X-Git-Url: http://git.indexdata.com/?p=yaz-moved-to-github.git;a=blobdiff_plain;f=doc%2Ftools.xml;h=6c02fc5cc920f498ae323057c7315b9de0ef5060;hp=2122e696a45592951a041f376ce12b3a3a0064fd;hb=b7dce0eae6656ccb499233e04f5a5bf90178c7cd;hpb=51d28a42486be5dd8bef3e09097d40eeacc94377 diff --git a/doc/tools.xml b/doc/tools.xml index 2122e69..6c02fc5 100644 --- a/doc/tools.xml +++ b/doc/tools.xml @@ -1,4 +1,4 @@ - + Supporting Tools @@ -16,11 +16,11 @@ Z_RPNQuery structure. Some programmers will prefer to construct the query manually, perhaps using odr_malloc() to simplify memory management. - The &yaz; distribution includes two separate, query-generating tools + The &yaz; distribution includes three separate, query-generating tools 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. + 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 Second set + is obsolete and is only provided to ensure backwards compatibility. + - The PQF is defined by the pquery module in the YAZ library. The - pquery.h file provides the declaration of the - functions + First set of functions all operate on a PQF parser handle: - -Z_RPNQuery *p_query_rpn (ODR o, oid_proto proto, const char *qbuf); + + #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. @@ -72,92 +126,302 @@ int p_query_attset (const char *arg); The grammar of the PQF is as follows: - - Query ::= [ '@attrset' AttSet ] QueryStruct. + + query ::= top-set query-struct. - AttSet ::= string. + top-set ::= [ '@attrset' string ] - QueryStruct ::= [ Attribute ] Simple | Complex. + query-struct ::= attr-spec | simple | complex | '@term' term-type query - Attribute ::= '@attr' [ AttSet ] AttributeType '=' AttributeValue. + attr-spec ::= '@attr' [ string ] string query-struct - AttributeType ::= integer. + complex ::= operator query-struct query-struct. - AttributeValue ::= integer || string. + operator ::= '@and' | '@or' | '@not' | '@prox' proximity. - Complex ::= Operator QueryStruct QueryStruct. + simple ::= result-set | term. - Operator ::= '@and' | '@or' | '@not' | '@prox' Proximity. + result-set ::= '@set' string. - Simple ::= ResultSet | Term. + term ::= string. - ResultSet ::= '@set' string. + proximity ::= exclusion distance ordered relation which-code unit-code. - Term ::= string | '"' string '"'. + exclusion ::= '1' | '0' | 'void'. - Proximity ::= Exclusion Distance Ordered Relation WhichCode UnitCode. + distance ::= integer. - Exclusion ::= '1' | '0' | 'void'. + ordered ::= '1' | '0'. - Distance ::= integer. + relation ::= integer. - Ordered ::= '1' | '0'. + which-code ::= 'known' | 'private' | integer. - Relation ::= integer. + unit-code ::= integer. - WhichCode ::= 'known' | 'private' | 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 following are all examples of valid queries in the PQF. + The @attr operator is followed by an attribute specification + (attr-spec above). The specification consists + of an optional attribute set, an attribute type-value pair and + a sub-query. The attribute type-value pair is packed in one string: + an attribute type, an equals sign, and an attribute value, like this: + @attr 1=1003. + 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). + A string attribute-value is encoded as a Type-1 ``complex'' + attribute with the list of values containing the single string + specified, and including no semantic indicators. - - dylan - - "bob dylan" - - @or "dylan" "zimmerman" - - @set Result-1 - - @or @and bob dylan @set Result-1 - - @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming" - - @attr 4=1 @attr 1=4 "self portrait" - - @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 - + + Version 3 of the Z39.50 specification defines various encoding of terms. + Use @term type + string, + where type is one of: general, + numeric or string + (for InternationalString). + If no term type has been given, the general form + is used. This is the only encoding allowed in both versions 2 and 3 + of the Z39.50 standard. + + + + Using Proximity Operators with PQF + + + This is an advanced topic, describing how to construct + queries that make very specific requirements on the + relative location of their operands. + You may wish to skip this section and go straight to + the example PQF queries. + + + + + Most Z39.50 servers do not support proximity searching, or + support only a small subset of the full functionality that + can be expressed using the PQF proximity operator. Be + aware that the ability to express a + query in PQF is no guarantee that any given server will + be able to execute it. + + + + + + The proximity operator @prox is a special + and more restrictive version of the conjunction operator + @and. Its