3 record_transform: allow OPACXML to OPAC conversion
5 zoom: document content-proxy
7 zoom: document db parm content-{user,password}, torus_url. Also
8 <torus auth_url="..> which makes zoom operate in authenticated mode
13 zoom: fix http://-check. SRU search broken in 1.3.51.
17 zoom: only append http:// for SRU if not already given . Makes it
18 possible to use https-URLs.
20 Use yazpp 1.4 or later due to new ABI.
22 frontend_net: allow max package size to be specified. Controlled by
23 attribute 'max_recv_bytes' of element 'port'.
27 For most generated diagnostics by filters, typically temporary
28 system error, augment addinfo message with filter name.
30 Add support for CentOS 6 packages.
32 sru_z3950: interpret Z39.50 diagnostics part of Init Response.
34 Add man page for metaproxy-config.
38 zoom: new config element passthru. This defines an element set that is
39 passed verbatim to the backend in pz2 mode.
41 auth_simple: allow both idPass and open auth. Also fix SEGV that could
46 z3950_client: fix string handling for init diagnostics in the case where
49 query_rewrite: no charset conversion for error queries. Avoid performing
50 charset conversion for query conversion errors. The resulting Type-1
51 query is invalid in this case.
55 For graceful stop (SIGUSR1), metaproxy will kill children processes.
57 Log when metaproxy is invoked in test mode (-t).
59 Log PID for each log message.
61 multi: combine both NSDs and multiple NSDs into one (diagnostics).
63 z3950_client: fixup multiple NSD's too. Like surrogate diagnostics,
64 a (backend=target) is appended for each diagnostic so that can be
65 determined the origin of error.
67 multi: hideerrors also in use for present response.
69 Solr example in zoom man page.
71 Fix typo in query_rewrite config example.
73 Log at least first non surrogate diagnostic. Instead of
74 "Z_Records_multipleNSD"
76 multi: Fix check for opt Records in present response. A SEGV could occur
77 if a target did not return records and no diagnostics.
81 Yet another fix for graceful stop.
85 sru_z3950: relay surrogate diagnostics.
89 zoom: Honor extraArgs, strip # in zurl.
91 multi: fix SEGV for scan. Reported by Rustam T. Usmanov.
93 zoom: url_recipe allow %{var[reg]} substitutions.
94 It's like ${var[reg]} but does URI component encoding as well.
98 RPM/Deb: require yazpp 1.3.2, because it fixes a missing close of
99 non-keepalive HTTP sessions.
101 http_file: allow zero size files (bug fix)
103 Fix zoom schema: auth_url is optional
105 --- 1.3.42 2012/08/20
107 zoom: fix un-init memory (could result in SEGV at session close)
109 frontend_net: handle X-Forwarded-For. This is stored in package.origin()
110 and may be used in filters as usual.
112 zoom: authentication via Torus lookup
113 Enabled by new configuration setting: auth_url . If this is defined,
114 the zoom module will contact Torus for auth/IP lookup and that will
115 define realm to be used in session.
117 --- 1.3.41 2012/08/10
119 virt_db: Fix database name - first character we removed by mistake.
120 Bug introduced in 1.3.40.
122 --- 1.3.40 2012/08/06
124 virt_db: Don't use "unix path" as database for Unix sockets.
126 --- 1.3.39 2012/08/02
128 z3950_client: Don't tamper with / in zurl - fixes problems
129 using Unix sockets for backends.
131 session_shared: fix integer overflow problem with hit count.
133 session_shared: avoid long usage of cached queries.
135 zoom: New database argument , torus_url to set URL of Torus
136 record to be fetched.
138 --- 1.3.38 2012/07/04
140 Fixes for 'metaproxy reload' for RPM/Debian packages.
142 zoom: Allow rpn2cql conversion to be augmented with a properties file.
143 Element rpn2cql can be specified per-target for the zoom filter.
145 log: New category "line" which is a single-line log message with
146 most important parts of a HTTP/Z39.50 request/response.
148 --- 1.3.37 2012/06/01
150 frontend_net: add facility to report live statistics about response
151 times and current thread usage. The report is an XML document
152 and is triggered for a specific URL path. This is set by <stat-req>
153 in the configuration of frontend_net. By default this report is
154 disabled (same as empty value for <stat-req>).
