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15 <title>Pazpar2 - User's Guide and Reference</title>
17 <firstname>Sebastian</firstname><surname>Hammer</surname>
20 <firstname>Adam</firstname><surname>Dickmeiss</surname>
23 <firstname>Marc</firstname><surname>Cromme</surname>
25 <releaseinfo>&version;</releaseinfo>
27 <year>©right-year;</year>
28 <holder>Index Data</holder>
32 Pazpar2 is a high-performance, user interface-independent, data
33 model-independent metasearching
34 middle-ware featuring merging, relevance ranking, record sorting,
38 This document is a guide and reference to Pazpar2 version &version;.
43 <imagedata fileref="common/id.png" format="PNG"/>
46 <imagedata fileref="common/id.eps" format="EPS"/>
53 <chapter id="introduction">
54 <title>Introduction</title>
56 Pazpar2 is a stand-alone metasearch client with a web-service API, designed
57 to be used either from a browser-based client (JavaScript, Flash, Java,
58 etc.), from server-side code, or any combination of the two.
59 Pazpar2 is a highly optimized client designed to
60 search many resources in parallel. It implements record merging,
61 relevance-ranking and sorting by arbitrary data content, and facet
62 analysis for browsing purposes. It is designed to be data model
63 independent, and is capable of working with MARC, DublinCore, or any
64 other <ulink url="&url.xml;">XML</ulink>-structured response format
65 -- <ulink url="&url.xslt;">XSLT</ulink> is used to normalize and extract
66 data from retrieval records for display and analysis. It can be used
67 against any server which supports the
68 <ulink url="&url.z39.50;">Z39.50</ulink> protocol. Proprietary
69 backend modules can be used to support a large number of other protocols
70 (please contact Index Data for further information about this).
73 Additional functionality such as
74 user management, attractive displays are expected to be implemented by
75 applications that use Pazpar2. Pazpar2 is user interface independent.
76 Its functionality is exposed through a simple REST-style web-service API,
77 designed to be simple to use from an Ajax-enabled browser, Flash
78 animation, Java applet, etc., or from a higher-level server-side language
79 like PHP or Java. Because session information can be shared between
80 browser-based logic and your server-side scripting, there is tremendous
81 flexibility in how you implement your business logic on top of Pazpar2.
84 Once you launch a search in Pazpar2, the operation continues behind the
85 scenes. Pazpar2 connects to servers, carries out searches, and
86 retrieves, deduplicates, and stores results internally. Your application
87 code may periodically inquire about the status of an ongoing operation,
88 and ask to see records or other result set facets. Result become
89 available immediately, and it is easy to build end-user interfaces which
90 feel extremely responsive, even when searching more than 100 servers
94 Pazpar2 is designed to be highly configurable. Incoming records are
95 normalized to XML/UTF-8, and then further normalized using XSLT to a
96 simple internal representation that is suitable for analysis. By
97 providing XSLT stylesheets for different kinds of result records, you
98 can tune Pazpar2 to work against different kinds of information
99 retrieval servers. Finally, metadata is extracted, in a configurable
100 way, from this internal record, to support display, merging, ranking,
101 result set facets, and sorting. Pazpar2 is not bound to a specific model
102 of metadata, such as DublinCore or MARC -- by providing the right
103 configuration, it can work with a number of different kinds of data in
104 support of many different applications.
107 Pazpar2 is designed to be efficient and scalable. You can set it up to
108 search several hundred targets in parallel, or you can use it to support
109 hundreds of concurrent users. It is implemented with the same attention
110 to performance and economy that we use in our indexing engines, so that
111 you can focus on building your application, without worrying about the
112 details of metasearch logic. You can devote all of your attention to
113 usability and let Pazpar2 do what it does best -- metasearch.
116 If you wish to connect to commercial or other databases which do not
117 support open standards, please contact Index Data. We have a licensing
118 agreement with a third party vendor which will enable Pazpar2 to access
119 thousands of online databases, in addition the vast number of catalogs
120 and online services that support the Z39.50 protocol.
