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#include "nsIRequest.idl"

interface nsISimpleEnumerator;
interface nsIRequestObserver;
interface nsIInterfaceRequestor;

/**
 * A load group maintains a collection of nsIRequest objects. 
 */
[scriptable, uuid(3de0a31c-feaf-400f-9f1e-4ef71f8b20cc)]
interface nsILoadGroup : nsIRequest
{
    /**
     * The group observer is notified when requests are added to and removed
     * from this load group.  The groupObserver is weak referenced.
     */
    attribute nsIRequestObserver groupObserver;

    /**
     * Accesses the default load request for the group.  Each time a number
     * of requests are added to a group, the defaultLoadRequest may be set
     * to indicate that all of the requests are related to a base request.
     *
     * The load group inherits its load flags from the default load request.
     * If the default load request is NULL, then the group's load flags are
     * not changed.
     */
    attribute nsIRequest defaultLoadRequest;

    /**
     * Adds a new request to the group.  This will cause the default load
     * flags to be applied to the request.  If this is a foreground
     * request then the groupObserver's onStartRequest will be called.
     *
     * If the request is the default load request or if the default load
     * request is null, then the load group will inherit its load flags from
     * the request.
     */
    void addRequest(in nsIRequest aRequest,
                    in nsISupports aContext);

    /**
     * Removes a request from the group.  If this is a foreground request
     * then the groupObserver's onStopRequest will be called.
     *
     * By the time this call ends, aRequest will have been removed from the
     * loadgroup, even if this function throws an exception.
     */
    void removeRequest(in nsIRequest aRequest, 
                       in nsISupports aContext,
                       in nsresult aStatus);

    /**
     * Returns the requests contained directly in this group.
     * Enumerator element type: nsIRequest.
     */
    readonly attribute nsISimpleEnumerator requests;

    /**
     * Returns the count of "active" requests (ie. requests without the
     * LOAD_BACKGROUND bit set).
     */
    readonly attribute unsigned long activeCount;

    /**
     * Notification callbacks for the load group.
     */
    attribute nsIInterfaceRequestor notificationCallbacks;
};