156 Fix reload problem in init.d script for RPM/Debian.
157 The '/etc/init.d/metaproxy reload' in some cases would stop but not
158 start metaproxy - effectively stopping the service.
160 Don't display start log message when config testing (-t).
162 zoom: avoid CCL message limit of 1K in ZOOM filter.
164 --- 1.3.36 2012/05/10
166 metaproxy init script reacts to reload which does graceful stop +
167 start and is used by logrorate script.
169 --- 1.3.35 2012/05/09
171 Fixes for Windows compilation.
173 Metaproxy daemon reacts to SIGUSR1 in which case it will leave
174 existing sessions running but terminate the monitor process that is
175 used in keepalive mode.
177 Change start log message to 'metaproxy start'. Was 'Metaproxy start'
178 before. Consistent with 'metaproxy stop' message.
180 zoom: document zoom's proxy_timeout
182 z3950_client: fixup addinfo for init response
184 virt_db: return other diagnostic if init is rejected. Diagnostic 236:
185 "Access to specified database denied" is returned, but only if init
186 response from backend does not carry diagnostics already.
188 multi: relays user info for first rejected target. The other-information
189 field for init response for first rejected target is in common init
190 response. This ensures that some backend init diagnostics are returned to
193 --- 1.3.34 2012/04/25
195 frontend_log: extend logging (when message is given in config).
197 --- 1.3.33 2012/04/25
199 zoom: Fix check for proxy. Use diagnostic 1074 for proxy failures.
201 --- 1.3.32 2012/04/24
203 sru_z3950 filter passes through incoming Z39.50 requests again. Was
204 not handled by mistake in Metaproxy versions 1.3.29, 1.3.30 and 1.3.31.
206 --- 1.3.31 2012/04/24
208 zoom: fixes for retry/proxy failover logic. More logging.
210 --- 1.3.30 2012/04/23
212 zoom: return addinfo="proxy failure" for proxy failures. This also
213 changes the scheme for dealing with proxies a bit. zoom now always
214 do proxy check, even if there's no failover. Fortunately, that's not
217 zoom: Init rejected wo diagnostics maps to Bib-1:1014.
218 Bib-1 1014, "Init/AC: Authentication System error", seems pretty
219 generic. We don't know why the init would fail; IP, user, block IP, etc.
220 sru_z3950 filter maps this to SRU diagnostic 3: "Authentication error".
222 zoom: guess if invalid SRU response was an auth failure
224 session_shared: disable session retry by default . Can be enabled by
225 restart="true" in resultset section.
227 --- 1.3.29 2012/04/18
229 zoom: may read cf-proxy's config settings.
230 This reduces manual configuration of the content proxy server host.
231 The ZOOM module will use the old style session.proxyhost if "server"
232 is given (deprecated) and use the new style proxyhost/session if
233 "config_file" is in use.
235 frontend_net: remove incoming requests that can not be handled
236 Requests in queue for filter frontend_net are removed if client
237 closes connection for the session and request is not yet handled.
239 sru_z3950: serialize requests. This is to ensure that pipelined
240 HTTP requests are handled properly.
242 --- 1.3.28 2012/04/04
244 New class, wrbuf, that wraps YAZ' WRBUF.
246 --- 1.3.27 2012/03/30
248 Metaproxy daemon is now running as user "metaproxy". This user is
249 managed by package maintainer scripts. The user information is stored
250 in /etc/metaproxy/metaproxy.user .
252 --- 1.3.26 2012/03/20
254 New filter, sort, that allows sorting of XML records via Z39.50
257 Filter record_transform: USEMarcon support. For example:
258 <retrieval syntax="usmarc">
259 <backend syntax="unimarc" name="F">
260 <usemarcon stage1="/etc/usemarcon/uni2us/uni2us.ini"/>
264 Filter multi: empty route pattern uses route as default.
266 <target route="z3950.indexdata.com">z3950.indexdata.com</route>
267 may use the shorter notation
268 <target route="z3950.indexdata.com"/>
270 Filter query_rewrite: use config path to locate XSLT.
272 Filter frontend_net: log statistics.
273 If a custom message element in frontend_net configuration it makes
274 the frontend_net filter produce a log entry whenever an operation
275 is completed. The log is always written using yaz_log with the
276 custom message given, the package ID (session ID) , the time
277 the operation has been active (end-to-end) , the threads currently
278 active/total and the size of the request input/output queues.