semantics are described in + section 3.7.2 (Proximity) of Z39.50 the standard itself, which + can be read on-line at + + + + In PQF, the proximity operation is represented by a sequence + of the form + +@prox exclusion distance ordered relation which-code unit-code + + in which the meanings of the parameters are as described in in + the standard, and they can take the following values: + + exclusion + 0 = false (i.e. the proximity condition specified by the + remaining parameters must be satisfied) or + 1 = true (the proximity condition specified by the + remaining parameters must not be + satisifed). + + distance + An integer specifying the difference between the locations + of the operands: e.g. two adjacent words would have + distance=1 since their locations differ by one unit. + + ordered + 1 = ordered (the operands must occur in the order the + query specifies them) or + 0 = unordered (they may appear in either order). + + relation + Recognised values are + 1 (lessThan), + 2 (lessThanOrEqual), + 3 (equal), + 4 (greaterThanOrEqual), + 5 (greaterThan) and + 6 (notEqual). + + which-code + known + or + k + (the unit-code parameter is taken from the well-known list + of alternatives described in below) or + private + or + p + (the unit-code paramater has semantics specific to an + out-of-band agreement such as a profile). + + unit-code + If the which-code parameter is known + then the recognised values are + 1 (character), + 2 (word), + 3 (sentence), + 4 (paragraph), + 5 (section), + 6 (chapter), + 7 (document), + 8 (element), + 9 (subelement), + 10 (elementType) and + 11 (byte). + If which-code is private then the + acceptable values are determined by the profile. + + + (The numeric values of the relation and well-known unit-code + parameters are taken straight from + the ASN.1 of the proximity structure in the standard.) + + + PQF queries + + PQF queries using simple terms + + + dylan + "bob dylan" + + + + PQF boolean operators + + + @or "dylan" "zimmerman" + @and @or dylan zimmerman when + @and when @or dylan zimmerman + + + + PQF references to result sets + + + @set Result-1 + @and @set seta setb + + + + Attributes for terms + + + @attr 1=4 computer + @attr 1=4 @attr 4=1 "self portrait" + @attrset exp1 @attr 1=1 CategoryList + @attr gils 1=2008 Copenhagen + @attr 1=/book/title computer + + + + PQF Proximity queries + + + @prox 0 3 1 2 k 2 dylan zimmerman + + + Here the parameters 0, 3, 1, 2, k and 2 represent exclusion, + distance, ordered, relation, which-code and unit-code, in that + order. So: + + + exclusion = 0: the proximity condition must hold + + + distance = 3: the terms must be three units apart + + + ordered = 1: they must occur in the order they are specified + + + relation = 2: lessThanOrEqual (to the distance of 3 units) + + + which-code is ``known'', so the standard unit-codes are used + + + unit-code = 2: word. + + + So the whole proximity query means that the words + dylan and zimmerman must + both occur in the record, in that order, differing in position + by three or fewer words (i.e. with two or fewer words between + them.) The query would find ``Bob Dylan, aka. Robert + Zimmerman'', but not ``Bob Dylan, born as Robert Zimmerman'' + since the distance in this case is four. + + + + PQF specification of search term + + + @term string "a UTF-8 string, maybe?" + + + + PQF mixed queries + + + @or @and bob dylan @set Result-1 + + @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming" + + @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109 + + + + The last of these examples is a spatial search: in + the GILS attribute set, + access point + 2038 indicates West Bounding Coordinate and + 2030 indicates East Bounding Coordinate, + so the query is for areas extending from -114 degrees + to no more than -109 degrees. + + + + + - Common Command Language + CCL Not all users enjoy typing in prefix query structures and numerical attribute values, even in a minimalistic test client. In the library - world, the more intuitive Common Command Language (or ISO 8777) has - enjoyed some popularity - especially before the widespread + world, the more intuitive Common Command Language - CCL (ISO 8777) + has enjoyed some popularity - especially before the widespread availability of graphical interfaces. It is still useful in applications where you for some reason or other need to provide a symbolic language for expressing boolean query structures. - 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 @@ -215,40 +479,43 @@ int p_query_attset (const char *arg); -- Proximity operator - - - The following queries are all valid: - - - - dylan - - "bob dylan" - - dylan or zimmerman - - set=1 - - (dylan and bob) or set=1 - - - - Assuming that the qualifiers ti, au - and date are defined we may use: - - - - ti=self portrait - - au=(bob dylan and slow train coming) - - date>1980 and (ti=((self portrait))) - - - + + CCL queries + + The following queries are all valid: + + + + dylan + + "bob dylan" + + dylan or zimmerman + + set=1 + + (dylan and bob) or set=1 + + + + Assuming that the qualifiers ti, + au + and date are defined we may use: + + + + ti=self portrait + + au=(bob dylan and slow train coming) + + date>1980 and (ti=((self portrait))) + + + + CCL Qualifiers - + Qualifiers are used to direct the search to a particular searchable index, such as title (ti) and author indexes (au). The CCL standard @@ -256,72 +523,335 @@ int p_query_attset (const char *arg); suggest a few short-hand notations. You can customize the CCL parser to support a particular set of qualifiers to reflect the current target profile. Traditionally, a qualifier would map to a particular - use-attribute within the BIB-1 attribute set. However, you could also - define qualifiers that would set, for example, the - structure-attribute. + use-attribute within the BIB-1 attribute set. It is also + possible to set other attributes, such as the structure + attribute. - Consider a scenario where the target support ranked searches in the - title-index. In this case, the user could specify + A CCL profile is a set of predefined CCL qualifiers that may be + read from a file or set in the CCL API. + The YAZ client reads its CCL qualifiers from a file named + default.bib. There are four types of + lines in a CCL profile: qualifier specification, + qualifier alias, comments and directives. - - - ti,ranked=knuth computer - - - and the ranked would map to relation=relevance - (2=102) and the ti would map to title (1=4). - - - - A "profile" with a set predefined CCL qualifiers can be read from a - file. The YAZ client reads its CCL qualifiers from a file named - default.bib. Each line in the file has the form: - - - - qualifier-name - type=val - type=val ... - - - - where qualifier-name is the name of the - qualifier to be used (eg. ti), - type is a BIB-1 category type and - val is the corresponding BIB-1 attribute - value. - The type can be either numeric or it may be - either u (use), r (relation), - p (position), s (structure), - t (truncation) or c (completeness). - The qualifier-name term - has a special meaning. - The types and values for this definition is used when - no qualifiers are present. - - - - Consider the following definition: - - - - ti u=4 s=1 - au u=1 s=1 - term s=105 - - - Two qualifiers are defined, ti and - au. - They both set the structure-attribute to phrase (1). - ti - sets the use-attribute to 4. au sets the - use-attribute to 1. - When no qualifiers are used in the query the structure-attribute is - set to free-form-text (105). - - + Qualifier specification + + A qualifier specification is of the form: + + + + qualifier-name + [attributeset,]type=val + [attributeset,]type=val ... + + + + where qualifier-name is the name of the + qualifier to be used (eg. ti), + type is attribute type in the attribute + set (Bib-1 is used if no attribute set is given) and + val is attribute value. + The type can be specified as an + integer or as it be specified either as a single-letter: + u for use, + r for relation,p for position, + s for structure,t for truncation + or c for completeness. + The attributes for the special qualifier name term + are used when no CCL qualifier is given in a query. + Common Bib-1 attributes + + + + + + Type + Description + + + + + u=value + + Use attribute. Common use attributes are + 1 Personal-name, 4 Title, 7 ISBN, 8 ISSN, 30 Date, + 62 Subject, 1003 Author), 1016 Any. Specify value + as an integer. + + + + + r=value + + Relation attribute. Common values are + 1 <, 2 <=, 3 =, 4 >=, 5 >, 6 <>, + 100 phonetic, 101 stem, 102 relevance, 103 always matches. + + + + + p=value + + Position attribute. Values: 1 first in field, 2 + first in any subfield, 3 any position in field. + + + + + s=value + + Structure attribute. Values: 1 phrase, 2 word, + 3 key, 4 year, 5 date, 6 word list, 100 date (un), + 101 name (norm), 102 name (un), 103 structure, 104 urx, + 105 free-form-text, 106 document-text, 107 local-number, + 108 string, 109 numeric string. + + + + + t=value + + Truncation attribute. Values: 1 right, 2 left, + 3 left& right, 100 none, 101 process #, 102 regular-1, + 103 regular-2, 104 CCL. + + + + + c=value + + Completeness attribute. Values: 1 incomplete subfield, + 2 complete subfield, 3 complete field. + + + + + +
