<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1//EN"
"http://www.oasis-open.org/docbook/xml/4.1/docbookx.dtd"
[
- <!ENTITY local SYSTEM "local.ent">
+ <!ENTITY % local SYSTEM "local.ent">
+ %local;
<!ENTITY manref SYSTEM "manref.xml">
<!ENTITY progref SYSTEM "progref.xml">
<!ENTITY % common SYSTEM "common/common.ent">
-->
<!NOTATION PDF SYSTEM "PDF">
]>
-<!-- $Id: book.xml,v 1.41 2006-10-12 11:34:07 marc Exp $ -->
+<!-- $Id: book.xml,v 1.49 2007-01-12 15:43:00 adam Exp $ -->
<book id="metaproxy">
<bookinfo>
<title>Metaproxy - User's Guide and Reference</title>
<firstname>Mike</firstname><surname>Taylor</surname>
</author>
<copyright>
- <year>2006</year>
+ <year>2005-2007</year>
<holder>Index Data ApS</holder>
</copyright>
<abstract>
<simpara>
+ This manual is part of Metaproxy version &version;.
+ </simpara>
+ <simpara>
Metaproxy is a universal router, proxy and encapsulated
metasearcher for information retrieval protocols. It accepts,
processes, interprets and redirects requests from IR clients using
<para>
<ulink url="&url.metaproxy;">Metaproxy</ulink>
- is a standalone program that acts as a universal router, proxy and
+ is a stand alone program that acts as a universal router, proxy and
encapsulated metasearcher for information retrieval protocols such
as <ulink url="&url.z39.50;">Z39.50</ulink>, and in the future
<ulink url="&url.sru;">SRU</ulink> and <ulink url="&url.srw;">SRW</ulink>.
being more powerful, flexible, configurable and extensible. Among
its many advantages over the older, more pedestrian work are
support for multiplexing (encapsulated metasearching), routing by
- database name, authentication and authorisation and serving local
+ database name, authentication and authorization and serving local
files via HTTP. Equally significant, its modular architecture
facilitites the creation of pluggable modules implementing further
functionality.
You may modify your copy of the software (fix bugs, add features)
if you need to. We encourage you to send your changes back to us for
integration into the master copy, but you are not obliged to do so. You
- may NOT pass your changes on to any other party.
+ may NOT pass your changes on to any other party.
</para>
</listitem>
<listitem>
for more information.
</para>
<para>
- We have succesfully built Metaproxy using the compilers
+ We have successfully built Metaproxy using the compilers
<ulink url="&url.gcc;">GCC</ulink> version 4.0 and
<ulink url="&url.vstudio;">Microsoft Visual Studio</ulink> 2003/2005.
</para>
<literal>\boost\lib</literal>, <literal>\boost\include</literal>.
</para>
<para>
- For more informatation about installing Boost refer to the
+ For more information about installing Boost refer to the
<ulink url="&url.boost.getting.started;">getting started</ulink>
pages.
</para>
<ulink url="&url.libxml2.download.win32;">here</ulink>.
</para>
<para>
- Libxslt has other dependencies, but thes can all be downloaded
+ Libxslt has other dependencies, but these can all be downloaded
from the same site. Get the following:
iconv, zlib, libxml2, libxslt.
</para>
<section id="installation.windows.metaproxy">
<title>Metaproxy</title>
<para>
- Metaproxy is shipped with NMAKE makfiles as well - similar
+ Metaproxy is shipped with NMAKE makefiles as well - similar
to those found in the YAZ++/YAZ packages. Adjust this Makefile
to point to the proper locations of Boost, Libxslt, Libxml2,
zlib, iconv, yaz and yazpp.
</variablelist>
<para>
- After succesful compilation you'll find
+ After successful compilation you'll find
<literal>metaproxy.exe</literal> in the
<literal>bin</literal> directory.
