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+<title>The Apache EBCDIC Port - Apache HTTP Server</title>
+<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
+<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
+<link href="../images/favicon.ico" rel="shortcut icon" /></head>
+<body id="manual-page"><div id="page-header">
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.0</p>
+<img alt="" src="../images/feather.gif" /></div>
+<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.0</a> > <a href="./">Platform Specific Notes</a></div><div id="page-content"><div id="preamble"><h1>The Apache EBCDIC Port</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/platform/ebcdic.html" title="English"> en </a> |
+<a href="../ko/platform/ebcdic.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
+</div>
+
+
+ <div class="warning"><strong>Warning:</strong> This document
+ has not been updated to take into account changes made in
+ the 2.0 version of the Apache HTTP Server. Some of the
+ information may still be relevant, but please use it with care.
+ </div>
+
+ </div>
+<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#overview">Overview of the Apache EBCDIC Port</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#design">Design Goals</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#technical">Technical Solution</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#porting">Porting Notes</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#document">Document Storage Notes</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#modules">Apache Modules' Status</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#third-party">Third Party Modules' Status</a></li>
+</ul></div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="overview" id="overview">Overview of the Apache EBCDIC Port</a></h2>
+
+
+
+ <p>Version 1.3 of the Apache HTTP Server is the first version
+ which includes a port to a (non-ASCII) mainframe machine which
+ uses the EBCDIC character set as its native codeset.</p>
+
+ <p>(It is the SIEMENS family of mainframes running the <a href="http://www.siemens.de/servers/bs2osd/osdbc_us.htm">BS2000/OSD
+ operating system</a>. This mainframe OS nowadays features a
+ SVR4-derived POSIX subsystem).</p>
+
+ <p>The port was started initially to</p>
+
+ <ul>
+ <li>prove the feasibility of porting <a href="http://dev.apache.org/">the Apache HTTP server</a> to
+ this platform</li>
+
+ <li>find a "worthy and capable" successor for the venerable
+ <a href="http://www.w3.org/Daemon/">CERN-3.0</a> daemon
+ (which was ported a couple of years ago), and to</li>
+
+ <li>prove that Apache's preforking process model can on this
+ platform easily outperform the accept-fork-serve model used
+ by CERN by a factor of 5 or more.</li>
+ </ul>
+
+ <p>This document serves as a rationale to describe some of the
+ design decisions of the port to this machine.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="design" id="design">Design Goals</a></h2>
+
+
+
+ <p>One objective of the EBCDIC port was to maintain enough
+ backwards compatibility with the (EBCDIC) CERN server to make
+ the transition to the new server attractive and easy. This
+ required the addition of a configurable method to define
+ whether a HTML document was stored in ASCII (the only format
+ accepted by the old server) or in EBCDIC (the native document
+ format in the POSIX subsystem, and therefore the only realistic
+ format in which the other POSIX tools like <code>grep</code> or
+ <code>sed</code> could operate on the documents). The current
+ solution to this is a "pseudo-MIME-format" which is intercepted
+ and interpreted by the Apache server (see below). Future versions
+ might solve the problem by defining an "ebcdic-handler" for all
+ documents which must be converted.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="technical" id="technical">Technical Solution</a></h2>
+
+
+
+ <p>Since all Apache input and output is based upon the BUFF
+ data type and its methods, the easiest solution was to add the
+ conversion to the BUFF handling routines. The conversion must
+ be settable at any time, so a BUFF flag was added which defines
+ whether a BUFF object has currently enabled conversion or not.
+ This flag is modified at several points in the HTTP
+ protocol:</p>
+
+ <ul>
+ <li><strong>set</strong> before a request is received
+ (because the request and the request header lines are always
+ in ASCII format)</li>
+
+ <li><strong>set/unset</strong> when the request body is
+ received - depending on the content type of the request body
+ (because the request body may contain ASCII text or a binary
+ file)</li>
+
+ <li><strong>set</strong> before a reply header is sent
+ (because the response header lines are always in ASCII
+ format)</li>
+
+ <li><strong>set/unset</strong> when the response body is sent
+ - depending on the content type of the response body (because
+ the response body may contain text or a binary file)</li>
+ </ul>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="porting" id="porting">Porting Notes</a></h2>
+
+
+
+ <ol>
+ <li>
+ <p>The relevant changes in the source are <code>#ifdef</code>'ed
+ into two categories:</p>
+
+ <dl>
+ <dt><code><strong>#ifdef
+ CHARSET_EBCDIC</strong></code></dt>
+
+ <dd>
+ <p>Code which is needed for any EBCDIC based machine.
