X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Fzoom.xml;h=c748e969f12fdf2496b5b5ef9d4c896a2e759d96;hb=f7471d960fb2671c714bdfcd74dae39ce8112652;hp=1a0aa9eba6987c446df0ae59e14ac0d59de38242;hpb=69bcd68523a9a8da083faef16887100369152673;p=yaz-moved-to-github.git diff --git a/doc/zoom.xml b/doc/zoom.xml index 1a0aa9e..c748e96 100644 --- a/doc/zoom.xml +++ b/doc/zoom.xml @@ -1,20 +1,23 @@ - - ZOOM + + Building clients with ZOOM - &zoom; is an acronym for Z39.50 Object Oriented Model and is - an initiative started by Mike Taylor. The goal of &zoom; is to + &zoom; is an acronym for 'Z39.50 Object-Orientation Model' and is + an initiative started by Mike Taylor (Mike is from the UK, which + explains the peculiar name of the model). The goal of &zoom; is to provide a common Z39.50 client API not bound to a particular programming language or toolkit. - The lack of a simple Z39.50 client API for &yaz; was more apparanet - than ever. So, when the first ZOOM specification was available - an implementation for &yaz; was developed. For the first time, it is - now easier to develop clients than servers with &yaz;. This - chapter describes the ZOOM C binding. Before going futher - reconsider whether C is still the programming language of your - choice. There are other language bindings available and others + 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 + 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 + 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 zoom.z3950.org for more information. @@ -29,7 +32,7 @@ The C language misses many features found in object oriented languages - such as C++, Java, etc. For example, you'll have to, manually, + 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 _create - and a _destroy variant. @@ -37,10 +40,9 @@ that because of typedefs. All destroy methods should gracefully ignore a NULL pointer. - Connections + Connections - The connection object Z3950_connection describes - the connection between your client and a server. + The Connection object is a session with a target. #include <yaz/zoom.h> @@ -57,25 +59,26 @@ Connection objects are created with either function Z3950_connection_new or Z3950_connection_create. - The former both creates and attempts to establishes a network - connection with the target. The latter doesn't establishes - a connection immediately, thus allowing you to set specify options - before establishing network connection using 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 Z3950_connection_connect. If the portnumber, portnum, is zero, the host is consulted for a port specification. If no port is given, 210 is used. A colon denotes the beginning of a port number in the host string. If the host string includes a - slash that specifies a database for the connection. + slash, the following part specifies a database for the connection. - Connection objects should be destroyed using function + Connection objects should be destroyed using the function Z3950_connection_destroy. const char *Z3950_connection_option (Z3950_connection c, const char *key, const char *val); + const char *Z3950_connection_host (Z3950_connection c); The Z3950_connection_option allows you to @@ -83,17 +86,56 @@ for the connection. If val is non-NULL that holds the new value for option. - Otherwise, if val is NULL + Otherwise, if val is + NULL, the option is unchanged. The function returns the previous value of the option. - - const char *Z3950_connection_host (Z3950_connection c); - - + ZOOM Connection Options + + + + + + + Option + Description + Default + + + + + implementationNameName of Your client + none + + userAuthentication user name + none + + groupAuthentication group name + none + + passAuthentication password + none + + proxyProxy host + none + + asyncIf true (1) the connection operates in + asynchronous operation which means that all calls are non-blocking + except Z3950_event. + 0 + + maximumRecordSize Maximum size of single record. + 1 MB + + preferredMessageSize Maximum size of multiple records. + 1 MB + + +
Function Z3950_connection_host returns - the host for the connection as specified in either a call to + the host for the connection as specified in a call to Z3950_connection_new or Z3950_connection_connect. This function returns NULL if host isn't @@ -112,7 +154,7 @@ non-NULL. - Search objects + Search objects Search objects defines how result sets are obtained. They act like queries. @@ -129,19 +171,21 @@ Create search objects using Z3950_search_create and destroy them by calling Z3950_search_destroy. - RPN-queries can be specified in PQF notation by using the + RPN-queries can be specified in PQF + notation by using the function Z3950_search_prefix. More - query types will be added later, such as CCL to RPN-mapping, CCL - query, etc. - In addition to a search a sort critieria may be set. Function - Z3950_search_sortby specifies a sort - criteria using the same string notation for sort as