280 query_rewrite: charset conversion of query terms.
281 This is an optional feature. Enabled by element <charset> in
282 configuration with attribute 'from' and 'to' that specifies
283 from/to encodings. The default 'from' encoding is UTF-8.
285 Filter record_transform: honor piggyback searches.
287 Filter zoom: re-connect when database is reused.
288 Re-connect is necessary if a connection is lost or a timeout occurs.
289 If not, we'll be seeing zero hits, when we shouldn't.
291 --- 1.3.25 2012/02/29
293 zoom: Change scheme for dealing with content proxy URLs. The module
294 now has its own common XSL transform that is enabled by record_xsl
295 attribute in the configuration. This XSL gets parameter cproxyhost
296 that holds the host for the content proxy session . The genearted-url
297 is created only if urlRecipe is enabled. In previous version default
298 value of urlRecipe was ${md-electronic-url}; it is now empty and
299 disabled by default. Also generated-url no longer includes the content
300 proxy host. Content proxying URLs is supposed to the handle in the record_xsl
303 zoom: new setting timeout that specifies timeout for outgoing Z39.50/SRU
304 connections. Default value is 40 (seconds).
306 zoom: tune CCL to Z39.50 diagnostics mapping. Throw Bib-1: 108
307 "Malformed query" for syntax errors and related ones; throw
308 Bib-1: 3 "Unsupported search" for everything else. Details from
309 the CCL parser is provided as additional-info.
311 multi: new setting hideerrors that makes multi only relay diagnostics
312 to a client if all backends fail.
314 --- 1.3.24 2012/02/23
316 zoom: empty ccl_map field-mappings disables CCL map.
318 zoom: fix Explain search that could return error if session was
321 --- 1.3.23 2012/02/10
323 zoom: returns Explain records for database IR-Explain---1. The
324 target profile records are converted to Explain records via XSLT.
326 session_shared: make error recovery configurable. Whether a search
327 is restarted on errors or not, is configurable by attribute "restart"
328 in element "resultset" in configuration.
330 session_shared: only relay init for first request. session_shared, for
331 each backend class, now only relays first init request (rather than all).
332 The module only needs to save init response info once. This avoids the
333 need to check for session max.
335 --- 1.3.22 2012/02/02
337 zoom: fix memory leaks.
339 session_shared: maximum number of sessons is configurable. Default
340 value is 100. Result-sets for backends without named result sets are
341 only re-used if databases is identical for a search. This is under the
342 assumption that performance may suffer for those backends when
343 changing the database for each search.
345 multi: combines diagnostics from all backends. All diagnostics from
346 backends are combined into multiple non-surrogate diagnostics; rather
347 than just one diagnostic from first backend.
349 --- 1.3.21 2011/12/27
351 zoom: relay realm to cproxy parameter file.
353 Configuration: Allow filter collection element inside route. This
354 makes it possible to include multiple filters at once.
356 zoom: nocproxy also disables urlRecipe.
358 --- 1.3.20 2011/12/21
360 zoom: return diagnostic if CQL sortby conv fails. Diagnostic Bib-1 214
361 "Illegal sort relation" is returned. Gets translated to SRU diagnostic
362 90: "Unsupported direction value".
364 zoom: honor database argument nocproxy. This disables creating a content
365 connector session (for non-CF targets, usually) and also relays nocproxy
366 as database argument to a CF target.
368 --- 1.3.19 2011/12/16
370 zoom: Multiple proxy hosts may be given for proxy rich database
371 parameter. List is comma separated.
373 http_file: decodes URI paths properly. Does not return 404: not found
374 if no prefix are matches. Instead packages are passed on.
376 --- 1.3.18 2011/12/08
378 zoom: content-{user,password,proxy} are passed on to content proxy
379 system and takes precedence over user,password,proxy .
381 sru_z3950: SRU extra argument x-log-enable=1 enables a search response
382 with a log element including log material from children filters. At
383 this point, only the zoom filter uses this log facility. It will
384 eventually be used by other filters as well. In particular it might be
385 useful for this feature to track all filters in used during a search.
387 zoom: for x-log-enable=1, APDUs sent by ZOOM C, records as received
388 and queries as they are manipulated are logged.
