-<!-- $Id: tools.xml,v 1.38 2004-10-02 13:41:46 adam Exp $ -->
+<!-- $Id: tools.xml,v 1.50 2006-06-13 16:01:51 adam Exp $ -->
<chapter id="tools"><title>Supporting Tools</title>
<para>
<literal>@and</literal>. Its semantics are described in
section 3.7.2 (Proximity) of Z39.50 the standard itself, which
can be read on-line at
- <ulink url="http://lcweb.loc.gov/z3950/agency/markup/09.html"/>
+ <ulink url="&url.z39.50.proximity;"/>
</para>
<para>
In PQF, the proximity operation is represented by a sequence
</itemizedlist>
(The numeric values of the relation and well-known unit-code
parameters are taken straight from
- <ulink url="http://lcweb.loc.gov/z3950/agency/asn1.html#ProximityOperator"
+ <ulink url="&url.z39.50.proximity.asn1;"
>the ASN.1</ulink> of the proximity structure in the standard.)
</para>
</sect3>
<para>
<screen>
dylan
+
"bob dylan"
</screen>
</para>
<para>
<screen>
@or "dylan" "zimmerman"
+
@and @or dylan zimmerman when
+
@and when @or dylan zimmerman
</screen>
</para>
<para>
<screen>
@set Result-1
- @and @set seta setb
+
+ @and @set seta @set setb
</screen>
</para>
</example>
<para>
<screen>
@attr 1=4 computer
+
@attr 1=4 @attr 4=1 "self portrait"
+
@attrset exp1 @attr 1=1 CategoryList
+
@attr gils 1=2008 Copenhagen
+
@attr 1=/book/title computer
</screen>
</para>
</table>
</para>
<para>
- The complete list of Bib-1 attributes can be found
- <ulink url="http://lcweb.loc.gov/z3950/agency/defns/bib1.html">
- here
- </ulink>.
+ Refer to the complete
+ <ulink url="&url.z39.50.attset.bib1;">list of Bib-1 attributes</ulink>
</para>
<para>
It is also possible to specify non-numeric attribute values,
</sect2>
<sect2 id="tools.cql"><title>CQL</title>
<para>
- <ulink url="http://www.loc.gov/z3950/agency/zing/cql/">CQL</ulink>
+ <ulink url="&url.cql;">CQL</ulink>
- Common Query Language - was defined for the
- <ulink url="http://www.loc.gov/z3950/agency/zing/srw/">SRW</ulink>
- protocol.
+ <ulink url="&url.sru;">SRU</ulink> protocol.
In many ways CQL has a similar syntax to CCL.
The objective of CQL is different. Where CCL aims to be
an end-user language, CQL is <emphasis>the</emphasis> protocol
- query language for SRW.
+ query language for SRU.
</para>
<tip>
<para>
If you are new to CQL, read the
- <ulink url="http://zing.z3950.org/cql/intro.html">Gentle
- Introduction</ulink>.
+ <ulink url="&url.cql.intro;">Gentle Introduction</ulink>.
</para>
</tip>
<para>
<listitem>
<para>
The parser converts a valid CQL query to PQF, thus providing a
- way to use CQL for both SRW/SRU servers and Z39.50 targets at the
+ way to use CQL for both SRU servers and Z39.50 targets at the
same time.
</para>
</listitem>
<listitem>
<para>
The parser converts CQL to
- <ulink url="http://www.loc.gov/z3950/agency/zing/cql/xcql.html">
- XCQL</ulink>.
+ <ulink url="&url.xcql;">XCQL</ulink>.
XCQL is an XML representation of CQL.
- XCQL is part of the SRW specification. However, since SRU
+ XCQL is part of the SRU specification. However, since SRU
supports CQL only, we don't expect XCQL to be widely used.
Furthermore, CQL has the advantage over XCQL that it is
easy to read.
If an index is unspecified for a search term,
<literal>index</literal> will be NULL.
</para>
+ </listitem>
+ <listitem>
<para>
<literal>index_uri</literal>: index URi for search term
or NULL if none could be resolved for the index.
Conversion to PQF (and Z39.50 RPN) is tricky by the fact
that the resulting RPN depends on the Z39.50 target
capabilities (combinations of supported attributes).
- In addition, the CQL and SRW operates on index prefixes
+ In addition, the CQL and SRU operates on index prefixes
(URI or strings), whereas the RPN uses Object Identifiers
for attribute sets.
