely Fusion Tables (here's one) which has a full REST API, infact that's what it is, a kinda web db merged with csv merged with RESTful goodness - and you can use them with V3 Maps which gives some really sweet results - like this heatmap of designated beaches on the coast of Brazil. Convergence check, you noticed that protovis can be used with google maps ya?

If there's one app I wish google would opensource, it's Google Moderator for an example see the one for TipJar. Btw, did you see 3D Lego Star Wars running in Chrome with HTML5 (credit to Unity 3D truth be told) - oh, and if you ever wondered how those 3D Lego videos we see on youtube all the time are made, you'll be looking for this.

Generally I'm really admiring ushahidi (projects on github), and especially Swift River and SiLCC - there was a good post on 10 ways to use Swift River which is certainly worth a read. Related, but don't ask why, here's a good post on prediction services which has a few good links. Crossover check, remember earlier I mentioned Fusion Tables w/ Maps V3 and Protovis.

Digital Bazaar have been working on a Javascript implementation of TLS (part2) namely Forge - code on github -explaining why this is such a big deal is outside the scope of this post, but I'd encourage you to look at PaySwarm and Digital Bazaar's fantastic blog which'll give you a good overview of what they're up to. Related and similar, it's worth noting jsSHA - a JavaScript implementation of the entire family of SHA hashes, random.org for all the true random data you could need, Bitcoin a peer-to-peer network based digital currency and amf.js a js implementation of AMF. Also there's the HTTPS Everywhere extension for Firefox.

And in non technical land, I've really been enjoying How to be a Retronaut, it features amazing media from the past, such as Colours of the Rothschilds… which amongst other things has a colour photograph of King Edward VII, taken in 1909 - other recent favourites include the Eiffel Tower being built, the first ever music video (1895) and the instant eye of Jacques Henri Lartigue.

If you haven't seen Hans Rosling's talk on global population growth go watch it now, v recommended - and finally, they figured out what came first, the chicken or the egg..

Here's the setup, a blog post which is a review of a new music album, the post has the familiar facebook 'like' button on there.

Here's the problem, my partner finds that people will only click the 'like' button if they 'like' the album, it's not about the post, the site, the quality of the writing in the review. All points to something wrong in the kudos chain.

It's not just like though, let's introduce a simple '5 Star' rating system on the posts, just what are the users rating, the post, or the album?

Now, let's change the example somewhat, scenario: a well write article about a horrific genocide - hundreds of people saying 'I Like this', as humans we can quickly infer (and somewhat hope) that people are saying they like the article, and not the genocide, but what about a machine.

For your consideration, each web page typically includes multiple distinct things, so we need a way to be able provide users with a way to do 'stuff' which each thing, I like this review, I like this author, this topic is worth noting, I like the primary topic, I've read this and so forth - any semantic web readers will quickly say "ahh problem solved! give everything a URI" (I hope) - but the problem isn't solved, it brings up (yet again) the issue that we need a whole new generation of UX/UI improvements, one 'like' button will not do, when you've got 10-100 things on a page, and different actions for each, this is something that's clearly going to have to be abstracted out from the page and handled in a different way - just how I don't know..

Will leave it there, you can see the challenge..

The specific issues are:

• Read-Write Linked Data
• Socially Aware Cloud Storage
• Levels of Abstraction: Net, Web, Graph

I'm yet to disseminate all that's changed, but they certainly are filled out and refined, remember folks the devils in the details!

Quite sure that I'll follow up with a bunch of notes, as will a few others - but for now, there's the heads up that it's time to do a bit of reading.

