Annotation of libwww/Library/src/HTEvent.html, revision 2.12
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"
2.11 eric 50: #ifdef IN_EVENT
51: typedef struct _HTTimer HTTimer;
52: #endif
2.2 frystyk 53:
2.8 frystyk 54: #if 0
2.4 frystyk 55: #define FD_NONE 0
56: #define FD_ALL (FD_READ | FD_WRITE | FD_OOB | FD_ACCEPT | FD_CONNECT |FD_CLOSE)
57: #define FD_UNREGISTER (((FD_ALL) << 1) & (~(FD_ALL)))
2.8 frystyk 58: #endif
2.4 frystyk 59:
2.2 frystyk 60: typedef enum _HTPriority {
61: HT_PRIORITY_INV = -1,
62: HT_PRIORITY_OFF = 0,
63: HT_PRIORITY_MIN = 1,
64: HT_PRIORITY_MAX = 20
65: } HTPriority;
66:
2.10 eric 67: #define HTEVENT_INDEX 0x10
2.8 frystyk 68: typedef enum {
2.9 eric 69: #ifdef WWW_WIN_ASYNC
2.10 eric 70: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
71: HTEvent_WRITE = (0x002 | 1 << HTEVENT_INDEX),
72: HTEvent_OOB = (0x004 | 2 << HTEVENT_INDEX),
73: HTEvent_ACCEPT = (0x008 | 3 << HTEVENT_INDEX),
74: HTEvent_CONNECT = (0x010 | 4 << HTEVENT_INDEX),
75: HTEvent_CLOSE = (0x020 | 5 << HTEVENT_INDEX),
2.9 eric 76: HTEvent_TYPES = 6, /* winsock has seperate events for all of these */
2.10 eric 77: #define HTEVENT_TYPES 6 /* use in constructing the fake event below */
2.9 eric 78: #else /* WWW_WIN_ASYNC */
2.10 eric 79: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
80: HTEvent_ACCEPT = (0x002 | 0 << HTEVENT_INDEX),
81: HTEvent_CLOSE = (0x004 | 0 << HTEVENT_INDEX),
82: HTEvent_WRITE = (0x008 | 1 << HTEVENT_INDEX),
83: HTEvent_CONNECT = (0x010 | 1 << HTEVENT_INDEX),
84: HTEvent_OOB = (0x020 | 2 << HTEVENT_INDEX),
2.9 eric 85: HTEvent_TYPES = 3, /* only READ, WRITE, and OOB are real types */
2.10 eric 86: #define HTEVENT_TYPES 3 /* use in constructing the fake event below */
2.9 eric 87: #endif /* !WWW_WIN_ASYNC */
2.10 eric 88: /*
89: ** fake events - these don't correspond to event manager events, but they
90: ** are usefull for communicating with the protocol modules
91: */
92: HTEvent_TIMEOUT = (0x040 | HTEVENT_TYPES << HTEVENT_INDEX),
93: HTEvent_BEGIN = (0x000 | HTEVENT_TYPES << HTEVENT_INDEX),
94: HTEvent_END = (0x080 | HTEVENT_TYPES << HTEVENT_INDEX),
95: HTEvent_FLUSH = (0x100 | HTEVENT_TYPES << HTEVENT_INDEX),
96: HTEvent_RESET = (0x200 | HTEVENT_TYPES << HTEVENT_INDEX),
2.9 eric 97: HTEvent_ALL = 0xFFFF
2.8 frystyk 98: } HTEventType;
2.1 eric 99:
2.8 frystyk 100: #define HTEvent_BITS(type) (type & 0xFFFF)
2.10 eric 101: #define HTEvent_INDEX(type) (type >> HTEVENT_INDEX)
2.8 frystyk 102:
2.11 eric 103: #define HT_EVENT_INITIALIZER \
104: {HTEvent_READ, "HTEvent_READ"}, \
105: {HTEvent_ACCEPT, "HTEvent_ACCEPT"}, \
106: {HTEvent_CLOSE, "HTEvent_CLOSE"}, \
107: {HTEvent_WRITE, "HTEvent_WRITE"}, \
108: {HTEvent_CONNECT, "HTEvent_CONNECT"}, \
109: {HTEvent_OOB, "HTEvent_OOB"}, \
110: {HTEvent_TIMEOUT, "HTEvent_TIMEOUT"}, \
111: {HTEvent_BEGIN, "HTEvent_BEGIN"}, \
112: {HTEvent_END, "HTEvent_END"}, \
113: {HTEvent_FLUSH, "HTEvent_FLUSH"}, \
114: {HTEvent_RESET, "HTEvent_RESET"}
115:
116: extern char * HTEvent_type2str(HTEventType type);
2.12 ! frystyk 117: </PRE>
2.11 eric 118:
2.3 frystyk 119: <H2>
2.7 eric 120: <A NAME="eventHandlers">Event Handlers</A>
2.3 frystyk 121: </H2>
122: <P>
2.4 frystyk 123: A <I>location</I> is a function that can be registered by the event manager
124: and called at a later point in time in order to continue an operation. All
125: locations must be of type <CODE>HTEventCallback</CODE> as defined here:
2.2 frystyk 126: <PRE>
2.8 frystyk 127: typedef int HTEventCallback (SOCKET, void *, HTEventType);
2.12 ! frystyk 128: typedef struct _HTEvent HTEvent;
! 129:
! 130: /* Avoid circular include for HTReq->HTNet->HTHost: HTEvent blah */
! 131: #include "HTReq.h"
2.2 frystyk 132: </PRE>
2.4 frystyk 133: <P>
134: There are many default event handlers provided with the Library. For example,
135: all the protocol modules such as the <A HREF="HTTP.html">HTTP client module</A>