+ + + The complete list of Bib-1 attributes can be found + + here + . + + + It is also possible to specify non-numeric attribute values, + which are used in combination with certain types. + The special combinations are: + + Special attribute combos + + + + + + Name + Description + + + + + s=pw + The structure is set to either word or phrase depending + on the number of tokens in a term (phrase-word). + + + + s=al + Each token in the term is ANDed. (and-list). + This does not set the structure at all. + + + + s=ol + Each token in the term is ORed. (or-list). + This does not set the structure at all. + + + + r=o + Allows operators greather-than, less-than, ... equals and + sets relation attribute accordingly (relation ordered). + + + + t=l + Allows term to be left-truncated. + If term is of the form ?x, the resulting + Type-1 term is x and truncation is left. + + + + t=r + Allows term to be right-truncated. + If term is of the form x?, the resulting + Type-1 term is x and truncation is right. + + + + t=n + If term is does not include ?, the + truncation attribute is set to none (100). + + + + t=b + Allows term to be both left&right truncated. + If term is of the form ?x?, the + resulting term is x and trunctation is + set to both left&right. + + + + +
+ + CCL profile + + Consider the following definition: + + + + ti u=4 s=1 + au u=1 s=1 + term s=105 + ranked r=102 + date u=30 r=o + + + Four qualifiers are defined - ti, + au, ranked and + date. + + + ti and au both set + structure attribute to phrase (s=1). + ti + sets the use-attribute to 4. au sets the + use-attribute to 1. + When no qualifiers are used in the query the structure-attribute is + set to free-form-text (105) (rule for term). + The date sets the relation attribute to + the relation used in the CCL query and sets the use attribute + to 30 (Bib-1 Date). + + + You can combine attributes. To Search for "ranked title" you + can do + + ti,ranked=knuth computer + + which will set relation=ranked, use=title, structure=phrase. + + + Query + + year > 1980 + + is a valid query, while + + ti > 1980 + + is invalid. + + + + Qualifier alias + + A qualifier alias is of the form: + + + q + q1 q2 .. + + + which declares q to + be an alias for q1, + q2... such that the CCL + query q=x is equivalent to + q1=x or w2=x or .... + + + + Comments + + Lines with white space or lines that begin with + character # are treated as comments. + + + + Directives + + Directive specifications takes the form + + @directive value + + CCL directives + + + + + + + Name + Description + Default + + + + + truncation + Truncation character + ? + + + field + Specifies how multiple fields are to be + combined. There are two modes: or: + multiple qualifier fields are ORed, + merge: attributes for the qualifier + fields are merged and assigned to one term. + + merge + + + case + Specificies if CCL operatores and qualifiers should be + compared with case sensitivity or not. Specify 0 for + case sensitive; 1 for case insensitive. + 0 + + + + and + Specifies token for CCL operator AND. + and + + + + or + Specifies token for CCL operator OR. + or + + + + not + Specifies token for CCL operator NOT. + not + + + + set + Specifies token for CCL operator SET. + set + + + +
+ CCL API @@ -386,6 +916,558 @@ 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. + + + + 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); + + A parser is created by cql_parser_create and + is destroyed by cql_parser_destroy. + + + To parse a CQL query string, the following function + is provided: + +int cql_parser_string(CQL_parser cp, const char *str); + + 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 -1 is returned to indicate a syntax error. + + + +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 + + The the query string is valid, the CQL parser + generates a tree representing the structure of the + CQL query. + + + +struct cql_node *cql_parser_result(CQL_parser cp); + + cql_parser_result returns the + a pointer to the root node of the resulting tree. + + + Each node in a CQL tree is represented by a + struct cql_node. + It is defined as follows: + +#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; + } boolean; + 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). + + + + + + + CQL to PQF conversion + + Conversion to PQF (and Z39.50 RPN) is tricky by the fact + that the resulting RPN depends on the Z39.50 target + capabilities (combinations of supported attributes). + In addition, the CQL and SRW operates on index prefixes + (URI or strings), whereas the RPN uses Object Identifiers + for attribute sets. + + + The CQL library of &yaz; defines a cql_transform_t + type. It represents a particular mapping between CQL and RPN. + This