Annotation of libwww/Library/src/HTIOStream.html, revision 2.7
2.1 frystyk 1: <HTML>
2: <HEAD>
2.2 frystyk 3: <!-- Changed by: Henrik Frystyk Nielsen, 6-Apr-1996 -->
2.4 frystyk 4: <TITLE>W3C Sample Code Library libwww I/O Stream Classes</TITLE>
2.1 frystyk 5: </HEAD>
6: <BODY>
2.2 frystyk 7: <H1>
8: I/O Stream Classes
9: </H1>
2.1 frystyk 10: <PRE>
11: /*
12: ** (c) COPYRIGHT MIT 1995.
13: ** Please first read the full copyright statement in the file COPYRIGH.
14: */
15: </PRE>
2.2 frystyk 16: <P>
17: The I/O Stream class defines objects which accepts a sequence of characters
18: to and from a <A HREF="HTTrans.html">transport</A> The input and output
19: stream are mainly derived from the <A HREF="HTStream.html">generic stream
20: class</A> and contains much of the same functionality. The main difference
21: is that the I/O streams also contains methods for reading and writing to
22: a transport.
23: <P>
2.5 frystyk 24: This module is a part of the <A HREF="http://www.w3.org/Library/">W3C
2.4 frystyk 25: Sample Code Library</A>.
2.1 frystyk 26: <PRE>
27: #ifndef HTIOSTREAM_H
28: #define HTIOSTREAM_H
29:
2.7 ! vbancrof 30: #ifdef __cplusplus
! 31: extern "C" {
! 32: #endif
! 33:
2.1 frystyk 34: typedef struct _HTInputStream HTInputStream;
35: typedef struct _HTOutputStream HTOutputStream;
36:
37: #include "HTList.h"
38: #include "HTStream.h"
39: #include "HTChannl.h"
2.7 ! vbancrof 40:
2.1 frystyk 41: </PRE>
2.2 frystyk 42: <H2>
43: Input Stream
44: </H2>
45: <P>
46: An input stream is a stream that can read data from a transport and via a
47: <A HREF="HTChannl.html">channel</A> putting the data down to the application.
2.1 frystyk 48: <PRE>
49: typedef struct _HTInputStreamClass {
50:
51: char * name;
52: </PRE>
2.2 frystyk 53: <P>
2.1 frystyk 54: This field is for diagnostics only
55: <PRE>
56: int (*flush) (HTInputStream * me);
57: </PRE>
2.2 frystyk 58: <P>
59: The <B>flush</B> method is introduced in order to allow the stream to put
60: any buffered data down the stream pipe but without taking the stream pipe
61: down. It is for the stream to decide whether it has buffered data or not.
62: In some situations, the stream might not want to send buffered data down
63: the target as the date might be relevant for this stream only.
2.1 frystyk 64: <PRE>
65: int (*_free) (HTInputStream * me);
66: </PRE>
2.2 frystyk 67: <P>
68: The <CODE><B>free</B></CODE> method is like the <CODE>flush</CODE> method
69: but it also frees the current stream object and all stream objects down stream.
70: When the <CODE>free</CODE> method has been called, the <EM>whole</EM> stream
71: pipe (not only this object) should not accept any more data. See also the
72: <CODE>close</CODE> method below
2.1 frystyk 73: <PRE>
74: int (*abort) (HTInputStream * me, HTList * errorlist);
75: </PRE>
2.2 frystyk 76: <P>
77: The <B>abort</B> method should only be used if a stream is interrupted, for
78: example by the user, or an error occurs.
2.1 frystyk 79: <PRE>
80: int (*read) (HTInputStream * me);
81: </PRE>
2.2 frystyk 82: <P>
83: The <B>read</B> method is the method by which we can read data from the
84: <A HREF="HTTrans.html">transport layer</A>.
2.1 frystyk 85: <PRE>
86: int (*close) (HTInputStream * me);
87: </PRE>
2.2 frystyk 88: <P>
2.3 frystyk 89: Pipelined transports need to know how many bytes were <B>consumed</B> by
90: the net object.
