-<!-- $Id: zoom.xml,v 1.4 2001-10-24 21:24:38 quinn Exp $ -->
- <chapter id="zoom"><title>Building clients with ZOOM</title>
-
+<!-- $Id: zoom.xml,v 1.36 2003-11-25 09:55:20 mike Exp $ -->
+ <chapter id="zoom"><title>ZOOM</title>
<para>
- &zoom; is an acronym for 'Z39.50 Object-Orientation Model' and is
+ &zoom; is an acronym for 'Z39.50 Object-Orientation Model' and is
an initiative started by Mike Taylor (Mike is from the UK, which
explains the peculiar name of the model). The goal of &zoom; is to
provide a common Z39.50 client API not bound to a particular
programming language or toolkit.
</para>
+
+ <note>
+ <para>
+ A recent addition to &yaz; is SRW support. You can now make
+ SRW ZOOM connections by specifying scheme <literal>http://</literal>
+ for the hostname for a connection.
+ </para>
+ </note>
+
<para>
The lack of a simple Z39.50 client API for &yaz; has become more
- and more apparent over time. So when the first ZOOM specification
+ and more apparent over time. So when the first &zoom; specification
became available,
an implementation for &yaz; was quickly developed. For the first time, it is
now as easy (or easier!) to develop clients than servers with &yaz;. This
- chapter describes the ZOOM C binding. Before going futher, please
+ chapter describes the &zoom; C binding. Before going further, please
reconsider whether C is the right programming language for the job.
There are other language bindings available for &yaz;, and still
more
- are in active development. See the ZOOM website at
- <ulink url="http://zoom.z3950.org/">zoom.z3950.org</ulink> for
+ are in active development. See the
+ <ulink url="http://zoom.z3950.org/">ZOOM web-site</ulink> for
more information.
</para>
-
+
<para>
In order to fully understand this chapter you should read and
try the example programs <literal>zoomtst1.c</literal>,
<literal>zoomtst2.c</literal>, .. in the <literal>zoom</literal>
directory.
</para>
-
+
<para>
- The C language misses many features found in object oriented languages
+ The C language misses features found in object oriented languages
such as C++, Java, etc. For example, you'll have to manually,
destroy all objects you create, even though you may think of them as
temporary. Most objects has a <literal>_create</literal> - and a
that because of typedefs. All destroy methods should gracefully ignore a
<literal>NULL</literal> pointer.
</para>
+ <para>
+ In each of the sections below you'll find a sub section called
+ protocol behavior, that describes how the API maps to the Z39.50
+ protocol.
+ </para>
<sect1 id="zoom.connections"><title>Connections</title>
-
+
<para>The Connection object is a session with a target.
</para>
<synopsis>
- #include <yaz/zoom.h>
-
- Z3950_connection Z3950_connection_new (const char *host, int portnum);
-
- Z3950_connection Z3950_connection_create (Z3950_options options);
-
- void Z3950_connection_connect(Z3950_connection c, const char *host,
+ #include <yaz/zoom.h>
+
+ ZOOM_connection ZOOM_connection_new (const char *host, int portnum);
+
+ ZOOM_connection ZOOM_connection_create (ZOOM_options options);
+
+ void ZOOM_connection_connect(ZOOM_connection c, const char *host,
int portnum);
- void Z3950_connection_destroy (Z3950_connection c);
+ void ZOOM_connection_destroy (ZOOM_connection c);
</synopsis>
<para>
Connection objects are created with either function
- <function>Z3950_connection_new</function> or
- <function>Z3950_connection_create</function>.
+ <function>ZOOM_connection_new</function> or
+ <function>ZOOM_connection_create</function>.
The former creates and automatically attempts to establish a network
connection with the target. The latter doesn't establish
a connection immediately, thus allowing you to specify options
before establishing network connection using the function
- <function>Z3950_connection_connect</function>.
- If the portnumber, <literal>portnum</literal>, is zero, the
+ <function>ZOOM_connection_connect</function>.
+ If the port number, <literal>portnum</literal>, is zero, the
<literal>host</literal> is consulted for a port specification.
If no port is given, 210 is used. A colon denotes the beginning of
a port number in the host string. If the host string includes a
slash, the following part specifies a database for the connection.
</para>
<para>
+ You can prefix the host with a scheme followed by colon. The
+ default scheme is <literal>tcp</literal> (Z39.50 protocol).
+ The scheme <literal>http</literal> selects SRW over HTTP.
+ </para>
+ <para>
Connection objects should be destroyed using the function
- <function>Z3950_connection_destroy</function>.
+ <function>ZOOM_connection_destroy</function>.
</para>
<synopsis>
- const char *Z3950_connection_option (Z3950_connection c,
- const char *key,
- const char *val);
- const char *Z3950_connection_host (Z3950_connection c);
+ void ZOOM_connection_option_set (ZOOM_connection c,
+ const char *key,
+ const char *val);
+
+ const char *ZOOM_connection_option_get (ZOOM_connection c,
+ const char *key);
</synopsis>
<para>
- The <function>Z3950_connection_option</function> allows you to
- inspect or set an option given by <parameter>key</parameter>
- for the connection.
- If <parameter>val</parameter> is non-<literal>NULL</literal> that
- holds the new value for option.
- Otherwise, if <parameter>val</parameter> is
- <literal>NULL</literal>,
- the option is unchanged.