390 zoom: extend addinfo with native diagnostics. Diagnostics as received
391 by ZOOM C are put into addinfo - including ZOOM, HTTP, SRU and Bib-1
392 diagnostics. This indicates both a backend diagnostic and the original
395 zoom: default urlRecipe value is ${md-electronic-url}
397 zoom: target profile setting sruVersion is recognized.
399 --- 1.3.17 2011/11/17
401 zoom: log target profile record fetched (AKA Torus).
403 --- 1.3.16 2011/11/17
405 Change target profile parameter CfSubDb to CfSubDB.
407 --- 1.3.15 2011/11/12
409 zoom: bug fix: realm was relayed to CF targets by mistake (realm only
410 makes sense to the zoom module itself).
412 --- 1.3.14 2011/11/11
414 zoom: realm may be given as part of database.
416 --- 1.3.13 2011/10/26
418 Fix Origin class assigment method; was removd by mistake in 1.3.12.
420 --- 1.3.12 2011/10/26
422 zoom: database args x-name=value are passed through to backend database.
424 SRU filter: user may specify session ID that is passed to log entries
425 that follows. It is specified by using x-session-id in the SRU arguments.
427 zoom: fix null pointer reference which would occur for bad url parameter
428 inside "torus" or if url was not given.
430 --- 1.3.11 2011/09/09
431 Fix bug in filter session_shared where sessions would not expire
432 properly (session ttl). This in turn could make the target close the
433 connection before expected and session_shared would return diagnostic
434 2: system temporarily available.
436 --- 1.3.10 2011/09/09
438 zoom: new target profile setting: sortmap_field. If sortmap_field is given
439 the field is mapped to the value for the sortmap. Values not matching
440 sortmap_field are passed verbatim.
442 zoom: new target profile setting: sortStrategy. One of: "z3950", "type7",
443 "cql", "sru11" or "embed". The "embed" chooses type-7 or CQL sortby
444 depending on whether RPN or CQL is actually sent to the target.
448 zoom: urlRecipe result is stored in <pz:metadata type="generated-url">.
450 zoom: For content proxy authentication is stored in param name
451 "auth", instead of "authentication".
455 zoom: relay schema in SRU mode. Previously recordSchema was not affected
460 zoom: new target profile element literalTransform that holds XSLT
461 (encoded as string) for target. Only if present and non-zero length it is
462 considered present. This takes precedence over transform.
464 Don't rely on trang anymore for Git checkout builds. Configuration in etc
465 will only be properly validated if trang is available. From now on only
466 relax NC files are bundled with the source dist.
468 Updates to check for Boost unit test (autoconf stuff). On MacOSX this
469 component was not detected when it should be.
473 z3950_client: mark non-surrogate diagnostics from backend.
475 zoom: a proxy may be specified for HTTP fetch of target profiles.
479 Honor piggyback. Makes some SRU targets behave that insist on
480 maximumRecords > 0, but also increases performance.
484 Fix dlpath in installed metaproxy.xml for RPM/Deb package. The
485 file was not update for libdir/metaproxy4 in version 1.3.2.
489 Change location of Metaproxy modules from libdir/metaproxy to
490 libdir/metaproxy4. Directory libdir/metaproxy is also owned by
491 libmetaproxy3 and, thus, should not be used by libmetaproxy4.
493 New facility to dump APDUs from zoom filter. Enabled by
494 <log apdu="true"/> in the zoom filter configuation.
496 zoom filter bug fix: SRU diagnostics received from backend was
497 not properly converted to Bib-1 diagnostics.
499 Package metaproxy depends on libmetaproxy4, same version.
503 zoom: fix a bug WRT passing authentication parameters to backends.
507 Fixes for windows Makefile.
509 --- 1.2.10 2011/07/25
511 Change major version of metaproxy library from 3 to 4. This in turn
512 makes new package names for Debian and RPM.
516 zoom: enable marc-8 encoding by default for usmarc and opac (in pz2
519 zoom: configurable element sets for record transforms.
521 zoom: the target profile based transform is specified by element_transform
522 in element torus of of the ZOOM filter configuration ; default value
523 is "pz2". Target profile based retrieval is specified by element_raw
524 in configuration. It will perform same steps, but omit the XSL transform.
525 Default value is "raw".
527 zoom: element set is omitted if not set in profile. But only if pz2
528 transform is in effect. Previously the default element set was to "F".
530 zoom: For non-CF targets database arguments are parsed. User may supply
531 db,user=myuser&password=mypass for non-CF targets. These values override
532 what's given the authentication from the target profile.
