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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>
26 <firstname>Jakub</firstname><surname>Skoczen</surname>
28 <releaseinfo>&version;</releaseinfo>
30 <year>©right-year;</year>
31 <holder>Index Data</holder>
35 Pazpar2 is a high-performance, user interface-independent, data
36 model-independent metasearching
37 middle-ware featuring merging, relevance ranking, record sorting,
41 This document is a guide and reference to Pazpar2 version &version;.
46 <imagedata fileref="common/id.png" format="PNG"/>
49 <imagedata fileref="common/id.eps" format="EPS"/>
56 <chapter id="introduction">
57 <title>Introduction</title>
59 Pazpar2 is a stand-alone metasearch client with a web-service API, designed
60 to be used either from a browser-based client (JavaScript, Flash, Java,
61 etc.), from server-side code, or any combination of the two.
62 Pazpar2 is a highly optimized client designed to
63 search many resources in parallel. It implements record merging,
64 relevance-ranking and sorting by arbitrary data content, and facet
65 analysis for browsing purposes. It is designed to be data model
66 independent, and is capable of working with MARC, DublinCore, or any
67 other <ulink url="&url.xml;">XML</ulink>-structured response format
68 -- <ulink url="&url.xslt;">XSLT</ulink> is used to normalize and extract
69 data from retrieval records for display and analysis. It can be used
70 against any server which supports the
71 <ulink url="&url.z39.50;">Z39.50</ulink> protocol. Proprietary
72 backend modules can be used to support a large number of other protocols
73 (please contact Index Data for further information about this).
76 Additional functionality such as
77 user management, attractive displays are expected to be implemented by
78 applications that use Pazpar2. Pazpar2 is user interface independent.
79 Its functionality is exposed through a simple REST-style web-service API,
80 designed to be simple to use from an Ajax-enabled browser, Flash
81 animation, Java applet, etc., or from a higher-level server-side language
82 like PHP or Java. Because session information can be shared between
83 browser-based logic and your server-side scripting, there is tremendous
84 flexibility in how you implement your business logic on top of Pazpar2.
87 Once you launch a search in Pazpar2, the operation continues behind the
88 scenes. Pazpar2 connects to servers, carries out searches, and
89 retrieves, deduplicates, and stores results internally. Your application
90 code may periodically inquire about the status of an ongoing operation,
91 and ask to see records or other result set facets. Result become
92 available immediately, and it is easy to build end-user interfaces which
93 feel extremely responsive, even when searching more than 100 servers
97 Pazpar2 is designed to be highly configurable. Incoming records are
98 normalized to XML/UTF-8, and then further normalized using XSLT to a
99 simple internal representation that is suitable for analysis. By
100 providing XSLT stylesheets for different kinds of result records, you
101 can tune Pazpar2 to work against different kinds of information
102 retrieval servers. Finally, metadata is extracted, in a configurable
103 way, from this internal record, to support display, merging, ranking,
104 result set facets, and sorting. Pazpar2 is not bound to a specific model
105 of metadata, such as DublinCore or MARC -- by providing the right
106 configuration, it can work with a number of different kinds of data in
107 support of many different applications.
110 Pazpar2 is designed to be efficient and scalable. You can set it up to
111 search several hundred targets in parallel, or you can use it to support
112 hundreds of concurrent users. It is implemented with the same attention
113 to performance and economy that we use in our indexing engines, so that
114 you can focus on building your application, without worrying about the
115 details of metasearch logic. You can devote all of your attention to
116 usability and let Pazpar2 do what it does best -- metasearch.
119 If you wish to connect to commercial or other databases which do not
120 support open standards, please contact Index Data. We have a licensing
121 agreement with a third party vendor which will enable Pazpar2 to access
122 thousands of online databases, in addition the vast number of catalogs
123 and online services that support the Z39.50 protocol.
126 Pazpar2 is our attempt to re-think the traditional paradigms for
127 implementing and deploying metasearch logic, with an uncompromising
128 approach to performance, and attempting to make maximum use of the
129 capabilities of modern browsers. The demo user interface that
130 accompanies the distribution is but one example. If you think of new
131 ways of using Pazpar2, we hope you'll share them with us, and if we
132 can provide assistance with regards to training, design, programming,
133 integration with different backends, hosting, or support, please don't
134 hesitate to contact us. If you'd like to see functionality in Pazpar2
135 that is not there today, please don't hesitate to contact us. It may
136 already be in our development pipeline, or there might be a
137 possibility for you to help out by sponsoring development time or
138 code. Either way, get in touch and we will give you straight answers.
