+++ /dev/null
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-<HTML
-><HEAD
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->Server Organization</TITLE
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-TITLE="Embedded HTTP Server"
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-TITLE="Embedded HTTP Server"
-HREF="net-httpd-chapter.html"><LINK
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-TITLE="Server Configuration"
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->Chapter 48. Embedded HTTP Server</TD
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-><DIV
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-><H1
-CLASS="SECT1"
-><A
-NAME="NET-HTTPD-ORGANIZATION">Server Organization</H1
-><P
->The server consists of one or more threads running in parallel to any
-application threads and which serve web pages to clients. Apart from
-defining content, the application does not need to do anything to
-start the HTTP server.</P
-><P
->The HTTP server is started by a static constructor. This simply
-creates an initial thread and sets it running. Since this is called
-before the scheduler is started, nothing will happen until the
-application calls <TT
-CLASS="FUNCTION"
->cyg_scheduler_start()</TT
->.</P
-><P
->When the thread gets to run it first optionally delays for some period
-of time. This is to allow the application to perform any
-initialization free of any interference from the HTTP server. When the
-thread does finally run it creates a socket, binds it to the HTTP
-server port, and puts it into listen mode. It will then create any
-additional HTTPD server threads that have been configured before
-becoming a server thread itself.</P
-><P
->Each HTTPD server thread simply waits for a connection to be made to
-the server port. When the connection is made it reads the HTTP request
-and extracts the filename being accessed. If the request also contains
-form data, this is also preserved. The filename is then looked up in a
-table.</P
-><P
->Each table entry contains a filename pattern string, a
-pointer to a handler function, and a user defined argument for the
-function. Table entries are defined using the same link-time table
-building mechanism used to generate device tables. This is all handled
-by the <TT
-CLASS="LITERAL"
->CYG_HTTPD_TABLE_ENTRY()</TT
-> macro which has the
-following format:</P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
-> #include <cyg/httpd/httpd.h>
-
-CYG_HTTPD_TABLE_ENTRY( __name, __pattern, __handler, __arg ) </PRE
-></TD
-></TR
-></TABLE
-><P
->The <TT
-CLASS="PARAMETER"
-><I
->__name</I
-></TT
-> argument is a variable name for the
-table entry since C does not allow us to define anonymous data
-structures. This name should be chosen so that it is unique and does
-not pollute the name space. The <TT
-CLASS="PARAMETER"
-><I
->__pattern</I
-></TT
->
-argument is the match pattern. The <TT
-CLASS="PARAMETER"
-><I
->__handler</I
-></TT
->
-argument is a pointer to the handler function and
-<TT
-CLASS="PARAMETER"
-><I
->__arg</I
-></TT
-> the user defined value.</P
-><P
->The link-time table building means that several different pieces of
-code can define server table entries, and so long as the patterns do
-not clash they can be totally oblivious of each other. However, note
-also that this mechanism does not guarantee the order in which entries
-appear, this depends on the order of object files in the link, which
-could vary from one build to the next. So any tricky pattern matching
-that relies on this may not always work.</P
-><P
->A request filename matches an entry in the table if either it exactly
-matches the pattern string, or if the pattern ends in an asterisk, and
-it matches everything up to that point. So for example the pattern
-"/monitor/threads.html" will only match that exact filename,
-but the pattern "/monitor/thread-*" will match
-"/monitor/thread-0040.html",
-"/monitor/thread-0100.html" and any other filename starting
-with "/monitor/thread-".</P
-><P
->When a pattern is matched, the hander function is called. It has the
-following prototype:</P
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->cyg_bool cyg_httpd_handler(FILE *client,
- char *filename,
- char *formdata,
- void *arg);</PRE
-></TD
-></TR
-></TABLE
-><P
->The <TT
-CLASS="PARAMETER"
-><I
->client</I
-></TT
-> argument is the TCP connection to
-the client: anything output through this stream will be returned to
-the browser. The <TT
-CLASS="PARAMETER"
-><I
->filename</I
-></TT
-> argument is the
-filename from the HTTP request and the <TT
-CLASS="PARAMETER"
-><I
->formdata</I
-></TT
->
-argument is any form response data, or NULL if none was sent. The
-<TT
-CLASS="PARAMETER"
-><I
->arg</I
-></TT
-> argument is the user defined value from the
-table entry.</P
-><P
->The handler is entirely responsible for generating the response to the
-client, both HTTP header and content. If the handler decides that it
-does not want to generate a response it can return
-<TT
-CLASS="LITERAL"
->false</TT
->, in which case the table scan is resumed for
-another match. If no match is found, or no handler returns true, then
-a default response page is generated indicating that the requested
-page cannot be found.</P
-><P
->Finally, the server thread closes the connection to the client and
-loops back to accept a new connection.</P
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