</para>
<para>
In general, packages are doctored as they pass through
Metaproxy. For example, when the proxy performs authentication
- and authorisation on a Z39.50 Init request, it removes the
+ and authorization on a Z39.50 Init request, it removes the
authentication credentials from the package so that they are not
passed onto the back-end server; and when search-response
packages are obtained from multiple servers, they are merged
packages
(<literal>frontend_net</literal>);
others are sinks: they consume packages and return a result
- (<literal>z3950_client</literal>,
- <literal>backend_test</literal>,
+ (<literal>backend_test</literal>,
<literal>bounce</literal>,
- <literal>http_file</literal>);
+ <literal>http_file</literal>,
+ <literal>z3950_client</literal>);
the others are true filters, that read, process and pass on the
packages they are fed
(<literal>auth_simple</literal>,
<para>
We now briefly consider each of the types of filter supported by
the core Metaproxy binary. This overview is intended to give a
- flavour of the available functionality; more detailed information
+ flavor of the available functionality; more detailed information
about each type of filter is included below in
- <link linkend="filterref"
- >the reference guide to Metaproxy filters</link>.
+ <xref linkend="reference"/>.
</para>
<para>
The filters are here named by the string that is used as the
<title><literal>auth_simple</literal>
(mp::filter::AuthSimple)</title>
<para>
- Simple authentication and authorisation. The configuration
+ Simple authentication and authorization. The configuration
specifies the name of a file that is the user register, which
lists <varname>username</varname>:<varname>password</varname>
pairs, one per line, colon separated. When a session begins, it
A source that accepts Z39.50 connections from a port
specified in the configuration, reads protocol units, and
feeds them into the next filter in the route. When the result is
- revceived, it is returned to the original origin.
+ received, it is returned to the original origin.
</para>
</section>
</section>
<section>
+ <title><literal>load_balance</literal>
+ (mp::filter::LoadBalance)</title>
+ <para>
+ Performs load balancing for incoming Z39.50 init requests.
+ It is used together with the <literal>virt_db</literal> filter,
+ but unlike the <literal>multi</literal> filter it does send an
+ entire session to only one of the virtual backends. The
+ <literal>load_balance</literal> filter is assuming that
+ all backend targets have equal content, and chooses the backend
+ with least load cost for a new session.
+ <warning>
+ <para>
+ This filter is experimental and yet not mature for heavy load
+ production sites.
+ </para>
+ </warning>
+ </para>
+ </section>
+
+ <section>
<title><literal>log</literal>
(mp::filter::Log)</title>
<para>
as multiple different logging formats.
</para>
</section>
-
+
<section>
<title><literal>multi</literal>
(mp::filter::Multi)</title>
This filter acts only on Z3950 present requests, and let all
other types of packages and requests pass untouched. It's use is
twofold: blocking Z3950 present requests, which the backend
- server does not understand and can not honour, and transforming
+ server does not understand and can not honor, and transforming
the present syntax and elementset name according to the rules
- specified, to fetch only exisitng record formats, and transform
+ specified, to fetch only existing record formats, and transform
them on the fly to requested record syntaxes.
</para>
</section>
(mp::filter::SRUtoZ3950)</title>
<para>
This filter transforms valid
- SRU/GET or SRU/SOAP requests to Z3950 requests, and wraps the
- recieved hit counts and XML records into suitable SRU response messages.
+ SRU GET/POST/SOAP searchRetrieve requests to Z3950 init, search,
+ and present requests, and wraps the
+ received hit counts and XML records into suitable SRU response
+ messages.
+ The <literal>sru_z3950</literal> filter processes also SRU
+ GET/POST/SOAP explain requests, returning
+ either the absolute minimum required by the standard, or a full
+ pre-defined ZeeReX explain record.
+ See the
+ <ulink url="&url.zeerex.explain;">ZeeReX Explain</ulink>
+ standard pages and the
+ <ulink url="&url.sru.explain;">SRU Explain</ulink> pages
+ for more information on the correct explain syntax.
+ SRU scan requests are not supported yet.
</para>
</section>
are passed untouched.
</para>
</section>
+
+
+ <section>
+ <title><literal>zeerex_explain</literal>
+ (mp::filter::ZeerexExplain)</title>
+ <para>
+ This filter acts as a sink for
+ Z39.50 explain requests, returning a static ZeeReX
+ Explain XML record from the config section. All other packages
+ are passed through.
+ See the
+ <ulink url="&url.zeerex.explain;">ZeeReX Explain</ulink>
+ standard pages
+ for more information on the correct explain syntax.