+ This includes character translations, differences in
+ contiguity of the two character sets, flags which
+ indicate which part of the HTTP protocol has to be
+ converted and which part doesn't <em>etc.</em></p>
+ </dd>
+
+ <dt><code><strong>#ifdef _OSD_POSIX</strong></code></dt>
+
+ <dd>
+ <p>Code which is needed for the SIEMENS BS2000/OSD
+ mainframe platform only. This deals with include file
+ differences and socket implementation topics which are
+ only required on the BS2000/OSD platform.</p>
+ </dd>
+ </dl>
+ </li>
+
+ <li>
+ <p>The possibility to translate between ASCII and EBCDIC at
+ the socket level (on BS2000 POSIX, there is a socket option
+ which supports this) was intentionally <em>not</em> chosen,
+ because the byte stream at the HTTP protocol level consists
+ of a mixture of protocol related strings and non-protocol
+ related raw file data. HTTP protocol strings are always
+ encoded in ASCII (the <code>GET</code> request, any Header: lines,
+ the chunking information <em>etc.</em>) whereas the file transfer
+ parts (<em>i.e.</em>, GIF images, CGI output <em>etc.</em>)
+ should usually be just "passed through" by the server. This
+ separation between "protocol string" and "raw data" is
+ reflected in the server code by functions like <code>bgets()</code>
+ or <code>rvputs()</code> for strings, and functions like
+ <code>bwrite()</code> for binary data. A global translation
+ of everything would therefore be inadequate.</p>
+
+ <p>(In the case of text files of course, provisions must be
+ made so that EBCDIC documents are always served in
+ ASCII)</p>
+ </li>
+
+ <li>
+ <p>This port therefore features a built-in protocol level
+ conversion for the server-internal strings (which the
+ compiler translated to EBCDIC strings) and thus for all
+ server-generated documents. The hard coded ASCII escapes
+ <code>\012</code> and <code>\015</code> which are ubiquitous
+ in the server code are an exception: they are already the binary
+ encoding of the ASCII <code>\n</code> and <code>\r</code> and
+ must not be converted to ASCII a second time.
+ This exception is only relevant for server-generated strings;
+ and <em>external</em> EBCDIC documents are not expected to
+ contain ASCII newline characters.</p>
+ </li>
+
+ <li>
+ <p>By examining the call hierarchy for the BUFF management
+ routines, I added an "ebcdic/ascii conversion layer" which
+ would be crossed on every puts/write/get/gets, and a
+ conversion flag which allowed enabling/disabling the
+ conversions on-the-fly. Usually, a document crosses this
+ layer twice from its origin source (a file or CGI output) to
+ its destination (the requesting client): <code>file ->
+ Apache</code>, and <code>Apache -> client</code>.</p>
+
+ <p>The server can now read the header lines of a CGI-script
+ output in EBCDIC format, and then find out that the remainder
+ of the script's output is in ASCII (like in the case of the
+ output of a WWW Counter program: the document body contains a
+ GIF image). All header processing is done in the native
+ EBCDIC format; the server then determines, based on the type
+ of document being served, whether the document body (except
+ for the chunking information, of course) is in ASCII already
+ or must be converted from EBCDIC.</p>
+ </li>
+
+ <li>
+ <p>For Text documents (MIME types text/plain, text/html
+ <em>etc.</em>), an implicit translation to ASCII can be
+ used, or (if the users prefer to store some documents in
+ raw ASCII form for faster serving, or because the files
+ reside on a NFS-mounted directory tree) can be served
+ without conversion.</p>
+
+ <p><strong>Example:</strong></p>
+
+ <p>to serve files with the suffix <code>.ahtml</code> as a
+ raw ASCII <code>text/html</code> document without implicit
+ conversion (and suffix <code>.ascii</code> as ASCII
+ <code>text/plain</code>), use the directives:</p>
+
+ <div class="example"><p><code>
+ AddType text/x-ascii-html .ahtml <br />
+ AddType text/x-ascii-plain .ascii
+ </code></p></div>
+
+ <p>Similarly, any <code>text/foo</code> MIME type can be
+ served as "raw ASCII" by configuring a MIME type
+ "<code>text/x-ascii-foo</code>" for it using
+ <code>AddType</code>.</p>
+ </li>
+
+ <li>
+ <p>Non-text documents are always served "binary" without
+ conversion. This seems to be the most sensible choice for,
+ .<em>e.g.</em>, GIF/ZIP/AU file types. This of course
+ requires the user to copy them to the mainframe host using
+ the "<code>rcp -b</code>" binary switch.</p>
+ </li>
+
+ <li>
+ <p>Server parsed files are always assumed to be in native
+ (<em>i.e.</em>, EBCDIC) format as used on the machine, and
+ are converted after processing.</p>
+ </li>
+
+ <li>
+ <p>For CGI output, the CGI script determines whether a
+ conversion is needed or not: by setting the appropriate
+ Content-Type, text files can be converted, or GIF output can
+ be passed through unmodified. An example for the latter case
+ is the wwwcount program which we ported as well.</p>
+ </li>
+
+ </ol>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="document" id="document">Document Storage Notes</a></h2>
+
+
+
+ <h3><a name="binary" id="binary">Binary Files</a></h3>
+
+
+
+ <p>All files with a <code>Content-Type:</code> which does not
+ start with <code>text/</code> are regarded as <em>binary
+ files</em> by the server and are not subject to any conversion.