123 Pazpar2 is our attempt to re-think the traditional paradigms for
124 implementing and deploying metasearch logic, with an uncompromising
125 approach to performance, and attempting to make maximum use of the
126 capabilities of modern browsers. The demo user interface that
127 accompanies the distribution is but one example. If you think of new
128 ways of using Pazpar2, we hope you'll share them with us, and if we
129 can provide assistance with regards to training, design, programming,
130 integration with different backends, hosting, or support, please don't
131 hesitate to contact us. If you'd like to see functionality in Pazpar2
132 that is not there today, please don't hesitate to contact us. It may
133 already be in our development pipeline, or there might be a
134 possibility for you to help out by sponsoring development time or
135 code. Either way, get in touch and we will give you straight answers.
141 Pazpar2 is covered by the GNU license version 2.
142 See <xref linkend="license"/> for further information.
146 <chapter id="installation">
147 <title>Installation</title>
149 The Pazpar2 package very small. It includes documentation as well
150 as the Pazpar2 server. The package also includes a simple user
151 interface test1 which consists of a single HTML page and a single
152 JavaScript file to illustrate the use of Pazpar2.
155 Pazpar2 depends on the following tools/libraries:
157 <varlistentry><term><ulink url="&url.yaz;">YAZ</ulink></term>
160 The popular Z39.50 toolkit for the C language.
161 YAZ <emphasis>must</emphasis> be compiled with Libxml2/Libxslt support.
165 <varlistentry><term><ulink url="&url.icu;">International
166 Components for Unicode (ICU)</ulink></term>
169 ICU provides Unicode support for non-English languages with
170 character sets outside the range of 7bit ASCII, like
171 Greek, Russian, German and French. Pazpar2 uses the ICU
172 Unicode character conversions, Unicode normalization, case
173 folding and other fundamental operations needed in
174 tokenization, normalization and ranking of records.
177 Compiling, linking, and usage of the ICU libraries is optional,
178 but strongly recommended for usage in an international
186 In order to compile Pazpar2, a C compiler which supports C99 or later
190 <section id="installation.unix">
191 <title>Installation on Unix (from Source)</title>
193 The latest source code for Pazpar2 is available from
194 <ulink url="&url.pazpar2.download;"/>.
195 Only few systems have none of the required
196 tools binary packages.
197 If, for example, Libxml2/libXSLT libraries
198 are already installed as development packages use these.
202 Ensure that the development libraries + header files are
203 available on your system before compiling Pazpar2. For installation
204 of YAZ, refer to the YAZ installation chapter.
207 gunzip -c pazpar2-version.tar.gz|tar xf -
215 The <literal>make install</literal> will install manpages as well as the
216 Pazpar2 server, <literal>pazpar2</literal>,
217 in PREFIX<literal>/sbin</literal>.
218 By default, PREFIX is <literal>/usr/local/</literal> . This can be
219 changed with configure option <option>--prefix</option>.
223 <section id="installation.test1">
224 <title>Installation of test1 interface</title>
226 In this section we outline how to install a simple interface that
227 is part of the Pazpar2 source package. Note that Debian users can
228 save time by just installing package <literal>pazpar2-test1</literal>.
231 A web server must be installed and running on the system, such as Apache.
235 Start the Pazpar2 daemon using the 'in-source' binary of the Pazpar2
239 cp pazpar2.cfg.dist pazpar2.cfg
240 ../src/pazpar2 -f pazpar2.cfg -t edu.xml
242 This will start a Pazpar2 listener on port 8004. It will proxy
243 HTTP requests to localhost - port 80, which we assume will be the regular
244 HTTP server on the system. Inspect and modify pazpar2.cfg as needed
245 if this is to be changed. The -t option specifies the list of targets
249 Make a new console and move to the other stuff.
250 For more information about pazpar2 options refer to the manpage.
254 The test1 UI is located in <literal>www/test1</literal>. Ensure this
255 directory is available to the web server by either copying
256 <literal>test1</literal> to the document root, create a symlink or
257 use Apache's <literal>Alias</literal> directive.
