Annotation of libwww/Library/src/HTEvent.html, revision 2.18
2.1 eric 1: <HTML>
2: <HEAD>
2.13 frystyk 3: <TITLE>W3C Sample Code 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
2.17 frystyk 39: <A HREF="HTEvtLst.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
2.16 frystyk 44: a part of the <A HREF="http://www.w3.org/Library/">W3C Sample Code Library</A>.
2.4 frystyk 45: <PRE>
2.1 eric 46: #ifndef HTEVENT_H
47: #define HTEVENT_H
2.14 frystyk 48: #include "wwwsys.h"
2.18 ! vbancrof 49:
! 50: #ifdef __cplusplus
! 51: extern "C" {
! 52: #endif
! 53:
2.11 eric 54: #ifdef IN_EVENT
55: typedef struct _HTTimer HTTimer;
56: #endif
2.2 frystyk 57:
58: typedef enum _HTPriority {
59: HT_PRIORITY_INV = -1,
60: HT_PRIORITY_OFF = 0,
61: HT_PRIORITY_MIN = 1,
62: HT_PRIORITY_MAX = 20
63: } HTPriority;
64:
2.10 eric 65: #define HTEVENT_INDEX 0x10
2.8 frystyk 66: typedef enum {
2.9 eric 67: #ifdef WWW_WIN_ASYNC
2.10 eric 68: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
69: HTEvent_WRITE = (0x002 | 1 << HTEVENT_INDEX),
70: HTEvent_OOB = (0x004 | 2 << HTEVENT_INDEX),
71: HTEvent_ACCEPT = (0x008 | 3 << HTEVENT_INDEX),
72: HTEvent_CONNECT = (0x010 | 4 << HTEVENT_INDEX),
73: HTEvent_CLOSE = (0x020 | 5 << HTEVENT_INDEX),
2.9 eric 74: HTEvent_TYPES = 6, /* winsock has seperate events for all of these */
2.10 eric 75: #define HTEVENT_TYPES 6 /* use in constructing the fake event below */
2.9 eric 76: #else /* WWW_WIN_ASYNC */
2.10 eric 77: HTEvent_READ = (0x001 | 0 << HTEVENT_INDEX),
78: HTEvent_ACCEPT = (0x002 | 0 << HTEVENT_INDEX),
79: HTEvent_CLOSE = (0x004 | 0 << HTEVENT_INDEX),
80: HTEvent_WRITE = (0x008 | 1 << HTEVENT_INDEX),
81: HTEvent_CONNECT = (0x010 | 1 << HTEVENT_INDEX),
82: HTEvent_OOB = (0x020 | 2 << HTEVENT_INDEX),
2.9 eric 83: HTEvent_TYPES = 3, /* only READ, WRITE, and OOB are real types */
2.10 eric 84: #define HTEVENT_TYPES 3 /* use in constructing the fake event below */
2.9 eric 85: #endif /* !WWW_WIN_ASYNC */
2.10 eric 86: /*
87: ** fake events - these don't correspond to event manager events, but they
88: ** are usefull for communicating with the protocol modules
89: */
90: HTEvent_TIMEOUT = (0x040 | HTEVENT_TYPES << HTEVENT_INDEX),
91: HTEvent_BEGIN = (0x000 | HTEVENT_TYPES << HTEVENT_INDEX),
92: HTEvent_END = (0x080 | HTEVENT_TYPES << HTEVENT_INDEX),
93: HTEvent_FLUSH = (0x100 | HTEVENT_TYPES << HTEVENT_INDEX),
94: HTEvent_RESET = (0x200 | HTEVENT_TYPES << HTEVENT_INDEX),
2.9 eric 95: HTEvent_ALL = 0xFFFF
2.8 frystyk 96: } HTEventType;
2.1 eric 97:
2.16 frystyk 98: #define HTEvent_BITS(type) (type & 0xFFFF)
99: #define HTEvent_INDEX(type) (type >> HTEVENT_INDEX)
2.8 frystyk 100:
2.11 eric 101: #define HT_EVENT_INITIALIZER \
102: {HTEvent_READ, "HTEvent_READ"}, \
103: {HTEvent_ACCEPT, "HTEvent_ACCEPT"}, \
104: {HTEvent_CLOSE, "HTEvent_CLOSE"}, \
105: {HTEvent_WRITE, "HTEvent_WRITE"}, \
106: {HTEvent_CONNECT, "HTEvent_CONNECT"}, \
107: {HTEvent_OOB, "HTEvent_OOB"}, \
108: {HTEvent_TIMEOUT, "HTEvent_TIMEOUT"}, \
109: {HTEvent_BEGIN, "HTEvent_BEGIN"}, \
110: {HTEvent_END, "HTEvent_END"}, \
111: {HTEvent_FLUSH, "HTEvent_FLUSH"}, \
112: {HTEvent_RESET, "HTEvent_RESET"}
113:
114: extern char * HTEvent_type2str(HTEventType type);
2.12 frystyk 115: </PRE>
2.3 frystyk 116: <H2>
2.7 eric 117: <A NAME="eventHandlers">Event Handlers</A>
2.3 frystyk 118: </H2>
119: <P>
2.4 frystyk 120: A <I>location</I> is a function that can be registered by the event manager
121: and called at a later point in time in order to continue an operation. All
122: locations must be of type <CODE>HTEventCallback</CODE> as defined here:
2.2 frystyk 123: <PRE>
2.8 frystyk 124: typedef int HTEventCallback (SOCKET, void *, HTEventType);
2.12 frystyk 125: typedef struct _HTEvent HTEvent;
126:
2.16 frystyk 127: /* Avoid circular include for HTReq->HTNet->HTHost: HTEvent blah */
2.12 frystyk 128: #include "HTReq.h"
2.2 frystyk 129: </PRE>
2.4 frystyk 130: <P>
131: There are many default event handlers provided with the Library. For example,
132: all the protocol modules such as the <A HREF="HTTP.html">HTTP client module</A>
133: are implemented as event handlers. In stead of using blocking sockets, this
134: allows a protocol module to register itself when performing an operation
135: that would block. When the sockets becomes ready the handler is called with