- The function returns the previous value of the option.
+ The <function>ZOOM_connection_option_set</function> allows you to
+ set an option given by <parameter>key</parameter> to the value
+ <parameter>value</parameter> for the connection.
+ Function <function>ZOOM_connection_option_get</function> returns
+ the value for an option given by <parameter>key</parameter>.
</para>
<table frame="top"><title>ZOOM Connection Options</title>
<tgroup cols="3">
<colspec colwidth="4*" colname="name"></colspec>
<colspec colwidth="7*" colname="description"></colspec>
<colspec colwidth="3*" colname="default"></colspec>
- <thead>
- <row>
- <entry>Option</entry>
- <entry>Description</entry>
- <entry>Default</entry>
- </row>
- </thead>
- <tbody>
- <row><entry>
- implementationName</entry><entry>Name of Your client
- </entry><entry>none</entry></row>
- <row><entry>
- user</entry><entry>Authentication user name
- </entry><entry>none</entry></row>
- <row><entry>
- group</entry><entry>Authentication group name
- </entry><entry>none</entry></row>
- <row><entry>
- pass</entry><entry>Authentication password
- </entry><entry>none</entry></row>
- <row><entry>
- proxy</entry><entry>Proxy host
- </entry><entry>none</entry></row>
- <row><entry>
- async</entry><entry>If true (1) the connection operates in
- asynchronous operation which means that all calls are non-blocking
- except <function>Z3950_event</function>.
- </entry><entry>0</entry></row>
- <row><entry>
- maximumRecordSize</entry><entry> Maximum size of single record.
- </entry><entry>1 MB</entry></row>
- <row><entry>
- preferredMessageSize</entry><entry> Maximum size of multiple records.
- </entry><entry>1 MB</entry></row>
- </tbody>
- </tgroup>
+ <thead>
+ <row>
+ <entry>Option</entry>
+ <entry>Description</entry>
+ <entry>Default</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row><entry>
+ implementationName</entry><entry>Name of Your client
+ </entry><entry>none</entry></row>
+ <row><entry>
+ user</entry><entry>Authentication user name
+ </entry><entry>none</entry></row>
+ <row><entry>
+ group</entry><entry>Authentication group name
+ </entry><entry>none</entry></row>
+ <row><entry>
+ pass</entry><entry>Authentication password
+ </entry><entry>none</entry></row>
+ <row><entry>
+ host</entry><entry>Target host. This setting is "read-only".
+ It's automatically set internally when connecting to a target.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ proxy</entry><entry>Proxy host
+ </entry><entry>none</entry></row>
+ <row><entry>
+ async</entry><entry>If true (1) the connection operates in
+ asynchronous operation which means that all calls are non-blocking
+ except
+ <link linkend="zoom.events"><function>ZOOM_event</function></link>.
+ </entry><entry>0</entry></row>
+ <row><entry>
+ maximumRecordSize</entry><entry> Maximum size of single record.
+ </entry><entry>1 MB</entry></row>
+ <row><entry>
+ preferredMessageSize</entry><entry> Maximum size of multiple records.
+ </entry><entry>1 MB</entry></row>
+ <row><entry>
+ lang</entry><entry> Language for negotiation.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ charset</entry><entry> Character set for negotiation.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ serverImplementationId</entry><entry>
+ Implementation ID of server. (The old targetImplementationId
+ option is also supported for the benefit of old applications.)
+ </entry><entry>none</entry></row>
+ <row><entry>
+ targetImplementationName</entry><entry>
+ Implementation Name of server. (The old
+ targetImplementationName option is also supported for the
+ benefit of old applications.)
+ </entry><entry>none</entry></row>
+ <row><entry>
+ serverImplementationVersion</entry><entry>
+ Implementation Version of server. (the old
+ targetImplementationVersion option is also supported for the
+ benefit of old applications.)
+ </entry><entry>none</entry></row>
+ <row><entry>
+ databaseName</entry><entry>One or more database names
+ separated by character plus (<literal>+</literal>), which to
+ be used by subsequent search requests on this Connection.
+ </entry><entry>Default</entry></row>
+ <row><entry>
+ piggyback</entry><entry>True (1) if piggyback should be
+ used in searches; false (0) if not.
+ </entry><entry>1</entry></row>
+ <row><entry>
+ smallSetUpperBound</entry><entry>If hits is less than or equal to this
+ value, then target will return all records using small element set name
+ </entry><entry>0</entry></row>
+ <row><entry>
+ largeSetLowerBound</entry><entry>If hits is greater than this
+ value, the target will return no records.
+ </entry><entry>1</entry></row>
+ <row><entry>
+ mediumSetPresentNumber</entry><entry>This value represents
+ the number of records to be returned as part of a search when when
+ hits is less than or equal to large set lower bound and if hits
+ is greater than small set upper bound.
+ </entry><entry>0</entry></row>
+ <row><entry>
+ smallSetElementSetName</entry><entry>
+ The element set name to be used for small result sets.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ mediumSetElementSetName</entry><entry>
+ The element set name to be for medium-sized result sets.
+ </entry><entry>none</entry></row>
+ </tbody>
+ </tgroup>
</table>
<para>
- Function <function>Z3950_connection_host</function> returns
- the host for the connection as specified in a call to
- <function>Z3950_connection_new</function> or
- <function>Z3950_connection_connect</function>.