144 Pazpar2 is covered by the GNU license version 2.
145 See <xref linkend="license"/> for further information.
149 <chapter id="installation">
150 <title>Installation</title>
152 The Pazpar2 package very small. It includes documentation as well
153 as the Pazpar2 server. The package also includes a simple user
154 interface test1 which consists of a single HTML page and a single
155 JavaScript file to illustrate the use of Pazpar2.
158 Pazpar2 depends on the following tools/libraries:
160 <varlistentry><term><ulink url="&url.yaz;">YAZ</ulink></term>
163 The popular Z39.50 toolkit for the C language.
164 YAZ <emphasis>must</emphasis> be compiled with Libxml2/Libxslt support.
168 <varlistentry><term><ulink url="&url.icu;">International
169 Components for Unicode (ICU)</ulink></term>
172 ICU provides Unicode support for non-English languages with
173 character sets outside the range of 7bit ASCII, like
174 Greek, Russian, German and French. Pazpar2 uses the ICU
175 Unicode character conversions, Unicode normalization, case
176 folding and other fundamental operations needed in
177 tokenization, normalization and ranking of records.
180 Compiling, linking, and usage of the ICU libraries is optional,
181 but strongly recommended for usage in an international
189 In order to compile Pazpar2, a C compiler which supports C99 or later
193 <section id="installation.unix">
194 <title>Installation on Unix (from Source)</title>
196 The latest source code for Pazpar2 is available from
197 <ulink url="&url.pazpar2.download;"/>.
198 Only few systems have none of the required
199 tools binary packages.
200 If, for example, Libxml2/libXSLT libraries
201 are already installed as development packages use these.
205 Ensure that the development libraries + header files are
206 available on your system before compiling Pazpar2. For installation
207 of YAZ, refer to the YAZ installation chapter.
210 gunzip -c pazpar2-version.tar.gz|tar xf -
218 The <literal>make install</literal> will install manpages as well as the
219 Pazpar2 server, <literal>pazpar2</literal>,
220 in PREFIX<literal>/sbin</literal>.
221 By default, PREFIX is <literal>/usr/local/</literal> . This can be
222 changed with configure option <option>--prefix</option>.
226 <section id="installation.test1">
227 <title>Installation of test1 interface</title>
229 In this section we outline how to install a simple interface that
230 is part of the Pazpar2 source package. Note that Debian users can
231 save time by just installing package <literal>pazpar2-test1</literal>.
234 A web server must be installed and running on the system, such as Apache.
238 Start the Pazpar2 daemon using the 'in-source' binary of the Pazpar2
242 cp pazpar2.cfg.dist pazpar2.cfg
243 ../src/pazpar2 -f pazpar2.cfg -t edu.xml
245 This will start a Pazpar2 listener on port 8004. It will proxy
246 HTTP requests to localhost - port 80, which we assume will be the regular
247 HTTP server on the system. Inspect and modify pazpar2.cfg as needed
248 if this is to be changed. The -t option specifies the list of targets
252 Make a new console and move to the other stuff.
253 For more information about pazpar2 options refer to the manpage.
257 The test1 UI is located in <literal>www/test1</literal>. Ensure this
258 directory is available to the web server by either copying
259 <literal>test1</literal> to the document root, create a symlink or
260 use Apache's <literal>Alias</literal> directive.
264 The interface test1 interface should now be available on port 8004.
267 If you don't see the test1 interface. See if test1 is really available
268 on the same URL but on port 80. If it's not, the Apache configuration
269 (or other) is not correct.
272 In order to use Apache as frontend for the interface on port 80
273 for public access etc., refer to
274 <xref linkend="installation.apache2proxy"/>.
278 <section id="installation.debian">
279 <title>Installation on Debian GNU/Linux</title>
281 Index Data provides Debian packages for Pazpar2. These are prepared
282 for Debian versions Etch and Lenny (as of 2007).
283 These packages are available at
284 <ulink url="&url.pazpar2.download.debian;"/>.
288 <section id="installation.apache2proxy">
289 <title>Apache 2 Proxy</title>
292 <ulink url="http://httpd.apache.org/docs/2.2/mod/mod_proxy.html">
294 </ulink> which allows Pazpar2 to become a backend to an Apache 2
295 based web service. The Apache 2 proxy must operate in the
296 <emphasis>Reverse</emphasis> Proxy mode.