261 The interface test1 interface should now be available on port 8004.
264 If you don't see the test1 interface. See if test1 is really available
265 on the same URL but on port 80. If it's not, the Apache configuration
266 (or other) is not correct.
269 In order to use Apache as frontend for the interface on port 80
270 for public access etc., refer to
271 <xref linkend="installation.apache2proxy"/>.
275 <section id="installation.debian">
276 <title>Installation on Debian GNU/Linux</title>
278 Index Data provides Debian packages for Pazpar2. These are prepared
279 for Debian versions Etch and Lenny (as of 2007).
280 These packages are available at
281 <ulink url="&url.pazpar2.download.debian;"/>.
285 <section id="installation.apache2proxy">
286 <title>Apache 2 Proxy</title>
289 <ulink url="http://httpd.apache.org/docs/2.2/mod/mod_proxy.html">
291 </ulink> which allows Pazpar2 to become a backend to an Apache 2
292 based web service. The Apache 2 proxy must operate in the
293 <emphasis>Reverse</emphasis> Proxy mode.
297 On a Debian based Apache 2 system, the relevant modules can
300 sudo a2enmod proxy_http
305 Traditionally Pazpar2 interprets URL paths with suffix
306 <literal>/search.pz2</literal>.
309 url="http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass"
310 >ProxyPass</ulink> directive of Apache must be used to map a URL path
311 the the Pazpar2 server (listening port).
316 The ProxyPass directive takes a prefix rather than
317 a suffix as URL path. It is important that the Java Script code
318 uses the prefix given for it.
322 <example id="installation.apache2proxy.example">
323 <title>Apache 2 proxy configuration</title>
325 If Pazpar2 is running on port 8004 and the portal is using
326 <filename>search.pz2</filename> inside portal in directory
327 <filename>/myportal/</filename> we could use the following
328 Apache 2 configuration:
331 <IfModule mod_proxy.c>
335 AddDefaultCharset off
340 ProxyPass /myportal/search.pz2 http://localhost:8004/search.pz2
351 <title>Using Pazpar2</title>
353 This chapter provides a general introduction to the use and
354 deployment of Pazpar2.
357 <section id="architecture">
358 <title>Pazpar2 and your systems architecture</title>
360 Pazpar2 is designed to provide asynchronous, behind-the-scenes
361 metasearching functionality to your application, exposing this
362 functionality using a simple webservice API that can be accessed
363 from any number of development environments. In particular, it is
364 possible to combine Pazpar2 either with your server-side dynamic
365 website scripting, with scripting or code running in the browser, or
366 with any combination of the two. Pazpar2 is an excellent tool for
367 building advanced, Ajax-based user interfaces for metasearch
368 functionality, but it isn't a requirement -- you can choose to use
369 Pazpar2 entirely as a backend to your regular server-side scripting.
370 When you do use Pazpar2 in conjunction
371 with browser scripting (JavaScript/Ajax, Flash, applets,
372 etc.), there are special considerations.
376 Pazpar2 implements a simple but efficient HTTP server, and it is
377 designed to interact directly with scripting running in the browser
378 for the best possible performance, and to limit overhead when
379 several browser clients generate numerous webservice requests.
380 However, it is still desirable to use a conventional webserver,
381 such as Apache, to serve up graphics, HTML documents, and
382 server-side scripting. Because the security sandbox environment of
383 most browser-side programming environments only allows communication
384 with the server from which the enclosing HTML page or object
385 originated, Pazpar2 is designed so that it can act as a transparent
386 proxy in front of an existing webserver (see <xref
387 linkend="pazpar2_conf"/> for details).