- This function returns <literal>NULL</literal> if host isn't
- set for the connection.
+ If either option <literal>lang</literal> or <literal>charset</literal>
+ is set, then
+ <ulink url="http://lcweb.loc.gov/z3950/agency/defns/charneg-3.html">
+ Character Set and Language Negotiation</ulink> is in effect.
</para>
<synopsis>
- int Z3950_connection_error (Z3950_connection c, const char **cp,
- const char **addinfo);
+ int ZOOM_connection_error (ZOOM_connection c, const char **cp,
+ const char **addinfo);
+ int ZOOM_connection_error_x (ZOOM_connection c, const char **cp,
+ const char **addinfo, const char **dset);
</synopsis>
<para>
- Use <function>Z3950_connection_error</function> to check for
- errors for the last operation(s) performed. The function returns
- zero if no errors occurred; non-zero otherwise indicating the error.
- Pointers <parameter>cp</parameter> and <parameter>addinfo</parameter>
- holds messages for the error and additional-info if passed as
- non-<literal>NULL</literal>.
+ Function <function>ZOOM_connection_error</function> checks for
+ errors for the last operation(s) performed. The function returns
+ zero if no errors occurred; non-zero otherwise indicating the error.
+ Pointers <parameter>cp</parameter> and <parameter>addinfo</parameter>
+ holds messages for the error and additional-info if passed as
+ non-<literal>NULL</literal>. Function
+ <function>ZOOM_connection_error_x</function> is an extended version
+ of <function>ZOOM_connection_error</function> that is capable of
+ returning name of diagnostic set in <parameter>dset</parameter>.
</para>
+ <sect2><title>Z39.50 Protocol behavior</title>
+ <para>
+ The calls <function>ZOOM_connection_new</function> and
+ <function>ZOOM_connection_connect</function> establishes a TCP/IP
+ connection and sends an Initialize Request to the target if
+ possible. In addition, the calls waits for an Initialize Response
+ from the target and the result is inspected (OK or rejected).
+ </para>
+ <para>
+ If <literal>proxy</literal> is set then the client will establish
+ a TCP/IP connection with the peer as specified by the
+ <literal>proxy</literal> host and the hostname as part of the
+ connect calls will be set as part of the Initialize Request.
+ The proxy server will then "forward" the PDU's transparently
+ to the target behind the proxy.
+ </para>
+ <para>
+ For the authentication parameters, if option <literal>user</literal>
+ is set and both options <literal>group</literal> and
+ <literal>pass</literal> are unset, then Open style
+ authentication is used (Version 2/3) in which case the username
+ is usually followed by a slash, then by a password.
+ If either <literal>group</literal>
+ or <literal>pass</literal> is set then idPass authentication
+ (Version 3 only) is used. If none of the options are set, no
+ authentication parameters are set as part of the Initialize Request
+ (obviously).
+ </para>
+ <para>
+ When option <literal>async</literal> is 1, it really means that
+ all network operations are postponed (and queued) until the
+ function <literal>ZOOM_event</literal> is invoked. When doing so
+ it doesn't make sense to check for errors after
+ <literal>ZOOM_connection_new</literal> is called since that
+ operation "connecting - and init" is still incomplete and the
+ API cannot tell the outcome (yet).
+ </para>
+ </sect2>
+ <sect2><title>SRW Protocol behavior</title>
+ <para>
+ The SRW protocol doesn't feature an Inititialize Request, so
+ the connection phase merely establishes a TCP/IP connection
+ with the SOAP service.
+ </para>
+ <para>Most of the ZOOM connection options do not
+ affect SRW and they are ignored. However, future versions
+ of &yaz; might honor <literal>implementationName</literal> and
+ put that as part of User-Agent header for HTTP requests.
+ </para>
+ <para>
+ The <literal>charset</literal> is used in the Content-Type header
+ of HTTP requests.
+ </para>
+ </sect2>
</sect1>
- <sect1 id="zoom.search"><title>Search objects</title>
+ <sect1 id="zoom.query"><title>Queries</title>
<para>
- Search objects defines how result sets are obtained. They
- act like queries.
+ Query objects represents queries.
</para>
<synopsis>
- Z3950_search Z3950_search_create(void);
+ ZOOM_query ZOOM_query_create(void);
+
+ void ZOOM_query_destroy(ZOOM_query q);
- void Z3950_search_destroy(Z3950_search s);
+ int ZOOM_query_prefix(ZOOM_query q, const char *str);
- int Z3950_search_prefix(Z3950_search s, const char *str);
+ int ZOOM_query_cql(ZOOM_query s, const char *str);
- int Z3950_search_sortby(Z3950_search s, const char *criteria);
+ int ZOOM_query_sortby(ZOOM_query q, const char *criteria);
</synopsis>
<para>
- Create search objects using <function>Z3950_search_create</function>
- and destroy them by calling <function>Z3950_search_destroy</function>.
- RPN-queries can be specified in <link linkend="PQF">PQF</link>
- notation by using the
- function <function>Z3950_search_prefix</function>. More
- query types will be added later, such as
- <link linkend="CCL">CCL</link> to RPN-mapping, native CCL query,
- etc. In addition to a search, a sort criteria may be set. Function
- <function>Z3950_search_sortby</function> specifies a
- sort criteria using the same string notation for sort as offered by
- the <link linkend="sortspec">YAZ client</link>.
