Duncan Cragg on Declarative Architectures
About All Things...
...taking programming beyond:
Threads, Message Queues, Client-Server, CORBA, Web Services, SOAs, Agents, Synchronous Architectures, Imperative Programming - and even Applications, Desktops and Documents
Duncan Cragg...
...works for ThoughtWorks UK; originally from April 2002 to July 2007 and now recently re-joined. Previously worked as a Web Architect for the Financial Times.
...went to both UCL and Imperial College of the University of London (in the Eighties); specialising in Logic during his MSc.
...wonders when his LinkedIn Account will be useful
...has a phone-cam, and used it on himself once, just before his weekly shave:
Photo of Duncan Cragg
...can be contacted by and followed on Twitter.
Posts tagged 'forest' Atom Feed for Posts tagged 'forest'
EUP, IoT, AR and Minecraft | NetMash | Object Network
February 10, 2015 15:58

These days I seem to mainly use this blog for once-a-year announcements of what I'm up to, which is useful as record for myself when I need to reflect.

So here's where I'm at, as 2015 begins..   ...

CoAP and a Web of Things watching Things
May 19, 2014 21:21

With the expansion of the Internet of Things (IoT), and the diversity of products and technologies, the one thing that everyone agrees on is that it's time to start agreeing: the Internet of Things needs standards. Many agree that it needs open standards, like those that underpin the Web.

Obviously, a Web of Things is going to be quite different from the Web of Documents and Applications: it'll be much more fine-grained and much more "buzzy", with many sensors and actuators working together with many hubs and services. It's more likely to be at home with the next generation of the Internet Protocol: IPv6.

To meet the fine-grained and buzzy nature of the IoT, the Constrained Application Protocol, or CoAP, was created. CoAP is an open Internet standard for the Web of Things. It's based on the Web's core pipe: HTTP, but has many differences to allow it to be used by very resource-constrained devices and local radio networks.

CoAP can be used in many different ways, but there's a danger that a lack of clarity in exactly how it's used means it doesn't achieve its full potential to link up the world's embedded devices.

This article proposes a simple and clear way that CoAP could be used to build a uniform, global, decentralised Web of interacting and discoverable Things.

This article first appeared on the ThoughtWorks Insights pages.   ...

The Object Network Approach to Augmented Reality and the Internet of Things
March 1, 2014 11:24

After filling up that other blog recently with 61 pages of content, one page a day, I was challenged by my ThoughtWorks colleague, Andy McWilliams, to help him get in more easily to my explanations of the Object Network applied to Augmented Reality and the Internet of Things, especially around how my approach differs and is better than other approaches.   ...

Building The Object Network
January 27, 2014 11:36

I've started another blog called Building The Object Network, about how I'm experimenting with Augmented Reality for the Internet of Things using the Object Network approach.

So far I've been blogging every day.

Do subscribe!   ...

Cyrus in 2013
January 16, 2013 17:09

Well that worked out pretty well: I have a 3D environment on Android programmed in a simple but powerful declarative language which I've called "Cyrus".

Cyrus basically uses JSON all the way through: from user interface and scene graph to rewrite rules, on the wire and on disk. The Cyrus programming language is essentially JSON itself, as JSON rewrite rules. I've reduced the noise of JSON in Cyrus by taking out redundant double-quotes, square brackets and commas. It looks very nice to me.   ...

The Basics | The Object Network
January 20, 2012 18:07
Updated: January 23, 2012 19:45

Right, let's get started with some basic conventions in the Object Network!

This part in the Object Network series will cover URLs, HTTP headers and some common JSON patterns.

Updated 23/1/12: I changed the URLs in the example to have one of each type.   ...

Why we should link up our Web APIs | The Object Network
January 19, 2012 20:58
Updated: January 22, 2012 16:05

OK, I'm trying to take a Big Idea and make it as Simple As Possible to grasp.

If we link our JSON data together and use the same formats, then our mobile, browser and server apps can become much simpler - through clean, stable, common, shared, re-used code - and much more powerful - through clean, stable, common, shared, linked, cached data.

This is the second part in the Object Network series, which will guide you away from building isolated Web APIs to engaging in a linked-up data landscape.   ...

Introduction | The Object Network
November 29, 2011 23:11
Updated: January 22, 2012 16:03

It's interesting to compare the current growth of Web APIs with the early growth of the Web itself. To save you jumping those links: the Web dramatically beats the APIs.

I believe that the most likely cause of such relatively slow growth (in what should be a booming ecosystem) is that each API forms a closed silo and cannot benefit from any network effects. Every API is different and there are no links between them. There usually aren't any links within a silo. You can't even use a given API without first consulting the documentation.

The Object Network is designed to fix this, with linked-up JSON in common formats. This will allow easier mashing, sharing and cacheing of data and allow client code to be shared and reused.   ...

OTS: The Benefits of both Native and Web Mobile
May 10, 2011 11:11

The Web, in its purest form - declarative HTML and CSS documents, XML feeds - is mashable, linkable, sharable. It's easy to create documents that slot into the global Web and can be accessed on any device; accessed by just a simple link. Servers can easily scale through statelessness and cacheing.

Native Mobile Apps are fast and slick. They are intimate with the dynamic, interactive, tactile mobile user interface, intimate with the capabilities of the device and intimate with the domain of mobile: photos, locations, contacts, messages.

OTS is a simple, clean, powerful approach to delivering Mobile functionality and content that is designed to realise these benefits of both Native Apps and the Web.   ...

February 12, 2011 14:07

Here's a quick catch-up of developments in FOREST.

I've been working much more on FOREST than Fjord or JSON-Mash recently, and it's coming along very nicely.

