4. Records

A record object is a retrieval record on the client side - created from result sets.

     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);

     int ZOOM_record_error(ZOOM_record rec, const char **msg,
                           const char **addinfo, const char **diagset);

     ZOOM_record ZOOM_record_clone(ZOOM_record rec);

     void ZOOM_record_destroy(ZOOM_record rec);
   

References to temporary records are returned by functions ZOOM_resultset_records or ZOOM_resultset_record.

If a persistent reference to a record is desired ZOOM_record_clone should be used. It returns a record reference that should be destroyed by a call to ZOOM_record_destroy.

A single record is returned by function ZOOM_resultset_record that takes a position as argument. First record has position zero. If no record could be obtained NULL is returned.

Error information for a record can be checked with ZOOM_record_error which returns non-zero (error code) if record is in error, called Surrogate Diagnostics in Z39.50.

Function ZOOM_resultset_records retrieves a number of records from a result set. Parameter start and count specifies the range of records to be returned. Upon completion array recs[0], ..recs[count-1] holds record objects for the records. The array of records recs should be allocated prior the call ZOOM_resultset_records. Note that for those records that couldn't be retrieved from the target recs[ ..] is set to NULL.

In order to extract information about a single record, ZOOM_record_get is provided. The function returns a pointer to certain record information. The nature (type) of the pointer depends on the parameter, type.

The type is a string of the format:

format[;charset=from[/opacfrom][,to]][;format=v]

where format specifies the format of the returned record, from specifies the character set of the record in its original form (as returned by the server), to specifies the output (returned) character set encoding. If to is omitted UTF-8 is assumed. If charset is not given, then no character set conversion takes place.

OPAC records may be returned in a different set from the bibliographic MARC record. If this is this the case, opacfrom should be set to the character set of the OPAC record part.

Note

Specifying the OPAC record character set requires YAZ 4.1.5 or later.

The format argument controls whether record data should be XML pretty-printed (post process operation). It is enabled only if format value v is 1 and the record content is XML well-formed.

In addition, for certain types, the length len passed will be set to the size in bytes of the returned information.

The following are the supported values for form.

database

Database of record is returned as a C null-terminated string. Return type const char *.

syntax

The transfer syntax of the record is returned as a C null-terminated string containing the symbolic name of the record syntax, e.g. Usmarc. Return type is const char *.

schema

The schema of the record is returned as a C null-terminated string. Return type is const char *.

render

The record is returned in a display friendly format. Upon completion buffer is returned (type const char *) and length is stored in *len.

raw

The record is returned in the internal YAZ specific format. For GRS-1, Explain, and others, the raw data is returned as type Z_External * which is just the type for the member retrievalRecord in type NamePlusRecord. For SUTRS and octet aligned record (including all MARCs) the octet buffer is returned and the length of the buffer.

xml

The record is returned in XML if possible. SRU, Solr and Z39.50 records with transfer syntax XML are returned verbatim. MARC records are returned in MARCXML (converted from ISO2709 to MARCXML by YAZ). OPAC records are also converted to XML and the bibliographic record is converted to MARCXML (when possible). GRS-1 records are not supported for this form. Upon completion, the XML buffer is returned (type const char *) and length is stored in *len.

opac

OPAC information for record is returned in XML if an OPAC record is present at the position given. If no OPAC record is present, a NULL pointer is returned.

txml

The record is returned in TurboMARC if possible. SRU and Z39.50 records with transfer syntax XML are returned verbatim. MARC records are returned in TurboMARC (converted from ISO2709 to TurboMARC by YAZ). Upon completion, the XML buffer is returned (type const char *) and length is stored in *len.

json

Like xml, but MARC records are converted to MARC-in-JSON.

Most MARC21 records uses the MARC-8 character set encoding. An application that wishes to display in Latin-1 would use

     render; charset=marc8,iso-8859-1
    

4.1. Z39.50 Protocol behavior

The functions ZOOM_resultset_record and ZOOM_resultset_records 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 async is 1, because they return records objects. (and there's no way to return records objects without retrieving them!).

There is a trick, however, in the usage of function ZOOM_resultset_records that allows for delayed retrieval (and makes it non-blocking). By using a null pointer for recs you're indicating you're not interested in getting records objects now.

4.2. SRU/Solr Protocol behavior

The ZOOM driver for SRU/Solr treats records returned by a SRU/Solr server as if they where Z39.50 records with transfer syntax XML and no element set name or database name.