Why isn't the Web Object-Oriented?

A big part of the Web is web services, but often these services are not modelled using an object oriented paradigm, even though it is well suited for complex behaviours. Web services are often modelled using a simple request/response paradigm or a service oriented paradigm using a RESTful framework, but many of these resource oriented frameworks can be adapted to support some object oriented concepts.

Many people think of classes and methods when they think of Object-Oriented Programming (OOP). However, I like to think of OOP as message passing with class specialization. This is particularly helpful when designing Web services, which also use a message passing model. Even RESTful Web services use forms of message passing between nodes.

Consider the simple URL below. When followed a GET request is sent to a Google server. This can be thought of as sending Google's search object a message with the given search term parameter (using the Google network as the authority). The search object (in this case a proxy) responds with an HTML page with the search results.

   Object Authority
 _________|_________
/                   \
http://www.google.com/search?q=Why+isn%27t+the+Web+Object-Oriented%3F
\__________________________/  \_____________________________________/
             |                                  |
       Object Identity                       message

All HTTP requests can be thought of as messages being sent to remote objects. The request method, query parameters, headers, and body make up the message, and the request URI identifies the message's target object. The HTTP response is the message's return value.

However, OOP is more than simply message passing. A big part of OOP is the association of behaviour with data. The relationship between behaviour and data drives at the difference between service oriented and object oriented paradigms. A service oriented model is like an object oriented model, but all objects are stateless singletons with their own unique behaviour. Because of this, pure service oriented systems can be more efficient (less data access), but is more expensive to maintain, as each service must consider all possible variations at once. In contrast, OOP supports behaviour specialization and can more closely reflect the structure of systems 'in the real world'.

While many services are identified by a single request URI (scheme+authority+path), most RESTful frameworks allow data to also be associated with the URI. JAX-RS, for example, allows path parameters that are often populated with a unique entity ID. By incorporating the entity ID in the URI, data is associated with the behaviour in the same way as in an OOP paradigm. However, most RESTful frameworks fail to provide any support for object or resource behaviour specialization -- a feature that is incredibly powerful in class-based OOP.

The Web is actually fairly close to seamlessly supporting an object-oriented paradigm. Processing efficiency seems to be the only barrier. However, with the growing costs of maintaining complex Web systems, I'm not sure how long this argument can hold up. When do you think we'll have an object oriented Web framework and what would it look it?

The Complicated Software Stack

To aspiring Web application developers or people looking to put together their own Web application: the road to building a modern working Web application is a long and complicated journey.

Today's Web application developer is nothing short of a jack-of-all-trates, requiring deep knowledge of everything from HTML and CSS to Java and SQL. Everything from common CRUD tasks to sophisticated work-flows requires knowledge of half a dozen computer languages along with their quirks and variations across platforms and applications.

Today's software is built using a mix of programming paradigms and data models. Every level in the software stack requires explicit data mapping between paradigms. Many Web applications include the following levels in their software stack:
• Relational for persistence,
• Object oriented (class-based) in the model,
• Aspects peppered throughout,
• Resource (or activity) oriented Web services,
• Functional template engines,
• Markup using key/value pairs, and
• Prototype based objects for UI behaviour.

The above complication comes at a price. Software takes longer to develop and is more expensive to maintain than it used to be. This is causing a greater divide between small tools and large software systems.

Applications, like Microsoft Excel, which combine data processing and persistence using a consistent programming paradigm, have grown in popularity as a cheap alternatives to the complexity of modern Web applications.

While the market for Web applications has grown, the scope has decreased, favouring large high volume systems. Smaller Web applications are too often over-architected and over-budget. There is a large (and growing) opportunity for software vendors to fill this divide and create a new platform that combines data processing and persistence, using a single programming paradigm, for Web applications.

Can Web applications be built to use a single programming paradigm?

AtomPub as a Discovery Protocol

AtomPub was designed as a blog API, but with all the advancement the browsers have made as an application platform, it hasn't achieved wide spread use among bloggers. However, that doesn't limit the usefulness of it as a general publishing protocol.

My colleagues at Zepheira and I have been putting AtomPub into action recently. In our latest project we used AtomPub for a marketplace service registry. This allows others to publish the existence of their web service into collections. Because of the thorough documentation of AtomPub, it was easy to get everybody on board. With a simple example everybody started seeing the advantages of using a standard protocol. Generally speaking the AtomPub server was a breeze to maintain as all operations could be done using curl.

In the same project we also used OpenSearch with Atom to integrate multiple (private) search engines into a unified result. With some sugar and spice added to the "self" links we created a very impressive search solution.

Although AtomPub hasn't achieved much popularity within the blogging world, there are lots of benefits in using a standard protocol and AtomPub has proven itself as a great discovery protocol to us.