+ Create query objects using <function>ZOOM_query_create</function>
+ and destroy them by calling <function>ZOOM_query_destroy</function>.
+ RPN-queries can be specified in <link linkend="PQF">PQF</link>
+ notation by using the
+ function <function>ZOOM_query_prefix</function>.
+ The <function>ZOOM_query_cql</function> specifies a CQL
+ query to be sent to the server/target.
+ More query types will be added in future versions of &yaz;, such as
+ <link linkend="CCL">CCL</link> to RPN-mapping, native CCL query,
+ etc. In addition to a search, a sort criteria may be set. Function
+ <function>ZOOM_query_sortby</function> specifies a
+ sort criteria using the same string notation for sort as offered by
+ the <link linkend="sortspec">YAZ client</link>.
</para>
+ <sect2><title>Protocol behavior</title>
+ <para>
+ The query object is just an interface for the member Query
+ in the SearchRequest. The sortby-function is an interface to the
+ sortSequence member of the SortRequest.
+ </para>
+ </sect2>
</sect1>
<sect1 id="zoom.resultsets"><title>Result sets</title>
<para>
- The result set object is a container for records returned from
- a target.
- search.
+ The result set object is a container for records returned from
+ a target.
</para>
<synopsis>
- Z3950_resultset Z3950_connection_search(Z3950_connection,
- Z3950_search q);
+ ZOOM_resultset ZOOM_connection_search(ZOOM_connection,
+ ZOOM_query q);
- Z3950_resultset Z3950_connection_search_pqf(Z3950_connection c,
- const char *q);
+ ZOOM_resultset ZOOM_connection_search_pqf(ZOOM_connection c,
+ const char *q);
- void Z3950_resultset_destroy(Z3950_resultset r);
+ void ZOOM_resultset_destroy(ZOOM_resultset r);
</synopsis>
<para>
- Function <function>Z3950_connection_search</function> creates
- a result set given a connection - and search object.
- Destroy a result set by calling
- <function>Z3950_resultset_destroy</function>.
- Simple clients using PQF only may use function
- <function>Z3950_connection_search_pqf</function> instead.
+ Function <function>ZOOM_connection_search</function> creates
+ a result set given a connection and query.
+ Destroy a result set by calling
+ <function>ZOOM_resultset_destroy</function>.
+ Simple clients may using PQF only may use function
+ <function>ZOOM_connection_search_pqf</function> in which case
+ creating query objects is not necessary.
</para>
<synopsis>
- const char *Z3950_resultset_option (Z3950_resultset r,
- const char *key,
- const char *val);
+ void ZOOM_resultset_option_set (ZOOM_resultset r,
+ const char *key,
+ const char *val);
- int Z3950_resultset_size (Z3950_resultset r);
+ const char *ZOOM_resultset_option_get (ZOOM_resultset r,
+ const char *key);
- void *Z3950_resultset_get (Z3950_resultset s, int pos,
- const char *type, int *len);
+ size_t ZOOM_resultset_size (ZOOM_resultset r);
</synopsis>
<para>
- Function <function>Z3950_resultset_options</function> sets or
- modifies an option for a result set similar to
- <function>Z3950_connection_option</function>.
+ Functions <function>ZOOM_resultset_options_set</function> and
+ <function>ZOOM_resultset_get</function> sets and gets an option
+ for a result set similar to <function>ZOOM_connection_option_get</function>
+ and <function>ZOOM_connection_option_set</function>.
</para>
<para>
- The number of hits also called result-count is returned by
- function <function>Z3950_resultset_size</function>.
- </para>
- <para>
- Function <function>Z3950_resultset_get</function> is similar to
- <link linkend="zoom.record.get">
- <function>Z3950_record_get</function></link> but
- instead of operating on a record object, it operates on a record on
- a given offset within a result set.
+ The number of hits also called result-count is returned by
+ function <function>ZOOM_resultset_size</function>.
</para>
<table frame="top"><title>ZOOM Result set Options</title>
<tgroup cols="3">
<colspec colwidth="4*" colname="name"></colspec>
<colspec colwidth="7*" colname="description"></colspec>
<colspec colwidth="2*" colname="default"></colspec>
- <thead>
- <row>
- <entry>Option</entry>
- <entry>Description</entry>
- <entry>Default</entry>
- </row>
- </thead>
- <tbody>
- <row><entry>
- piggyback</entry><entry>True (1) if piggyback should be
- used in searches; false (0) if not.
- </entry><entry>1</entry></row>
- <row><entry>
- start</entry><entry>Offset of first record we wish to
- retrieve from the target. Note first record has offset 0
- unlike the protocol specifications where first record has position
- 1.
- </entry><entry>0</entry></row>
- <row><entry>
- count</entry><entry>Number of records to be retrieved.
- </entry><entry>0</entry></row>
- <row><entry>
- elementSetName</entry><entry>Element-Set name of records.
- Most targets should honor element set name <literal>B</literal>
- and <literal>F</literal> for brief and full respectively.
- </entry><entry>none</entry></row>
- <row><entry>
- preferredRecordSyntax</entry><entry>Preferred Syntax, such as
- <literal>USMARC</literal>, <literal>SUTRS</literal>, etc.
