X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Ffrontend.xml;h=985f4bd18348a9985b74ea7db56e3f8b4afcef5a;hb=60f5103f542e3f6dd2e22b6df7015f7bc4b3a937;hp=99f49094e835fccd4651498f8720acbe030b7283;hpb=519fe26fff30687caa26c4a26038d02dcc0429c8;p=yaz-moved-to-github.git diff --git a/doc/frontend.xml b/doc/frontend.xml index 99f4909..985f4bd 100644 --- a/doc/frontend.xml +++ b/doc/frontend.xml @@ -1,4 +1,4 @@ - + Generic server Introduction @@ -13,7 +13,7 @@ If you have a database system that you would like to make available by - means of Z39.50, &yaz; basically offers your two options. You + means of Z39.50, SRW o SRU, &yaz; basically offers your two options. You can use the APIs provided by the &asn;, &odr;, and &comstack; modules to create and decode PDUs, and exchange them with a client. @@ -41,6 +41,12 @@ too many structural changes in existing applications. + + + + The &yaz; server does not support XCQL. + + The Database Frontend @@ -93,6 +99,10 @@ Result-Set Sort (optional). + + Return Explain for SRW/SRU (optional). + + @@ -226,7 +236,7 @@ statserv_options_block *statserv_getcontrol(void); int idle_timeout; Maximum session idle-time, in minutes. Zero indicates - no (infinite) timeout. Default is 120 minutes. + no (infinite) timeout. Default is 15 minutes. @@ -324,6 +334,13 @@ bend_initresult (*bend_init)(bend_initrequest *r); bend_init handler is passed in the call to statserv_start. + + + This handler is also called when operating in SRW/SRU mode - when + a connection has been made (even though SRW/SRU does not offer + this service). + + Unlike previous versions of YAZ, the bend_init also serves as a handler that defines the Z39.50 services that the backend @@ -354,6 +371,13 @@ typedef struct bend_initrequest int (*bend_delete)(void *handle, bend_delete_rr *rr); int (*bend_scan)(void *handle, bend_scan_rr *rr); int (*bend_segment)(void *handle, bend_segment_rr *rr); + + ODR decode; /* decoding stream */ + /* character set and language negotiation - see include/yaz/z-charneg.h */ + Z_CharSetandLanguageNegotiation *charneg_request; + Z_External *charneg_response; + int (*bend_srw_explain)(void *handle, bend_explain_rr *rr); + int (*bend_srw_scan)(void *handle, bend_scan_rr *rr); } bend_initrequest; typedef struct bend_initresult @@ -440,13 +464,13 @@ typedef struct { int hits; /* number of hits */ int errcode; /* 0==OK */ char *errstring; /* system error string or NULL */ + Z_OtherInformation *search_info; } bend_search_rr; - The bend_search handler is a fairly close - approximation of a protocol Search Request - and Response PDUs + approximation of a protocol Z39.50 Search Request - and Response PDUs The setname is the resultSetName from the protocol. You are required to establish a mapping between the set name and whatever your backend database likes to use. @@ -477,7 +501,24 @@ typedef struct { defined error codes, and the suggested uses of the addinfo field. + + The bend_search handler is also called when + the frontend server receives a SRW/SRU SearchRetrieveRequest. + For SRW/SRU, a CQL query is usually provided by the client. + The CQL query is available as part of Z_Query + structure (note that CQL is now part of Z39.50 via an external). + To support CQL in existing implementations that only do Type-1, + we refer to the CQL-to-PQF tool described + here. + + + To maintain backwards compatibility, the frontend server + of yaz always assume that error codes are BIB-1 diagnostics. + For SRW/SRU operation, a Bib-1 diagnostic code is mapped to + SRW/SRU diagnostic. + + int (*bend_fetch) (void *handle, bend_fetch_rr *rr); @@ -500,21 +541,22 @@ typedef struct bend_fetch_rr { int errcode; /* 0==success */ char *errstring; /* system error string or NULL */ int surrogate_flag; /* surrogate diagnostic */ + char *schema; /* string record schema input/output */ } bend_fetch_rr; The frontend server calls the bend_fetch handler - when it needs database records to fulfill a Search Request or a Present - Request. + when it needs database records to fulfill a Z39.50 Search Request, a + Z39.50 Present Request or a SRW SearchRetrieveRequest. The setname is simply the name of the result set that holds the reference to the desired