Something to try

Next time you start an application, why not create a subdomain for your data tier, create a script for each SQL query and call it via HTTP (honestly you won't notice a speed difference), similarly expose all static files your system uses on the same (or a different) sub domain. Here's the advantages:

1. You can scale without changing your application
2. You can swap servers without changing your application
3. You can move data around your server and take advantage of all the HTTP servers features.
4. You can cache your resources and utilize HTTP caching.
5. You can distribute or relocation your application anywhere on the net without worrying about data.
6. You can migrate over to different data systems (swap database vendors etc) without changing your application.
7. You can call every resource on the web in the same manner, from APIs through to linked data and all in between.
8. You're critical SQL and data mapping code will be fully abstracted and in self contained files (ultra easy to edit, bug fix, maintain).
9. You can take advantage of HTTP logging, and HTTP status codes instead of custom exceptions.
10. You have a ready made RESTful API in to your data tier, so you can hook on other applications, or open it up to third parties, or the entire net.

So much more, all by one simple step - and that's only the first half of the cartoon ;)

Generations One and Two

Historically we have been through two generations of the web so far, not web 1 and web 2.0, but rather the first round of mounting the presentation tier on the web (static publishing documents and media), then the second round of mounting the application tier on the web (from forms through to the current api's we see everywhere).

The next round, and what many are currently hacking at, is mounting the data tier on the web, mainly via the "Linked Data" movement which you may have noted.

This third round is critical for two primary reasons:

1. By mounting the data tier on the web, it allows us to remount the application tier again, but this time properly, where HTTP is the API between the Application tier and the Data tier. (true REST)
2. The "Internet of Things" is very much dependant on the "Things" speaking the same language and sharing a single Data Model, where the model remains the same but the vocabulary can change.

Generation Three

"Linked Data" is in many ways the solution to the above, because it has a Universal Data Model (EAV), a Universal API (HTTP), and Universal Addressing & Identification (the duality of http URIs) - more importantly though, "Linked Data" provides the means to mount and expose both ABox and TBox statements on the web - this is the key detail where RDF wins over other EAV based data models; the ability to store both the data and the vocabularies on the web, and both in the same manner.

Linked Data is currently tied (but not bound) to RDF. However, RDF still has very critical limitations, primarily it doesn't have any notion of Named Graphs or Quads. Trust and provenance are essential moving forwards (with quads you can select which data your application trusts, and which it doesn't, based on the source, the Named Graph - without it you can't), as is the ability to transfer data from multiple sources at the same time (update streams, batch operations, merged data with provenance - again needing quads).

The above means we need an RDF2 (or standardisation & adoption of N3+rules), and moreover we need standardized non-xml serializations of said RDF(+2), the most important being rdf/json.

This brings me to HTML5, the key here isn't the new HTML5 document format, the semantics, the ability to embed microdata or anything like that - it's the introduced (or implied) dependency on JS /ECMAScript via the JS APIs. This leads to JS being rolled out on to the majority of devices - it's also important to note the server side JS movement in this too.

Generation Four

We've had a "Web of Documents", we're building a "Web of Data", the next logical step is to have a "Web of Applications", for this we need two things: a Universal Programming Language (JS...) and an "Internet of Things" which support the universal data model and the universal programming language.

As far as I'm concerned HTML5 plays a critical part in the big picture:

- Short term, it at least unites the browser vendors to better support the techs which developers use.
- Presently (and from here on) it allows us to start hacking at the web of applications.
- In the future it's legacy will be it's introduction of JS as a Universal Programming Language.

Sides:
It stands to reasons that RDF/JSON (or whatever supersedes RDF serialized in JSON) will also play a major part in this round.

We may well see a shift from client-server, server-server to application-application; where each machine on both sides comprises of HTTP Client, Server and Cache.

Generation Five

Leading on from here we get to the fifth round of the web, remounting the Presentation Tier, but this time where the presentation tier speaks to the application tier through HTTP, the Universal Interface.

HTML (together with JS and CSS) again plays a critical role in round five, because up until this point it remains the only way for the hackers to create this fifth generation, notably it will be a lot more than we are have now, after years of maturity, hacking and support universally. Naturally then we can assert that HTML will remain the core of the Web's presentation tier so long as the Web exists.

