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<HTML> <HEAD> <TITLE>Asyncronous Socket Management</TITLE>  </HEAD> <BODY> <H1>Asyncronous Socket Management</H1> <PRE> /* ** (c) COPYRIGHT MIT 1995. ** Please first read the full copyright statement in the file COPYRIGH. */ </PRE> This module contains the routines for handling the set of active sockets currently in use by the multithreaded clients. It is an internal module to the Library, the application interface is implemented in the <A HREF="HTEvntrg.html">Event Module</A>. Look for more information in the <A HREF="http://www.w3.org/pub/WWW/Library/User/Architecture/"> Multithread Specifications</A>. <P> This module is implemented by <A HREF="HTNet.c">HTNet.c</A>, and it is a part of the <A HREF="http://www.w3.org/pub/WWW/Library/">W3C Reference Library</A>. <PRE> #ifndef HTNET_H #define HTNET_H #include "HTEvntrg.h" #include "HTReq.h" </PRE> <H2>The HTNet Object</H2> The <CODE>HTNet</CODE> object is the core of the request queue management. This object contains information about the socket descriptor, the input read buffer etc. required to identify and service a request. <P> <PRE> typedef struct _HTNet HTNet; </PRE> <H2>Request Call Back Functions</H2> Callback functions can be registered to be called <EM>before</EM> and <EM>after</EM> a request has either been started or has terminated. The following functions are the generic registration mechanisms where we use lists as the basic data container. Then there is two methods for binding a list of callback functions to the set which is called <EM>before</EM> and to the set set which is called <EM>after</EM> <P> In both cases there can be more than one callback function which are called on turn and each callback function can be associated with a status code of the request. For example one callback function can be registered for HT_LOADED, another for HT_ERROR etc. <H3>Register a Request Callback</H3> Register a call back function that is to be called on every termination of a request. Several call back functions can be registered in which case all of them are called in the reverse order of which they were registered (last one first). We name the calling mechansm of calling the functions for the <EM>before</EM> loop and the <EM>after</EM> loop.<P> In case the callback function is registered as being called <EM>after</EM> the request has terminated the result of the request is passed to the fucntion. The status signifies which call back function to call depending of the result of the request. This can be <DL> <DT>HT_ERROR <DD>An error occured <DT>HT_LOADED <DD>The document was loaded <DT>HT_NO_DATA <DD>OK, but no data <DT>HT_RETRY <DD>Retry request after at a later time <DT>HT_REDIRECT <DD>The request has been redirected and we send back the new URL <DT>HT_ALL <DD>All of above </DL> Any callback function any code it likes, but <B>IF NOT</B> the code is <EM>HT_OK</EM>, then the callback loop is stopped. If we are in the <EM>before</EM> loop and a function returns anything else than <EM>HT_OK</EM> then we immediately jump to the <EM>after</EM> loop <B>passing</B> the last return code from the <EM>before</EM> loop. <PRE> typedef int HTNetCallback (HTRequest * request, int status); extern BOOL HTNetCall_add (HTList * list, HTNetCallback *cbf, int status); </PRE> <H3>Delete a single Callbak</H3> Removes a callback function from a list <PRE> extern BOOL HTNetCall_delete (HTList * list, HTNetCallback *cbf); </PRE> <H3>Delete a list of Callbacks</H3> Unregisters all call back functions in the list <PRE> extern BOOL HTNetCall_deleteAll (HTList * list); </PRE> <H3>Call List of Registered Callback Functions</H3> Call all the call back functions registered in the list IF not the status is HT_IGNORE. The callback functions are called in the order of which they were registered. At the moment an application callback function is called, it can free the request object - it is no longer used by the Library. Returns what the last callback function returns <PRE> extern int HTNetCall_execute (HTList * list, HTRequest * request, int status); </PRE> <H3>BEFORE Callbacks</H3> Global set of callback functions BEFORE the request is issued. The list can be NULL. <PRE> extern BOOL HTNetCall_addBefore (HTNetCallback *cbf, int status); extern BOOL HTNet_setBefore (HTList * list); extern HTList * HTNet_before (void); extern int HTNet_callBefore (HTRequest *request, int status); </PRE> <H3>AFTER Callbacks</H3> Global set of callback functions AFTER the request is issued. The list can be NULL <PRE> extern BOOL HTNetCall_addAfter (HTNetCallback *cbf, int status); extern BOOL HTNet_setAfter (HTList * list); extern HTList * HTNet_after (void); extern int HTNet_callAfter (HTRequest *request, int status); </PRE> <H2>Request Queue</H2> The request queue ensures that no more than a fixed number of TCP connections are open at the same time. If more requests are handed to the Library, they are put into the pending queue and initiated when sockets become free. <H3>Number of Simultanous open TCP connections</H3> Set the max number of simultanous sockets. The default value is HT_MAX_SOCKETS which is 6. The number of persistent connections depend on this value as a deadlock can occur if all available sockets a persistent (see the <A HREF="HTDNS.html">DNS Manager</A> for more information on setting the number of persistent connections). The number of persistent connections can never be more than the max number of sockets-2, so letting newmax=2 prevents persistent sockets. <PRE> extern BOOL HTNet_setMaxSocket (int newmax); extern int HTNet_maxSocket (void); </PRE> <H3>List Active Queue</H3> Returns the list of active requests that are currently having an open connection. Returns list of HTNet objects or NULL if error. <PRE> extern HTList *HTNet_activeQueue (void); extern BOOL HTNet_idle (void); </PRE> <H3>Are we Active?