Annotation of libwww/Library/src/HTChannl.html, revision 2.2
2.1 frystyk 1: <HTML>
2: <HEAD>
2.2 ! frystyk 3: <TITLE>W3C Reference Library libwww Channel Class</TITLE>
2.1 frystyk 4: </HEAD>
5: <BODY>
2.2 ! frystyk 6: <H1>
! 7: The Channel Class
! 8: </H1>
2.1 frystyk 9: <PRE>
10: /*
11: ** (c) COPYRIGHT MIT 1995.
12: ** Please first read the full copyright statement in the file COPYRIGH.
13: */
14: </PRE>
2.2 ! frystyk 15: <P>
! 16: A channel contains information about sockets and their input and output streams.
! 17: A <CODE>channel</CODE> represents the front end for receiving data towards
! 18: the underlying transport. The definition of a channel describes how we are
! 19: to read the data coming in on a socket, for example. In other words - a channel
! 20: represents the first part of how to get handle incoming data in the Library:
! 21: <P>
2.1 frystyk 22: <UL>
2.2 ! frystyk 23: <LI>
! 24: Reading data on a channel
! 25: <LI>
! 26: Defining a target for incoming data
! 27: <LI>
! 28: Defining a protocol state machine that can handle the data
2.1 frystyk 29: </UL>
2.2 ! frystyk 30: <P>
! 31: This module is implemented by <A HREF="HTChannl.c">HTChannl.c</A>, and it
! 32: is a part of the <A HREF="http://www.w3.org/pub/WWW/Library/"> W3C Reference
! 33: Library</A>.
2.1 frystyk 34: <PRE>
35: #ifndef HTCHANNL_H
36: #define HTCHANNL_H
37:
38: typedef enum _HTChannelMode {
39: HT_CH_SINGLE = 0, /* One single request at a time */
40: HT_CH_BATCH = 1, /* Use batch requests */
41: HT_CH_INTERLEAVED = 2 /* Can we interleave requests? */
42: } HTChannelMode;
43:
44: typedef struct _HTChannel HTChannel;
45:
46: #include <A HREF="HTTrans.html">"HTTrans.h"</A>
47: #include <A HREF="HTReq.html">"HTReq.h"</A>
48: #include <A HREF="HTNet.html">"HTNet.h"</A>
49: #include <A HREF="HTIOStream.html">"HTIOStream.h"</A>
50: </PRE>
2.2 ! frystyk 51: <H2>
! 52: The Channel Object
! 53: </H2>
! 54: <P>
! 55: A channel can be in a certain <CODE>mode</CODE> which determines how it behaves.
! 56: The set of modes is defined as:
! 57: <H3>
! 58: Creating a Channel Object
! 59: </H3>
! 60: <P>
! 61: The following methods can be used to instantiate objects of a particular
! 62: channel mode:
2.1 frystyk 63: <PRE>
64: extern HTChannel * HTChannel_new (HTNet * net, BOOL active);
65: </PRE>
2.2 ! frystyk 66: <H3>
! 67: Deleting a Channel Object
! 68: </H3>
2.1 frystyk 69: <PRE>
70: extern BOOL HTChannel_delete (HTChannel * channel);
71: extern BOOL HTCannel_deleteAll (void);
72: </PRE>
2.2 ! frystyk 73: <H3>
! 74: Control the Channel Mode
! 75: </H3>
! 76: <P>
! 77: A channel may change mode in the middle of a connection. The mode signifies
! 78: how we can use the channel: Does it accept multiple requets at the same time
! 79: or do we have to wait until a response is received? Can it handle interleaved
! 80: (multiplexed) requests/responses etc. All this is defined by the
! 81: <CODE>HTChannelMode</CODE>. At the same time we return whether the channel
! 82: is active or passive which means whether we did the initial "connect" or
! 83: the "accept". The "connect" and the "accept" term is of course a function
! 84: of the underlying transport but I think you get the point!
2.1 frystyk 85: <PRE>
86: extern HTChannelMode HTChannel_mode (HTChannel * channel, BOOL * active);
87:
88: extern BOOL HTChannel_setMode (HTChannel * channel, HTChannelMode mode);
89: </PRE>
2.2 ! frystyk 90: <H3>
! 91: Search for a Channel
! 92: </H3>
! 93: <P>
2.1 frystyk 94: Look for a channel object if we for some reason should have lost it
95: <PRE>
96: extern HTChannel * HTChannel_find (SOCKET sockfd);
97: </PRE>
2.2 ! frystyk 98: <H3>
! 99: Is the Channel Idle?
! 100: </H3>
! 101: <P>
! 102: Check whether a channel is idle meaning if it is ready for a new request
! 103: which depends on the mode of the channel. If the channel is idle, i.e. ready
! 104: for use then return YES else NO.
2.1 frystyk 105: <PRE>
106: extern BOOL HTChannel_idle (HTChannel * channel);
107: </PRE>
2.2 ! frystyk 108: <H3>
! 109: Get Transport Descriptor for Channel
! 110: </H3>
! 111: <P>
! 112: A transport descriptor can be either a ANSI C file descriptor or a BSD socket.
! 113: As it is difficult for the channel to know which one is used by a specific
! 114: transport, we leave this to the caller to figure out. This is probably not
! 115: the best way of doing it.
! 116: <PRE>extern SOCKET HTChannel_socket (HTChannel * channel);
! 117: extern FILE * HTChannel_file (HTChannel * channel);
! 118:
! 119: </PRE>
! 120: <H3>
! 121: Semaphores
! 122: </H3>
! 123: <P>
! 124: Adjust the semaphore on a channel. As many <A HREF="HTNet.html">Net objects
! 125: </A>can point to the same channel we need to keep count of them so that we
! 126: know if we can delete a channel or if it is still in use. We do this by having
! 127: a simple semaphore associated with each channel object
2.1 frystyk 128: <PRE>
129: extern void HTChannel_upSemaphore (HTChannel * channel);
130: extern void HTChannel_downSemaphore (HTChannel * channel);
131: </PRE>
2.2 ! frystyk 132: <H3>
! 133: Create Input and Output Streams
! 134: </H3>
! 135: <P>
! 136: You create the input stream and bind it to the channel using the following
! 137: methods. Please read the description in the
! 138: <A HREF="HTIOStream.html">HTIOStream module</A> on the parameters
! 139: <EM>target</EM>, <EM>param</EM>, and <EM>mode</EM>. The input and output
! 140: stream are instances created by the <A HREF="HTTrans.html">Transport
! 141: object</A>. The Transport Object defines the creation methods for the inout
! 142: and output streams and the Channel object contains the actualy stream objects.
2.1 frystyk 143: <PRE>
144: extern BOOL HTChannel_setInput (HTChannel * ch,
145: HTInputStream * input, HTChannelMode mode);
2.2 ! frystyk 146: extern HTInputStream * HTChannel_input (HTChannel * ch);
! 147:
2.1 frystyk 148:
149: extern BOOL HTChannel_setOutput (HTChannel * ch,
150: HTOutputStream * output, HTChannelMode mode);
151: extern HTOutputStream * HTChannel_output (HTChannel * ch);
152:
153: </PRE>
154: <PRE>
155: #endif /* HTCHANNL */
156: </PRE>
2.2 ! frystyk 157: <P>
! 158: <HR>
2.1 frystyk 159: <ADDRESS>
2.2 ! frystyk 160: @(#) $Id: HTChannl.html,v 2.1 1996/04/12 17:46:13 frystyk Exp $
2.1 frystyk 161: </ADDRESS>
2.2 ! frystyk 162: </BODY></HTML>
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