- </entry><entry>none</entry></row>
- <row><entry>
- databaseName</entry><entry>One or more database names
- separated by character plus (<literal>+</literal>).
- </entry><entry>Default</entry></row>
- </tbody>
- </tgroup>
+ <thead>
+ <row>
+ <entry>Option</entry>
+ <entry>Description</entry>
+ <entry>Default</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row><entry>
+ start</entry><entry>Offset of first record to be
+ retrieved from target. First record has offset 0 unlike the
+ protocol specifications where first record has position 1.
+ </entry><entry>0</entry></row>
+ <row><entry>
+ count</entry><entry>Number of records to be retrieved.
+ </entry><entry>0</entry></row>
+ <row><entry>
+ presentChunk</entry><entry>The number of records to be
+ requested from the server in each chunk (present requst). The
+ value 0 means to request all the records in a single chunk.
+ (The old <literal>step</literal>
+ option is also supported for the benefit of old applications.)
+ </entry><entry>0</entry></row>
+ <row><entry>
+ elementSetName</entry><entry>Element-Set name of records.
+ Most targets should honor element set name <literal>B</literal>
+ and <literal>F</literal> for brief and full respectively.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ preferredRecordSyntax</entry><entry>Preferred Syntax, such as
+ <literal>USMARC</literal>, <literal>SUTRS</literal>, etc.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ schema</entry><entry>Schema for retrieval, such as
+ <literal>Gils-schema</literal>, <literal>Geo-schema</literal>, etc.
+ </entry><entry>none</entry></row>
+ <row><entry>
+ setname</entry><entry>Name of Result Set (Result Set ID).
+ If this option isn't set, the ZOOM module will automatically
+ allocate a result set name.
+ </entry><entry>default</entry></row>
+ </tbody>
+ </tgroup>
</table>
+ <sect2>
+ <title>Z39.50 Protocol behavior</title>
+ <para>
+ The creation of a result set involves at least a SearchRequest
+ - SearchResponse protocol handshake. Following that, if a sort
+ criteria was specified as part of the query, a SortRequest -
+ SortResponse handshake takes place. Note that it is necessary to
+ perform sorting before any retrieval takes place, so no records will
+ be returned from the target as part of the SearchResponse because these
+ would be unsorted. Hence, piggyback is disabled when sort criteria
+ are set. Following Search - and a possible sort - Retrieval takes
+ place - as one or more Present Requests/Response pairs being
+ transferred.
+ </para>
+ <para>
+ The API allows for two different modes for retrieval. A high level
+ mode which is somewhat more powerful and a low level one.
+ The low level is enabled when searching on a Connection object
+ for which the settings
+ <literal>smallSetUpperBound</literal>,
+ <literal>mediumSetPresentNumber</literal> and
+ <literal>largeSetLowerBound</literal> are set. The low level mode
+ thus allows you to precisely set how records are returned as part
+ of a search response as offered by the Z39.50 protocol.
+ Since the client may be retrieving records as part of the
+ search response, this mode doesn't work well if sorting is used.
+ </para>
+ <para>
+ The high-level mode allows you to fetch a range of records from
+ the result set with a given start offset. When you use this mode
+ the client will automatically use piggyback if that is possible
+ with the target and perform one or more present requests as needed.
+ Even if the target returns fewer records as part of a present response
+ because of a record size limit, etc. the client will repeat sending
+ present requests. As an example, if option <literal>start</literal>
+ is 0 (default) and <literal>count</literal> is 4, and
+ <literal>piggyback</literal> is 1 (default) and no sorting criteria
+ is specified, then the client will attempt to retrieve the 4
+ records as part the search response (using piggyback). On the other
+ hand, if either <literal>start</literal> is positive or if
+ a sorting criteria is set, or if <literal>piggyback</literal>
+ is 0, then the client will not perform piggyback but send Present
+ Requests instead.
+ </para>
+ <para>
+ If either of the options <literal>mediumSetElementSetName</literal> and
+ <literal>smallSetElementSetName</literal> are unset, the value
+ of option <literal>elementSetName</literal> is used for piggyback
+ searches. This means that for the high-level mode you only have
+ to specify one elementSetName option rather than three.
+ </para>
+ </sect2>
+ <sect2>
+ <title>SRW Protocol behavior</title>
+ <para>
+ Current version of &yaz; does not take advantage of a result set id
+ returned by the SRW server. Future versions might do, however.
+ Since, the ZOOM driver does not save result set IDs any
+ present (retrieval) is transformed to a SRW SearchRetrieveRequest
+ with same query but, possibly, different offsets.
+ </para>
+ <para>
+ Option <literal>schema</literal> specifies SRW schema
+ for retrieval. However, options <literal>elementSetName</literal> and
+ <literal>preferredRecordSyntax</literal> are ignored.
+ </para>
+ <para>
+ Options <literal>start</literal> and <literal>count</literal>
+ are supported by SRW.
+ The remaining options
+ <literal>piggyback</literal>,
+ <literal>smallSetUpperBound</literal>,
+ <literal>largeSetLowerBound</literal>,
+ <literal>mediumSetPresentNumber</literal>,
+ <literal>mediumSetElementSetName</literal>,
+ <literal>smallSetElementSetName</literal> are
+ unsupported.