136: th socket in question, the request object, and the socket operation
2.3 frystyk 137: <H2>
2.17 frystyk 138: Registering and Unregistering Events
2.3 frystyk 139: </H2>
140: <P>
2.4 frystyk 141: As mentioned above, the only interface libwww requires from an event manager
2.17 frystyk 142: is a method to <I>register</I> an event when an operation would block and
143: <I>unregister</I> it when the operation has completed The library registers
144: and unregisters events by calling the following two functions:
2.8 frystyk 145: <PRE>
146: extern int HTEvent_register (SOCKET, HTEventType, HTEvent *);
147: extern int HTEvent_unregister (SOCKET, HTEventType);
2.4 frystyk 148: </PRE>
149: <P>
150: The register function contains information about which socket we are waiting
151: on to get ready and which operation we are waiting for (read, write, etc.),
152: the request object containing the current request, the event handler that
153: we want to be called when the socket becomes reasy, and finally the priority
154: by which we want the thread to be processed by the event manager. Likewise,
155: libwww can unregister a operation on a socket which means that libwww is
156: no longer waiting for this actiion to become ready.
157: <H2>
158: Registering an Event Manager
159: </H2>
160: <P>
2.17 frystyk 161: Libwww core does not contain any event manager as it depends on whether you
162: want to use pseudo threads no threads, or real threads. Instead, libwww comes
163: with a <A HREF="HTEvtLst.html">default implementation</A> that you may register,
164: but you may as well implement and register your own. The register and unregister
165: functions above actually does nothing than looking for a registered event
166: manager and then passes the call on to that. You register your own event
167: manager by using the methods below:
2.1 eric 168: <PRE>
2.8 frystyk 169: typedef int HTEvent_registerCallback(SOCKET, HTEventType, HTEvent *);
170: typedef int HTEvent_unregisterCallback(SOCKET, HTEventType);
2.1 eric 171:
172: extern void HTEvent_setRegisterCallback(HTEvent_registerCallback *);
173: extern void HTEvent_setUnregisterCallback(HTEvent_unregisterCallback *);
2.17 frystyk 174: </PRE>
175: <H3>
176: Has Register and Unregister Callbacks been setup?
177: </H3>
178: <P>
179: Replies YES if both an <TT>HTEvent_setRegisterCallback</TT> and
180: <TT>HTEvent_setUnregisterCallback</TT> have been called with non NULL callbacks.
181: <PRE>
182: extern BOOL HTEvent_isCallbacksRegistered(void);
183: </PRE>
184: <H2>
185: Create and Delete Events
186: </H2>
187: <PRE>
2.8 frystyk 188: extern HTEvent * HTEvent_new (HTEventCallback * cbf, void * context,
189: HTPriority pritority, int timeoutInMillis);
190: extern BOOL HTEvent_delete (HTEvent * event);
2.17 frystyk 191: </PRE>
192: <H3>
193: Event Timeouts, Priorities, Callbacks, and Contexts
194: </H3>
195: <P>
196: Normally, these are set when creating the event.
197: <PRE>
2.8 frystyk 198: extern BOOL HTEvent_setParam(HTEvent * event, void * param);
199: extern BOOL HTEvent_setPriority(HTEvent * event, HTPriority priority);
200: extern BOOL HTEvent_setTimeout(HTEvent * event, int timeoutInMillis);
2.17 frystyk 201: extern BOOL HTEvent_setCallback(HTEvent * event, HTEventCallback * cbf);
202: </PRE>
203: <H2>
204: The Raw Event Type
205: </H2>
206: <P>
207: Don't use this directly, use the methods above instead.
208: <PRE>
209: struct _HTEvent {
210: HTPriority priority; /* Priority of this request (event) */
211: int millis; /* Timeout in ms for this event */
212: #ifdef IN_EVENT
213: HTTimer * timer;
214: #endif
215: HTEventCallback * cbf; /* Protocol state machine */
216: void * param; /* HTEvent_register parameter */
217: HTRequest * request;
218: };
2.1 eric 219: </PRE>
2.3 frystyk 220: <P>
2.4 frystyk 221: You can register the event manager provided together with libwww by using
2.6 frystyk 222: the <CODE>HTEventInit()</CODE> in the <A HREF="HTInit.html">HTInit module</A>
2.1 eric 223: <PRE>
2.18 ! vbancrof 224: #ifdef __cplusplus
! 225: }
! 226: #endif
! 227:
2.1 eric 228: #endif /* HTEVENT_H */
229: </PRE>
2.3 frystyk 230: <P>
231: <HR>
2.1 eric 232: <ADDRESS>
2.18 ! vbancrof 233: @(#) $Id: HTEvent.html,v 2.17 1998/08/10 02:42:12 frystyk Exp $
2.1 eric 234: </ADDRESS>
2.3 frystyk 235: </BODY></HTML>
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