300 On a Debian based Apache 2 system, the relevant modules can
303 sudo a2enmod proxy_http
308 Traditionally Pazpar2 interprets URL paths with suffix
309 <literal>/search.pz2</literal>.
312 url="http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass"
313 >ProxyPass</ulink> directive of Apache must be used to map a URL path
314 the the Pazpar2 server (listening port).
319 The ProxyPass directive takes a prefix rather than
320 a suffix as URL path. It is important that the Java Script code
321 uses the prefix given for it.
325 <example id="installation.apache2proxy.example">
326 <title>Apache 2 proxy configuration</title>
328 If Pazpar2 is running on port 8004 and the portal is using
329 <filename>search.pz2</filename> inside portal in directory
330 <filename>/myportal/</filename> we could use the following
331 Apache 2 configuration:
334 <IfModule mod_proxy.c>
338 AddDefaultCharset off
343 ProxyPass /myportal/search.pz2 http://localhost:8004/search.pz2
354 <title>Using Pazpar2</title>
356 This chapter provides a general introduction to the use and
357 deployment of Pazpar2.
360 <section id="architecture">
361 <title>Pazpar2 and your systems architecture</title>
363 Pazpar2 is designed to provide asynchronous, behind-the-scenes
364 metasearching functionality to your application, exposing this
365 functionality using a simple webservice API that can be accessed
366 from any number of development environments. In particular, it is
367 possible to combine Pazpar2 either with your server-side dynamic
368 website scripting, with scripting or code running in the browser, or
369 with any combination of the two. Pazpar2 is an excellent tool for
370 building advanced, Ajax-based user interfaces for metasearch
371 functionality, but it isn't a requirement -- you can choose to use
372 Pazpar2 entirely as a backend to your regular server-side scripting.
373 When you do use Pazpar2 in conjunction
374 with browser scripting (JavaScript/Ajax, Flash, applets,
375 etc.), there are special considerations.
379 Pazpar2 implements a simple but efficient HTTP server, and it is
380 designed to interact directly with scripting running in the browser
381 for the best possible performance, and to limit overhead when
382 several browser clients generate numerous webservice requests.
383 However, it is still desirable to use a conventional webserver,
384 such as Apache, to serve up graphics, HTML documents, and
385 server-side scripting. Because the security sandbox environment of
386 most browser-side programming environments only allows communication
387 with the server from which the enclosing HTML page or object
388 originated, Pazpar2 is designed so that it can act as a transparent
389 proxy in front of an existing webserver (see <xref
390 linkend="pazpar2_conf"/> for details).
391 In this mode, all regular
392 HTTP requests are transparently passed through to your webserver,
393 while Pazpar2 only intercepts search-related webservice requests.
397 If you want to expose your combined service on port 80, you can
398 either run your regular webserver on a different port, a different
399 server, or a different IP address associated with the same server.
403 Pazpar2 can also work behind
404 a reverse Proxy. Refer to <xref linkend="installation.apache2proxy"/>)
405 for more information.
406 This allows your existing HTTP server to operate on port 80 as usual.
407 Pazpar2 can be started on another (internal) port.
411 Sometimes, it may be necessary to implement functionality on your
412 regular webserver that makes use of search results, for example to
413 implement data import functionality, emailing results, history
414 lists, personal citation lists, interlibrary loan functionality
415 ,etc. Fortunately, it is simple to exchange information between
416 Pazpar2, your browser scripting, and backend server-side scripting.
417 You can send a session ID and possibly a record ID from your browser
418 code to your server code, and from there use Pazpar2s webservice API
419 to access result sets or individual records. You could even 'hide'
420 all of Pazpar2s functionality between your own API implemented on
421 the server-side, and access that from the browser or elsewhere. The
422 possibilities are just about endless.
426 <section id="data_model">
427 <title>Your data model</title>
429 Pazpar2 does not have a preconceived model of what makes up a data
430 model. There are no assumption that records have specific fields or
431 that they are organized in any particular way. The only assumption
432 is that data comes packaged in a form that the software can work
433 with (presently, that means XML or MARC), and that you can provide
434 the necessary information to massage it into Pazpar2's internal
439 Handling retrieval records in Pazpar2 is a two-step process. First,
440 you decide which data elements of the source record you are
441 interested in, and you specify any desired massaging or combining of
442 elements using an XSLT stylesheet (MARC records are automatically
443 normalized to <ulink url="&url.marcxml;">MARCXML</ulink> before this step).
444 If desired, you can run multiple XSLT stylesheets in series to accomplish
445 this, but the output of the last one should be a representation of the
446 record in a schema that Pazpar2 understands.
