初探RESTful-II

Resources
A RESTful resource is anything that is addressable over the Web. By addressable, we mean resources that can be accessed and transferred between clients and servers. Subsequently, a resource is a logical, temporal mapping to a concept in the problem domain for which we are implementing a solution.

if we request a text file from CNN, our browser receives a text file. If we request a Flash movie from YouTube, our browser receives a Flash movie. The data is streamed in both cases over TCP/IP and the browser knows how to interpret the binary streams because of the HTTP protocol response header Content-Type. Consequently, in a RESTful system, the representation of a resource depends on the caller's desired type(MIME type), which is specified within the communication protocol's request.

Representation
the life of a web service there may be a variety of clients requesting resources. Different clients are able to consume different representations of the same resource. Therefore, a representation can take various forms, such as an image, a text file, or an XML stream or a JSON stream, but has to be available through the same URI.

URI
A Uniform Resource Identifier, or URI, in a RESTful web service is a hyperlink to a resource, and it's the only means for clients and servers to exchange representations.(The set of RESTful constraints don't dictate that URIs must be hyperlinks.)

In a RESTful system, the URI is not meant to change over time, as the architecture's implementation is what manages the services, locates the resources, negotiates the representations, and then sends back responses with the requested resources.
ps.在沒有使用RESTful的情況下,若改變檔名,那麼link也會跟著變動