Request uri what is

This can't be the whole story, since nothing in Figure 1 above looks anything like a weather report. What Web users experience in practice involves a further relationship, between a representation and what we might call a presentation :. Figures 1 and 2 above illustrate the static relationship between the various constituents of the URI story. There is also a dynamic story, which is where the Web comes in:. The underlying mechanism for accessing representations via the Web, the HyperText Transfer Protocol, or HTTP, provides for control over the first three kinds of variation.

That is, by specifying parameters in the request from client to server to access a URI, the consumer can determine which representation the server responds with. In Figure 3 above, for example, we see the initial request includes an Accept header which specifies the XHTML media type, and that is indeed what the server sends back in the response. The fourth kind of variation, variation of representation over time, is quite different, and leads on to some new and very interesting issues.

In the cases of the Oaxaca weather report or the home page of your favourite online newspaper, it does seem right to say there is only one resource, despite the fact that the representations you can retrieve of such resources will vary a great deal from day to day.

There's an illuminating parallel here with the class of words in ordinary language which linguists call indexical , words such as this , here and tomorrow , as well as you and I. An indexical such as now has a single meaning but multiple interpretations. The meaning is something like "the time at which the utterance containing the word is made", and is the same for every use of the word. But the interpretation is, well, whatever time it happens to be when the word is used, and this of course changes all the time.

More generally, the meaning of an indexical can be understood as a function from contexts that is, contexts of utterance to interpretations. The situation with time-varying resources is just the same—indeed the gloss we gave to the examples above yesterday's weather report, etc. To sum up: Although historically URIs were understood as a kind of Web-enabled file name, with a simple "URI points to web page" model, the move to separate conceptually the stable resource identified by a URI from its potentially varied representations was necessary to make sense of actual practice.

The resource abstraction has gone on to provide powerful new functionality, a subject we will return to below. The phrase "Web 2. What a user sees on the screen today as a result of accessing a resource identified by a URI often depends as much if not more on running Javascript programs embedded in the retrieved X HTML representation, and on the results of other , behind-the-scenes, resource accesses, as it does on the X HTML itself. The coinage AJAX refers to this approach. For example, the presentation of a map which a user sees when using Google Maps is entirely constructed from images retrieved behind the scenes by the Javascript which makes up virtually all of the original representation as retrieved from the Google Maps URI.

As the proportion of a presentation that depends directly and declaratively on the initially retrieved representation diminishes, and the proportion based on local computation and representations retrieved behind the scenes increases, there is a kind of historical regression going on, which goes back to treating URIs instrumentally, as ways of moving data. What you can send and retrieve is all that matters, and the resource-representation distinction no longer seems to be doing useful work.

There are two things underlying this blurring of the resource-representation distinction in Web 2. If behind-the-scenes URI usage tends to encourage a near-equation of resource and representation, other aspects of sophisticated Web 2. If the presentation experienced by a user varies independently of any user-controllable aspect of URI access, or evolves in response to user actions, the sense in which the URI visible at the top of the browser can be said to still 'identify' a representation which corresponds to that presentation has become attenuated almost to the point of vanishing.

If what you see depends on a cookie, you can't post a pointer to it in an email message, because the recipient won't have the right cookie. That's not necessarily a bad thing you probably wouldn't want to be able to send an email message which lets someone into your bank account , but does act to diminish the connection between URI, resource and representation.

If what you see depends on the IP address your request comes from or on a radio button value that doesn't show up as a URI parameter, then not only can you not point to it in email, but you can't reliably bookmark it, and Google doesn't index it, because its crawlers will never see it: crawlers don't tick boxes or share your IP address. The original value proposition of the Web was produced by the network effect: for anything you were interested in, someone else somewhere was too, and they had produced a website about it, and search engines could find it for you.

But the Web as information appliance has evolved: not only is large amounts of web-delivered information not available via search engines, for the kind of reasons discussed above, even the famous pagerank algorithm which launched Google's success doesn't work particularly well anymore, as the proportion of hand-authored pages has declined, and information access is increasingly controlled by a self-reinforcing feedback loop between Google and the big players in the information aggregation game, such as Wikipedia, Tripadvisor and MedicineNet: page ranking in Google today depends to a substantial extent on statistics over search terms and clickthroughs.

From the user perspective, a related phenomenon which threatens to further erode the centrality of the URI-resource connection is the use of the search entry field in browsers instead of the address field. Already in December of , for example, 8 of the top 15 search terms reported by one service over the last five months were in fact the core parts of domain names non- www.

When overridden in a descendant class, the RequestUri property contains the Uri instance that Create method uses to create the request. The WebRequest class is an abstract class. The actual behavior of WebRequest instances at run time is determined by the descendant class returned by the WebRequest.

Create method. For more information about default values and exceptions, see the documentation for the descendant classes, such as HttpWebRequest and FileWebRequest.

RequestUri must contain the original Uri instance passed to the Create Uri method. If the protocol is able to redirect the request to a different URI to service the request, the descendant must provide a property to contain the URI that actually services the request.

Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Nowadays, it is mostly an abstraction handled by Web servers without any physical reality. The Web server can use those parameters to do extra stuff before returning the resource to the user. Each Web server has its own rules regarding parameters, and the only reliable way to know how a specific Web server is handling parameters is by asking the Web server owner.

SomewhereInTheDocument is an anchor to another part of the resource itself. An anchor represents a sort of "bookmark" inside the resource, giving the browser the directions to show the content located at that "bookmarked" spot. On an HTML document, for example, the browser will scroll to the point where the anchor is defined; on a video or audio document, the browser will try to go to the time the anchor represents.

It is worth noting that the part after the , also known as the fragment identifier, is never sent to the server with the request. Increasingly, browsers are removing support for using FTP to load subresources, for security reasons.