91: <PRE>
92: int (*consumed) (HTInputStream * me, size_t bytes);
93: </PRE>
94: <P>
2.2 frystyk 95: The <CODE>close</CODE> method closes the transport and deletes the input
96: stream object. Note that this is different than the free method which doesn't
97: have to delete the input stream object itself.
2.1 frystyk 98: <PRE>
99: } HTInputStreamClass;
100: </PRE>
2.2 frystyk 101: <H2>
102: Output Stream
103: </H2>
104: <P>
105: The output stream is similar to the <A HREF="HTStream.html">generic stream
106: definition</A> in that it has a superset of methods. The <CODE>param</CODE>
107: parameter and the <CODE>mode</CODE> parameter can be used for whatever purpose
108: suited.
2.1 frystyk 109: <PRE>
110: typedef struct _HTOutputStreamClass {
111:
112: char * name;
113:
114: int (*flush) (HTOutputStream * me);
115:
116: int (*_free) (HTOutputStream * me);
117:
118: int (*abort) (HTOutputStream * me, HTList * errorlist);
119:
120: int (*put_character)(HTOutputStream * me, char ch);
121:
122: int (*put_string) (HTOutputStream * me, const char * str);
123:
124: int (*put_block) (HTOutputStream * me, const char * str, int len);
125: </PRE>
2.2 frystyk 126: <P>
127: See the <A HREF="HTStream.html">generic Stream Definition</A> for an explanation
128: of these methods. Note that they all have a <CODE>HTOutputStream</CODE> object
129: a the parameter, not a generic stream. This is to avoid <EM>incompatible
130: pointer</EM> warnings
2.1 frystyk 131: <PRE>
132: int (*close) (HTOutputStream * me);
133: </PRE>
2.2 frystyk 134: <P>
135: The <CODE>close</CODE> method closes the transport and deletes the input
136: stream object. Note that this is different than the free method which doesn't
137: have to delete the input stream object itself.
2.1 frystyk 138: <PRE>
139: } HTOutputStreamClass;
140: </PRE>
2.2 frystyk 141: <H2>
142: Transport Streams
143: </H2>
144: <P>
145: Transport streams are special streams with creation methods like defined
146: below. Transport streams can be registered in a
147: <A HREF="HTTrans.html">transport object</A> as ways of communicating with
148: the a transport.
149: <H3>
150: Transport Input Stream
151: </H3>
152: <P>
153: We have two modes of the input stream depending on model used for data reading
154: is <B>PUSH</B> or <B>PULL</B>. The PUSH model is suitable if we are using
155: pseudo threads based on a <CODE>select()</CODE> call or equivalent and the
156: <B>PULL</B> is suitable in a real thread environment. In the latter case
157: it doesn't matter if a read procedure blocks as this only concerns a single
158: thread.
2.1 frystyk 159: <PRE>
2.3 frystyk 160: typedef HTInputStream * HTInput_new (HTHost * host,
2.1 frystyk 161: HTChannel * ch,
162: void * param,
163: int mode);
164: </PRE>
2.2 frystyk 165: <H3>
166: Transport Output Stream
167: </H3>
2.1 frystyk 168: <PRE>
2.3 frystyk 169: typedef HTOutputStream * HTOutput_new (HTHost * host,
2.1 frystyk 170: HTChannel * ch,
171: void * param,
172: int mode);
173: </PRE>
2.6 frystyk 174: <H3>
175: Transport Output Stream Converter
176: </H3>
177: <PRE>
178: typedef HTOutputStream * HTOutputConverter_new(
179: HTHost * host,
180: HTChannel * ch,
181: void * param,
182: int mode,
183: HTOutputStream * target);
184: </PRE>
2.1 frystyk 185: <PRE>
2.7 ! vbancrof 186: #ifdef __cplusplus
! 187: }
! 188: #endif
! 189:
2.1 frystyk 190: #endif /* HTIOSTREAM_H */
191: </PRE>
2.2 frystyk 192: <P>
193: <HR>
2.1 frystyk 194: <ADDRESS>
2.7 ! vbancrof 195: @(#) $Id: HTIOStream.html,v 2.6 1999/04/04 00:12:00 frystyk Exp $
2.1 frystyk 196: </ADDRESS>
2.2 frystyk 197: </BODY></HTML>
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