</para>
</para>
<para>
If conversion failed, <function>cql_transform_buf</function>
- returns a non-zero SRW error code; otherwise zero is returned
+ returns a non-zero SRU error code; otherwise zero is returned
(conversion successful). The meanings of the numeric error
- codes are listed in the SRW specifications at
- <ulink url="http://www.loc.gov/srw/diagnostic-list.html"/>
+ codes are listed in the SRU specifications at
+ <ulink url="&url.sru.diagnostics.list;"/>
</para>
<para>
If conversion fails, more information can be obtained by calling
context set that was not recognised.
</para>
<para>
- The SRW error-codes may be translated into brief human-readable
+ The SRU error-codes may be translated into brief human-readable
error messages using
<synopsis>
const char *cql_strerror(int code);
</para>
</sect3>
<sect3 id="tools.cql.map">
- <title>Specification of CQL to RPN mapping</title>
+ <title>Specification of CQL to RPN mappings</title>
<para>
The file supplied to functions
<function>cql_transform_open_FILE</function>,
<para>
again, corresponding to the specific OIDs defined by the standard.
Refer to the
- <ulink url="http://lcweb.loc.gov/z3950/agency/defns/oids.html">
+ <ulink url="&url.z39.50.oids;">
Registry of Z39.50 Object Identifiers</ulink> for the
whole list.
</para>
</sect1>
+ <sect1 id="tools.log"><title>Log</title>
+ <para>
+ &yaz; has evolved a fairly complex log system which should be useful both
+ for debugging &yaz; itself, debugging applications that use &yaz;, and for
+ production use of those applications.
+ </para>
+ <para>
+ The log functions are declared in header <filename>yaz/log.h</filename>
+ and implemented in <filename>src/log.c</filename>.
+ Due to name clash with syslog and some math utilities the logging
+ interface has been modified as of YAZ 2.0.29. The obsolete interface
+ is still available if in header file <filename>yaz/log.h</filename>.
+ The key points of the interface are:
+ </para>
+ <screen>
+ void yaz_log(int level, const char *fmt, ...)
+
+ void yaz_log_init(int level, const char *prefix, const char *name);
+ void yaz_log_init_file(const char *fname);
+ void yaz_log_init_level(int level);
+ void yaz_log_init_prefix(const char *prefix);
+ void yaz_log_time_format(const char *fmt);
+ void yaz_log_init_max_size(int mx);
+
+ int yaz_log_mask_str(const char *str);
+ int yaz_log_module_level(const char *name);
+ </screen>
+
+ <para>
+ The reason for the whole log module is the <function>yaz_log</function>
+ function. It takes a bitmask indicating the log levels, a
+ <literal>printf</literal>-like format string, and a variable number of
+ arguments to log.
+ </para>
+
+ <para>
+ The <literal>log level</literal> is a bit mask, that says on which level(s)
+ the log entry should be made, and optionally set some behaviour of the
+ logging. In the most simple cases, it can be one of <literal>YLOG_FATAL,
+ YLOG_DEBUG, YLOG_WARN, YLOG_LOG</literal>. Those can be combined with bits
+ that modify the way the log entry is written:<literal>YLOG_ERRNO,
+ YLOG_NOTIME, YLOG_FLUSH</literal>.
+ Most of the rest of the bits are deprecated, and should not be used. Use
+ the dynamic log levels instead.
+ </para>
+
+ <para>
+ Applications that use &yaz;, should not use the LOG_LOG for ordinary
+ messages, but should make use of the dynamic loglevel system. This consists
+ of two parts, defining the loglevel and checking it.
+ </para>
+
+ <para>
+ To define the log levels, the (main) program should pass a string to
+ <function>yaz_log_mask_str</function> to define which log levels are to be
+ logged. This string should be a comma-separated list of log level names,
+ and can contain both hard-coded names and dynamic ones. The log level
+ calculation starts with <literal>YLOG_DEFAULT_LEVEL</literal> and adds a bit
+ for each word it meets, unless the word starts with a '-', in which case it
+ clears the bit. If the string <literal>'none'</literal> is found,
+ all bits are cleared. Typically this string comes from the command-line,
+ often identified by <literal>-v</literal>. The
+ <function>yaz_log_mask_str</function> returns a log level that should be
+ passed to <function>yaz_log_init_level</function> for it to take effect.