450 The intermediate, internal representation of the record looks like
453 <record xmlns="http://www.indexdata.com/pazpar2/1.0"
454 mergekey="title The Shining author King, Stephen">
456 <metadata type="title">The Shining</metadata>
458 <metadata type="author">King, Stephen</metadata>
460 <metadata type="kind">ebook</metadata>
462 <!-- ... and so on -->
466 As you can see, there isn't much to it. There are really only a few
467 important elements to this file.
471 Elements should belong to the namespace
472 <literal>http://www.indexdata.com/pazpar2/1.0</literal>.
473 If the root node contains the
474 attribute 'mergekey', then every record that generates the same
475 merge key (normalized for case differences, white space, and
476 truncation) will be joined into a cluster. In other words, you
477 decide how records are merged. If you don't include a merge key,
478 records are never merged. The 'metadata' elements provide the meat
479 of the elements -- the content. the 'type' attribute is used to
480 match each element against processing rules that determine what
481 happens to the data element next.
485 The next processing step is the extraction of metadata from the
486 intermediate representation of the record. This is governed by the
487 'metadata' elements in the 'service' section of the configuration
488 file. See <xref linkend="config-server"/> for details. The metadata
489 in the retrieval record ultimately drives merging, sorting, ranking,
490 the extraction of browse facets, and display, all configurable.
494 <section id="client">
495 <title>Client development overview</title>
497 You can use Pazpar2 from any environment that allows you to use
498 webservices. The initial goal of the software was to support
499 Ajax-based applications, but there literally are no limits to what
500 you can do. You can use Pazpar2 from Javascript, Flash, Java, etc.,
501 on the browser side, and from any development environment on the
502 server side, and you can pass session tokens and record IDs freely
503 around between these environments to build sophisticated applications.
504 Use your imagination.
508 The webservice API of Pazpar2 is described in detail in <xref
509 linkend="pazpar2_protocol"/>.
513 In brief, you use the 'init' command to create a session, a
514 temporary workspace which carries information about the current
515 search. You start a new search using the 'search' command. Once the
516 search has been started, you can follow its progress using the
517 'stat', 'bytarget', 'termlist', or 'show' commands. Detailed records
518 can be fetched using the 'record' command.
524 <section id="nonstandard">
525 <title>Connecting to non-standard resources</title>
527 Pazpar2 uses Z39.50 as its switchboard language -- i.e. as far as it
528 is concerned, all resources speak Z39.50. It is, however, equipped
529 to handle a broad range of different server behavior, through
530 configurable query mapping and record normalization. If you develop
531 configuration, stylesheets, etc., for a new type of resources, we
532 encourage you to share your work. But you can also use Pazpar2 to
533 connect to hundreds of resources that do not support standard
538 For a growing number of resources, Z39.50 is all you need. Over the
539 last few years, a number of commercial, full-text resources have
540 implemented Z39.50. These can be used through Pazpar2 with little or
541 no effort. Resources that use non-standard record formats will
542 require a bit of XSLT work, but that's all.
546 But what about resources that don't support Z39.50 at all? The NISO
547 SRU (MXG) protocol is slowly gathering steam. Other resources might
548 support OpenSearch, private, XML/HTTP-based protocols, or something
549 else entirely. Some databases exist only as web user interfaces and
550 will require screen-scraping. Still others exist only as static
551 files, or perhaps as databases supporting the OAI-PMH protocol.
552 There is hope! Read on.
556 Index Data continues to advocate the support of open standards. We
557 work with database vendors to support standards, so you don't have
558 to worry about programming against non-standard services. We also
559 provide tools (see <ulink
560 url="http://www.indexdata.com/simpleserver">SimpleServer</ulink>)
561 which make it comparatively easy to build gateways against servers
562 with non-standard behavior. Again, we encourage you to share any
563 work you do in this direction.
567 But the bottom line is that working with non-standard resources in
568 metasearching is really, really hard. If you want to build a
569 project with Pazpar2, and you need access to resources with
570 non-standard interfaces, we can help. We run gateways to more than
571 2,000 popular, commercial databases and other resources,
573 to plug them directly into Pazpar2. For a small annual fee per
574 database, we can help you establish connections to your licensed
575 resources. Meanwhile, you can help! If you build your own
576 standards-compliant gateways, host them for others, or share the
577 code! And tell your vendors that they can save everybody money and
578 increase the appeal of their resources by supporting standards.