+ </para>
+ <warning>
+ <para>
+ This filter is not yet completed.
+ </para>
+ </warning>
+ </section>
+
+
</section>
</listitem>
</varlistentry>
<varlistentry>
- <term><literal>frontend_sru</literal> (source)</term>
- <listitem>
- <para>
- Receive SRU (and perhaps SRW) requests.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>sru2z3950</literal> (filter)</term>
- <listitem>
- <para>
- Translate SRU requests into Z39.50 requests.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
<term><literal>sru_client</literal> (sink)</term>
<listitem>
<para>
- SRU searching and retrieval.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>srw_client</literal> (sink)</term>
- <listitem>
- <para>
- SRW searching and retrieval.
+ SRU/GET and SRU/SOAP searching and retrieval.
</para>
</listitem>
</varlistentry>
<para>
If Metaproxy is an interpreter providing operations on packages, then
its configuration file can be thought of as a program for that
- interpreter. Configuration is by means of a single file, the name
+ interpreter. Configuration is by means of a single XML file, the name
of which is supplied as the sole command-line argument to the
<command>metaproxy</command> program. (See
- <link linkend="progref">the reference guide</link>
- below for more information on invoking Metaproxy.)
- </para>
- <para>
- The configuration files are written in XML. (But that's just an
- implementation detail - they could just as well have been written
- in YAML or Lisp-like S-expressions, or in a custom syntax.)
+ <xref linkend="reference"/> below for more information on invoking
+ Metaproxy.)
</para>
</section>
<title>Overview of the config file XML structure</title>
<para>
All elements and attributes are in the namespace
- <ulink url="http://indexdata.dk/yp2/config/1"/>.
+ <ulink url="http://indexdata.com/metaproxy"/>.
This is most easily achieved by setting the default namespace on
the top-level element, as here:
</para>
<screen>
- <yp2 xmlns="http://indexdata.dk/yp2/config/1">
+ <metaproxy xmlns="http://indexdata.com/metaproxy" version="1.0">
</screen>
<para>
- The top-level element is <yp2>. This contains a
+ The top-level element is <metaproxy>. This contains a
<start> element, a <filters> element and a
<routes> element, in that order. <filters> is
optional; the other two are mandatory. All three are
and contain various elements that provide suitable configuration
for a filter of its type. The filter-specific elements are
described in
- <link linkend="filterref">the reference guide below</link>.
+ <xref linkend="reference"/>.
Filters defined in this part of the file must carry an
<literal>id</literal> attribute so that they can be referenced
from elsewhere.
client-server dialogues.
</para>
<screen><![CDATA[<?xml version="1.0"?>
-<yp2 xmlns="http://indexdata.dk/yp2/config/1">
+<metaproxy xmlns="http://indexdata.com/metaproxy" version="1.0">
<start route="start"/>
<filters>
<filter id="frontend" type="frontend_net">
<filter type="bounce"/>
</route>
</routes>
-</yp2>
+</metaproxy>
]]></screen>
<para>
It works by defining a single route, called
<literal>z3950_client</literal> filter, with the response data
filled by the external Z39.50 server targeted.
All non-Z39.50 packages are passed through to the
- <literal>bounce</literal> filter, which defitely bounces
+ <literal>bounce</literal> filter, which definitely bounces
everything, including fish, bananas, cold pyjamas,
mutton, beef and trout packages.
When the response arrives, it is handed
<para>
The distribution contains RelaxNG Compact and XML syntax checking
files, as well as XML Schema files. These are found in the
- distribution pathes
+ distribution paths
<screen>
xml/schema/metaproxy.rnc
xml/schema/metaproxy.rng
The interaction between
these two filters is necessarily complex: it reflects the real,
irreducible complexity of multi-database searching in a protocol such
- as Z39.50 that separates initialisation from searching, and in
- which the database to be searched is not known at initialisation
+ as Z39.50 that separates initialization from searching, and in
+ which the database to be searched is not known at initialization
time.
</para>
<para>
It's possible to use these filters without understanding the
details of their functioning and the interaction between them; the
- next two sections of this chapter are ``HOWTO'' guides for doing
+ next two sections of this chapter are ``HOW-TO'' guides for doing
just that. However, debugging complex configurations will require
a deeper understanding, which the last two sections of this
chapters attempt to provide.