record. The number is the offset into the set (with 1 being the first record in the set). The format field - is the record format requested by the client (See section - Object Identifiers). The value - VAL_NONE indicates that the client did not - request a specific format. The stream argument + is the record format requested by the client (See + ). + The value VAL_NONE indicates that the client did + not request a specific format. The stream argument is an &odr; stream which should be used for allocating space for structured data records. The stream will be reset when all records have been assembled, and @@ -524,11 +566,21 @@ typedef struct bend_fetch_rr { + If a SRW/SRU SearchRetrieveRequest is received by the frontend server, + the referenceId is NULL and the + request_format (transfer syntax) is XML (OID name + VAL_TEXT_XML). + The schema for SRW/SRU is stored in both the + Z_RecordComposition + structure and schema (simple string). + + + In the structure, the basename is the name of the database that holds the record. len is the length of the record returned, in bytes, and record is a pointer to the record. - Last_in_set should be nonzero only if the record + last_in_set should be nonzero only if the record returned is the last one in the given result set. errcode and errstring, if given, will be interpreted as a global error pertaining to the @@ -588,7 +640,8 @@ typedef struct { The bend_present handler is called when - the server receives a Present Request. The setname, + the server receives a Z39.50 Present Request. + The setname, start and number is the name of the result set - start position - and number of records to be retrieved respectively. format and @@ -669,8 +722,22 @@ typedef struct bend_scan_rr { bend_scan_status status; int errcode; char *errstring; + char *scanClause; /* CQL scan clause */ } bend_scan_rr; + + This backend server handles both Z39.50 scan + and SRW/SRU scan. In order for a + handler to distinguish between SRW/SRU (CQL) scan + Z39.50 Scan , it must check for a non-NULL value of + scanClause. + + + + if designed today, it would be a choice using a union or similar, + but that would break binary compatibility with existing servers. + + @@ -680,27 +747,13 @@ typedef struct bend_scan_rr { The finished application has the following invocation syntax (by way of statserv_main()): - - - appname - - - - - - - - - - - - listener-spec - + + &gfs-synopsis; The options are: - &ztest-options; + &gfs-options; @@ -718,7 +771,7 @@ typedef struct bend_scan_rr { hostname | IP-number [: portnumber] - + The port number defaults to 210 (standard Z39.50 port). @@ -728,22 +781,62 @@ typedef struct bend_scan_rr { - For TCP/IP and SSL, the special hostname "@" is mapped to - the address INADDR_ANY, which causes the - server to listen on any local interface. - - - - Examples: - - tcp:@:210 - - ssl:@:3000 - - unix:/tmp/yaz - + For TCP/IP and SSL, the special hostname @ + (at sign) is mapped to the address INADDR_ANY, + which causes the server to listen on any local interface. + Running the GFS on Unix + + Assuming the server application appname is + started as root, the following will make it listen on port 210. + The server will change identity to nobody + and write its log to /var/log/app.log. + + appname -l /var/log/app.log -u nobody tcp:@:210 + + + + The server will accept Z39.50 requests and offer SRW/SRU service + on port 210. + + + Setting up Apache as SRW/SRU Frontend + + If you use Apache + as your public web server and want to offer HTTP port 80 + access to the YAZ server on 210, you can use the + + ProxyPass + directive. + If you have virtual host + srw.mydomain you can use the following directives + in Apache's httpd.conf: + + <VirtualHost *> + ErrorLog /home/srw/logs/error_log + TransferLog /home/srw/logs/access_log + ProxyPass / http://srw.mydomain:210/ + </VirtualHost> + + + + The above for the Apache 1.3 series. + + + Running a server with local access only + + Servers that is only being accessed from the local host should listen + on UNIX file socket rather than a Internet socket. To listen on + /tmp/mysocket start the server as follows: + + appname tcp:/tmp/mysocket + + + + + Virtual Hosts + &gfs-virtual;