582 There are those who will ask us why we are using Z39.50 as our
583 switchboard language rather than a different protocol. Basically,
584 we believe that Z39.50 is presently the most widely implemented
585 information retrieval protocol that has the level of functionality
586 required to support a good metasearching experience (structured
587 searching, structured, well-defined results). It is also compact and
588 efficient, and there is a very broad range of tools available to
593 <section id="unicode">
594 <title>Unicode Compliance</title>
596 Pazpar2 is Unicode compliant and language and locale aware but relies
597 on character encoding for the targets to be specified correctly if
598 the targets themselves are not UTF-8 based (most aren't).
599 Just a few bad behaving targets can spoil the search experience
600 considerably if for example Greek, Russian or otherwise non 7-bit ASCII
601 search terms are entered. In these cases some targets return
602 records irrelevant to the query, and the result screens will be
603 cluttered with noise.
606 While noise from misbehaving targets can not be removed, it can
607 be reduced using truly Unicode based ranking. This is an
608 option which is available to the system administrator if ICU
609 support is compiled into Pazpar2, see
610 <xref linkend="installation"/> for details.
613 In addition, the ICU tokenization and normalization rules must
614 be defined in the master configuration file described in
615 <xref linkend="config-server"/>.
619 </chapter> <!-- Using Pazpar2 -->
621 <reference id="reference">
622 <title>Reference</title>
623 <partintro id="reference-introduction">
625 The material in this chapter is drawn directly from the individual
632 <appendix id="license"><title>License</title>
634 <section id="gpl"><title>GPL</title>
638 Copyright © ©right-year; Index Data.
642 Pazpar2 is free software; you can redistribute it and/or modify it under
643 the terms of the GNU General Public License as published by the Free
644 Software Foundation; either version 2, or (at your option) any later
649 Pazpar2 is distributed in the hope that it will be useful, but WITHOUT ANY
650 WARRANTY; without even the implied warranty of MERCHANTABILITY or
651 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
656 You should have received a copy of the GNU General Public License
657 along with Pazpar2; see the file LICENSE. If not, write to the
658 Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
663 GNU GENERAL PUBLIC LICENSE
666 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
667 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
668 Everyone is permitted to copy and distribute verbatim copies
669 of this license document, but changing it is not allowed.
673 The licenses for most software are designed to take away your
674 freedom to share and change it. By contrast, the GNU General Public
675 License is intended to guarantee your freedom to share and change free
676 software--to make sure the software is free for all its users. This
677 General Public License applies to most of the Free Software
678 Foundation's software and to any other program whose authors commit to
679 using it. (Some other Free Software Foundation software is covered by
680 the GNU Library General Public License instead.) You can apply it to
683 When we speak of free software, we are referring to freedom, not
684 price. Our General Public Licenses are designed to make sure that you
685 have the freedom to distribute copies of free software (and charge for
686 this service if you wish), that you receive source code or can get it
687 if you want it, that you can change the software or use pieces of it
688 in new free programs; and that you know you can do these things.
690 To protect your rights, we need to make restrictions that forbid
691 anyone to deny you these rights or to ask you to surrender the rights.
692 These restrictions translate to certain responsibilities for you if you
693 distribute copies of the software, or if you modify it.
695 For example, if you distribute copies of such a program, whether
696 gratis or for a fee, you must give the recipients all the rights that
697 you have. You must make sure that they, too, receive or can get the
698 source code. And you must show them these terms so they know their
701 We protect your rights with two steps: (1) copyright the software, and
702 (2) offer you this license which gives you legal permission to copy,
703 distribute and/or modify the software.
705 Also, for each author's protection and ours, we want to make certain
706 that everyone understands that there is no warranty for this free
707 software. If the software is modified by someone else and passed on, we
708 want its recipients to know that what they have is not the original, so
709 that any problems introduced by others will not reflect on the original
710 authors' reputations.
712 Finally, any free program is threatened constantly by software
713 patents. We wish to avoid the danger that redistributors of a free
714 program will individually obtain patent licenses, in effect making the
715 program proprietary. To prevent this, we have made it clear that any
716 patent must be licensed for everyone's free use or not licensed at all.
718 The precise terms and conditions for copying, distribution and
721 GNU GENERAL PUBLIC LICENSE
722 TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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781 distribute the same sections as part of a whole which is a work based
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817 The source code for a work means the preferred form of the work for
818 making modifications to it. For an executable work, complete source
819 code means all the source code for all modules it contains, plus any
820 associated interface definition files, plus the scripts used to
821 control compilation and installation of the executable. However, as a
822 special exception, the source code distributed need not include
823 anything that is normally distributed (in either source or binary
824 form) with the major components (compiler, kernel, and so on) of the
825 operating system on which the executable runs, unless that component
826 itself accompanies the executable.
