nsIHttpChannel

IID:9277fe09-f0cc-4cd9-bbce-581dd94b0260
Inherits From:nsIChannel
Status:FROZEN

This interface allows for the modification of HTTP request parameters and the inspection of the resulting HTTP response status and headers when they become available.


Properties

PRBool allowPipelining

This attribute is a hint to the channel to indicate whether or not the underlying HTTP transaction should be allowed to be pipelined with other transactions. This should be set to FALSE, for example, if the application knows that the corresponding document is likely to be very large.

This attribute is true by default, though other factors may prevent pipelining.

This attribute may only be set before the channel is opened.

PRUint32 redirectionLimit

This attribute specifies the number of redirects this channel is allowed to make. If zero, the channel will fail to redirect and will generate a NS_ERROR_REDIRECT_LOOP failure status.

NOTE: An HTTP redirect results in a new channel being created. If the new channel supports nsIHttpChannel, then it will be assigned a value to its redirectionLimit attribute one less than the value of the redirected channel's redirectionLimit attribute. The initial value for this attribute may be a configurable preference (depending on the implementation).

nsIURI referrer

Get/set the HTTP referrer URI. This is the address (URI) of the resource from which this channel's URI was obtained (see RFC2616 section 14.36).

This attribute may only be set before the channel is opened.

NOTE: The channel may silently refuse to set the Referer header if the URI does not pass certain security checks (e.g., a "https://" URL will never be sent as the referrer for a plaintext HTTP request). The implementation is not required to throw an exception when the referrer URI is rejected.

ACString requestMethod

Set/get the HTTP request method (default is "GET"). Setter is case insensitive; getter returns an uppercase string.

This attribute may only be set before the channel is opened.

NOTE: The data for a "POST" or "PUT" request can be configured via nsIUploadChannel; however, after setting the upload data, it may be necessary to set the request method explicitly. The documentation for nsIUploadChannel has further details.

readonly PRBool requestSucceeded

Returns true if the HTTP response code indicates success. The value of nsIRequest::status will be NS_OK even when processing a 404 response because a 404 response may include a message body that (in some cases) should be shown to the user.

Use this attribute to distinguish server error pages from normal pages, instead of comparing the response status manually against the set of valid response codes, if that is required by your application.

readonly PRUint32 responseStatus

Get the HTTP response code (e.g., 200).

readonly ACString responseStatusText

Get the HTTP response status text (e.g., "OK").

NOTE: This returns the raw (possibly 8-bit) text from the server. There are no assumptions made about the charset of the returned text. You have been warned!


Methods

ACString getRequestHeader ( ACString header ) ACString getResponseHeader ( ACString header ) PRBool isNoCacheResponse ( ) PRBool isNoStoreResponse ( ) void setRequestHeader ( ACString header , ACString value , PRBool merge ) void setResponseHeader ( ACString header , ACString value , PRBool merge ) void visitRequestHeaders ( nsIHttpHeaderVisitor visitor ) void visitResponseHeaders ( nsIHttpHeaderVisitor visitor )

ACString getRequestHeader ( ACString header )

Get the value of a particular request header.

Arguments:
header: The case-insensitive name of the request header to query (e.g., "Cache-Control").
Returns:
the value of the request header.

ACString getResponseHeader ( ACString header )

Get the value of a particular response header.

Arguments:
header: The case-insensitive name of the response header to query (e.g., "Set-Cookie").
Returns:
the value of the response header.

PRBool isNoCacheResponse ( )

Returns true if the server sent the equivalent of a "Cache-control: no-cache" response header. Equivalent response headers include: "Pragma: no-cache", "Expires: 0", and "Expires" with a date value in the past relative to the value of the "Date" header.


PRBool isNoStoreResponse ( )

Returns true if the server sent a "Cache-Control: no-store" response header.


void setRequestHeader ( ACString header , ACString value , PRBool merge )

Set the value of a particular request header.

This method allows, for example, the cookies module to add "Cookie" headers to the outgoing HTTP request.

This method may only be called before the channel is opened.

If value is empty and merge is false, the header will be cleared.

Arguments:
header: The case-insensitive name of the request header to set (e.g., "Cookie").
value: The request header value to set (e.g., "X=1").
merge: If true, the new header value will be merged with any existing values for the specified header. This flag is ignored if the specified header does not support merging (e.g., the "Content- Type" header can only have one value). The list of headers for which this flag is ignored is an implementation detail. If this flag is false, then the header value will be replaced with the contents of |value|.

void setResponseHeader ( ACString header , ACString value , PRBool merge )

Set the value of a particular response header.

This method allows, for example, the HTML content sink to inform the HTTP channel about HTTP-EQUIV headers found in HTML tags.

If value is empty and merge is false, the header will be cleared.

Arguments:
header: The case-insensitive name of the response header to set (e.g., "Cache-control").
value: The response header value to set (e.g., "no-cache").
merge: If true, the new header value will be merged with any existing values for the specified header. This flag is ignored if the specified header does not support merging (e.g., the "Content- Type" header can only have one value). The list of headers for which this flag is ignored is an implementation detail. If this flag is false, then the header value will be replaced with the contents of |value|.

void visitRequestHeaders ( nsIHttpHeaderVisitor visitor )

Call this method to visit all request headers. Calling setRequestHeader while visiting request headers has undefined behavior. Don't do it!

Arguments:
visitor: the header visitor instance.

void visitResponseHeaders ( nsIHttpHeaderVisitor visitor )

Call this method to visit all response headers. Calling setResponseHeader while visiting response headers has undefined behavior. Don't do it!

Arguments:
visitor: the header visitor instance.

References

This interface is passed as an argument to the following methods:

nsICookieConsent.getConsent, nsIHttpAuthenticator.challengeReceived, nsIHttpAuthenticator.generateCredentials, nsIHttpEventSink.onRedirect

Reference documentation is generated from Mozilla's source.

Add a note User Contributed Notes
October 3, 2004, 2:22 am edwin at bitstorm dot org
To examine HTTP headers when requests are made, use global notifications (http://www.xulplanet.com/tutorials/mozsdk/observerserv.php) to get an instance of nsIHttpChannel. Use the topics http-on-modify-request and/or http-on-examine-response.

Copyright © 1999 - 2005 XULPlanet.com