Annotation of libwww/Library/src/WWWApp.html, revision 2.6
2.1 frystyk 1: <HTML>
2: <HEAD>
2.2 frystyk 3: <TITLE>Non-Mandatory Application Include File</TITLE>
2.6 ! frystyk 4: <!-- Changed by: Henrik Frystyk Nielsen, 8-Dec-1995 -->
2.1 frystyk 5: <NEXTID N="z11">
6: </HEAD>
7: <BODY>
8:
2.2 frystyk 9: <H1>Non-Mandatory Application Include File</H1>
2.1 frystyk 10:
11: <PRE>
12: /*
13: ** (c) COPYRIGHT MIT 1995.
14: ** Please first read the full copyright statement in the file COPYRIGH.
15: */
16: </PRE>
17:
18: In addition top the basic W3C Reference Library include file called <A
19: HREF="WWWLib.html">WWWLib.h</A> you <EM>can</EM> also include this
20: file called WWWApp.h depending on the needs of your
21: application. However, it is not required and none of the files
22: included below are ever used in the core part of the Library
23: itself. Only if this file is included, the extra modules will get
24: included in the linked object code. It is also possible to include
25: only a subset of the files below if the functionality you are after is
26: covered by them.
27:
28: <PRE>
29: #ifndef WWWAPP_H
30: #define WWWAPP_H
31: </PRE>
32:
33: <PRE>
34: #ifdef __cplusplus
35: extern "C" {
36: #endif
37: </PRE>
38:
39: <H2>Initialization</H2>
40:
41: The core parts of the Library is a framework for adding
2.3 frystyk 42: functionality. It has hooks for adding protocol modules, like for
2.1 frystyk 43: example HTTP, FTP, and also for adding streams that can convert from
44: one media type to some other type, or presenting the result to the
45: user. In the distribution file of the Library you will find a large
2.3 frystyk 46: set of protocol modules and streams already implemented. However, in
2.1 frystyk 47: order to use these you need to initialize them. This can be done by
48: using the files in the <A HREF="HTInit.html">HTInit</A> module. You
49: can modify this module as you like to fit your particular needs.
50:
51: <PRE>
2.2 frystyk 52: #include "<A HREF="HTInit.html">HTInit.h</A>"
2.6 ! frystyk 53: #include "<A HREF="HTInit.html">HTBInit.h</A>"
2.2 frystyk 54: </PRE>
55:
2.3 frystyk 56: <H3>Generating the First Anchor</H3>
2.2 frystyk 57:
58: This module provides some "make life easier" functions in order to get
59: the application going. They help you generate the first anchor, also
60: called the <EM>home anchor</EM>. It also contains a nice set of
61: default WWW addresses.
62:
63: <PRE>
64: #include "<A HREF="HTHome.html">HTHome.h</A>"
2.1 frystyk 65: </PRE>
66:
2.3 frystyk 67: <H2>Before a Request</H2>
68:
2.4 frystyk 69: When a request has been issued there are a number of things that an
2.3 frystyk 70: application might want to do with the request before it actually goes
71: on the wire, for example to talk to a remote HTTP server. Examples are
72: checking if the object already is kept in a cache managed by the
73: application, if the request should be redirected to a proxy or a
74: gateway, or there is some other kind of translation of the URL taking
75: place. The Library provides a variety of modules that handles many
76: common place translations such as <EM>redirection of URLs</EM> and
2.4 frystyk 77: <EM>caching</EM>.<P>
2.3 frystyk 78:
79: These modules are not part of the <A HREF="WWWCore.html">Library
80: Core</A> as the registration process depends on the application. It
81: can for example use a database or some other means of registering
82: translation rules, proxy servers. etc. The Library implementations are
83: deliberately made as platform independent as possible and will cover
2.4 frystyk 84: most situations. You can find a function called
2.5 frystyk 85: <CODE>HTLoadStart</CODE> in the <A HREF="HTHome.html">HTHome module</A>
2.4 frystyk 86: that enables all the functionality for translating URLs.