Additional Shifts

Widespread adoption and understanding of REST, truly without this we'll never get past generation three.

Data transformation, for a very long time data transformation will be an everyday service we all require, for legacy systems, legacy data, proprietry systems, data model conversion and so on - the key isn't to be able to understand all kinds of data / serializations / models, but to transform it in to what you do understand, easily.

The enabling of the Semantic Web, Linked Data provides the means to do this, it is the enabler - each EAV triple we put out is also a triple that can be reasoned over, full machine understanding of all our data is an ultimate goal that will take many years. Generation three very much pushes the semantic web in to the realms of the real world, no longer for the strictly academic.

The great cleanse, all the data from generations one through three (and possibly beyond) will need cleansed - as primary universal vocabularies emerge the task will be to clean what's on the web and migrate it in to the new models, reasoning and cleaning it as we go.

Cross compilation and seperation of syntax from machine code - another movement that is gaining momentum, no longer are we tied to a specific syntax for a specific JVM - not far off is the day where we can program in our preffered language, and compile it to whatever target we need. This is all ready happening in many quarters (like haxe) and soon will be the norm.

Seperation of human readable data syntax and data storage/transfer serialization. This has long been understood, however with EXI comes a light serialization of XML for the machine & transfer; logically from there we can expect the same in the future for RDF(2) and most data moving forwards.

Much of the code needed for the Application Tier will disappear over time, typically most application code involves taking some data and turning it in to some new data, processing it - when you can do this on the fly via data transformations, rules, reasoning, inference, querying and similar, you remove the need for most f the code in between. It is entirely possible that most server side web applications could disappear.

End

It is testament to the strength and design of the web that it can support every incarnation of the web thus far and in the future all at the same time - All credit to Tim Berners-Lee, Roy T Fielding and the many, many others who contributed, evolved and continue to forge this thing we call the web.

Disclaimer
Obviously, this is all just my humble opinion, none of it is fact - but from stepping back a bit this is what I conclude, for now.

I've skipped loads of things, most of the techs I work on and think about daily, FOAF+SSL, web access control, read write web of structured linked data, loads more - the above is just a summary of where I think we're headed, primarily for my own reference :)

Universal doesn't necessarily mean universal - but it's a good enough word to convey what I'm thinking. Any other use of terminology you don't quite agree with, likewise, terminology is not the point of the post ;)

Best & happy to hear your thoughts and additions,

Nathan

The Standard Way
This way essentially exports all SSL data, certs, client and server side if you read the notes has performance penalty.

SSLVerifyClient optional_no_ca
SSLVerifyDepth 1
SSLOptions +StdEnvVars
SSLOptions +ExportCertData


The Lighter Way
This way simply passes in the SSL_CLIENT_CERT in to the env REMOTE_USER and skips the rest which you don't use (for FOAF+SSL).

SSLVerifyClient optional_no_ca
SSLVerifyDepth 1
SSLUserName SSL_CLIENT_CERT


Tested and works very nicely (again, imho).

note: Enabling SSLOptions +FakeBasicAuth will overwrite this with the Subject from the client side certificate.

I'm assuming that if you are reading this, you know what linked data is, and REST as per the dissertation of Roy T. Fielding. If not go do some reading :)

Interface Constraints

REST is defined by four interface constraints:

1. identification of resources
2. manipulation of resources through representations
3. self-descriptive messages
4. hypermedia as the engine of application state.

From here I'll look at each of these four constraints and build up the approach as I go.

What a resource is

Quoting extensively from REST 5.2.1.1 Resources and Resource Identifiers:

The key abstraction of information in REST is a resource. Any information that can be named can be a resource: a document or image, a temporal service (e.g. "today's weather in Los Angeles"), a collection of other resources, a non-virtual object (e.g. a person), and so on. In other words, any concept that might be the target of an author's hypertext reference must fit within the definition of a resource...