388 In this mode, all regular
389 HTTP requests are transparently passed through to your webserver,
390 while Pazpar2 only intercepts search-related webservice requests.
394 If you want to expose your combined service on port 80, you can
395 either run your regular webserver on a different port, a different
396 server, or a different IP address associated with the same server.
400 Pazpar2 can also work behind
401 a reverse Proxy. Refer to <xref linkend="installation.apache2proxy"/>)
402 for more information.
403 This allows your existing HTTP server to operate on port 80 as usual.
404 Pazpar2 can be started on another (internal) port.
408 Sometimes, it may be necessary to implement functionality on your
409 regular webserver that makes use of search results, for example to
410 implement data import functionality, emailing results, history
411 lists, personal citation lists, interlibrary loan functionality
412 ,etc. Fortunately, it is simple to exchange information between
413 Pazpar2, your browser scripting, and backend server-side scripting.
414 You can send a session ID and possibly a record ID from your browser
415 code to your server code, and from there use Pazpar2s webservice API
416 to access result sets or individual records. You could even 'hide'
417 all of Pazpar2s functionality between your own API implemented on
418 the server-side, and access that from the browser or elsewhere. The
419 possibilities are just about endless.
423 <section id="data_model">
424 <title>Your data model</title>
426 Pazpar2 does not have a preconceived model of what makes up a data
427 model. There are no assumption that records have specific fields or
428 that they are organized in any particular way. The only assumption
429 is that data comes packaged in a form that the software can work
430 with (presently, that means XML or MARC), and that you can provide
431 the necessary information to massage it into Pazpar2's internal
436 Handling retrieval records in Pazpar2 is a two-step process. First,
437 you decide which data elements of the source record you are
438 interested in, and you specify any desired massaging or combining of
439 elements using an XSLT stylesheet (MARC records are automatically
440 normalized to <ulink url="&url.marcxml;">MARCXML</ulink> before this step).
441 If desired, you can run multiple XSLT stylesheets in series to accomplish
442 this, but the output of the last one should be a representation of the
443 record in a schema that Pazpar2 understands.
447 The intermediate, internal representation of the record looks like
450 <record xmlns="http://www.indexdata.com/pazpar2/1.0"
451 mergekey="title The Shining author King, Stephen">
453 <metadata type="title">The Shining</metadata>
455 <metadata type="author">King, Stephen</metadata>
457 <metadata type="kind">ebook</metadata>
459 <!-- ... and so on -->
463 As you can see, there isn't much to it. There are really only a few
464 important elements to this file.
468 Elements should belong to the namespace
469 <literal>http://www.indexdata.com/pazpar2/1.0</literal>.
470 If the root node contains the
471 attribute 'mergekey', then every record that generates the same
472 merge key (normalized for case differences, white space, and
473 truncation) will be joined into a cluster. In other words, you
474 decide how records are merged. If you don't include a merge key,
475 records are never merged. The 'metadata' elements provide the meat
476 of the elements -- the content. the 'type' attribute is used to
477 match each element against processing rules that determine what
478 happens to the data element next.
482 The next processing step is the extraction of metadata from the
483 intermediate representation of the record. This is governed by the
484 'metadata' elements in the 'service' section of the configuration
485 file. See <xref linkend="config-server"/> for details. The metadata
486 in the retrieval record ultimately drives merging, sorting, ranking,
487 the extraction of browse facets, and display, all configurable.
491 <section id="client">
492 <title>Client development overview</title>
494 You can use Pazpar2 from any environment that allows you to use
495 webservices. The initial goal of the software was to support
496 Ajax-based applications, but there literally are no limits to what
497 you can do. You can use Pazpar2 from Javascript, Flash, Java, etc.,
498 on the browser side, and from any development environment on the
499 server side, and you can pass session tokens and record IDs freely
500 around between these environments to build sophisticated applications.