2.3 frystyk 87:
88: <H3>Rule File Management</H3>
89:
90: Another way to initialize applications is to use a rule file, also
91: known as a configuration file. This is for example the case with the
92: W3C httpd and the W3C Line Mode Browser. This module provides basic
93: support for configuration file management and the application can use
94: this is desired. The module is not referred to by the Library. Reading
95: a rule file is implemented as a stream converter so that a rule file
96: can come from anywhere, even across the network!
97:
98: <PRE>
99: #include "<A HREF="HTRules.html">HTRules.h</A>"
100: </PRE>
101:
102: <H3>Proxies and Gateways</H3>
103:
104: Applications do not have to provide native support for all protocols,
105: they can in many situations rely on the support of proxies and
106: gateways to help doing the job. Proxy servers are often used to carry
107: client requests through a firewall where they can provide services
108: like corporate caching and other network optimizations. Both Proxy
109: servers and gateways can serve as "protocol translators" which can
110: convert a request in the main Web protocol, HTTP, to an equivalent
111: request in another protocol, for example NNTP, FTP, or Gopher. In case
112: a proxy server or a gateway is available to the application, it can
113: therefore by use of HTTP forward all requests to for example a proxy
114: server which then handle the communications with the remote server,
115: for example using FTP about the document and return it to the
116: application (proxy client) using HTTP.
117:
118: <PRE>
119: #include "<A HREF="HTProxy.html">HTProxy.h</A>"
120: </PRE>
121:
122: <H3>Cache Manager</H3>
123:
124: Caching is a required part of any efficient Internet access
125: applications as it saves bandwidth and improves access performance
126: significantly in almost all types of accesses. The Library supports
127: two different types of cache: The memory cache and the file cache. The
128: two types differ in several ways which reflects their two main
129: purposes: The memory cache is for short term storage of graphic
130: objects whereas the file cache is for intermediate term storage of
131: data objects. Often it is desirable to have both a memory and a file
132: version of a cached document, so the two types do not exclude each
133: other.
134:
135: <PRE>
136: #include "<A HREF="HTCache.html">HTCache.h</A>"
137: </PRE>
138:
139: <H2>After a Request</H2>
140:
141: When a request is terminated, the application often has to do some
142: action as a result of the request (and of the result of the
143: request). The Application part of the Library provides two following
144: modules to handle <EM>logging</EM> and <EM>history
145: management</EM>. You can register a <EM>POST request handler</EM> in
146: the <A HREF="HTNet.html">Net Manager</A> as described in the <A
2.4 frystyk 147: HREF="../User/Using/Overview.html">User's Guide</A>. <P>
148:
149: You can find a function called <CODE>HTLoadTerminate</CODE> in the <A
2.5 frystyk 150: HREF="HTHome.html">HTHome module</A> that enables all the functionality
2.4 frystyk 151: for handling a request result.
2.3 frystyk 152:
153: <H3>Logging</H3>
2.1 frystyk 154:
155: Often it is required to log the requests issued to the Library. This
156: can either be the case if the application is a server or it can also
157: be useful in a client application. This module provides a simple
158: logging mechanism which can be enabled if needed.
159:
160: <PRE>
2.2 frystyk 161: #include "<A HREF="HTLog.html">HTLog.h</A>"
2.1 frystyk 162: </PRE>
163:
2.3 frystyk 164: <H3>History Management</H3>
2.1 frystyk 165:
166: Another type of logging is keeping track of which documents a user has
167: visited when browsing along on the Web. The Library history manager
168: provides a basic set of functionality to keep track of a linear
169: history list.
170:
171: <PRE>
2.2 frystyk 172: #include "<A HREF="HTHist.html">HTHist.h</A>"
2.1 frystyk 173: </PRE>
174:
175: End of application specific modules
176:
177: <PRE>
178: #ifdef __cplusplus
179: } /* end extern C definitions */
180: #endif
181:
182: #endif
183: </PRE>
184:
185: End of WWWAPP definition
186:
187: </BODY>
188: </HTML>
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