When a resource is constructed such that parameters within the effective request URI have the effect of selecting an action, it is the resource owner's responsibility to ensure that the action is consistent with the request method semantics.
Slack System Status
Selection of alternatives might be performed automatically by the user agent or manually by the user selecting from a generated possibly hypertext menu. A client can alter the semantics of GET to be a "range request", requesting transfer of only some part s of the selected representation, by sending a Range header field messqge the request [ RFC ].
If the request method is GET or HEAD and the response status code is Non-Authoritative Informationthe payload is a potentially modified or enhanced representation of the target resource as provided by an intermediary. Typically, the representation is only decoded just prior to rendering or analogous usage.
In some cases, a payload might contain only the associated representation's header fields e. Considerations for New Header Fields A client constructs request messages to communicate specific intentions, examines received responses to see if the intentions were carried out, and determines how to interpret the.
For example, most servers append request information to access log files at the completion of every response, regardless of the method, and that is considered safe even though the log storage might become full and crash the server. Response Context If there is a conflict between the method semantics and any semantic implied by the URI itself, as described in Section 4. Reactive Negotiation With reactive negotiation a. The consistency with which an origin server responds to requests, over time messate message the varying dimensions of content negotiation, and thus the stastus of a resource's observed representations over time, is determined entirely by whatever entity or algorithm selects or generates those responses.
This specification defines two patterns of content negotiation that can be made visible within messwge protocol: "proactive", where the server selects the representation based upon the user agent's stated preferences, and "reactive" negotiation, where the server provides a list of representations for the user agent to choose from.
Thus, if the content is intended only for a Danish-literate audience, the appropriate field is Content-Language: da If no Content-Language is specified, the default is that the content is messwge for all language audiences. Normative References Proactive negotiation has serious disadvantages: o It is impossible for the server to accurately determine what might be "best" for any given user, since that would require complete knowledge of both the capabilities of the user agent and the intended use for the response e.
A charset is identified by a case-insensitive token.
Content-Language MAY be applied to any media type -- it is not limited to textual documents. It does not define what a resource might be, in any sense of that word, beyond the interface provided via HTTP. The primary purpose of Content-Language is to allow a user to identify and differentiate representations according to the users' own preferred language.
Collected ABNF Partial content updates are possible by targeting a separately identified resource with state that overlaps a portion of the larger resource, or by using a different method that has been specifically defined for partial updates for example, the PATCH method defined in [ RFC ]. For a state-changing request like PUT Section 4.
That abstraction is called a representation [ REST ]. Validator Header Fields The Conflict or Unsupported Media Type status codes are suggested, with the latter being specific to constraints on Content-Type values.
This specification defines a of standardized methods that are commonly used in HTTP, as outlined by the following table. A PUT request applied to the target resource can have side effects on other resources.
Message Status Notification Parameters
This method can be used for obtaining metadata about the selected representation without transferring the representation data and is often used for message hypertext links for validity, accessibility, and recent modification. Clients that do so risk drawing incorrect conclusions, which might expose additional security risks e. Content codings are primarily used to allow a representation to be compressed or otherwise usefully transformed without losing the identity of its underlying media type and without loss of information.
Informative References The presence or absence of a parameter might be ificant to stastus processing of a media-type, depending on its definition within the media type registry. This might mean that the sender does not consider it to be specific to any natural language, or that the sender does not know for which language it is intended.
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Content Coding Registry The data type of the representation data is determined via the header fields Content-Type and Content-Encoding. Note that, in all cases, HTTP is not aware of the resource semantics. A Vary header field Section 7. Method Definitions 4. In such cases, some algorithm is used by the origin server to select one of those representations as most applicable to a given request, usually based on content negotiation. If the result of processing a POST would be equivalent to a representation of an existing resource, an message server MAY redirect the user agent to that resource by sending a See Other response with the existing stastus identifier in the Location field.
When a request method is received that is unrecognized or not implemented by shastus origin server, the origin server SHOULD respond with the Not Implemented status code. Content-Encoding is primarily used to allow a representation's data to be compressed without losing the identity of its underlying media type. Representation Metadata Representation header fields provide metadata about the representation.
Computer languages are explicitly excluded. What is important, however, is that the stasths did not request that additional behavior and cannot be held able for it. POST Perform resource-specific processing on the 4.
Disclosure of Fragment after Redirects However, the performance characteristics of deployments i. It knows that repeating the request will have the same intended effect, even if the original request succeeded, though the response might differ. A parameter value that matches the token production can be transmitted either as a token or within a quoted-string.
Content-Language The "Content-Language" header field describes the natural language s of the intended audience for the representation.
In effect, this method is similar to the rm command in UNIX: it expresses a deletion operation on the URI mapping of the origin server rather than an expectation that the messagd associated information be deleted. A user agent SHOULD distinguish between safe and unsafe methods when presenting potential actions to a user, such that the user can be made aware of an unsafe action before it is requested.