+ </para>
+ <para>
+ SRW supports CQL queries, <emphasis>not</emphasis> PQF.
+ If PQF is used, however, the PQF query is transferred anyway
+ using non-standard element <literal>pQuery</literal> in
+ SRW SearchRetrieveRequest.
+ </para>
+ <para>
+ Unfortunately, SRW does not define a database setting. Hence,
+ <literal>databaseName</literal> is unsupported and ignored.
+ However, the path part in host parameter for functions
+ <function>ZOOM_connecton_new</function> and
+ <function>ZOOM_connection_connect</function> acts as a
+ database (at least for the &yaz; SRW server).
+ </para>
+ </sect2>
</sect1>
<sect1 id="zoom.records"><title>Records</title>
<para>
- A record object is a retrival record on the client side -
- created from result sets.
+ A record object is a retrieval record on the client side -
+ created from result sets.
</para>
<synopsis>
- void Z3950_resultset_records (Z3950_resultset r,
- Z3950_record *recs,
- size_t *cnt);
- Z3950_record Z3950_resultset_record (Z3950_resultset s, int pos);
+ void ZOOM_resultset_records (ZOOM_resultset r,
+ ZOOM_record *recs,
+ size_t start, size_t count);
+ ZOOM_record ZOOM_resultset_record (ZOOM_resultset s, size_t pos);
+
+ const char *ZOOM_record_get (ZOOM_record rec, const char *type,
+ size_t *len);
- void *Z3950_record_get (Z3950_record rec, const char *type,
- int *len);
+ ZOOM_record ZOOM_record_clone (ZOOM_record rec);
- void Z3950_record_destroy (Z3950_record rec);
+ void ZOOM_record_destroy (ZOOM_record rec);
</synopsis>
<para>
- Records are created by functions
- <function>Z3950_resultset_records</function> or
- <function>Z3950_resultset_record</function>
- and destroyed by <function>Z3950_record_destroy</function>.
+ References to temporary records are returned by functions
+ <function>ZOOM_resultset_records</function> or
+ <function>ZOOM_resultset_record</function>.
+ </para>
+ <para>
+ If a persistent reference to a record is desired
+ <function>ZOOM_record_clone</function> should be used.
+ It returns a record reference that should be destroyed
+ by a call to <function>ZOOM_record_destroy</function>.
</para>
<para>
- A single record is created and returned by function
- <function>Z3950_resultset_record</function> that takes a
- position as argument. First record has position zero.
- If no record could be obtained <literal>NULL</literal> is returned.
+ A single record is returned by function
+ <function>ZOOM_resultset_record</function> that takes a
+ position as argument. First record has position zero.
+ If no record could be obtained <literal>NULL</literal> is returned.
</para>
<para>
- Function <function>Z3950_resultset_records</function> retrieves
- a number of records from a result set. Options <literal>start</literal>
- and <literal>count</literal> specifies the range of records to
- be returned. Upon completion <literal>recs[0], ..recs[*cnt]</literal>
- holds record objects for the records. These array of records
- <literal>recs</literal> should be allocate prior to calling
- <function>Z3950_resultset_records</function>. Note that for
- records that couldn't be retrieved from the target
- <literal>recs[ ..]</literal> is <literal>NULL</literal>.
+ Function <function>ZOOM_resultset_records</function> retrieves
+ a number of records from a result set. Parameter <literal>start</literal>
+ and <literal>count</literal> specifies the range of records to
+ be returned. Upon completion array
+ <literal>recs[0], ..recs[count-1]</literal>
+ holds record objects for the records. The array of records
+ <literal>recs</literal> should be allocated prior the call
+ <function>ZOOM_resultset_records</function>. Note that for those
+ records that couldn't be retrieved from the target
+ <literal>recs[ ..]</literal> is set to <literal>NULL</literal>.
</para>
<para id="zoom.record.get">
- In order to extract information about a single record,
- <function>Z3950_record_get</function> is provided. The
- function returns a pointer to certain record information. The
- nature (type) of the pointer depends on the <function>type</function>
- given. In addition for certain types, the length
- <literal>len</literal> passed will be set to the size in bytes of
- the returned information. The types <literal>database</literal>,
- <literal>syntax</literal> and <literal>render</literal> are
- supported. More will be added later.
+ In order to extract information about a single record,
+ <function>ZOOM_record_get</function> is provided. The
+ function returns a pointer to certain record information. The
+ nature (type) of the pointer depends on the parameter,
+ <parameter>type</parameter>.
+ </para>
+ <para>
+ The <parameter>type</parameter> is a string of the format:
+ </para>
+ <para>
+ <replaceable>form</replaceable>[; charset=<replaceable>from</replaceable>[,<replaceable>to</replaceable>]]
+ </para>
+ <para>
+ where <replaceable>form</replaceable> specifies the format of the
+ returned record, <replaceable>from</replaceable>
+ specifies the character set of the record in its original form
+ (as returned by the server), <replaceable>to</replaceable> specifies
+ the output (returned)
+ character set encoding.
+ If charset is not given, then no character set conversion takes place.
+ If <replaceable>to</replaceable> is omitted UTF-8 is assumed.
</para>
+ <para>
+ In addition, for certain types, the length
+ <literal>len</literal> passed will be set to the size in bytes of
+ the returned information.