A resource is a conceptual mapping to a set of entities, not the entity that corresponds to the mapping at any particular point in time...

The values in the set may be resource representations and/or resource identifiers...

A resource can map to the empty set, which allows references to be made to a concept before any realization of that concept exists...

The only thing that is required to be static for a resource is the semantics of the mapping, since the semantics is what distinguishes one resource from another...

What a representation is

Again, quoting extensively from REST 5.2.1.2 Representations:

... A representation is a sequence of bytes, plus representation metadata to describe those bytes. Other commonly used but less precise names for a representation include: document, file, and HTTP message entity, instance, or variant...

If the value set of a resource at a given time consists of multiple representations, content negotiation may be used to select the best representation for inclusion in a given message...

The data format of a representation is known as a media type

Identification of resources

To do this properly I need to identify some resources, so for this I'm going to work with "Something" :)

• "Something" - a resource, a non-virtual object

At any point in time I have a description of Something which has multiple representations in different mediatypes, all semantically matching or equivalent:

• "something.rdf" - representation of Something with mediatype RDF+XML
• "something.n3" - representation of Something with mediatype RDF+N3
• "something.en.html" - representation of Something, in english, with mediatype text/html
• "something.de.html" representation of Something, in german, with mediatype text/html

Each one of those representations is also a resource because they can be the target of a hyperlink. Of course by resource I mean a conceptual mapping to each of the things listed, and I haven't assigned URIs but will..

To be able to make this set of representations manageable and to indicate they are in a set, I'm going to add in another resource which is a collection of resources, which can be considered a set of these equivalent representations of Something at a fixed point in time. For the purpose of this exercise, that point in time is today.

• "Something-20100311" - a resource which is a collection of equivalent representations of Something on the 11th March 2010.

Additionally, for the sake of argument, I'm going to say that a new set of representations (or version) is added every day - to handle this I then need one more resource, a collection of resources, where each resource in the collection is itself a collection of resources (one of the aforementioned and including the example "Something-20100311"). This will give me a conceptual mapping which covers time, and therefore everything I could need.

• "Somethings" - a resource which is a collection of resources, see above for full description!

Finally, I'm going to add in two shortcut resources which have no representation and are simply conceptual maps to the first and most current sets of representations.

• "first" - a resource which always maps to the first collection of representations of Something.
• "latest" - a resource which maps to the most recent collection of representations of Something.

Giving the resources URIs

Now to assign some URIs for this use case, there is no set structure and I'm not going to define one because it is up to each server (or manager of) to control it's own URI space, but for the sake of this exercise I'll define mine as follows:


base: http://data.webr3.org
...
/d/Something
/rg/Somethings
/rg/Somethings/first
/rg/Somethings/latest
/rg/Somethings/Something-20100311
/rg/Somethings/Something-20100311/something.rdf
/rg/Somethings/Something-20100311/something.n3
/rg/Somethings/Something-20100311/something.en.html
/rg/Somethings/Something-20100311/something.de.html
...
/rg/Somethings/Something-20100305
/rg/Somethings/Something-20100305/something.rdf
/rg/Somethings/Something-20100305/something.n3
/rg/Somethings/Something-20100305/something.en.html
/rg/Somethings/Something-20100305/something.de.html
...


From the above you can see that every possible representation has its own URI, in addition every collection of equivalent representations has its own URI, as does the collection of all those collections; and so does "Something" our non virtual object.

Also we've exposed multiple resources which could also be RESTful CRUD access points operating on an atompub style protocol. Small sentence, big potential, will cover approaches and protocols in later posts.

The Key resource

The most important thing, which I haven't yet covered, is that we've exposed a key resource, namely /rg/Somethings. This is a resource at the top of the representation chain which can be used to expose content negotiation, be it server or agent driven (or a mix of both), and regardless of the mappings and levels of collection further down the line this can always be a single point of entry to get representations.

I'll cover just how in a moment, but for now something important.