handle is created and destroyed by the functions: + +cql_transform_t cql_transform_open_FILE (FILE *f); +cql_transform_t cql_transform_open_fname(const char *fname); +void cql_transform_close(cql_transform_t ct); + + The first two functions create a tranformation handle from + either an already open FILE or from a filename respectively. + + + The handle is destroyed by cql_transform_close + in which case no further reference of the handle is allowed. + + + When a cql_transform_t handle has been created + you can convert to RPN. + +int cql_transform_buf(cql_transform_t ct, + struct cql_node *cn, char *out, int max); + + This function converts the CQL tree cn + using handle ct. + For the resulting PQF, you supply a buffer out + which must be able to hold at at least max + characters. + + + If conversion failed, cql_transform_buf + returns a non-zero SRW error code; otherwise zero is returned + (conversion successful). The meanings of the numeric error + codes are listed in the SRW specifications at + + + + If conversion fails, more information can be obtained by calling + +int cql_transform_error(cql_transform_t ct, char **addinfop); + + This function returns the most recently returned numeric + error-code and sets the string-pointer at + *addinfop to point to a string containing + additional information about the error that occurred: for + example, if the error code is 15 (``Illegal or unsupported context + set''), the additional information is the name of the requested + context set that was not recognised. + + + The SRW error-codes may be translated into brief human-readable + error messages using + +const char *cql_strerror(int code); + + + + If you wish to be able to produce a PQF result in a different + way, there are two alternatives. + +void cql_transform_pr(cql_transform_t ct, + struct cql_node *cn, + void (*pr)(const char *buf, void *client_data), + void *client_data); + +int cql_transform_FILE(cql_transform_t ct, + struct cql_node *cn, FILE *f); + + The former function produces output to a user-defined + output stream. The latter writes the result to an already + open FILE. + + + + Specification of CQL to RPN mapping + + The file supplied to functions + cql_transform_open_FILE, + cql_transform_open_fname follows + a structure found in many Unix utilities. + It consists of mapping specifications - one per line. + Lines starting with # are ignored (comments). + + + Each line is of the form + + CQL pattern = RPN equivalent + + + + An RPN pattern is a simple attribute list. Each attribute pair + takes the form: + + [set] type=value + + The attribute set is optional. + The type is the attribute type, + value the attribute value. + + + The following CQL patterns are recognized: + + + index.set.name + + + + This pattern is invoked when a CQL index, such as + dc.title is converted. set + and name are the context set and index + name respectively. + Typically, the RPN specifies an equivalent use attribute. + + + For terms not bound by an index the pattern + index.cql.serverChoice is used. + Here, the prefix cql is defined as + http://www.loc.gov/zing/cql/cql-indexes/v1.0/. + If this pattern is not defined, the mapping will fail. + + + + + qualifier.set.name + (DEPRECATED) + + + + For backwards compatibility, this is recognised as a synonym of + index.set.name + + + + + relation.relation + + + + This pattern specifies how a CQL relation is mapped to RPN. + pattern is name of relation + operator. Since = is used as + separator between CQL pattern and RPN, CQL relations + including = cannot be + used directly. To avoid a conflict, the names + ge, + eq, + le, + must be used for CQL operators, greater-than-or-equal, + equal, less-than-or-equal respectively. + The RPN pattern is supposed to include a relation attribute. + + + For terms not bound by a relation, the pattern + relation.scr is used. If the pattern + is not defined, the mapping will fail. + + + The special pattern, relation.* is used + when no other relation pattern is matched. + + + + + + relationModifier.mod + + + + This pattern specifies how a CQL relation modifier is mapped to RPN. + The RPN pattern is usually a relation attribute. + + + + + + structure.type + + + + This pattern specifies how a CQL structure is mapped to RPN. + Note that this CQL pattern is somewhat to similar to + CQL pattern relation. + The type is a CQL relation. + + + The pattern, structure.* is used + when no other structure pattern is matched. + Usually, the RPN equivalent specifies a structure attribute. + + + + + + position.type + + + + This pattern specifies how the anchor (position) of + CQL is mapped to RPN. + The type is one + of first, any, + last, firstAndLast. + + + The pattern, position.