534 session_shared: fix reference to freed memory. Would occur if a search
535 response had non-surrogate diagnostics.
539 Route may be given for each port in frontend_net.
543 Documentation for zoom filter. Local target profiles may be specified.
545 Fixes for zoom filter.
549 First version with zoom filter.
553 Filter z3950_client may be configured to always send a close APDU
554 to backend target when connection/session is closed. This will only
555 happen if close APDU is not already sent. Enabled by configuration
556 for z3950_client (force_close).
558 Filter virt_db and multi: relay close APDU.
560 Filter virt_db and multi: relay init size parameters
561 preferredMessageSize and maximumRecordSize.
563 Filter sru_z3950: increase init sz parameters from 1MB to 10 MB.
567 RPM package for Metaproxy works for both SLES11 and Centos 5.5.
569 metaproxy-config: exec_prefix, libdir, includedir. Use these variables
570 as determined by configure.
572 RPM: Release includes 'indexdata' name. Use indexdata in release name so
573 this package can be distinguished from other vendors.
577 Fix filter multi: relay idAuthentication parameters.
581 Add metaproxy-config for returning compiler flags, libraries.
585 Fix --with-boost=PREFIX .
589 session_shared: fix use of maintenance thread.
591 Introduce 'start' method for filters and routers. It gets called after
592 configure and after fork, but before processing. This changes API -
593 from libmetaproxy2 to libmetaproxy3.
597 session_shared: ensure backend session is closed if init rejected
600 z3950_client: fix NULL ptr reference that could occur if two clients
601 connected concurrently and if max-sockets was in effect.
605 Fix bug 3497 - Metaproxy unstable while stopping.
607 Fix bug 3495 - SEGV in SRU filter.
611 Filter multi throws diagnostic 'Present Out of Range' when
612 appropriate - rather than returning 0 records.
614 Filter virt_db: fix bad result reuse. Could happen if a result
615 was overriden and a backend did not supported named result sets.
619 Filter log: category access logs diagnostics even if searchStatus
620 or presentStatus is 'success'.
624 The SRU to Z39.50 filter does repeated Z39.50 present requests
625 to fetch all records. Needed when a Z39.50 server returns partial
626 results (due to message size limits).
630 Metaproxy now kills all child processes that are spawned by
631 modules (in case of fork, exec).
635 Debian package now installs /etc/metaproxy/metaproxy.xml which
636 includes all XML files /etc/metaproxy/filters-enabled .
637 The include facility uses YAZ' yaz_xml_include_simple (YAZ 4.0.1).
641 Package based on YAZ version 4 and YAZ++ 1.2.0. It now includes a
642 development package to facilitate 3rd party Metaproxy modules.
644 --- 1.0.23 2010/01/04
646 Filter virt_db: Close backend filter session when Init rejected is received
647 from it (in which case it's not really closed yet). This will ensure we don't
648 run out of resources such as FDs in this case.
650 sru_z3950 filter: Accept any database (including those not listed).
652 --- 1.0.22 2009/12/03
654 Prepare for 64-bit YAZ. yazproxy will still work with YAZ++ 1.1.4 or
655 later which means YAZ 3.0.47 or later.
657 --- 1.0.20 2009/11/19
659 For filter virt_db, the database is a glob pattern and the virtual
660 database sections are consulted in the order given.
662 --- 1.0.19 2009/07/08
664 For filter multi, the target (for routing) may be given as a glob-pattern.
666 More documentation for filters virt_db and multi.
668 Update schema to allow for no database in sru_z3950 filter.
670 --- 1.0.18 2009/06/30
672 Added limit filter to put sleep (penalty) for heavy use.
674 Filter frontend_net may be configured to limit the number of new connections
675 from same IP to some value (connect-max).
677 Fixed the load_balance filter.
679 --- 1.0.17 2009/06/16
681 Fix path for metaproxy executable for Debian init.d script.
683 --- 1.0.16 2009/06/10
685 SRU to Z39.50 filter honors x-username and x-password. If only
686 x-username is given that translates to open authentication (Z39.50v2). If
687 both x-username and x-password is present that translates to idPass
688 authentication (Z39.50v3).