828 If distribution of executable or object code is made by offering
829 access to copy from a designated place, then offering equivalent
830 access to copy the source code from the same place counts as
831 distribution of the source code, even though third parties are not
832 compelled to copy the source along with the object code.
834 4. You may not copy, modify, sublicense, or distribute the Program
835 except as expressly provided under this License. Any attempt
836 otherwise to copy, modify, sublicense or distribute the Program is
837 void, and will automatically terminate your rights under this License.
838 However, parties who have received copies, or rights, from you under
839 this License will not have their licenses terminated so long as such
840 parties remain in full compliance.
842 5. You are not required to accept this License, since you have not
843 signed it. However, nothing else grants you permission to modify or
844 distribute the Program or its derivative works. These actions are
845 prohibited by law if you do not accept this License. Therefore, by
846 modifying or distributing the Program (or any work based on the
847 Program), you indicate your acceptance of this License to do so, and
848 all its terms and conditions for copying, distributing or modifying
849 the Program or works based on it.
851 6. Each time you redistribute the Program (or any work based on the
852 Program), the recipient automatically receives a license from the
853 original licensor to copy, distribute or modify the Program subject to
854 these terms and conditions. You may not impose any further
855 restrictions on the recipients' exercise of the rights granted herein.
856 You are not responsible for enforcing compliance by third parties to
859 7. If, as a consequence of a court judgment or allegation of patent
860 infringement or for any other reason (not limited to patent issues),
861 conditions are imposed on you (whether by court order, agreement or
862 otherwise) that contradict the conditions of this License, they do not
863 excuse you from the conditions of this License. If you cannot
864 distribute so as to satisfy simultaneously your obligations under this
865 License and any other pertinent obligations, then as a consequence you
866 may not distribute the Program at all. For example, if a patent
867 license would not permit royalty-free redistribution of the Program by
868 all those who receive copies directly or indirectly through you, then
869 the only way you could satisfy both it and this License would be to
870 refrain entirely from distribution of the Program.
872 If any portion of this section is held invalid or unenforceable under
873 any particular circumstance, the balance of the section is intended to
874 apply and the section as a whole is intended to apply in other
877 It is not the purpose of this section to induce you to infringe any
878 patents or other property right claims or to contest validity of any
879 such claims; this section has the sole purpose of protecting the
880 integrity of the free software distribution system, which is
881 implemented by public license practices. Many people have made
882 generous contributions to the wide range of software distributed
883 through that system in reliance on consistent application of that
884 system; it is up to the author/donor to decide if he or she is willing
885 to distribute software through any other system and a licensee cannot
888 This section is intended to make thoroughly clear what is believed to
889 be a consequence of the rest of this License.
891 8. If the distribution and/or use of the Program is restricted in
892 certain countries either by patents or by copyrighted interfaces, the
893 original copyright holder who places the Program under this License
894 may add an explicit geographical distribution limitation excluding
895 those countries, so that distribution is permitted only in or among
896 countries not thus excluded. In such case, this License incorporates
897 the limitation as if written in the body of this License.
899 9. The Free Software Foundation may publish revised and/or new versions
900 of the General Public License from time to time. Such new versions will
901 be similar in spirit to the present version, but may differ in detail to
902 address new problems or concerns.
904 Each version is given a distinguishing version number. If the Program
905 specifies a version number of this License which applies to it and "any
906 later version", you have the option of following the terms and conditions
907 either of that version or of any later version published by the Free
908 Software Foundation. If the Program does not specify a version number of
909 this License, you may choose any version ever published by the Free Software
912 10. If you wish to incorporate parts of the Program into other free
913 programs whose distribution conditions are different, write to the author
914 to ask for permission. For software which is copyrighted by the Free
915 Software Foundation, write to the Free Software Foundation; we sometimes
916 make exceptions for this. Our decision will be guided by the two goals
917 of preserving the free status of all derivatives of our free software and
918 of promoting the sharing and reuse of software generally.
922 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
923 FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
924 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
925 PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
926 OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
927 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
928 TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
929 PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
930 REPAIR OR CORRECTION.
932 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
933 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
934 REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
935 INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
936 OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
937 TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
938 YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
939 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
940 POSSIBILITY OF SUCH DAMAGES.
942 END OF TERMS AND CONDITIONS
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