Important

I've had to give a fixed example just to make some progress, but we have to remember that every system has different needs, in some cases it may be that there is only a single fixed representation for a resource, whilst in others each strand of representation (like something.de.html) may take it's own versioning / temporal path. This could indicate that a structure such as the following may be in order:

...
/d/Something
/rg/Somethings
/rg/Somethings/first
/rg/Somethings/latest
/rg/Somethings/Something-20100311
/rg/Somethings/Something-20100305
/rg/Somethings/Something-rdf
/rg/Somethings/Something-rdf/20100311.rdf
/rg/Somethings/Something-rdf/20100305.rdf
/rg/Somethings/Something-html-en
/rg/Somethings/Something-html-en/20100311.html
/rg/Somethings/Something-html-en/20100305.html
/rg/Somethings/Something-html-de
/rg/Somethings/Something-html-de/20100308.html
/rg/Somethings/Something-html-de/20100303.html


The above highlights that whilst we may have added more resources, the core resources are still the same; remember that they are "conceptual maps", meaning that Something-20100311 may "map" to the version of en-html on the 11th and de-html on the 8th, because the de version was written first, then translated to english and from there rdf and so forth, but they are all semantically equivalent, containing the same information even though they were created at different times.

The Conceptual Maps are as follows, from what I can tell this should always cover any use-case, no matter how complex.


Thing 1-1 CollectionOfCollections
CollectionOfCollections 1-* CollectionOfEquivalentRepresentations
CollectionOfEquivalentRepresentations 1-* Representation


aside:At times like this I wish I'd had a chance to study computer science so that I could express these things formally, so you'll have to make sense of it as best you can :( sorry.

Exposing via Content Negotiation

In my research so far, I've been able to figure out how to expose all of the aforementioned via HTTP, RESTfully using content negotiation in a manner which seems to be transparent to existing web browsers, but exposes all the information needed in a manner that is visible to machines; without using any additional extensions headers. As follows:

1 The client does a normal GET request on our "Something", notice that no content negotiation is happening yet, we are simply asserting via a 303 "that the requested resource does not have a representation of its own that can be transferred by the server over HTTP."

#Request
GET /d/Something HTTP/1.1
Host: data.webr3.org
Accept: text/html;q=0.5, application/rdf+xml


#Response
HTTP/1.1 303 See Other
Location: http://data.webr3.org/rg/Somethings


2The client does a GET on the URI we specified in the Location field, namely to our key resource that can be used for content negotiation over all the representations.

#Request
GET /rg/Somethings HTTP/1.1
Host: data.webr3.org
Accept: text/html;q=0.5, application/rdf+xml


#Response
HTTP/1.1 300 Multiple Choices
Location: http://data.webr3.org/rg/Somethings/latest
Content-Type: application/xhtml+xml
Content-Length: 17400


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN"
"http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:foaf="http://xmlns.com/foaf/0.1/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
version="XHTML+RDFa 1.0" xml:lang="en">
...


Here's where it gets interesting and clients can take different routes; first the route of the typical user agent:

User Agent Route


#Request
GET /rg/Somethings/latest HTTP/1.1
Host: data.webr3.org
Accept: text/html;q=0.5, application/rdf+xml


#Response
HTTP/1.1 307 Temporary Redirect
Location: http://data.webr3.org/rg/Somethings/Something-20100311


#Request
GET /rg/Somethings/Something-20100311 HTTP/1.1
Host: data.webr3.org
Accept: text/html;q=0.5, application/rdf+xml


#Response
HTTP/1.1 302 Found
Vary: Accept
ETag: W/"xyzzy"
Last-Modified: Wed, 11 Mar 2010 12:45:26 GMT
Content-Type: application/xhtml+xml
Content-Length: 17400
Content-Language: en
Content-Location: http://data.webr3.org/rg/Somethings/Something-20100311/something.en.html


<!DOCTYPE html...


