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So it is literally impossible for the result of a service call to identify the related entities (I can't call them resources) for that call. At the top end of the scale, it is not clear in any given case what resources should be exposed and what their representation should be. But HTTP, combined with suitably chosen URIs, and combined with more program-oriented representations such as XML and JSON, can provide us the combined advantages of the interconnected web and programmable 'services'.In the ReST model the HTTP methods (GET, PUT, POST, DELETE, and maybe HEAD) are the only methods that would be exposed by a web 'service'. But there are many challenges. This is both a manifesto for what the authors term 'REST-Oriented Architecture' (ROA), and a technical dive into the mechanics and semantics of REST.
At the low end of the scale, there is the issue that browsers know only the GET and POST methods - not DELETE, PUT, and HEAD. Each resource can have one or many representations - for example, as XML, JSON, HTML, PDF, etc. So POST has to be overloaded to provide the functionality of PUT and DELETE. We need a book entitled 'Resource Oriented Design Patterns' to fill this gap.In the meantime, RESTful Web Services is a terrific guide to developing web applications. Instead, the client-side programmer must understand the documentation (possibly by poring over the service's WSDL description) to know how to accomplish any given task. The situation is (or can be) different in an ROA application: knowing the set of basic resource types gives immediate knowledge of how to access any particular resource instance.
It comes as a big breath of fresh air after years of being harangued by the putative benefits of Service-Oriented Architecture (SOA) with its plethora of web-service standards centered on XML, SOAP, and WSDL, and the many competing and largely incompatible SOA toolkits.REST (or ReST) stands for 'Representational State Transfer', a term and concept introduced by Roy Fielding nearly a decade ago. There are multiple ways of selecting a representation: for example, adding an 'Accept' header to the HTTP request, or adding some kind of 'qualifier' to the basic URI (for example, a.xml or.pdf suffix).Representations can (and in the view of the authors, should) provide links to related resources - in fact this ability to link to other resources is the source of much of the power and attractiveness of the ReST model. Knowing the relationships between resources (for example, which resources are containers, which resource types are related to other resource types) gives knowledge of how to 'navigate' the application - without the service provider having to document every detail of that navigation.This is exciting stuff. The basic idea is that, in current practice, the www consists in large part of interconnected resources where the connections are implemented by the basic HTTP methods of GET and POST, and resource representation is typically HTML, heavily annotated and marked-up, and difficult to work with programmatically. Unless the service designers used great care, the service calls within the SOA application bear little relationship to one another, so understanding some portion of the API provides no great insight into the remainder of the API. As the authors note, an SOA application normally has few URIs, sometimes only one.
The service exposes URI (universal resource identifiers) for each of the resources provided by the service (a possibly unbounded set of resources), and the methods are applied to those URIs. This ability to identify resources by URI sets ROA apart from SOA.
Even after reading 4 chapters I am not sure If this book gave a clear distinction between a "RESTFul" web service and a XML Web Services.All I gathered wasRESTFul Webservice = All Web Services - XML RPC (or SOAP) On a side note all the analogy in the first few chapters actually added to the confusion rather than helping clearing the picture. The author could have done without all the bashing of Big Company (Microsoft) SOAP based web service. Bought the book seeing all the five star reviews, but was kind of disappointed. Too much fluff.
If you're a developer and not planning on building a RESTful web service, it is still a great read. Insight into HTTP methods & status codes, URI design, resources & modeling data, and pertinent examples from modern frameworks like django and rails, make this book so useful. RESTful ideas can be applied to many aspects of cs/developing (distributed computing, web sites, component based engineering). The term "REST web service" is often abused. This book gives a very clear idea of what true RESTful web services should be like (and even goes as far as to propose a "Resource Oriented Architecture").
I am still working on this book, but I must say I like this book. I received this book in three days, which was a fast delivery.
Restful web services are more important and useful than most people realize but this book provides an immediate update for anyone working in computing. Useful not just as a guide to working with web services but also provides a solid overview of what constitutes a good computing platform in general.
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