+ Examples for binary files are GIF images, gzip-compressed files
+ and the like.</p>
+
+ <p>When exchanging binary files between the mainframe host and
+ a Unix machine or Windows PC, be sure to use the ftp "binary"
+ (<code>TYPE I</code>) command, or use the
+ <code>rcp -b</code> command from the mainframe host (the
+ <code>-b</code> switch is not supported in unix
+ <code>rcp</code>'s).</p>
+
+
+
+ <h3><a name="text" id="text">Text Documents</a></h3>
+
+
+
+ <p>The default assumption of the server is that Text Files
+ (<em>i.e.</em>, all files whose <code>Content-Type:</code>
+ starts with <code>text/</code>) are stored in the native
+ character set of the host, EBCDIC.</p>
+
+
+
+ <h3><a name="ssi" id="ssi">Server Side Included Documents</a></h3>
+
+
+
+ <p>SSI documents must currently be stored in EBCDIC only.
+ No provision is made to convert it from ASCII before
+ processing.</p>
+
+
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="modules" id="modules">Apache Modules' Status</a></h2>
+
+
+
+ <table class="bordered">
+ <tr>
+ <th>Module</th>
+ <th>Status</th>
+ <th>Notes</th>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/core.html">core</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_access.html">mod_access</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_asis.html">mod_asis</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_auth.html">mod_auth</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_auth_anon.html">mod_auth_anon</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_auth_dbm.html">mod_auth_dbm</a></code></td>
+ <td class="centered">?</td>
+ <td>with own <code>libdb.a</code></td>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_cern_meta.html">mod_cern_meta</a></code></td>
+ <td class="centered">?</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code>mod_digest</code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_so.html">mod_so</a></code></td>
+ <td class="centered">-</td>
+ <td>no shared libs</td>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_env.html">mod_env</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_example.html">mod_example</a></code></td>
+ <td class="centered">-</td>
+ <td>(test bed only)</td>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_expires.html">mod_expires</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_headers.html">mod_headers</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_imap.html">mod_imap</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_include.html">mod_include</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_info.html">mod_info</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code>mod_log_agent</code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code>mod_log_referer</code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_mime_magic.html">mod_mime_magic</a></code></td>
+ <td class="centered">?</td>
+ <td>not ported yet</td>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
+ <td class="centered">+</td>
+ <td>untested</td>
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_setenvif.html">mod_setenvif</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_speling.html">mod_speling</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_status.html">mod_status</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_userdir.html">mod_userdir</a></code></td>
+ <td class="centered">+</td>
+ <td />
+ </tr>
+
+ <tr>
+ <td><code class="module"><a href="../mod/mod_usertrack.html">mod_usertrack</a></code></td>
+ <td class="centered">?</td>
+ <td>untested</td>
+ </tr>
+ </table>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="third-party" id="third-party">Third Party Modules' Status</a></h2>
+
+
+
+ <table class="bordered">
+ <tr>
+ <th>Module</th>
+ <th>Status</th>
+ <th>Notes</th>
+ </tr>
+
+ <tr>
+ <td><code><a href="http://java.apache.org/">mod_jserv</a>
+ </code></td>
+ <td class="centered">-</td>
+ <td>JAVA still being ported.</td>
+ </tr>
+
+ <tr>
+ <td><code><a href="http://www.php.net/">mod_php3</a></code></td>
+ <td class="centered">+</td>
+ <td><code>mod_php3</code> runs fine, with LDAP and GD
+ and FreeType libraries.</td>
+ </tr>
+
+ <tr>
+ <td><code><a href="http://hpwww.ec-lyon.fr/~vincent/apache/mod_put.html">mod_put</a></code></td>
+ <td class="centered">?</td>
+ <td>untested</td>
+ </tr>
+
+ <tr>
+ <td><code><a href="ftp://hachiman.vidya.com/pub/apache/">mod_session</a></code></td>
+ <td class="centered">-</td>
+ <td>untested</td>
+ </tr>
+ </table>
+
+ </div></div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="../en/platform/ebcdic.html" title="English"> en </a> |
+<a href="../ko/platform/ebcdic.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
+</div><div id="footer">
+<p class="apache">Copyright 2009 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>
+</body></html>
\ No newline at end of file
Code Review / bottlenecks.git / blobdiff