+ </para>
+ <para>
+ The following are the supported values for <replaceable>form</replaceable>.
+ <variablelist>
+ <varlistentry><term><literal>database</literal></term>
+ <listitem><para>Database of record is returned
+ as a C null-terminated string. Return type
+ <literal>const char *</literal>.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term><literal>syntax</literal></term>
+ <listitem><para>The transfer syntax of the record is returned
+ as a C null-terminated string containing the symbolic name of
+ the record syntax, e.g. <literal>Usmarc</literal>. Return type
+ is
+ <literal>const char *</literal>.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term><literal>render</literal></term>
+ <listitem><para>The record is returned in a display friendly
+ format. Upon completion buffer is returned
+ (type <literal>const char *</literal>) and length is stored in
+ <literal>*len</literal>.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term><literal>raw</literal></term>
+ <listitem><para>The record is returned in the internal
+ YAZ specific format. For GRS-1, Explain, and others, the
+ raw data is returned as type
+ <literal>Z_External *</literal> which is just the type for
+ the member <literal>retrievalRecord</literal> in
+ type <literal>NamePlusRecord</literal>.
+ For SUTRS and octet aligned record (including all MARCs) the
+ octet buffer is returned and the length of the buffer.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term><literal>xml</literal></term>
+ <listitem><para>The record is returned in XML if possible.
+ SRW/SRU and Z39.50 records with transfer syntax XML are
+ returned verbatim. MARC records are returned in
+ <ulink url="http://www.loc.gov/standards/marcxml/">
+ MARCXML
+ </ulink>
+ (converted from ISO2709 to MARCXML by YAZ).
+ GRS-1 and OPAC records are not supported for this form.
+ Upon completion, the XML buffer is returned
+ (type <literal>const char *</literal>) and length is stored in
+ <literal>*len</literal>.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term><literal>opac</literal></term>
+ <listitem><para>OPAC for record is returned in XML.
+ </para></listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ <para>
+ Most
+ <ulink url="http://www.loc.gov/marc/">
+ MARC21
+ </ulink>
+ records uses the
+ <ulink url="http://www.loc.gov/marc/specifications/speccharmarc8.html">
+ MARC-8
+ </ulink>
+ character set encoding.
+ An application that wishes to display in Latin-1 would use
+ <screen>
+ render; charset=marc8,iso-8859-1
+ </screen>
+ </para>
+ <sect2><title>Z39.50 Protocol behavior</title>
+ <para>
+ The functions <function>ZOOM_resultset_record</function> and
+ <function>ZOOM_resultset_records</function> inspects the client-side
+ record cache. Records not found in cache are fetched using
+ Present.
+ The functions may block (and perform network I/O) - even though option
+ <literal>async</literal> is 1, because they return records objects.
+ (and there's no way to return records objects without retrieving them!).
+ </para>
+ <para>
+ There is a trick, however, in the usage of function
+ <function>ZOOM_resultset_records</function> that allows for
+ delayed retrieval (and makes it non-blocking). By using
+ a null pointer for <parameter>recs</parameter> you're indicating
+ you're not interested in getting records objects
+ <emphasis>now</emphasis>.
+ </para>
+ </sect2>
+ <sect2><title>SRW Protocol behavior</title>
+ <para>
+ The ZOOM driver for SRW treats records returned by a SRW server
+ as if they where Z39.50 records with transfer syntax XML and
+ no element set name or database name.
+ </para>
+ </sect2>
+ </sect1>
+ <sect1 id="zoom.scan"><title>Scan</title>
+ <para>
+ This section describes an interface for Scan. Scan is not an
+ official part of the ZOOM model yet. The result of a scan operation
+ is the <literal>ZOOM_scanset</literal> which is a set of terms
+ returned by a target.
+ </para>
+
+ <para>
+ The Scan interface is Z39.50 only. SRW version 1.0 does not
+ support this.
+ </para>
+
+ <synopsis>
+ ZOOM_scanset ZOOM_connection_scan (ZOOM_connection c,
+ const char *startterm);
+
+ size_t ZOOM_scanset_size(ZOOM_scanset scan);
+
+ const char * ZOOM_scanset_term(ZOOM_scanset scan, size_t pos,
+ int *occ, size_t *len);
+
+ const char * ZOOM_scanset_display_term(ZOOM_scanset scan, size_t pos,
+ int *occ, size_t *len);
+
+ void ZOOM_scanset_destroy (ZOOM_scanset scan);
+
+ const char *ZOOM_scanset_option_get (ZOOM_scanset scan,
+ const char *key);
+
+ void ZOOM_scanset_option_set (ZOOM_scanset scan, const char *key,
+ const char *val);
+ </synopsis>
+ <para>
+ The scan set is created by function
+ <function>ZOOM_connection_scan</function> which performs a scan
+ operation on the connection using the specified startterm.
+ If the operation was successful, the size of the scan set can be
+ retrieved by a call to <function>ZOOM_scanset_size</function>.
+ Like result sets, the items are numbered 0,..size-1.
+ To obtain information about a particular scan term, call function
+ <function>ZOOM_scanset_term</function>. This function takes
+ a scan set offset <literal>pos</literal> and returns a pointer
+ to a <emphasis>raw term</emphasis> or <literal>NULL</literal> if
+ non-present.