offered by - the YAZ client. + query types will be added later, such as + CCL to RPN-mapping, native CCL query, + etc. In addition to a search, a sort criteria may be set. Function + Z3950_search_sortby specifies a + sort criteria using the same string notation for sort as offered by + the YAZ client. - Result sets + Result sets - The result set describes a collection of records obtained from + The result set object is a container for records returned from + a target. search. @@ -158,9 +202,8 @@ a result set given a connection - and search object. Destroy a result set by calling Z3950_resultset_destroy. - Simple clients using YAZ' prefix query format may use - function Z3950_connection_search_pqf - instead. + Simple clients using PQF only may use function + Z3950_connection_search_pqf instead. const char *Z3950_resultset_option (Z3950_resultset r, @@ -171,35 +214,121 @@ void *Z3950_resultset_get (Z3950_resultset s, int pos, const char *type, int *len); - void Z3950_resultset_records (Z3950_resultset r, - Z3950_record *recs, - size_t *cnt); - Description of result sets here. + Function Z3950_resultset_options sets or + modifies an option for a result set similar to + Z3950_connection_option. + + The number of hits also called result-count is returned by + function Z3950_resultset_size. + + + Function Z3950_resultset_get is similar to + + Z3950_record_get but + instead of operating on a record object, it operates on a record on + a given offset within a result set. + + ZOOM Result set Options + + + + + + + Option + Description + Default + + + + + piggybackTrue (1) if piggyback should be + used in searches; false (0) if not. + 1 + + startOffset of first record we wish to + retrieve from the target. Note first record has offset 0 + unlike the protocol specifications where first record has position + 1. + 0 + + countNumber of records to be retrieved. + 0 + + elementSetNameElement-Set name of records. + Most targets should honor element set name B + and F for brief and full respectively. + none + + preferredRecordSyntaxPreferred Syntax, such as + USMARC, SUTRS, etc. + none + + databaseNameOne or more database names + separated by character plus (+). + Default + + +
- Records + Records A record object is a retrival record on the client side - created from result sets. + void Z3950_resultset_records (Z3950_resultset r, + Z3950_record *recs, + size_t *cnt); Z3950_record Z3950_resultset_record (Z3950_resultset s, int pos); - Z3950_record Z3950_resultset_record_immediate (Z3950_resultset s, - int pos); - void *Z3950_record_get (Z3950_record rec, const char *type, int *len); void Z3950_record_destroy (Z3950_record rec); + + Records are created by functions + Z3950_resultset_records or + Z3950_resultset_record + and destroyed by Z3950_record_destroy. + + + A single record is created and returned by function + Z3950_resultset_record that takes a + position as argument. First record has position zero. + If no record could be obtained NULL is returned. + + + Function Z3950_resultset_records retrieves + a number of records from a result set. Options start + and count specifies the range of records to + be returned. Upon completion recs[0], ..recs[*cnt] + holds record objects for the records. These array of records + recs should be allocate prior to calling + Z3950_resultset_records. Note that for + records that couldn't be retrieved from the target + recs[ ..] is NULL. + + + In order to extract information about a single record, + Z3950_record_get is provided. The + function returns a pointer to certain record information. The + nature (type) of the pointer depends on the type + given. In addition for certain types, the length + len passed will be set to the size in bytes of + the returned information. The types database, + syntax and render are + supported. More will be added later. + - Options + Options - Most objects in &zoom; allows you to specify options to change - behaviour. From an implementation point of view a set of options + Most objects in &zoom; allow you to specify options to change + default behaviour. From an implementation point of view a set of options is just like an associate array / hash array, etc. @@ -225,14 +354,29 @@ void *handle); - Events + Events - If you're developing non-blocking applications you have to deal + If you're developing non-blocking applications, you have to deal with events. int Z3950_event (int no, Z3950_connection *cs); + + The Z3950_event executes pending events for + a number of connections. Supply the number of connections in + no and an array of connections in + cs (cs[0] ... cs[no-1]). + 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 + returns a positive integer n denoting that an event + occurred for connection cs[n-1]. + When no events are pending for the connections, a value of zero is + returned. + To make sure all outstanding requests are performed call this function + repeatedly until zero is returned. +