The modern web is defined by its standard interfaces and protocols, not how those interfaces and protocols are implemented in a given piece of software. Option 1, the traditional client-server style , allows all information about the true nature of the data to remain hidden within the sender, preventing assumptions from being made about the data structure and making client implementation easier. Client connectors examine the resource identifier in order to select an appropriate communication mechanism for each request. The only reason it is modeled as part of rest and not abstracted away as part of the network infrastructure is that some rest components may dynamically switch from active component behavior to that of a tunnel Buy now Chapter 3 In Thesis
We next add a constraint to the client-server interaction communication must be stateless in nature, as in the client-stateless-server (css) style of ), such that each request from client to server must contain all of the information necessary to understand the request, and cannot take advantage of any stored context on the server. The goal is to improve server scalability by eliminating any need for the server to maintain an awareness of the client state beyond the current request. Urn ) require an intermediary to translate a permanent identifier to a more transient address in order to access the identified resource. Another good way is to begin a free write, im supposed to write an essay about Chapter 3 In Thesis Buy now
Note that the rendering ability of a representation can also be impacted by the choice of content. Rest allows client functionality to be extended by downloading and executing code in the form of applets or scripts. The tunnel disappears when both ends terminate their communication. Rest is a hybrid style derived from several of the network-based architectural styles described in chapter 3 and combined with additional constraints that define a uniform connector interface. However, it does have a purpose in the architectural design of a system that encompasses multiple organizational boundaries.
The stateless nature of rest allows each interaction to be independent of the others, removing the need for an awareness of the overall component topology, an impossible task for an internet-scale architecture, and allowing components to act as either destinations or intermediaries, determined dynamically by the target of each request Buy Chapter 3 In Thesis at a discount
Perhaps most significant to the web, however, is that the separation allows the components to evolve independently, thus supporting the internet-scale requirement of multiple organizational domains. Naturally, the quality of an identifier is often proportional to the amount of money spent to retain its validity, which leads to broken links as ephemeral (or poorly supported) information moves or disappears over time. It is the starting point for our description of rest. The topic of your essay is the general category your essay is about. A user agent uses a client connector to initiate a request and becomes the ultimate recipient of the response.
The trade-off, though, is that a uniform interface degrades efficiency, since information is transferred in a standardized form rather than one which is specific to an applications needs Buy Online Chapter 3 In Thesis
The naming authority that assigned the resource identifier, making it possible to reference the resource, is responsible for maintaining the semantic validity of the mapping over time (i. Use of one or more intermediate resolvers can improve the longevity of resource references through indirection, though doing so adds to the request latency. The advantage of adding cache constraints is that they have the potential to partially or completely eliminate some interactions, improving efficiency, scalability, and user-perceived performance by reducing the average latency of a series of interactions. Dont worry if its not a complete sentence. Shared caching can be effective at reducing the impact of flash crowds on the load of a popular server, particularly when the caching is arranged hierarchically to cover large groups of users, such as those within a companys intranet, the customers of an internet service provider, or universities sharing a national network backbone Buy Chapter 3 In Thesis Online at a discount
Any data that must be received before the recipient can begin rendering the representation adds to the latency of an interaction. The component containing the state (equivalent to an origin server in rest) issues an event whenever the state changes, whether or not any component is actually interested in or listening for such an event. Where the first emphasizes creativity and unbounded vision, the second emphasizes restraint and understanding of the system context. This constraint induces the properties of visibility, reliability, and scalability. Finally, it allows an author to reference the concept rather than some singular representation of that concept, thus removing the need to change all existing links whenever the representation changes (assuming the author used the right identifier) Chapter 3 In Thesis For Sale
Work had also begun on intermediary components, in the form of proxies , but extensions to the protocols were needed in order for them to communicate reliably. For a browser application, this state corresponds to a web page, including the primary representation and ancillary representations, such as in-line images, embedded applets, and style sheets. For example, remote authoring of a resource requires that the author send a representation to the server, thus establishing a value for that resource that can be retrieved by later requests. Rest is defined by four interface constraints identification of resources manipulation of resources through representations self-descriptive messages and, hypermedia as the engine of application state For Sale Chapter 3 In Thesis
For example, if all of the client software within an organization is known to support java applets , then services within that organization can be constructed such that they gain the benefit of enhanced functionality via downloadable java classes. Rest is a hybrid style derived from several of the network-based architectural styles described in chapter 3 and combined with additional constraints that define a uniform connector interface. Although this is less efficient when viewed as a single client wishing to monitor a single resource, the scale of the web makes an unregulated push model infeasible. The stateless nature of rest allows each interaction to be independent of the others, removing the need for an awareness of the overall component topology, an impossible task for an internet-scale architecture, and allowing components to act as either destinations or intermediaries, determined dynamically by the target of each request Sale Chapter 3 In Thesis