-<!-- $Id: zoom.xml,v 1.8 2001-11-13 23:00:42 adam Exp $ -->
+<!-- $Id: zoom.xml,v 1.15 2002-01-02 10:30:25 adam Exp $ -->
<chapter id="zoom"><title>Building clients with ZOOM</title>
<para>
</para>
<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 futher, 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 website</ulink> for
more information.
</para>
</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
<synopsis>
#include <yaz/zoom.h>
- Z3950_connection Z3950_connection_new (const char *host, int portnum);
+ ZOOM_connection ZOOM_connection_new (const char *host, int portnum);
- Z3950_connection Z3950_connection_create (Z3950_options options);
+ ZOOM_connection ZOOM_connection_create (ZOOM_options options);
- void Z3950_connection_connect(Z3950_connection c, const char *host,
+ 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>.
+ <function>ZOOM_connection_connect</function>.
If the portnumber, <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
</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 (new) 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>
+ <table frame="sides" colsep="1"><title>ZOOM Connection Options</title>
<tgroup cols="3">
<colspec colwidth="4*" colname="name"></colspec>
<colspec colwidth="7*" colname="description"></colspec>
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>Z3950_event</function></link>.
+ <link linkend="zoom.events"><function>ZOOM_event</function></link>.
</entry><entry>0</entry></row>
<row><entry>
maximumRecordSize</entry><entry> Maximum size of single record.
</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.
- </para>
<synopsis>
- int Z3950_connection_error (Z3950_connection c, const char **cp,
+ int ZOOM_connection_error (ZOOM_connection c, const char **cp,
const char **addinfo);
</synopsis>
<para>
- Use <function>Z3950_connection_error</function> to check for
+ Use <function>ZOOM_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>
</para>
<sect2><title>Protocol behavior</title>
<para>
- The calls <function>Z3950_connection_new</function> and
- <function>Z3950_connection_connect</function> establises a TCP/IP
+ The calls <function>ZOOM_connection_new</function> and
+ <function>ZOOM_connection_connect</function> establises 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>
When option <literal>async</literal> is 1, it really means that
all network operations are postponed (and queued) until the
- function <literal>Z3950_event</literal> is invoked. When doing so
+ function <literal>ZOOM_event</literal> is invoked. When doing so
it doesn't make sense to check for errors after
- <literal>Z3950_connection_new</literal> is called since that
+ <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>
Query objects represents queries.
</para>
<synopsis>
- Z3950_query Z3950_query_create(void);
+ ZOOM_query ZOOM_query_create(void);
- void Z3950_query_destroy(Z3950_query q);
+ void ZOOM_query_destroy(ZOOM_query q);
- int Z3950_query_prefix(Z3950_query q, const char *str);
+ int ZOOM_query_prefix(ZOOM_query q, const char *str);
- int Z3950_query_sortby(Z3950_query q, const char *criteria);
+ int ZOOM_query_sortby(ZOOM_query q, const char *criteria);
</synopsis>
<para>
- Create query objects using <function>Z3950_query_create</function>
- and destroy them by calling <function>Z3950_query_destroy</function>.
+ 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>Z3950_query_prefix</function>. More
+ function <function>ZOOM_query_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_query_sortby</function> specifies a
+ <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>
a target.
</para>
<synopsis>
- Z3950_resultset Z3950_connection_search(Z3950_connection,
- Z3950_query 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
+ Function <function>ZOOM_connection_search</function> creates
a result set given a connection and query.
Destroy a result set by calling
- <function>Z3950_resultset_destroy</function>.
+ <function>ZOOM_resultset_destroy</function>.
Simple clients may using PQF only may use function
- <function>Z3950_connection_search_pqf</function> in which case
+ <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, size_t pos,
- const char *type, size_t *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.
+ function <function>ZOOM_resultset_size</function>.
</para>
<table frame="top"><title>ZOOM Result set Options</title>
<tgroup cols="3">
<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>
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>
databaseName</entry><entry>One or more database names
separated by character plus (<literal>+</literal>).
</entry><entry>Default</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>
created from result sets.
</para>
<synopsis>
- void Z3950_resultset_records (Z3950_resultset r,
- Z3950_record *recs,
- size_t start, size_t count);
- Z3950_record Z3950_resultset_record (Z3950_resultset s, size_t 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);
+
+ void *ZOOM_record_get (ZOOM_record rec, const char *type,
+ size_t *len);
- void *Z3950_record_get (Z3950_record rec, const char *type,
- size_t *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
+ 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
+ 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 allocate prior to calling
- <function>Z3950_resultset_records</function>. Note that for those
+ <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>ZOOM_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
+ nature (type) of the pointer depends on the parameter,
+ <function>type</function>.
+ In addition, for certain types, the length
<literal>len</literal> passed will be set to the size in bytes of
the returned information.
<variablelist>
<varlistentry><term><literal>database</literal></term>
- <listitem><para>The database that holds the record is returned
- as a C string. Return type <literal>char *</literal>.
+ <listitem><para>Database of record is returned
+ as a C null-terminated string. Return type <literal>char *</literal>.
</para></listitem>
</varlistentry>
<varlistentry><term><literal>syntax</literal></term>
<listitem><para>The transfer syntax (OID) of the record is returned
- as a C string. Return type <literal>char *</literal>.
+ as a C null-terminated string. Return type <literal>char *</literal>.
</para></listitem>
</varlistentry>
<varlistentry><term><literal>render</literal></term>
<varlistentry><term><literal>raw</literal></term>
<listitem><para>The record is returned in the internal
YAZ specific format. The raw data is returned as type
- <literal>Z_External *</literal> is just the type for
+ <literal>Z_External *</literal> which is just the type for
the member <literal>retrievalRecord</literal> in
type <literal>NamePlusRecord</literal>.
</para></listitem>
</para>
<sect2><title>Protocol behavior</title>
<para>
- The functions <function>Z3950_resultset_record</function> and
- <function>Z3950_resultset_records</function> inspects the client-side
- record cache. If the records(s) were not found, i.e. not yet retrieved
- from, they are fetched using Present Requests.
+ 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 passing
+ a null pointer for <parameter>recs</parameter> you're indicating
+ you're not interested in getting records objects
+ <emphasis>now</emphasis>.
</para>
</sect2>
</sect1>
<sect1 id="zoom.options"><title>Options</title>
<para>
- Most &zoom; objects provide a way to specify options to default behavior.
+ 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 associate array / hash array, etc.
+ 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.scan"><title>Scsn</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>
+ <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);
+
+
+ void ZOOM_scanset_destroy (ZOOM_scanset scan);
+ </synopsis>
+ <para>
+ The scan set is created by function
+ <function>ZOOM_connection_scan</function> which performs a scan
+ operation on the connection and start term given.
+ If the operation was successful, the size of the scan set can be
+ retrived 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 an actual term 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.
+ A scan set may be freed by a call to function
+ <function>ZOOM_scanset_destroy</function>.
+ </para>
+ </sect1>
<sect1 id="zoom.events"><title>Events</title>
<para>
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
+ 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 a occured for one of the connections, this function
+ When an event has 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
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