First you can see that the user agent simply goes straight through to the most recent content and what they expect to see; which is nice, with additional Server driven content negotiation.

Further, we can see that full cache control is in there which as we know speeds up the net, and further still we have a rather nifty "weak" entity tag; this entity tag is shared by all representations which are semantically equal, and asserts they are equal via the entity tag. It's also worth noting that you could add this entity tag to your RDF graphs and further assert provenance which could come in very handy down the line for POST and PUT implementations.

To recap, common user agents just go straight through to the expected resource via server driven content negotiation and can take full advantage of cache / control data.

The Machine Route

Back at 2 the server returned a 300 Multiple Choices as soon as /rg/Somethings was requested. All important was that the entity returned was XHTML+RDFa (although this could have been Atom or similar..), which means we can give both a human and machine readable list of all our various representations, the "machine" can then select which one it finds most fitting. The choices could be expressed using any suitable ontology; and further both Alternative and Link headers could be added if publishers wished.

I think that covers it all, if there are any errors or things I've missed please do let me know asap; but for now that'll do me - it's verbose, but I like verbose - prove it works then optimise it later :)

I'm primarily documenting this journey for my own benefit, for reference and to unload it from my brain; but hopefully it'll be of use to the wider community and any feedback will be massively appreciated.

Here goes, I'll start by analysing the web thus far:

The Web till now

The power and the success of the web so far, in my opinion, has come from four main things:

• The URI
• Hyperlink
• The Resource
• HTTP and it's RESTful design.

More importantly it's the combination of the four working together that makes the web so great, because, they let you cut out everything else and go straight to the resource you want. This is a point that we need to concentrate on for a minute.

Going straight to the resource

Back at the start of the web, this allowed people to (for the first time) jump from a resource in the bowels of one companies hierarchy straight to another resource in a different companies hierarchy - very much like reading a book, looking at the references and suddenly having the book or paper it references right there in your lap - amazing to say the least.

Skip forwards a few years and we have the search engines, suddenly simply by typing a few keywords you can jump right to a resource (page/image/...) anywhere on the web. Fast forward some more and we get to web 2.0 where again people are amazed every time direct access to a resource is exposed. Yup.. all your web 2.0 is just this simple principal..

An RSS feed, well it lets you read a resource (a post) outside the context of the website and inside lets say google reader. You can rip a resource (video) out of youtube and embed it anywhere you like. You can interact with a web application super fast thanks to targeting a resource directly with say ajax and only updating that resource rather than updating the entire view (page). You can interact with web applications using desktop clients because they let you access one resource at a time; and so on and so forth, virtually every improvement you see on the web comes down to that one thing, directly accessing a resource (and creating resources at a more granular level).

How we made the web faster

Negating the rather obvious upgrades in technology over the years, there is one primary thing that speeds up the web and virtually everything computer oriented, the cache.

Before all the web 2.0 stuff, resource caching was at an all time high and was making the web faster for all of us; caching at the resource level is enabled by HTTP and its RESTful design. Control Data allows us to limit how much information needs transferred over the web, request an image once and it gets transferred, request it a second time and thanks to caching and HTTP odds are very high that it won't get transferred again. When you consider that the average web page can easily have 30, 50, 300 images and static files embedded in it this is a huge speed increase, and frankly one we could not live without.

Skipping forwards to web 2.0 and the present day again, we've gone wild with caching; anybody who's been involved with a high traffic site will tell you that the only way to do it is to cache everything you can; from data in memory, through to code and op code caches. But this is only half the story.. a strange this has happened..

How we made the web slower

Simply, we forgot HTTP and a RESTful web somehow - that all important web caching whether it be at intermediate servers or in a web browser, it's forgotten.