690 New facility to change current working directory (-w).
692 Update to upstream skeleton of init.d script. Should fix bug #2619.
694 Filter session_shared now caches records (used to only cache connections
697 Filter session_shared now invalidates a Z39.50 session if a server
698 returns -1 hits. This facility was also part of yazproxy and gets around
699 a bug in Voyager-based Z39.50 servers.
701 --- 1.0.15 2008/11/18
703 Fixed reference counting bug in Z39.50 client module (could cause SEGV).
705 --- 1.0.14 2008/06/09
707 Fixed the value of SRU record schema in searchRetrieve response. It was set
708 to a fixed value of "dc" before.
710 Serialize identical SRU requests. This is useful if HTTP client software
711 fires identical requests against metaproxy.
713 Allow Z39.50 target to be specified for SRU requests by using SRU extra
714 parameter x-target. Allows SRU to contact arbitrary Z39.50 targets and
715 avoid static configuration. This facility is handled by the sru_z3950 module
716 and the z3950_client module.
718 Allow maximum number of sockets to be used for a Z39.50 client by the
719 use of SRU extra parameter x-max-sockets. This facility is handled by the
720 sru_z3950 module and the z3950_client module.
722 --- 1.0.13.1 2008/02/29
724 Simplified check for Boost libraries.
726 --- 1.0.13 2008/02/29
728 First Debian package.
730 The sru_z9350 filter now recognizes SRU parameter z-target as being
731 a ZURL of the form host/database .
733 Mergetype may be specified for filter 'multi'.
735 --- 1.0.12 2007/09/19
737 Fixed problem in Makefile WRT library specifictions. This could produce
738 linker errors (when they should not happen).
740 Fixed bug #1341: MetaProxy returning different results. Problem was that
741 fix-up of record database did not normalize the database name.
743 Documentation updates for Windows compilation.
745 --- 1.0.11 2007/06/14
747 Fixed problem with logfile being truncated.
749 --- 1.0.10 2007/05/23
751 Fixed bug #1136: Access rights not enforced.
753 Extension for log module. The log category 'access' logs more details.
754 New category 'user-access' added which is simlar to 'access' but adds
755 the Z39.50 user as for all entries in a session.
759 Added support for configurable default/force target/vhost for module Z39.50
764 Implemented filter, session_shared, which optimizes usage of Z39.50
765 sessions and result sets.
767 New filter, record_transform, which converts MARC/XML records.
769 New filter, sru_z3950, which converts SRU to Z39.50 packages.
771 New filter, load_balance, in development.
773 New filter, zeerex_xplain.
775 XML framework for config files started.
777 Master RelaxNG Compact schema's are found in xml/schema/*.rnc,
778 RelaxNG XML schemas and XML Schema's are generated from RNC syntax.
779 XML config files are checked against RNG and XML Schema's.
781 XSLT transformation framework added in xml/xslt/*.xsl, consisting mainly of
782 LOC Marc21 stylesheets found at http://www.loc.gov/marcxml/xslt.
783 Added stylesheet explain2cqlpqftxt.xsl which transforms a standard SRU ZeeReX
784 explain record to YAZ CQL-to-PQF text config file.
788 Added 'timeout' setting for filter frontend_net which specifies the number
789 of seconds a session is idle before it is closed. Default timeout is
794 Database name in records returned set for virt_db/multi filters.
796 Filter session_shared now functional.
798 Log filter can be configured to write to a given file using 'filename'
799 element. Also information category can be specified with 'category'. If
800 filename is omitted, the log filter writes to stdout. See etc/config5.xml
805 Fixed compilation on Windows.
809 Added documentation for the hidenavailable option for the multi filter.
813 Fixed bug #573: Hide errors for individual servers. If the element
814 'hideunavailable' is given in the configuration, individual servers
815 being unavailable are hidden (unless all are unavailable).
817 Fixed bug #574: Database names are recognised case-sensitively.
819 Fixed bug #567: Fix up database name in Name-Plus-Record.
821 Fixed bug #568: Update win/makefile for VS 2005.
823 Fixed bug #569: Some options throws unknown exception.
827 More information about virtual hosts. The 'etc' directory is part of the
832 Build instructions for Windows. NMake makefile part of distribution tar.
838 Filters functional: auth_simple, backend_test, frontend_net, http_file,
839 log, multi, query_rewrite, template, virt_db, z3950_client.
841 Filters in development: session_shared.
843 Pseudo-filters: template, dl