+ </para>
+
+ <para>
+ Each module should check what log bits it should be used, by calling
+ <function>yaz_log_module_level</function> with a suitable name for the
+ module. The name is cleared from a preceding path and an extension, if any,
+ so it is quite possible to use <literal>__FILE__</literal> for it. If the
+ name has been passed to <function>yaz_log_mask_str</function>, the routine
+ returns a non-zero bitmask, which should then be used in consequent calls
+ to yaz_log. (It can also be tested, so as to avoid unnecessary calls to
+ yaz_log, in time-critical places, or when the log entry would take time
+ to construct.)
+ </para>
+
+ <para>
+ Yaz uses the following dynamic log levels:
+ <literal>server, session, request, requestdetail</literal> for the server
+ functionality.
+ <literal>zoom</literal> for the zoom client api.
+ <literal>ztest</literal> for the simple test server.
+ <literal>malloc, nmem, odr, eventl</literal> for internal debugging of yaz itself.
+ Of course, any program using yaz is welcome to define as many new ones, as
+ it needs.
+ </para>
+
+ <para>
+ By default the log is written to stderr, but this can be changed by a call
+ to <function>yaz_log_init_file</function> or
+ <function>yaz_log_init</function>. If the log is directed to a file, the
+ file size is checked at every write, and if it exceeds the limit given in
+ <function>yaz_log_init_max_size</function>, the log is rotated. The
+ rotation keeps one old version (with a <literal>.1</literal> appended to
+ the name). The size defaults to 1GB. Setting it to zero will disable the
+ rotation feature.
+ </para>
+
+ <screen>
+ A typical yaz-log looks like this
+ 13:23:14-23/11 yaz-ztest(1) [session] Starting session from tcp:127.0.0.1 (pid=30968)
+ 13:23:14-23/11 yaz-ztest(1) [request] Init from 'YAZ' (81) (ver 2.0.28) OK
+ 13:23:17-23/11 yaz-ztest(1) [request] Search Z: @attrset Bib-1 foo OK:7 hits
+ 13:23:22-23/11 yaz-ztest(1) [request] Present: [1] 2+2 OK 2 records returned
+ 13:24:13-23/11 yaz-ztest(1) [request] Close OK
+ </screen>
+
+ <para>
+ The log entries start with a time stamp. This can be omitted by setting the
+ <literal>YLOG_NOTIME</literal> bit in the loglevel. This way automatic tests
+ can be hoped to produce identical log files, that are easy to diff. The
+ format of the time stamp can be set with
+ <function>yaz_log_time_format</function>, which takes a format string just
+ like <function>strftime</function>.
+ </para>
+
+ <para>
+ Next in a log line comes the prefix, often the name of the program. For
+ yaz-based servers, it can also contain the session number. Then
+ comes one or more logbits in square brackets, depending on the logging
+ level set by <function>yaz_log_init_level</function> and the loglevel
+ passed to <function>yaz_log_init_level</function>. Finally comes the format
+ string and additional values passed to <function>yaz_log</function>
+ </para>
+
+ <para>
+ The log level <literal>YLOG_LOGLVL</literal>, enabled by the string
+ <literal>loglevel</literal>, will log all the log-level affecting
+ operations. This can come in handy if you need to know what other log
+ levels would be useful. Grep the logfile for <literal>[loglevel]</literal>.
+ </para>
+
+ <para>
+ The log system is almost independent of the rest of &yaz;, the only
+ important dependence is of <filename>nmem</filename>, and that only for
+ using the semaphore definition there.
+ </para>
+
+ <para>
+ The dynamic log levels and log rotation were introduced in &yaz; 2.0.28. At
+ the same time, the log bit names were changed from
+ <literal>LOG_something</literal> to <literal>YLOG_something</literal>,
+ to avoid collision with <filename>syslog.h</filename>.
+ </para>
+
+ </sect1>
+
<sect1 id="tools.marc"><title>MARC</title>
<para>
#define YAZ_MARC_OAIMARC 2
#define YAZ_MARC_MARCXML 3
#define YAZ_MARC_ISO2709 4
+ #define YAZ_MARC_XCHANGE 5
/* supply iconv handle for character set conversion .. */
void yaz_marc_iconv(yaz_marc_t mt, yaz_iconv_t cd);
projects / yaz-moved-to-github.git / blobdiff