Annotation of libwww/Library/src/HTEvent.html, revision 2.7.2.5
2.1 eric 1: <HTML>
2: <HEAD>
2.4 frystyk 3: <TITLE>W3C Reference Library libwww Event Class</TITLE>
2.1 eric 4: </HEAD>
5: <BODY>
2.4 frystyk 6: <H1>
7: The Event Class
2.3 frystyk 8: </H1>
2.1 eric 9: <PRE>
10: /*
11: ** (c) COPYRIGHT MIT 1995.
12: ** Please first read the full copyright statement in the file COPYRIGH.
13: */
2.4 frystyk 14: </PRE>
15: <P>
16: The Event Class defines any event manager to be used by libwww for handling
17: events. An <I>event</I> is not strictly defined as it is highly platform
18: dependent and hence out of scope for the Library. If you are using the libwww
19: pseudo threads on Unix then an event is when the <I>select()</I> system
20: call returns a notification on a socket descriptor, but it may as well
21: be an asynchronous event from the windows manager etc. If your application
22: is not using anything but traditional blocking sockets then you do not need
23: an event manager at all. In that case, libwww will block on any socket or
24: system call until the process can proceed.
25: <P>
26: The libwww interface to an event manager is very simple as it consists of
27: <B>registering</B> a <I>socket descriptor</I>, the <I>location</I> in the
28: program, and the <I>current state</I> when an operation (for example
29: <CODE>read</CODE>) would block. When the event manager at a later point in
30: time gets a notification that the socket has become ready, it can then call
31: libwww with the state saved from the registration and libwww can continue.
32: Second, libwww must be able to <B>unregister</B> a socket when it is not
33: anymore in a state where it can block. <I>Only</I> in case the application
34: wishes to use <I>non-blocking</I> sockets it should register methods for
35: handling the <B>registration</B> process as described below.
36: <P>
37: <B>Note</B>: The library <B>core</B> does <I>not</I> define any event manager
38: - it is considered part of the application. The library comes with a
39: <A HREF="HTEvntrg.html">default event manager</A> which can be initiated
2.6 frystyk 40: using the function <CODE>HTEventInit()</CODE> in <A HREF="HTInit.html">HTInit
41: module</A>
2.4 frystyk 42: <P>
43: This module is implemented by <A HREF="HTEvent.c">HTEvent.c</A>, and it is
44: a part of the <A HREF="http://www.w3.org/pub/WWW/Library/">W3C Reference
45: Library</A>.
46: <PRE>
2.1 eric 47: #ifndef HTEVENT_H
48: #define HTEVENT_H
2.2 frystyk 49: #include "sysdep.h"
50:
2.7.2.4 eric 51: #if 0
2.4 frystyk 52: #define FD_NONE 0
53: #define FD_ALL (FD_READ | FD_WRITE | FD_OOB | FD_ACCEPT | FD_CONNECT |FD_CLOSE)
54: #define FD_UNREGISTER (((FD_ALL) << 1) & (~(FD_ALL)))
2.7.2.4 eric 55: #endif
2.4 frystyk 56:
2.2 frystyk 57: typedef enum _HTPriority {
58: HT_PRIORITY_INV = -1,
59: HT_PRIORITY_OFF = 0,
60: HT_PRIORITY_MIN = 1,
61: HT_PRIORITY_MAX = 20
62: } HTPriority;
63:
2.7.2.1 eric 64: typedef enum {
2.7.2.5 ! frystyk 65: HTEvent_READ = (0x001 | 0 << 16),
! 66: HTEvent_ACCEPT = (0x002 | 0 << 16),
! 67: HTEvent_CLOSE = (0x004 | 0 << 16),
! 68: HTEvent_WRITE = (0x008 | 1 << 16),
! 69: HTEvent_CONNECT = (0x010 | 1 << 16),
! 70: HTEvent_OOB = (0x020 | 2 << 16),
! 71: HTEvent_TIMEOUT = (0x100 | 3 << 16),
! 72: HTEvent_BEGIN = (0x000 | 3 << 16),
! 73: HTEvent_END = (0x080 | 3 << 16),
! 74: HTEvent_ALL = 0xFFFF,
! 75: HTEvent_TYPES = 4
2.7.2.3 frystyk 76: } HTEventType;
77:
2.7.2.5 ! frystyk 78: #define HTEvent_BITS(type) (type & 0xFFFF)
! 79: #define HTEvent_INDEX(type) (type >> 16)
2.1 eric 80:
2.7.2.1 eric 81: /* Avoid circular include for HTReq->HTNet->HTHost: HTEvent blah */
82: typedef struct _HTEvent HTEvent;
2.1 eric 83: #include "HTReq.h"
84: </PRE>
2.3 frystyk 85: <H2>
2.7 eric 86: <A NAME="eventHandlers">Event Handlers</A>
2.3 frystyk 87: </H2>
88: <P>
2.4 frystyk 89: A <I>location</I> is a function that can be registered by the event manager
90: and called at a later point in time in order to continue an operation. All
91: locations must be of type <CODE>HTEventCallback</CODE> as defined here:
2.2 frystyk 92: <PRE>