501 Use your imagination.
505 The webservice API of Pazpar2 is described in detail in <xref
506 linkend="pazpar2_protocol"/>.
510 In brief, you use the 'init' command to create a session, a
511 temporary workspace which carries information about the current
512 search. You start a new search using the 'search' command. Once the
513 search has been started, you can follow its progress using the
514 'stat', 'bytarget', 'termlist', or 'show' commands. Detailed records
515 can be fetched using the 'record' command.
519 <section id="nonstandard">
520 <title>Connecting to non-standard resources</title>
522 Pazpar2 uses Z39.50 as its switchboard language -- i.e. as far as it
523 is concerned, all resources speak Z39.50. It is, however, equipped
524 to handle a broad range of different server behavior, through
525 configurable query mapping and record normalization. If you develop
526 configuration, stylesheets, etc., for a new type of resources, we
527 encourage you to share your work. But you can also use Pazpar2 to
528 connect to hundreds of resources that do not support standard
533 For a growing number of resources, Z39.50 is all you need. Over the
534 last few years, a number of commercial, full-text resources have
535 implemented Z39.50. These can be used through Pazpar2 with little or
536 no effort. Resources that use non-standard record formats will
537 require a bit of XSLT work, but that's all.
541 But what about resources that don't support Z39.50 at all? The NISO
542 SRU (MXG) protocol is slowly gathering steam. Other resources might
543 support OpenSearch, private, XML/HTTP-based protocols, or something
544 else entirely. Some databases exist only as web user interfaces and
545 will require screen-scraping. Still others exist only as static
546 files, or perhaps as databases supporting the OAI-PMH protocol.
547 There is hope! Read on.
551 Index Data continues to advocate the support of open standards. We
552 work with database vendors to support standards, so you don't have
553 to worry about programming against non-standard services. We also
554 provide tools (see <ulink
555 url="http://www.indexdata.com/simpleserver">SimpleServer</ulink>)
556 which make it comparatively easy to build gateways against servers
557 with non-standard behavior. Again, we encourage you to share any
558 work you do in this direction.
562 But the bottom line is that working with non-standard resources in
563 metasearching is really, really hard. If you want to build a
564 project with Pazpar2, and you need access to resources with
565 non-standard interfaces, we can help. We run gateways to more than
566 2,000 popular, commercial databases and other resources,
568 to plug them directly into Pazpar2. For a small annual fee per
569 database, we can help you establish connections to your licensed
570 resources. Meanwhile, you can help! If you build your own
571 standards-compliant gateways, host them for others, or share the
572 code! And tell your vendors that they can save everybody money and
573 increase the appeal of their resources by supporting standards.
577 There are those who will ask us why we are using Z39.50 as our
578 switchboard language rather than a different protocol. Basically,
579 we believe that Z39.50 is presently the most widely implemented
580 information retrieval protocol that has the level of functionality
581 required to support a good metasearching experience (structured
582 searching, structured, well-defined results). It is also compact and
583 efficient, and there is a very broad range of tools available to
588 <section id="unicode">
589 <title>Unicode Compliance</title>
591 Pazpar2 is Unicode compliant and language and locale aware but relies
592 on character encoding for the targets to be specified correctly if
593 the targets themselves are not UTF-8 based (most aren't).
594 Just a few bad behaving targets can spoil the search experience
595 considerably if for example Greek, Russian or otherwise non 7-bit ASCII
596 search terms are entered. In these cases some targets return
597 records irrelevant to the query, and the result screens will be
598 cluttered with noise.
601 While noise from misbehaving targets can not be removed, it can
602 be reduced using truly Unicode based ranking. This is an
603 option which is available to the system administrator if ICU
604 support is compiled into Pazpar2, see
605 <xref linkend="installation"/> for details.
608 In addition, the ICU tokenization and normalization rules must
609 be defined in the master configuration file described in
610 <xref linkend="config-server"/>.
