gecko-dev/netwerk/base/public/nsICachingChannel.idl

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 * The Original Code is mozilla.org code.
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 * The Initial Developer of the Original Code is 
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 * Contributor(s):
 *   Darin Fisher <darin@netscape.com> (original author)
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#include "nsISupports.idl"

interface nsIFile;

/**
 * A channel may optionally implement this interface to allow clients
 * to effect its behavior with respect to how it uses the cache service.
 *
 * This interface provides:
 *   1) Support for "stream as file" semantics (for JAR and plugins).
 *   2) Support for "pinning" cached data in the cache (for printing and save-as).
 */
[scriptable, uuid(b1f95f5e-ee05-4434-9d34-89a935d7feef)]
interface nsICachingChannel : nsISupports
{
    /**
     * Set/get the cache token... uniquely identifies the data in the cache.
     * Holding a reference to this token prevents the cached data from being
     * removed.  A cache token retrieved from a particular instance of 
     * nsICachingChannel could be set on another instance of nsICachingChannel
     * provided the underlying implementations are compatible.  The implemen-
     * tation of nsICachingChannel would be expected to only read from the
     * cache entry identified by the cache token and not try to validate it.
     *
     * The cache token can be treated as an opaque object; however, it can be
     * QI'd to a nsICacheEntryDescriptor if more detailed information about the
     * cache entry is needed.
     */
    attribute nsISupports cacheToken;

    /**
     * Set/get the cache key... uniquely identifies the data in the cache.
     * Holding a reference to this key DOES NOT prevent the cached data from
     * being removed.  It is otherwise similar to the cacheToken.
     *
     * The fromCacheOnly flag inhibits fetching from the net if the data in the
     * cache has been evicted.  An error of NS_ERROR_DOCUMENT_NOT_CACHED will
     * be sent to the listener's onStopRequest in this case.
     */
    nsISupports getCacheKey();
    void        setCacheKey(in nsISupports cacheKey, in boolean fromCacheOnly);

    /**
     * Specifies whether or not the data should be cached to a file.  This
     * may fail if the disk cache is not present.  The value of this attribute
     * is usually only settable during the processing of a channel's
     * OnStartRequest.  The default value of this attribute depends on the
     * particular implementation of nsICachingChannel.
     */
    attribute boolean cacheAsFile;

    /**
     * Get the "file" where the cached data can be found.  This is valid for
     * as long as a reference to the cache token is held.  This may return
     * an error if cacheAsFile is false.
     */
    readonly attribute nsIFile cacheFile;
};

%{C++
/**
 * nsresult passed through onStopRequest if the document could not be fetched from the cache.
 */
#define NS_ERROR_DOCUMENT_NOT_CACHED NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_NETWORK, 70)
%}