+ If present, the <literal>occ</literal> and <literal>len</literal>
+ are set to the number of occurrences and the length
+ of the actual term respectively.
+ <function>ZOOM_scanset_display_term</function> is similar to
+ <function>ZOOM_scanset_term</function> except that it returns
+ the <emphasis>display term</emphasis> rather than the raw term.
+ In a few cases, the term is different from display term. Always
+ use the display term for display and the raw term for subsequent
+ scan operations (to get more terms, next scan result, etc).
+ </para>
+ <para>
+ A scan set may be freed by a call to function
+ <function>ZOOM_scanset_destroy</function>.
+ Functions <function>ZOOM_scanset_option_get</function> and
+ <function>ZOOM_scanset_option_set</function> retrieves and sets
+ an option respectively.
+ </para>
+
+ <table frame="top"><title>ZOOM Scan Set Options</title>
+ <tgroup cols="3">
+ <colspec colwidth="4*" colname="name"></colspec>
+ <colspec colwidth="7*" colname="description"></colspec>
+ <colspec colwidth="2*" colname="default"></colspec>
+ <thead>
+ <row>
+ <entry>Option</entry>
+ <entry>Description</entry>
+ <entry>Default</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row><entry>
+ number</entry><entry>Number of Scan Terms requested in next scan.
+ After scan it holds the actual number of terms returned.
+ </entry><entry>10</entry></row>
+ <row><entry>
+ position</entry><entry>Preferred Position of term in response
+ in next scan; actual position after completion of scan.
+ </entry><entry>1</entry></row>
+ <row><entry>
+ stepSize</entry><entry>Step Size
+ </entry><entry>0</entry></row>
+ <row><entry>
+ scanStatus</entry><entry>An integer indicating the Scan Status
+ of last scan.
+ </entry><entry>0</entry></row>
+ </tbody>
+ </tgroup>
+ </table>
+
</sect1>
<sect1 id="zoom.options"><title>Options</title>
<para>
- Most objects in &zoom; allow you to specify options to change
- default behaviour. From an implementation point of view a set of options
- is just like an associate array / hash array, etc.
+ Most &zoom; objects provide a way to specify options to change behavior.
+ From an implementation point of view a set of options is just like
+ an associative array / hash array, etc.
</para>
<synopsis>
- Z3950_options Z3950_options_create (void);
+ ZOOM_options ZOOM_options_create (void);
- Z3950_options Z3950_options_create_with_parent (Z3950_options parent);
+ ZOOM_options ZOOM_options_create_with_parent (ZOOM_options parent);
- void Z3950_options_destroy (Z3950_options opt);
+ void ZOOM_options_destroy (ZOOM_options opt);
</synopsis>
<synopsis>
- const char *Z3950_options_get (Z3950_options opt, const char *name);
+ const char *ZOOM_options_get (ZOOM_options opt, const char *name);
- void Z3950_options_set (Z3950_options opt, const char *name,
- const char *v);
+ void ZOOM_options_set (ZOOM_options opt, const char *name,
+ const char *v);
</synopsis>
<synopsis>
- typedef const char *(*Z3950_options_callback)
+ typedef const char *(*ZOOM_options_callback)
(void *handle, const char *name);
- Z3950_options_callback
- Z3950_options_set_callback (Z3950_options opt,
- Z3950_options_callback c,
- void *handle);
+ ZOOM_options_callback
+ ZOOM_options_set_callback (ZOOM_options opt,
+ ZOOM_options_callback c,
+ void *handle);
</synopsis>
</sect1>
<sect1 id="zoom.events"><title>Events</title>
<para>
- If you're developing non-blocking applications, you have to deal
- with events.
+ If you're developing non-blocking applications, you have to deal
+ with events.
</para>
<synopsis>
- int Z3950_event (int no, Z3950_connection *cs);
+ int ZOOM_event (int no, ZOOM_connection *cs);
</synopsis>
<para>
- The <function>Z3950_event</function> executes pending events for
- a number of connections. Supply the number of connections in
- <literal>no</literal> and an array of connections in
- <literal>cs</literal> (<literal>cs[0] ... cs[no-1]</literal>).
- A pending event could be a sending a search, receiving a response,
- etc.
- When an event has a occured for one of the connections, this function
- returns a positive integer <literal>n</literal> denoting that an event
- occurred for connection <literal>cs[n-1]</literal>.
- When no events are pending for the connections, a value of zero is
- returned.
- To make sure all outstanding requests are performed call this function
- repeatedly until zero is returned.
+ The <function>ZOOM_event</function> executes pending events for
+ a number of connections. Supply the number of connections in
+ <literal>no</literal> and an array of connections in
+ <literal>cs</literal> (<literal>cs[0] ... cs[no-1]</literal>).
+ A pending event could be a sending a search, receiving a response,
+ etc.
+ When an event has occurred for one of the connections, this function
+ returns a positive integer <literal>n</literal> denoting that an event
+ occurred for connection <literal>cs[n-1]</literal>.
+ When no events are pending for the connections, a value of zero is
+ returned.
+ To ensure that all outstanding requests are performed call this function
+ repeatedly until zero is returned.
</para>
</sect1>
</chapter>
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document: "yaz.xml"
- sgml-local-catalogs: "../../docbook/docbook.cat"
+ sgml-local-catalogs: nil
sgml-namecase-general:t
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