Actually, I've been lying flat out in bed with Pneumonia (and various other consequent ailments) for several weeks, so have been quietly tip-tapping away on a laptop resting on my tum, when I've had the energy.

Which has given me a chance to tidy up and finish off some FOREST stuff that I started last year...   ...

March 18, 2010 16:58

Around the middle of February I completed a basic persistence and networking implementation for Fjord, then had to do other things for a month. Just recently I fixed Fjord to work with the latest version of the Node.js APIs.

Next project: I'm going to use Fjord in a Web Framework to be called "JSON-Mash".

I intend to show that JSON-Mash will be a great framework for rapidly building truly interoperable and truly scalable online and distributed functionality.

Here's how JSON-Mash will work.   ...

Fjord in Memory
January 26, 2010 13:46

Right, I'm pleased to say that I've now implemented enough of the Fjord language on Node.js to be able to run the Instrument example that I introduced it with. As yet, this runs in memory only - i.e., no disk, no network.

Here's the code on GitHub with tests that show how it works. The language has changed a little so I'll show the example here again, copied over from the test code, in order to explain the differences.   ...

Fjord in Node
January 6, 2010 17:03

Well, I've put together the first few lines of Fjord, implemented on Node.js.

Here's the description on GitHub: Fjord is a language for expressing domain logic as match-rewrite functions over mashable JSON Web objects.

I'm developing Fjord very openly, in the hope someone out there will be interested in getting involved in helping guide its design and implementation. I suppose code speaks louder than blog posts.   ...

Introducing Fjord
December 11, 2009 08:22

Following on from my recent article where I derived FOREST, this article offers the beginnings of a JSON unification and rewriting language that can be used in a FOREST architecture.

Why JSON, not XHTML, now? Well, I recently discovered that JSON is overtaking XHTML in interest, and I was further inspired by Kris Zyp's recent announcement of his JSON Schema Internet-Draft.

Fjord is a language for describing how the state of a JSON resource at any time depends on both its current state and on the state of other JSON resources that it links to via hyperlinks.

Fjord is a Norwegian word, probably pronounced 'fiyourd', and might stand for some combination of the words: 'Functional JSON Object/Observer Resource/Rule/Rewrite Dependencies/Declarations'. Or maybe it's just because they're truly awesome, an' I wanna go.

Fjord also gives me an opportunity to show some examples of the "end-user" view of a FOREST interaction; starting with a simple finance example.   ...

Deriving FOREST
November 25, 2009 21:29

Say we want to integrate multiple applications which handle order processing. OK, that's got to be one of the dullest starts to a blog post. Never mind, bear with me...

So, we have applications on separate servers for handling and driving data such as orders, product descriptions and catalogues, stock lists, price lists, tracking, packing notes and delivery notes, invoices, payments, etc.

We may choose an SOA approach, of course. But let's say our sponsors have heard of this cheaper alternative: REST! Which to them means 'using Web technology to save money'.

Now .. suppose we push the time slider right back to before Mark Baker and the SOA -vs- REST Wars - or the 'SOAP -vs- REST Wars' as people naively called it. To when REST was simply (!) a description of the Web's architectural style...

What if we revisit the applicability of the Web, and its abstraction into REST, to the architecture of machine-to-machine distributed systems - to something like our order processing integration?

I think we'd quickly arrive at something that looks more like FOREST than, say, AtomPub...   ...

FOREST: a GET-only REST Integration Pattern
October 9, 2009 17:14
Updated: October 11, 2009 11:46

Since the day in 2006 that our dialogue took place with an imaginary eBay Architect, he has been promoted to imaginary Enterprise Architect in an investment bank! Convinced by the merits of REST, he took his enthusiasm for it into his new job and embarked on architecting a trading system using REST or ROA as an alternative to SOA.

Now, he hit upon a snag: he had a REST "bank server" generating bids on an instrument and POSTing them into that instrument's REST "market server". But then he had two copies of his bid! One held by the bank server on one URI, and the other in a "bid collection" held by the market server's instrument - on another URI.

He asked himself: "Which URI is the real one? Which host 'owns' the bid? Is the market's copy just a cache? If so, why does it have a new URI? Why doesn't the market host know the URI of the bank's original bid? Why can't servers become clients and just GET the data that their own data depends upon?" The server seemed to be dominating the conversation, not letting its 'client' server have a say in things.

Our worried Enterprise Architect noticed that such Service-Orientation permeated REST practice: there were "REST APIs" to Web sites, or "Web services" with a small 's'. Even AtomPub had a "service document"! Some patterns, like AtomPub, offered just simple read/write data services through the full HTTP method set. Some simply used such a read/write interface as a wrapper around more complex service functions.

He wondered: "Where's the Web in REST integration? The Web works great without PUT and DELETE: isn't using GET on its own RESTful enough?"

So, remembering something I said about "Symmetric REST", he contacted me again...   ...

FOREST: Functional Observer REST
October 6, 2009 10:28

  • Functional Observer REST = Hyperdata Interdependency requiring Symmetric REST
  • Hyperdata Interdependency = a resource's state is a Function of its linked resource context
  • Symmetric REST = servers become clients in order to Observe the dependencies of their resources


Recent Posts
EUP, IoT, AR and Minecraft | NetMash | Object Network
CoAP and a Web of Things watching Things
The Object Network Approach to Augmented Reality and the Internet of Things
Building The Object Network
Cyrus in 2013
Empowering the World | NetMash
Fun and Virtual Worlds | NetMash
The Basics | The Object Network
Why we should link up our Web APIs | The Object Network
Introduction | The Object Network
OTS: The Benefits of both Native and Web Mobile
Mature REST In Six Lines!
Minted Media Types are Usually Less RESTful Than JSON