2.7.2.2 eric 93: typedef int HTEventCallback (SOCKET, void *, HTEventType);
2.2 frystyk 94: </PRE>
2.4 frystyk 95: <P>
96: There are many default event handlers provided with the Library. For example,
97: all the protocol modules such as the <A HREF="HTTP.html">HTTP client module</A>
98: are implemented as event handlers. In stead of using blocking sockets, this
99: allows a protocol module to register itself when performing an operation
100: that would block. When the sockets becomes ready the handler is called with
101: th socket in question, the request object, and the socket operation
2.3 frystyk 102: <H2>
2.4 frystyk 103: Registering and Unregistering Event Handlers
2.3 frystyk 104: </H2>
105: <P>
2.4 frystyk 106: As mentioned above, the only interface libwww requires from an event manager
107: is a method to <I>register</I> an event handler when an operation would block
108: and <I>unregister</I> it when the operation has completed The library registers
109: and unregisters event handlers by calling the following two functions:
2.7.2.1 eric 110: <PRE>
2.7.2.2 eric 111: extern int HTEvent_register (SOCKET, HTEventType, HTEvent *);
112: extern int HTEvent_unregister (SOCKET, HTEventType);
2.4 frystyk 113: </PRE>
114: <P>
115: The register function contains information about which socket we are waiting
116: on to get ready and which operation we are waiting for (read, write, etc.),
117: the request object containing the current request, the event handler that
118: we want to be called when the socket becomes reasy, and finally the priority
119: by which we want the thread to be processed by the event manager. Likewise,
120: libwww can unregister a operation on a socket which means that libwww is
121: no longer waiting for this actiion to become ready.
122: <H2>
123: Registering an Event Manager
124: </H2>
125: <P>
126: The Library core does not contain any event manager as it depends on whether
127: you want to use pseudo threads no threads, or real threads. Instead, libwww
128: comes with a <A HREF="HTEvntrg.html">default implementation</A> that you
129: may register, but you may as well implement and register your own. The register
130: and unregister functions above actually does nothing than looking for a
131: registered event manager and then passes the call on to that. You register
132: your own event manager by using the methods below:
2.1 eric 133: <PRE>
2.7.2.5 ! frystyk 134: struct _HTEvent {
! 135: HTPriority priority; /* Priority of this request (event) */
! 136: int millis; /* Timeout in ms for this event */
! 137: HTEventCallback * cbf; /* Protocol state machine */
! 138: void * param; /* HTEvent_register parameter */
! 139: HTRequest * request;
! 140: };
! 141:
2.7.2.2 eric 142: typedef int HTEvent_registerCallback(SOCKET, HTEventType, HTEvent *);
143: typedef int HTEvent_unregisterCallback(SOCKET, HTEventType);
2.1 eric 144:
145: extern void HTEvent_setRegisterCallback(HTEvent_registerCallback *);
146: extern void HTEvent_setUnregisterCallback(HTEvent_unregisterCallback *);
2.7.2.1 eric 147: extern BOOL HTEvent_setCallback(HTEvent * event, HTEventCallback * cbf);
2.7.2.5 ! frystyk 148:
! 149: extern HTEvent * HTEvent_new (HTEventCallback * cbf, void * context,
! 150: HTPriority pritority, int timeoutInMillis);
! 151: extern BOOL HTEvent_delete (HTEvent * event);
! 152:
2.7.2.1 eric 153: extern BOOL HTEvent_setParam(HTEvent * event, void * param);
154: extern BOOL HTEvent_setPriority(HTEvent * event, HTPriority priority);
2.7.2.5 ! frystyk 155: extern BOOL HTEvent_setTimeout(HTEvent * event, int timeoutInMillis);
2.1 eric 156: </PRE>
2.3 frystyk 157: <P>
2.4 frystyk 158: You can register the event manager provided together with libwww by using
2.6 frystyk 159: the <CODE>HTEventInit()</CODE> in the <A HREF="HTInit.html">HTInit module</A>
2.1 eric 160: <PRE>
161: #endif /* HTEVENT_H */
162: </PRE>
2.3 frystyk 163: <P>
164: <HR>
2.1 eric 165: <ADDRESS>
2.7.2.5 ! frystyk 166: @(#) $Id: HTEvent.html,v 2.7.2.4 1996/11/08 19:49:26 eric Exp $
2.1 eric 167: </ADDRESS>
2.3 frystyk 168: </BODY></HTML>
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