614 </chapter> <!-- Using Pazpar2 -->
616 <reference id="reference">
617 <title>Reference</title>
618 <partintro id="reference-introduction">
620 The material in this chapter is drawn directly from the individual
627 <appendix id="license"><title>License</title>
629 <section id="gpl"><title>GPL</title>
633 Copyright © ©right-year; Index Data.
637 Pazpar2 is free software; you can redistribute it and/or modify it under
638 the terms of the GNU General Public License as published by the Free
639 Software Foundation; either version 2, or (at your option) any later
644 Pazpar2 is distributed in the hope that it will be useful, but WITHOUT ANY
645 WARRANTY; without even the implied warranty of MERCHANTABILITY or
646 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
651 You should have received a copy of the GNU General Public License
652 along with Pazpar2; see the file LICENSE. If not, write to the
653 Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
658 GNU GENERAL PUBLIC LICENSE
661 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
662 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
663 Everyone is permitted to copy and distribute verbatim copies
664 of this license document, but changing it is not allowed.
668 The licenses for most software are designed to take away your
669 freedom to share and change it. By contrast, the GNU General Public
670 License is intended to guarantee your freedom to share and change free
671 software--to make sure the software is free for all its users. This
672 General Public License applies to most of the Free Software
673 Foundation's software and to any other program whose authors commit to
674 using it. (Some other Free Software Foundation software is covered by
675 the GNU Library General Public License instead.) You can apply it to
678 When we speak of free software, we are referring to freedom, not
679 price. Our General Public Licenses are designed to make sure that you
680 have the freedom to distribute copies of free software (and charge for
681 this service if you wish), that you receive source code or can get it
682 if you want it, that you can change the software or use pieces of it
683 in new free programs; and that you know you can do these things.
685 To protect your rights, we need to make restrictions that forbid
686 anyone to deny you these rights or to ask you to surrender the rights.
687 These restrictions translate to certain responsibilities for you if you
688 distribute copies of the software, or if you modify it.
690 For example, if you distribute copies of such a program, whether
691 gratis or for a fee, you must give the recipients all the rights that
692 you have. You must make sure that they, too, receive or can get the
693 source code. And you must show them these terms so they know their
696 We protect your rights with two steps: (1) copyright the software, and
697 (2) offer you this license which gives you legal permission to copy,
698 distribute and/or modify the software.
700 Also, for each author's protection and ours, we want to make certain
701 that everyone understands that there is no warranty for this free
702 software. If the software is modified by someone else and passed on, we
703 want its recipients to know that what they have is not the original, so
704 that any problems introduced by others will not reflect on the original
705 authors' reputations.
707 Finally, any free program is threatened constantly by software
708 patents. We wish to avoid the danger that redistributors of a free
709 program will individually obtain patent licenses, in effect making the
710 program proprietary. To prevent this, we have made it clear that any
711 patent must be licensed for everyone's free use or not licensed at all.
713 The precise terms and conditions for copying, distribution and
716 GNU GENERAL PUBLIC LICENSE
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769 the Program is not required to print an announcement.)
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776 distribute the same sections as part of a whole which is a work based
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813 making modifications to it. For an executable work, complete source
814 code means all the source code for all modules it contains, plus any
815 associated interface definition files, plus the scripts used to
816 control compilation and installation of the executable. However, as a
817 special exception, the source code distributed need not include
818 anything that is normally distributed (in either source or binary
819 form) with the major components (compiler, kernel, and so on) of the
820 operating system on which the executable runs, unless that component
821 itself accompanies the executable.
823 If distribution of executable or object code is made by offering
824 access to copy from a designated place, then offering equivalent
825 access to copy the source code from the same place counts as
826 distribution of the source code, even though third parties are not
827 compelled to copy the source along with the object code.
829 4. You may not copy, modify, sublicense, or distribute the Program
830 except as expressly provided under this License. Any attempt
831 otherwise to copy, modify, sublicense or distribute the Program is
832 void, and will automatically terminate your rights under this License.