</virtual>
<virtual>
<database>marc</database>
- <target>indexdata.dk/marc</target>
+ <target>indexdata.com/marc</target>
</virtual>
</filter>]]></screen>
<para>
Index Data's tiny testing database of MARC records:
</para>
<screen><![CDATA[<?xml version="1.0"?>
-<yp2 xmlns="http://indexdata.dk/yp2/config/1">
+<metaproxy xmlns="http://indexdata.com/metaproxy" version="1.0">
<start route="start"/>
<routes>
<route id="start">
</virtual>
<virtual>
<database>marc</database>
- <target>indexdata.dk/marc</target>
+ <target>indexdata.com/marc</target>
</virtual>
<virtual>
<database>all</database>
<target>z3950.loc.gov:7090/voyager</target>
- <target>indexdata.dk/marc</target>
+ <target>indexdata.com/marc</target>
</virtual>
</filter>
<filter type="multi"/>
<filter type="bounce"/>
</route>
</routes>
-</yp2>]]></screen>
+</metaproxy>]]></screen>
<para>
(Using a
<literal>virt_db</literal>
can be inconvenient in deployment, when users typically don't want
to be bothered with problems of this kind and prefer just to get
the records from the databases that are available. To obtain this
- latter behaviour add an empty
+ latter behavior add an empty
<literal><hideunavailable></literal>
element inside the
<literal>multi</literal> filter:
[Here there should be a diagram showing the progress of
packages through the filters during a simple virtual-database
search and a multi-database search, but is seems that your
- toolchain has not been able to include the diagram in this
- document. This is because of LaTeX suckage. Time to move to
- OpenOffice. Yes, really.]
+ tool chain has not been able to include the diagram in this
+ document.]
</phrase>
</textobject>
<!-- ### This used to work with an older version of DocBook
<para>
<emphasis>Stop! Do not read this!</emphasis>
You won't enjoy it at all. You should just skip ahead to
- <link linkend="refguide">the reference guide</link>,
+ <xref linkend="reference"/>,
which tells
<!-- The remainder of this paragraph is lifted verbatim from
Douglas Adams' _Hitch Hiker's Guide to the Galaxy_, chapter 8 -->
<para>
This chapter contains documentation of the Metaproxy source code, and is
of interest only to maintainers and developers. If you need to
- change Metaproxy's behaviour or write a new filter, then you will most
+ change Metaproxy's behavior or write a new filter, then you will most
likely find this chapter helpful. Otherwise it's a waste of your
good time. Seriously: go and watch a film or something.
<citetitle>This is Spinal Tap</citetitle> is particularly good.
that part of the configuration file that pertains to this filter
instance, and is expected to walk that tree extracting relevant
information. And <literal>process()</literal> processes a
- package (see below). That surface simplicitly is a bit
+ package (see below). That surface simplicity is a bit
misleading, as <literal>process()</literal> needs to know a lot
about the <literal>Package</literal> class in order to do
anything useful.
<filename>filter_*.cpp</filename> respectively. All the header
files should be pretty much identical, in that they declare the
class, including a private <literal>Rep</literal> class and a
- member pointer to it, and the two public methods. The only extra
- information in any filter header is additional private types and
- members (which should really all be in the <literal>Rep</literal>
- anyway) and private methods (which should also remain known only
- to the source file, but C++'s brain-damaged design requires this
- dirty laundry to be exhibited in public. Thanks, Bjarne!)
+ member pointer to it, and the two public methods.
</para>
<para>
The source file for each filter needs to supply:
</chapter>
-
- <reference id="refguide">
- <title>Reference guide</title>
+ <reference id="reference">
+ <title>Reference</title>
+ <partintro>
<para>
The material in this chapter is drawn directly from the individual
manual entries. In particular, the Metaproxy invocation section is
on each individual filter is available using the name of the filter
as the argument to the <command>man</command> command.
</para>
- &manref;
+ </partintro>
+ &manref;
</reference>
</book>
projects / metaproxy-moved-to-github.git / blobdiff