* is used + when no other position pattern is matched. + + + + + + set.prefix + + + + This specification defines a CQL context set for a given prefix. + The value on the right hand side is the URI for the set - + not RPN. All prefixes used in + index patterns must be defined this way. + + + + + + CQL to RPN mapping file + + This simple file defines two context sets, three indexes and three + relations, a position pattern and a default structure. + + + + + With the mappings above, the CQL query + + computer + + is converted to the PQF: + + @attr 1=1016 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "computer" + + by rules index.cql.serverChoice, + relation.scr, structure.*, + position.any. + + + CQL query + + computer^ + + is rejected, since position.right is + undefined. + + + CQL query + + >my = "http://www.loc.gov/zing/cql/dc-indexes/v1.0/" my.title = x + + is converted to + + @attr 1=4 @attr 2=3 @attr 4=1 @attr 3=3 @attr 6=1 "x" + + + + + CQL to XCQL conversion + + Conversion from CQL to XCQL is trivial and does not + require a mapping to be defined. + There three functions to choose from depending on the + way you wish to store the resulting output (XML buffer + containing XCQL). + +int cql_to_xml_buf(struct cql_node *cn, char *out, int max); +void cql_to_xml(struct cql_node *cn, + void (*pr)(const char *buf, void *client_data), + void *client_data); +void cql_to_xml_stdio(struct cql_node *cn, FILE *f); + + Function cql_to_xml_buf converts + to XCQL and stores result in a user supplied buffer of a given + max size. + + + cql_to_xml writes the result in + a user defined output stream. + cql_to_xml_stdio writes to a + a file. + + + Object Identifiers @@ -418,7 +1500,7 @@ 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. @@ -445,15 +1527,13 @@ typedef struct oident PROTO_Z3950 - PROTO_SR + PROTO_GENERAL - If you don't care about talking to SR-based implementations (few - exist, and they may become fewer still if and when the ISO SR and ANSI - Z39.50 documents are merged into a single standard), you can ignore - this field on incoming packages, and always set it to PROTO_Z3950 - for outgoing packages. + Use PROTO_Z3950 for Z39.50 Object Identifers, + PROTO_GENERAL for other types (such as + those associated with ILL). @@ -540,6 +1620,10 @@ typedef struct oident again, corresponding to the specific OIDs defined by the standard. + Refer to the + + Registry of Z39.50 Object Identifiers for the + whole list. @@ -584,7 +1668,7 @@ 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. @@ -604,6 +1688,49 @@ typedef struct oident + Three utility functions are provided for translating OIDs' + symbolic names (e.g. Usmarc into OID structures + (int arrays) and strings containing the OID in dotted notation + (e.g. 1.2.840.10003.9.5.1). They are: + + + + int *oid_name_to_oid(oid_class oclass, const char *name, int *oid); + char *oid_to_dotstring(const int *oid, char *oidbuf); + char *oid_name_to_dotstring(oid_class oclass, const char *name, char *oidbuf); + + + + oid_name_to_oid() + translates the specified symbolic name, + interpreted as being of class oclass. (The + class must be specified as many symbolic names exist within + multiple classes - for example, Zthes is the + symbolic name of an attribute set, a schema and a tag-set.) The + sequence of integers representing the OID is written into the + area oid provided by the caller; it is the + caller's responsibility to ensure that this area is large enough + to contain the translated OID. As a convenience, the address of + the buffer (i.e. the value of oid) is + returned. + + + oid_to_dotstring() + Translates the int-array oid into a dotted + string which is written into the area oidbuf + supplied by the caller; it is the caller's responsibility to + ensure that this area is large enough. The address of the buffer + is returned. + + + oid_name_to_dotstring() + combines the previous two functions to derive a dotted string + representing the OID specified by oclass and + name, writing it into the buffer passed as + oidbuf and returning its address. + + + Finally, the module provides the following utility functions, whose meaning should be obvious: @@ -641,7 +1768,7 @@ typedef struct oident release the associated memory again. For the structures describing the Z39.50 PDUs and related structures, it is convenient to use the memory-management system of the &odr; subsystem (see - Using ODR). However, in some circumstances + ). However, in some circumstances where you might otherwise benefit from using a simple nibble memory management system, it may be impractical to use odr_malloc() and odr_reset().