ISO 23950:1998 download.Information and documentation — Information retrieval (Z39.50) — Application service definition and protocol specification.
ISO 23950 is one of a set of standards prIueed to Iiei I jUte the Interconnection o computer systems. It Is posit ioflCd iii respect to other related sLandLirds b> the Open Sstems Interconnection (OSI ) basic relerence model (ISO 749. This sLan(iard defines a protocol within the application layer of (he reference model, and is concerned in particular with (he search and reir ieval of in lormal i m in databases.
1.1 Scope and Field of Application
ISO 23950 defines the IntormaLion Retrieval Application Service (section 3 ) and specifics the Information Retrieval Application Protocol section 4. The service detinition describes services ihat support capabilities within an application: tlV ser ices are in turn supported by the Z39.5() protocol. Ihe descnption neither specifics nor constrains the iiiiplementatioti within a computer s stem. The protocol specihealion includes the definition of the protocol control intoriiiat ion, the rules fr c\changillg this information, and the conformance requirements to he met by implementation ol’ this protocol.
linended for systems supporIin! information retries a! services, and for organitations such as information ser\ ices. uniersitie. libraries, and union cataloue centers. this standard addresses connection—oriented. program—to—program communication. Ii does not address interchange of in format ion with terminals or Via other physical media.
1.2 ersion
There have been three publications of 1.39.50: 1.39.50— I 9. 1.39.50— I 992. and 1.39.50—1995: and there has been one publication
of the Search and Retrieve Proocol. ISo I  163—I: I 993. The three publications: Z39.50— I 992. ISO I  163—I: I 993. and 739.50— I 995 hut not 1.39.50— I 9S each incorporate the concept of a protocol erSion. and three protocol versions are defined: Version I
version 2. and version 3. ISO I  163—1: I 993 is based on protocol version I : Z39.50— 1992 is based on protocol version 2: Z39.50-
I 995 is based on pri nocol ersi m 2 as elI as protocol versi n 3. (There is no p[ )L( col version associated ii h Z39.50— I 9X.
ISO 23950, ISO 23950. is based on version 2 and Version 3. Ii assumes that version I and version 2 are
A 1)51 ract datahisc recor(I— An abstract represenllt ion ol the intonualioii in a Li tabase record. An abstract database record may be Formed 1 the appi icaLi( )Il ol an abstract record struct tire (defined h a schema ) to the database rect wd. An den lent sped tication may he applied to an abstract database record firming another instance nt the abstract database record.
Abstract record structure The priinar component of a database sche,iia. Au abstract record structure applie(I to a database record re suits in an abstract database record.
Abstract S iita —A description of a particular data type usin an abstract s\ulIaX ilotal lou. It caul be ref erenced h au 01 F) ()hJeLi identifier).
Abstract s nta notation A lauiguwe that allows the denotation ot data tpes in a representaiioui—iiidependent manner. ASN. I is at) c\alnple.
:LceSS P111I A Luiliqtle or ulofl—tllliLlLle kC that can he sped lied either singly or iui comhiuiation with ( ther access points in a search for records. i\ll access p01111 ma he equivalent to an elenient (dehined h an abstract synta\ ). derk ed Irouii a set of ouie or more elements, or unrelated to an clenient.
Access point eLitist’ —An operand of a type— 1 query ( intonual ).
Aggregate present rt’sioiise Segiuent requests (ii’ aui ) together with the Present response. for a Precuit operation. .PI)L See Application Protocol Data L nit.
ariant One of 1)ossihl several forms in which an element is available kw retries al. The oriin may request. or the target present. an element according to a specific variant. The target niav ititlicate what variants are available for an element.
Variant list A list pros ided h the target of the supported\ariants br a PaIticL1lit element.
Va na lit keq ut’st one of three usages l r a variant speci ticat u )n. A variant Request is a ariant sped licat ii n occurn hg within an element request. See also a)pIiL’(lariant and supporte(Iariant.
Variant set A definition of a set of classes: kw each class, a set of types: and for each type. a set of values. A variant specification consists of a set ol’ varianiSpeci tiers from a Iarlicu lar variant set.
Variant set idvntihvr —An 011) identifying a variant set.
Variant Spevitu’atioii —A variantkequest. applied Variant, or supportedVariant. A variant specification is a sequence of triples. each ol’ which is a variantSpeci 11cr.
Variant Specifier A coiiiponenl of a ariant specilication. It consists of a class. a t pe detincd tr that class. aiid a value defined for that type.
/—assutatiuii —See Z39.5O—assidaIion
A quer is applied to LI database. specif ing values to he matched LigLulist the access pomis of the database. i’he suhs( of records kwmed h appl ing a query is called the re.siiIt .c’I (see 3. 1 .6. A result set ma itself he reterenced in a subsequent query and ii’iuiiipulated to trm a new resulL seL.
A search request specilies one or more databases and includes a query. The type— I query defined in ISO 23950 (see 3.7) consists 1)1 either a single access point clause. or several access point clauses linked h logical operators. For example. In c database named B )oks Ii rid all records for hich the access p )iflI title word contains the value “evangel i ne” AND the access point authors contains the value “Iomtcllow.
Each access point clause consists of a search term and altnbuies. The attributes quality the term: usually, one of the attributes corresponds to a normalited access point agailist hich the term (as qttalihcd by the other attnhLnes ) is iiiatclied. Each attribute is a pair representing an attribute type and a alue of that type for example. t’ pe might he “access point and value “author”: or miht he “truncations’ and value “Icit” .
Each attn hiiie is qua Ii tied h an attribute set Id which ideut i ties the attn hiute set Co which the attribute be longs. An attribute set specihes a set of attribute types, and for each, a list oh attribute values.
3.1.5 Ret rie log Records from a I)atabase
Follo ing the processing of a search, the result set is riiade available h’ the target, to Lhe origin. for subsequent retrieval requests. \‘heii requesti ii the retries al of a record from a result set, the oriin ma suppl a tIciiuI’u.t’ ciu’nui identifier. elt’,ncui .s,wci/i( vIit’ii. and recurt! vn,a.v identifier.
hw the PLIIPO5C of retric\ ing records troiii a result SCI, associated with each database are one or more schemas. A schema represents a common understanding shared by the origin and target of the information contained in the records oh the database. to allow the subsequent selection of portions of that int’onnation ia an eleiiient sped tication.
A schema defines an (Ibsircic! revrd .siru(iure which. hen applied to a (latahase record results in an ih.!rcui ilahthci.w record.