136: are implemented as event handlers. In stead of using blocking sockets, this
137: allows a protocol module to register itself when performing an operation
138: that would block. When the sockets becomes ready the handler is called with
139: th socket in question, the request object, and the socket operation
2.3 frystyk 140: <H2>
2.4 frystyk 141: Registering and Unregistering Event Handlers
2.3 frystyk 142: </H2>
143: <P>
2.4 frystyk 144: As mentioned above, the only interface libwww requires from an event manager
145: is a method to <I>register</I> an event handler when an operation would block
146: and <I>unregister</I> it when the operation has completed The library registers
147: and unregisters event handlers by calling the following two functions:
2.8 frystyk 148: <PRE>
149: extern int HTEvent_register (SOCKET, HTEventType, HTEvent *);
150: extern int HTEvent_unregister (SOCKET, HTEventType);
2.4 frystyk 151: </PRE>
152: <P>
153: The register function contains information about which socket we are waiting
154: on to get ready and which operation we are waiting for (read, write, etc.),
155: the request object containing the current request, the event handler that
156: we want to be called when the socket becomes reasy, and finally the priority
157: by which we want the thread to be processed by the event manager. Likewise,
158: libwww can unregister a operation on a socket which means that libwww is
159: no longer waiting for this actiion to become ready.
160: <H2>
161: Registering an Event Manager
162: </H2>
163: <P>
164: The Library core does not contain any event manager as it depends on whether
165: you want to use pseudo threads no threads, or real threads. Instead, libwww
166: comes with a <A HREF="HTEvntrg.html">default implementation</A> that you
167: may register, but you may as well implement and register your own. The register
168: and unregister functions above actually does nothing than looking for a
169: registered event manager and then passes the call on to that. You register
170: your own event manager by using the methods below:
2.1 eric 171: <PRE>
2.8 frystyk 172: struct _HTEvent {
173: HTPriority priority; /* Priority of this request (event) */
174: int millis; /* Timeout in ms for this event */
2.11 eric 175: #ifdef IN_EVENT
176: HTTimer * timer;
177: #endif
2.8 frystyk 178: HTEventCallback * cbf; /* Protocol state machine */
179: void * param; /* HTEvent_register parameter */
180: HTRequest * request;
181: };
182:
183: typedef int HTEvent_registerCallback(SOCKET, HTEventType, HTEvent *);
184: typedef int HTEvent_unregisterCallback(SOCKET, HTEventType);
2.1 eric 185:
186: extern void HTEvent_setRegisterCallback(HTEvent_registerCallback *);
187: extern void HTEvent_setUnregisterCallback(HTEvent_unregisterCallback *);
2.8 frystyk 188: extern BOOL HTEvent_setCallback(HTEvent * event, HTEventCallback * cbf);
189:
190: extern HTEvent * HTEvent_new (HTEventCallback * cbf, void * context,
191: HTPriority pritority, int timeoutInMillis);
192: extern BOOL HTEvent_delete (HTEvent * event);
193:
194: extern BOOL HTEvent_setParam(HTEvent * event, void * param);
195: extern BOOL HTEvent_setPriority(HTEvent * event, HTPriority priority);
196: extern BOOL HTEvent_setTimeout(HTEvent * event, int timeoutInMillis);
2.1 eric 197: </PRE>
2.3 frystyk 198: <P>
2.4 frystyk 199: You can register the event manager provided together with libwww by using
2.6 frystyk 200: the <CODE>HTEventInit()</CODE> in the <A HREF="HTInit.html">HTInit module</A>
2.1 eric 201: <PRE>
202: #endif /* HTEVENT_H */
203: </PRE>
2.3 frystyk 204: <P>
205: <HR>
2.1 eric 206: <ADDRESS>
2.12 ! frystyk 207: @(#) $Id: HTEvent.html,v 2.11 1996/12/13 22:06:03 eric Exp $
2.1 eric 208: </ADDRESS>
2.3 frystyk 209: </BODY></HTML>
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