To illustrate, if you view an image and then view it again, it'll be there instantly - why? because last-modified, etag and other control data is sent by great web servers like apache for static files, until you force a refresh or the file changes on the server you'll simply get a 304 response telling whatever cache down the line to use it's own copy instead. Now, try jumping on to a web page, even this one and you'll find the whole thing is reloaded, every time. I'd estimate that circa 80% of all pages you visit are fully reloaded every single time you see them, if not more.

Here's the reason - most pages are generated by scripts now, and something that goes unnoticed by most developers is that the web server (like apache) hand over *full* control to the language runtimes, and in turn to the developer. In other words, unless developers are calculating, receiving and sending control data for each response, and validating every http message in to their scripts, then most of the benefits of HTTP and RESTful design are completely lost; especially caching.

Here's a fact, whether you agree with it or not, to me it is a fact: the web has to be RESTful for it to work properly, whether it's a web of documents, or a web of data, or both.

Looking at the current state of Linked Data

Linked Data is amazing because it takes the big four I mentioned earlier (URI, Hyperlink, Resource, HTTP) to a new level; we create resources at the most granular level possible, assign them URIs, link them together with typed hyperlinks then expose them via HTTP.

Notice I didn't mention REST in there? that's because I (and I'm not the only one) don't feel that Linked Data is currently RESTful. And as we can learn from web 2.0, unless this is addressed we'll face major problems down the line. In addition, because of this lack of RESTful-ness I feel like the data isn't linked; simply using URIs from different datasets on both sides of a triple does not link those datasets, well not from a client perspective anyway.

To expand and refining the issues:

SPARQL Silos

Issue one, is that SPARQL and the servers with RDF stores which power it are positioned at the wrong side of the client / server relationship imho. Because each major dataset effectively has it's own server and access point (SPARQL interface) it means that when you query it, it can only return the Linked Data which it stores. This leaves us three options at the minute:

• let that server pull in remote Linked Data and store it too (which makes the server fill up and slow down, and turns it in to a silo).
• use one great big server that tries to store all the linked data (which feels like a silo all over again to me, not distributed at all).
• Run our own server and only store limited data in it (limited.. and again a silo I guess)

If we moved SPARQL to the client side however, then all it would need is a starting point from which it could traverse the web of data, only pulling in what it needed for a query. This may sound slow but if all data was exposed as resources like it should be, and with control data so it could be cached, this slow down would soon disappear; lesson from web 1 and 2!

With regards the caching, this could happen at traditional intermediate caches within the internet and at ISPs, locally in client side triples stores (like a browsers cache) or the existing big servers that attempt to store all the linked data could be repositioned as linked data caches.

For example a small RDF document could simply delegate seeAlso http://datacac.he/http://subject.uri and that linked data cache could return back all the information it knows about the subject by returning the RDF results of a SPARQL describe. This alone would be a HUGE speed up, prevent silos and create a real web of data.

In addition, this would keep all linked data transferred through the web in RDF format, and thus machine readable and typed. At the minute we have lots and lots of SPARQL queries, which essentially are just untyped junk data that a machine couldn't possibly understand - SPARQL results remove all the goodness from RDF and give us something that is domain and developer specific, not re-usable. Think about that for a moment..

Clarification: I'm not saying SPARQL + RDF stores shouldn't be on the server side, they should as they are needed in most cases, I'm simply saying that the primary interface to linked data shouldn't be SPARQL over HTTP to a remote SPARQL endpoint. Rather we should be accessing RDF documents, or entities if you like via HTTP.

RESTful RDF

Issue two, the focus has been on getting data on the web, finding ways to link it, access it, store and query these vast datasets; and the work done thus far is amazing! But now that's handled it's time to go back to basics and find ways of both getting and publishing Linked Data RESTfully, at a granular per resource level.

This means handling RDF like ATOM, and essentially making atompub all over for RDF (as many are thinking and working on). I feel that regardless of what's implemented behind the interface, and whether triples stores and SPARUL are used, we still need to manage RDF / Linked Data in terms of documents and entities for it to be RESTful.

