More work on documentation.

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 <!doctype linuxdoc system>
 
 <!--
-  $Id: egate.sgml,v 1.5 1995/07/10 10:28:22 adam Exp $
+  $Id: egate.sgml,v 1.6 1995/07/10 13:55:25 adam Exp $
 -->
 
 <article>
 <title>Email/Z39.50 gateway guide
 <author>Europagate, 1995
-<date>$Revision: 1.5 $
+<date>$Revision: 1.6 $
 <abstract>
 This document describes a Email server that provides access to the
 Z39.50 protocol.
@@ -506,6 +506,9 @@ Information about each result set includes:
 <item>query
 </itemize>
 
+A persistency file is removed each time a new target is selected.
+It is our experiences that the persistency files are very small.
+
 <sect1>CCL
 
 <p>
@@ -526,10 +529,117 @@ CCL parser itself is not tied to Bib-1.
 <sect1>FML
 
 <p>
+The FML system is used to handle the presentation of MARC
+records. There are some deviations to the design report, however.
+The most important changes are:
+<itemize>
+<item>The <tt/expr/ function is not implemented. Instead arithmetic
+operators <tt/plus/, <tt/minus/, <tt/mult/ and <tt/div/ are
+implemented. Also relational operators <tt/gt/, <tt/lt/ ... are
+implemented.
+<item>The <tt/lindex/ function is called <tt/index/ and it is a binary
+operator where the left operand is the list and the right operand is
+the index integer.
+<item>The MARC extraction routines are not implemented.
+Instead, a MARC record is transferred as an argument
+to a formatting-routine (in list notation). The formatting
+routine then extracts fields from the list by list/string
+manipulation functions.
+<item>A new statement, <tt/bin/, is implemented to define
+binary operators (functions). 
+</itemize>
 
 <sect1>IPC
 
 <p>
+As described in the design, FIFOs are used to communicate between
+the ETI, MONITOR and KERNEL. The ES can run without the MONITOR,
+however. The primary reason for the presence of the MONITOR was
+to assure that the KERNELs would release the resources used by the
+persistency layer. But, since the persistency layer did turn out to
+use virtually no disk space at all, there was no point in starting
+a KERNEL process to remove its files &mdash; hence this facility 
+was not implemented. The only purpose of the MONITOR is to keep the
+number of running KERNELs at a maximum level and even that
+is probably useless since most unices will swap KERNEL processes
+out anyway.
+
+The idle time
+before a KERNEL exits and saves its persistency file is not
+controlled by the MONITOR. Saving the persistency file and
+keeping it is usually a good approach &mdash; even when a
+user doesn't reference/show old result-sets since the user
+has a notion of <em/current target/ and database.
+
+<sect1>Source
+
+<p>
+In this section a short description of each source module is
+given. Each module is implemented in a separate sub directory. 
+Any public headers are located in the <tt/include/ directory.
+
+<descrip>
+<tag/res+log/ is an implementation of the logging system
+and the resource management sub system. Note that the
+resource module depends on the logging facility. Logging
+is implemented in <tt>gw-log.c</tt> and <tt/gw-log.h/. The
+file <tt>gw-log-test.c</tt> is small test program for the
+logging system. The core of the resource management is implemented
+in <tt>gw-res.c</tt>. The files <tt>gw-res-bool.c</tt> and
+<tt>gw-res-int.c</tt> implement two utility routines &mdash
+on top of the resource management. The header file
+<tt>gw-resp.h</tt> is a private header file and <tt>gw-res.h</tt>
+is a public header file.
+
+<tag/ccl/ implements CCL to RPN mapping and a tokenization 
+ utility for other CCL commands. The mapping function is
+ implemented in <tt>cclfind.c</tt>. Qualifiers are handled in 
+ <tt>cclqual.c</tt> while reading of qualifier mappings from a
+ file is implemented in <tt>cclqfile.c</tt>. Scanning is implemented
+ in <tt>ccltoken.c</tt>. String utilities, which might be changed if
+ other character sets are needed, is implemented in
+ <tt>cclstr.c</tt>. Table of error messages is implemented in
+ <tt>cclerrms.c</tt>.
+
+<tag/util/ implements various utilities:
+  <descrip>
+  <tag>MARC utility</tag> implemented in <tt>iso2709</tt>...
+  <tag>Database utility</tag> implemented in <tt>gw-db.[ch]</tt>. This
+   utility is used to map a user (email) to an integer.
+  <tag>String queue utility</tag> implemented in <tt>strqueue.[ch]</tt>. This
+   utiltiy is used to queue incoming mail in the ETI, KERNEL and
+   the MONITOR.
+  <tag>Pretty printer</tag> implemented in <tt>ttyemit.[ch]</tt>
+   &mdash; used by the URP.
+  <tag>FIFO IPC utiltiy</tag> implemented in <tt>gip*.[ch]</tt> &mdash;
+   used by the ETI, KERNEL and MONITOR.    
+  </descrip>
+
+<tag/fml/ implements FML. The top level functions are implemented
+ in <tt>fml.c</tt>, <tt>fmlcall.c</tt> and <tt>fmlcalls.c</tt>.
+ Scanning is implemented in <tt>fmltoken.c</tt>.
+ Memory management is implemented in <tt>fmlmem.c</tt>. 
+ Arithmetic operators are implemented in <tt>fmlarit.c</tt>. 
+ String manipulation functions are implemented in <tt>fmlstr.c</tt>.
+ Relational operators are implemented in <tt>fmlrel.c</tt>.
+ List maniuplations are performed in <tt>fmllist.c</tt>.
+ FML symbol table management is implemented in <tt>fmlsym.c</tt>.
+ Conversion from ISO2709 to list notation is implemented in
+ <tt>fmlmarc.c</tt>.
+
+<tag/zlayer-zdist/ implements the high-level Z39.50 API on top
+  of Zdist. This task is implemented in <tt>zaccess.c</tt>. The
+ public header file is called <tt>zaccess.h</tt>.
+
+<tag/zlayer-yaz/ implements the high-level Z39.50 API on top
+  of YAZ. This task is implemented in <tt>zaccess.c</tt>. The
+ public header file is called <tt>zaccess.h</tt>.
+
+<tag/kernel/ implements the ETI, KERNEL and MONITOR. The kernel
+ itself is implemented in <tt>main.c</tt>, <tt>urp.c</tt> and
+ <tt>persist.c</tt>. The ETI is implemented in <tt>eti.c</tt> and
+ the MONITOR is implemented <tt>monitor.c</tt>.
+</descrip>
 
 <sect>LICENSE