833 However, parties who have received copies, or rights, from you under
834 this License will not have their licenses terminated so long as such
835 parties remain in full compliance.
837 5. You are not required to accept this License, since you have not
838 signed it. However, nothing else grants you permission to modify or
839 distribute the Program or its derivative works. These actions are
840 prohibited by law if you do not accept this License. Therefore, by
841 modifying or distributing the Program (or any work based on the
842 Program), you indicate your acceptance of this License to do so, and
843 all its terms and conditions for copying, distributing or modifying
844 the Program or works based on it.
846 6. Each time you redistribute the Program (or any work based on the
847 Program), the recipient automatically receives a license from the
848 original licensor to copy, distribute or modify the Program subject to
849 these terms and conditions. You may not impose any further
850 restrictions on the recipients' exercise of the rights granted herein.
851 You are not responsible for enforcing compliance by third parties to
854 7. If, as a consequence of a court judgment or allegation of patent
855 infringement or for any other reason (not limited to patent issues),
856 conditions are imposed on you (whether by court order, agreement or
857 otherwise) that contradict the conditions of this License, they do not
858 excuse you from the conditions of this License. If you cannot
859 distribute so as to satisfy simultaneously your obligations under this
860 License and any other pertinent obligations, then as a consequence you
861 may not distribute the Program at all. For example, if a patent
862 license would not permit royalty-free redistribution of the Program by
863 all those who receive copies directly or indirectly through you, then
864 the only way you could satisfy both it and this License would be to
865 refrain entirely from distribution of the Program.
867 If any portion of this section is held invalid or unenforceable under
868 any particular circumstance, the balance of the section is intended to
869 apply and the section as a whole is intended to apply in other
872 It is not the purpose of this section to induce you to infringe any
873 patents or other property right claims or to contest validity of any
874 such claims; this section has the sole purpose of protecting the
875 integrity of the free software distribution system, which is
876 implemented by public license practices. Many people have made
877 generous contributions to the wide range of software distributed
878 through that system in reliance on consistent application of that
879 system; it is up to the author/donor to decide if he or she is willing
880 to distribute software through any other system and a licensee cannot
883 This section is intended to make thoroughly clear what is believed to
884 be a consequence of the rest of this License.
886 8. If the distribution and/or use of the Program is restricted in
887 certain countries either by patents or by copyrighted interfaces, the
888 original copyright holder who places the Program under this License
889 may add an explicit geographical distribution limitation excluding
890 those countries, so that distribution is permitted only in or among
891 countries not thus excluded. In such case, this License incorporates
892 the limitation as if written in the body of this License.
894 9. The Free Software Foundation may publish revised and/or new versions
895 of the General Public License from time to time. Such new versions will
896 be similar in spirit to the present version, but may differ in detail to
897 address new problems or concerns.
899 Each version is given a distinguishing version number. If the Program
900 specifies a version number of this License which applies to it and "any
901 later version", you have the option of following the terms and conditions
902 either of that version or of any later version published by the Free
903 Software Foundation. If the Program does not specify a version number of
904 this License, you may choose any version ever published by the Free Software
907 10. If you wish to incorporate parts of the Program into other free
908 programs whose distribution conditions are different, write to the author
909 to ask for permission. For software which is copyrighted by the Free
910 Software Foundation, write to the Free Software Foundation; we sometimes
911 make exceptions for this. Our decision will be guided by the two goals
912 of preserving the free status of all derivatives of our free software and
913 of promoting the sharing and reuse of software generally.
917 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
918 FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
919 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
920 PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
921 OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
922 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
923 TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
924 PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
925 REPAIR OR CORRECTION.
927 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
928 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
929 REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
930 INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
931 OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
932 TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
933 YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
934 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
935 POSSIBILITY OF SUCH DAMAGES.
937 END OF TERMS AND CONDITIONS
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