X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;ds=sidebyside;f=doc%2Ftools.xml;h=841fb9a008345dfdf92299584505e528e6c3eb91;hb=e13889f2448f526c2d7be104228a76278fdd1e18;hp=a17b902c4f9f3c105dedadc83e38026c911c0c1d;hpb=3b3deb4d093d747360a5eb0e02c6b4e9c8a89b84;p=yaz-moved-to-github.git diff --git a/doc/tools.xml b/doc/tools.xml index a17b902..841fb9a 100644 --- a/doc/tools.xml +++ b/doc/tools.xml @@ -1,5 +1,5 @@ - - Supporting Tools + + Supporting Tools In support of the service API - primarily the ASN module, which @@ -7,7 +7,7 @@ a collection of tools that support the development of applications. - Query Syntax Parsers + Query Syntax Parsers Since the type-1 (RPN) query structure has no direct, useful string @@ -20,7 +20,7 @@ that may be of use to you. - Prefix Query Format + Prefix Query Format Since RPN or reverse polish notation is really just a fancy way of @@ -32,19 +32,73 @@ in simple test applications and scripting environments (like Tcl). The demonstration client included with YAZ uses the PQF. + + + + The PQF have been adopted by other parties developing Z39.50 + software. It is often referred to as Prefix Query Notation + - PQN. + + - The PQF is defined by the pquery module in the YAZ library. The - pquery.h file provides the declaration of the - functions + The PQF is defined by the pquery module in the YAZ library. + There are two sets of function that have similar behavior. First + set operates on a PQF parser handle, second set doesn't. First set + set of functions are more flexible than the second set. Second set + is obsolete and is only provided to ensure backwards compatibility. - -Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf); + + First set of functions all operate on a PQF parser handle: + + + #include <yaz/pquery.h> -Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto, - Odr_oid **attributeSetP, const char *qbuf); + YAZ_PQF_Parser yaz_pqf_create (void); -int p_query_attset (const char *arg); - + void yaz_pqf_destroy (YAZ_PQF_Parser p); + + Z_RPNQuery *yaz_pqf_parse (YAZ_PQF_Parser p, ODR o, const char *qbuf); + + Z_AttributesPlusTerm *yaz_pqf_scan (YAZ_PQF_Parser p, ODR o, + Odr_oid **attributeSetId, const char *qbuf); + + + int yaz_pqf_error (YAZ_PQF_Parser p, const char **msg, size_t *off); + + + A PQF parser is created and destructed by functions + yaz_pqf_create and + yaz_pqf_destroy respectively. + Function yaz_pqf_parse parses query given + by string qbuf. If parsing was successful, + a Z39.50 RPN Query is returned which is created using ODR stream + o. If parsing failed, a NULL pointer is + returned. + Function yaz_pqf_scan takes a scan query in + qbuf. If parsing was successful, the function + returns attributes plus term pointer and modifies + attributeSetId to hold attribute set for the + scan request - both allocated using ODR stream o. + If parsing failed, yaz_pqf_scan returns a NULL pointer. + Error information for bad queries can be obtained by a call to + yaz_pqf_error which returns an error code and + modifies *msg to point to an error description, + and modifies *off to the offset within last + query were parsing failed. + + + The second set of functions are declared as follows: + + + #include <yaz/pquery.h> + + Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf); + + Z_AttributesPlusTerm *p_query_scan (ODR o, oid_proto proto, + Odr_oid **attributeSetP, const char *qbuf); + + int p_query_attset (const char *arg); + The function p_query_rpn() takes as arguments an &odr; stream (see section The ODR Module) @@ -57,10 +111,10 @@ int p_query_attset (const char *arg); If the parse went well, p_query_rpn() returns a pointer to a Z_RPNQuery structure which can be - placed directly into a Z_SearchRequest. + placed directly into a Z_SearchRequest. + If parsing failed, due to syntax error, a NULL pointer is returned. - The p_query_attset specifies which attribute set to use if the query doesn't specify one by the @attrset operator. @@ -72,53 +126,71 @@ int p_query_attset (const char *arg); The grammar of the PQF is as follows: - - Query ::= [ '@attrset' AttSet ] QueryStruct. - - AttSet ::= string. + + query ::= top-set query-struct. - QueryStruct ::= [ Attribute ] Simple | Complex. + top-set ::= [ '@attrset' string ] - Attribute ::= '@attr' [ AttSet ] AttributeType '=' AttributeValue. + query-struct ::= attr-spec | simple | complex | '@term' term-type - AttributeType ::= integer. + attr-spec ::= '@attr' [ string ] string query-struct - AttributeValue ::= integer. + complex ::= operator query-struct query-struct. - Complex ::= Operator QueryStruct QueryStruct. + operator ::= '@and' | '@or' | '@not' | '@prox' proximity. - Operator ::= '@and' | '@or' | '@not' | '@prox' Proximity. + simple ::= result-set | term. - Simple ::= ResultSet | Term. + result-set ::= '@set' string. - ResultSet ::= '@set' string. + term ::= string. - Term ::= string | '"' string '"'. + proximity ::= exclusion distance ordered relation which-code unit-code. - Proximity ::= Exclusion Distance Ordered Relation WhichCode UnitCode. + exclusion ::= '1' | '0' | 'void'. - Exclusion ::= '1' | '0' | 'void'. + distance ::= integer. - Distance ::= integer. + ordered ::= '1' | '0'. - Ordered ::= '1' | '0'. + relation ::= integer. - Relation ::= integer. + which-code ::= 'known' | 'private' | integer. - WhichCode ::= 'known' | 'private' | integer. + unit-code ::= integer. - UnitCode ::= integer. - + term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'. + You will note that the syntax above is a fairly faithful - representation of RPN, except for the Attibute, which has been + representation of RPN, except for the Attribute, which has been moved a step away from the term, allowing you to associate one or more attributes with an entire query structure. The parser will automatically apply the given attributes to each term as required. + The @attr operator is followed by an attribute specification + (attr-spec above). The specification consists + of optional an attribute set, an attribute type-value pair and + a sub query. The attribute type-value pair is packed in one string: + an attribute type, a dash, followed by an attribute value. + The type is always an integer but the value may be either an + integer or a string (if it doesn't start with a digit character). + + + + Z39.50 version 3 defines various encoding of terms. + Use the @term operator to indicate the encoding type: + general, numeric, + string (for InternationalString), .. + If no term type has been given, the general form + is used which is the only encoding allowed in both version 2 - and 3 + of the Z39.50 standard. + + + The following are all examples of valid queries in the PQF. @@ -133,6 +205,8 @@ int p_query_attset (const char *arg); @or @and bob dylan @set Result-1 + @attr 1=4 computer + @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming" @attr 4=1 @attr 1=4 "self portrait" @@ -140,10 +214,14 @@ int p_query_attset (const char *arg); @prox 0 3 1 2 k 2 dylan zimmerman @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109 + + @term string "a UTF-8 string, maybe?" + + @attr 1=/book/title computer - Common Command Language + Common Command Language Not all users enjoy typing in prefix query structures and numerical @@ -156,14 +234,15 @@ int p_query_attset (const char *arg); - The EUROPAGATE research project working under the Libraries programme + The EUROPAGATE + research project working under the Libraries programme of the European Commission's DG XIII has, amongst other useful tools, implemented a general-purpose CCL parser which produces an output structure that can be trivially converted to the internal RPN - representation of YAZ (The Z_RPNQuery structure). + representation of &yaz; (The Z_RPNQuery structure). Since the CCL utility - along with the rest of the software - produced by EUROPAGATE - is made freely available on a liberal license, it - is included as a supplement to YAZ. + produced by EUROPAGATE - is made freely available on a liberal + license, it is included as a supplement to &yaz;. CCL Syntax @@ -206,7 +285,7 @@ int p_query_attset (const char *arg); | string -- Qualifiers is a list of strings separated by comma - Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<' + Relation ::= '=' | '>=' | '<=' | '<>' | '>' | '<' -- Relational operators. This really doesn't follow the ISO8777 -- standard. @@ -385,8 +464,230 @@ struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str, + CQL + + CQL + - Common Query Language - was defined for the + SRW + 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 the protocol + query language for SRW. Unlike PQF (Z39.50 Type-1), CQL is easy + to read. + + + + If you are new to CQL, read the + Gentle + Introduction. + + + + The CQL parser in &yaz; provides the following: + + + + It parses and validates a CQL query. + + + + + It generates a C structure that allows you to convert + a CQL query to some other query language, such as SQL. + + + + + 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 + same time. + + + + + The parser converts CQL to + + XCQL. + XCQL is an XML representation of CQL. + XCQL is part of the SRW 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. + + + + + CQL parsing + + A CQL parser is represented by the CQL_parser + handle. Its contents should be considered &yaz; internal (private). + +#include <yaz/cql.h> + +typedef struct cql_parser *CQL_parser; + +CQL_parser cql_parser_create(void); +void cql_parser_destroy(CQL_parser cp); + +int cql_parser_string(CQL_parser cp, const char *str); + + A parser is created by cql_parser_create and + is destroyed by cql_parser_destroy. + + + A CQL query is parsed by the cql_parser_string + which takes a query str. + If the query was valid (no syntax errors), then zero is returned; + otherwise a non-zero error code is returned. + + + +int cql_parser_stream(CQL_parser cp, + int (*getbyte)(void *client_data), + void (*ungetbyte)(int b, void *client_data), + void *client_data); + +int cql_parser_stdio(CQL_parser cp, FILE *f); + + The functions cql_parser_stream and + cql_parser_stdio parses a CQL query + - just like cql_parser_string. + The only difference is that the CQL query can be + fed to the parser in different ways. + The cql_parser_stream uses a generic + byte stream as input. The cql_parser_stdio + uses a FILE handle which is opened for reading. + + + CQL tree + + We now turn to the tree representation of a valid CQL query. + +#define CQL_NODE_ST 1 +#define CQL_NODE_BOOL 2 +#define CQL_NODE_MOD 3 +struct cql_node { + int which; + union { + struct { + char *index; + char *term; + char *relation; + struct cql_node *modifiers; + struct cql_node *prefixes; + } st; + struct { + char *value; + struct cql_node *left; + struct cql_node *right; + struct cql_node *modifiers; + struct cql_node *prefixes; + } bool; + struct { + char *name; + char *value; + struct cql_node *next; + } mod; + } u; +}; + + There are three kinds of nodes, search term (ST), boolean (BOOL), + and modifier (MOD). + + + The search term node has five members: + + + + index: index for search term. + If an index is unspecified for a search term, + index will be NULL. + + + + + term: the search term itself. + + + + + relation: relation for search term. + + + + + modifiers: relation modifiers for search + term. The modifiers is a simple linked + list (NULL for last entry). Each relation modifier node + is of type MOD. + + + + + prefixes: index prefixes for search + term. The prefixes is a simple linked + list (NULL for last entry). Each prefix node + is of type MOD. + + + + + + + The boolean node represents both and, + or, not as well as + proximity. + + + + left and right: left + - and right operand respectively. + + + + + modifiers: proximity arguments. + + + + + prefixes: index prefixes. + The prefixes is a simple linked + list (NULL for last entry). Each prefix node + is of type MOD. + + + + + + + The modifier node is a "utility" node used for name-value pairs, + such as prefixes, proximity arguements, etc. + + + + name name of mod node. + + + + + value value of mod node. + + + + + next: pointer to next node which is + always a mod node (NULL for last entry). + + + + + + + - Object Identifiers + Object Identifiers The basic YAZ representation of an OID is an array of integers, @@ -417,7 +718,7 @@ struct ccl_rpn_node *ccl_find_str (CCL_bibset bibset, const char *str, The OID module provides a higher-level representation of the - family of object identifers which describe the Z39.50 protocol and its + family of object identifiers which describe the Z39.50 protocol and its related objects. The definition of the module interface is given in the oid.h file. @@ -583,7 +884,7 @@ typedef struct oident The oid_ent_to_oid() function can be used whenever you need to prepare a PDU containing one or more OIDs. The separation of - the protocol element from the remainer of the + the protocol element from the remainder of the OID-description makes it simple to write applications that can communicate with either Z39.50 or OSI SR-based applications. @@ -632,7 +933,7 @@ typedef struct oident - Nibble Memory + Nibble Memory Sometimes when you need to allocate and construct a large, @@ -660,6 +961,7 @@ typedef struct oident void nmem_reset(NMEM n); int nmem_total(NMEM n); void nmem_init(void); + void nmem_exit(void); @@ -675,15 +977,18 @@ typedef struct oident allocated on the handle. - - - The nibble memory pool is shared amongst threads. POSIX - mutex'es and WIN32 Critical sections are introduced to keep the - module thread safe. On WIN32 function nmem_init() - initializes the Critical Section handle and should be called once - before any other nmem function is used. - - + + The nibble memory pool is shared amongst threads. POSIX + mutex'es and WIN32 Critical sections are introduced to keep the + module thread safe. Function nmem_init() + initializes the nibble memory library and it is called automatically + the first time the YAZ.DLL is loaded. &yaz; uses + function DllMain to achieve this. You should + not call nmem_init or + nmem_exit unless you're absolute sure what + you're doing. Note that in previous &yaz; versions you'd have to call + nmem_init yourself. + @@ -698,7 +1003,7 @@ typedef struct oident 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 End: -->