An additional issue raised by this is loosing the notion of a quad, g s p o, Named Graphs are vastly important to linked data, but we need to get named graphs in to triples and out of quads so we are always working with RDF through HTTP.

Also worth noting that temporal, provenance, multi-language, multiple representations etc will all need handled too; without using any HTTP extensions; no point half baking it or making the solution dependant on drafts - needs to work with the Universal Interface!

First Step

The above means one of the first challenges and things I'll try to tackle, is to find a way to fit a RESTful RDF publishing and exposing protocol in to the shared http space on a web server; taking in to account things like content negotiation, multiple representations, versions / time varying representations, and backwards compatibility with the current web.

note: I'm not going to define the protocols, plenty of more intelligent people than me are working on these things, just leverage a space where a full RESTful protocol can work in unison with the way we currently do things so that it's transparent to browsers and visible to linked data clients. This should then allow a stable test environment to try out different ways of doing things and test that the current web doesn't break.

To be continued.. often and frequently. I'm blocked on my current, v important project, and need to address these things.

I've grouped all the links in to two main sections, and then sub-grouped by how they make sense in my head! :)

Web, HTTP and REST

Roy T. Fielding Dissertation - Architectural Styles and the Design of Network-based Software Architectures Of particular relevance and note are chapters 4-6 (many only ever read chapter 5 and miss the context + summary *needed* in chapters 4 and 6!)

• Chapter 4 - Designing the Web Architecture: Problems and Insights
• Chapter 5 - Representational State Transfer (REST)
• Chapter 6 - Experience and Evaluation

Roy T. Fielding - REST APIs must be hypertext-driven
Discussion on HTML5 and RESTful HTTP in browsers
Discussion on URIs Resources and Switching content types w/ REST angle (v good)

RFC 2616 HTTP/1.1 and the HTTPbis Working Group HTTP/1.1 update in parts:

1. Messaging
2. Semantics
3. Payload
4. Conditional
5. Range
6. Cache
7. Authentication

Linked Data and the Semantic Web

Linking Open Data Community Project
Linked Data Applications
Equivalence Mining and Matching Frameworks
Linked Data Browsers, Mashups and other Client Applications

Dataset Dynamics - On the Dynamics of Linked Datasets
Realizing a write-enabled Web of Data
Web Access Control (WAC) - a decentralized system for allowing different users and groups various forms of access to resources where users and groups are identified by HTTP URIs.
Discussion of the WAC vocabulary
Socially Aware Cloud Storage Design Note
Distributed Social Networking through Socially Aware Cloud Storage from TimBL
AWWSW - "Architecture of the World Wide Semantic Web" Task Force

SPARQL 1.1 Uniform HTTP Protocol for Managing RDF Graphs
A Linked Data Frontend for SPARQL Endpoints
RAP - RDF API for PHP V0.9.6
Inav the Terrible - An idea for posting RDF through HTTP.

Talis Changesets
Triplify Update Vocabulary

skos as atom

RFC 4287 - The Atom Syndication Format
RFC 5023 - The Atom Publishing Protocol
AtomPub Tombstones - The Atom "deleted-entry" Element
RFC 5005 - Feed Paging and Archiving
Versioning Link Relations - Link Relation Types for Simple Version Navigation between Web Resources

Named Graphs, Provenance and Trust
Accessing Site-Specific APIs Through Write-Wrappers From The Web of Data
Provenance Information in the Web of Data - LDOW 2009 paper
Using Reification To Extend RDF (historical reification approach)
RDF Policy-based URI Access Control for Content Authoring
The Open Provenance Model Core Specification (v1.1)
W3C Provenance Incubator Group

History of the Web 1945, 1980 through 1997 on W3
LEIRI - Legacy extended IRIs for XML resource identification The type of "URI" used in xml:base
CSHALS 2010 W3C Semanic Web Tutorial
Mindswap online RDF Converter
W3 online RDF Validator