</H3> We have some small functions that tell whether there are registered requests in the Net manager. There are tree queues: The <EM>active</EM>, the <EM>pending</EM>, and the <EM>persistent</EM>. The <EM>active</EM> queue is the set of requests that are actively sending or receiving data. The <EM>pending</EM> is the requests that we have registered but which are waiting for a free socket. The <EM>Persistent</EM> queue are requets that are waiting to use the same socket in order to save network resoures (if the server understands persistent connections). <P> <H4>Active Reqeusts?</H4> Returns whether there are requests in the <EM>active</EM> queue or not <PRE> extern BOOL HTNet_idle (void); </PRE> <H4>Registered Requests?</H4> Returns whether there are requests registered in any of the lists or not <PRE> extern BOOL HTNet_isEmpty (void); </PRE> <H3>List Pending Queue</H3> Returns the list of pending requests that are waiting to become active. Returns list of HTNet objects or NULL if error <PRE> extern HTList *HTNet_pendingQueue (void); </PRE> <H2>Create an Object</H2> You can create a new HTNet object as a new request to be handled. If we have more than HTMaxActive connections already then put this into the pending queue, else start the request by calling the call back function registered with this access method. Returns YES if OK, else NO <PRE> extern BOOL HTNet_newClient (HTRequest * request); </PRE> You can create a new HTNet object as a new request to be handled. If we have more than HTMaxActive connections already then return NO. Returns YES if OK, else NO <PRE> extern BOOL HTNet_newServer (HTRequest * request, SOCKET sockfd, char *access); </PRE> And you can create a plain new HTNet object using the following method: <PRE> extern HTNet * HTNet_new (HTRequest * request, SOCKET sockfd); </PRE> <H3>Duplicate an Existing Object</H3> Creates a new HTNet object as a duplicate of the same request. Returns YES if OK, else NO. <PRE> extern HTNet * HTNet_dup (HTNet * src); </PRE> <H2>HTNet Object Methods</H2> <H3>Make an Object Wait</H3> Let a net object wait for a persistent socket. It will be launched from the HTNet_delete() function when the socket gets free. <PRE> extern BOOL HTNet_wait (HTNet *net); </PRE> <H3>Priority Management</H3> Each HTNet object is created with a priority which it inherits from the <A HREF="HTReq.html">Request manager</A>. However, in some stuations it is useful to be to change the current priority after the request has been started. These two functions allow you to do this. The effect will show up the first time (which might be imidiately) the socket blocks and control returns to the event loop. Also have a look at how you can do this before the request is issued in the <A HREF="HTReq.html">request manager</A>. <PRE> extern HTPriority HTNet_priority (HTNet * net); extern BOOL HTNet_setPriority (HTNet * net, HTPriority priority); </PRE> <H3>Delete an Object</H3> Deletes the HTNet object from the list of active requests and calls any registered call back functions IF not the status is HT_IGNORE. This is used if we have internal requests that the app doesn't know about. We also see if we have pending requests that can be started up now when we have a socket free. The callback functions are called in the reverse order of which they were registered (last one first); <PRE> extern BOOL HTNet_delete (HTNet * me, int status); </PRE> <H3>Delete ALL HTNet Objects</H3> Deletes all HTNet object that might either be active or pending We DO NOT call the call back functions - A crude way of saying goodbye! <PRE> extern BOOL HTNet_deleteAll (void); </PRE> <H3>Kill a Request</H3> Kill the request by calling the call back function with a request for closing the connection. Does not remove the object. This is done by HTNet_delete() function which is called by the load routine. Returns OK if success, NO on error <PRE> extern BOOL HTNet_kill (HTNet * me); </PRE> <H3>Kill ALL requests</H3> Kills all registered (active+pending) requests by calling the call back function with a request for closing the connection. We do not remove the HTNet object as it is done by HTNet_delete(). Returns OK if success, NO on error <PRE> extern BOOL HTNet_killAll (void); </PRE> <H2>Data Access Methods</H2> <H3>Socket Descriptor</H3> <PRE> extern BOOL HTNet_setSocket (HTNet * net, SOCKET sockfd); extern SOCKET HTNet_socket (HTNet * net); </PRE> <PRE> #endif /* HTNET_H */ </PRE> End of declaration module </BODY> </HTML>