PresentRequest ::= SEQUENCE {
referenceId [2] IMPLICIT OCTET STRING OPTIONAL,
resultSetId [31] IMPLICIT VisibleString,
resultSetStartPoint [30] IMPLICIT INTEGER,
numberOfRecordsRequested [30] IMPLICIT INTEGER,
elementSetNames ElementSetNames OPTIONAL,
preferredRecordSyntax [104] IMPLICIT OBJECT IDENTIFIER OPTIONAL
}
\270\020\237\037\007default\236\001\001\235\001\012What's behind it:
presentRequest = { \270\020
resultSetId = "default" \237\037\007default
resultSetStartPoint = 1 \236\001\001
numberOfRecordsRequested = 10 \235\001\012
}
One more view of the same thing (see ISO 8825 for details):
tag=24, Class=2, form=1, count=3
tag=31, Class=2, form=0, count=7
data=default
6666767
45615C4
tag=30, Class=2, form=0, count=1
data=.
0
1
tag=29, Class=2, form=0, count=1
data=.
0
A
1/1003 4/1 5/100 3/2 6/1 2/3 Type/Value Meaning 1/1003 author 4/1 with words structured as a phrase 5/100 no truncation 3/2 compared with the first item in the field 6/1 not necessarily consuming an entire subfield 2/3 and compared for equality
-> Begin Type-1 query
query = {
type-1 = {
-> Specify Bib-1 attribute set
attributeSet = OID 1.2.840.10003.3.1
-> Begin RPN query
rpn = {
rpnRpnOp = {
rpn1 = {
op = {
attrTerm = {
attributes = {
use = Body of text
position = Any position in subfield
structure = Word list
completeness = Incomplete subfield
}
-> User's first search term
term = {
general = "heart"
}
}
}
}
rpn2 = {
op = {
attrTerm = {
attributes = {
use = Body of text
position = Any position in subfield
structure = Word list
completeness = Incomplete subfield
}
-> User's second search term
term = {
general = "depression"
}
}
}
}
-> Boolean AND connecting user's first and second search terms
op = {
and = and
}
}
}
}
}
The actual communication between server and client is encoded in the BER binary format. What appears below is an annotated translation of a binary log of a Z39.50 session, as produced by a pretty-printer utility.
Note:
Client requests below are marked by lines beginning with C:
Server requests and actions are marked by lines beginning with S:
Lines beginning with -> are descriptive comments
-> Server senses an incoming TCP connection
S:Association with myhost.Berkeley.EDU
-> PDU 1: Client sends an initialization request
C:initRequest = {
-> Client states versions it supports
C: protocolVersion = {
C: version-1(0)
C: version-2(1)
C: }
C: options = {
-> Client states facilities & features it would use
C: search(0)
C: present(1)
C: delSet(2)
C: resourceReport(3)
C: triggerResourceCtrl(4)
C: resourceCtrl(5)
C: accessCtrl(6)
C: }
-> Client proposes some buffer sizes
C: preferredMessageSize = 4096
C: exceptionalRecordSize = 8192
-> Client software announces its identity
C: implementationId = "1991"
C: implementationName = "UCB Info Client"
C: implementationVersion = "0.2"
C:}
-> PDU 2: Server responds to initialization request
-> Server states versions it supports
S:initResponse = {
S: protocolVersion = {
S: version-1(0)
S: version-2(1)
S: }
-> Server states features it supports
S: options = {
S: search(0)
S: present(1)
S: delSet(2)
S: }
-> Server agrees with buffer sizes (the server always has the last word)
S: preferredMessageSize = 4096
S: exceptionalRecordSize = 8192
-> Z39.50 (not TCP) session "accepted"
S: result = true
-> Server software announces its identity
S: implementationId = "1994"
S: implementationName = "NLM MEDLARS Server"
S: implementationVersion = "0.3"
-> Server sends information that client may optionally display
S: userInformationField = {
S: data = "
S:Welcome to the NLM Z39.50 server (beta)
S:
S:"
S: }
S:}
-> PDU 3: Client sends a search request
C:searchRequest = {
-> Three numbers saying the client wants only one record back, and only if the total count < 100
C: smallSetUpperBound = 1
C: largeSetLowerBound = 100
C: mediumSetPresentNumber = 1
-> Replace any existing result set of the same name
C: replaceIndicator = true
-> Client sends the name of the result set
C: resultSetName = "default"
C: databaseNames = {
C: "medline"
C: }
-> Begin Type-1 query
C: query = {
C: type-1 = {
-> Specify Bib-1 attribute set
C: attributeSet = OID 1.2.840.10003.3.1
-> Begin RPN query
C: rpn = {
C: op = {
C: attrTerm = {
C: attributes = {
C: relation = Equal
C: use = Subject
C: }
-> User's search term
C: term = {
C: general = "heart"
C: }
C: }
C: }
C: }
C: }
C: }
C:}
-> PDU 4: Server responds to search request
S:searchResponse = {
S: resultCount = 7927
S: numberOfRecordsReturned = 0
S: nextResultSetPosition = 1
S: searchStatus = true
S: presentStatus = success(0)
S:}
-> PDU 5: Client sends a present request
C:presentRequest = {
C: resultSetId = "default"
-> Send one record starting at record 5555 within result set
C: resultSetStartPoint = 5555
C: numberOfRecordsRequested = 1
C:}
-> PDU 6: Server responds to present request
S:presentResponse = {
S: numberOfRecordsReturned = 1
-> Number of record following last one delivered
S: nextResultSetPosition = 5556
S: presentStatus = success(0)
S: records = {
S: responseRecords = {
S: {
-> The requested record
S: record = {
S: retrievalRecord = {
-> Record is in USMARC format
S: id = OID 1.2.840.10003.5.10
-> Beginning of the record itself (truncated)
S: data = "02729naa 2200336z 450000100[...]"
-> [Rest of record deleted in this example]
S: }
S: }
S: }
S: }
S: }
S:}
-> Server senses that client has closed TCP connection (no PDU sent to client)
S:Association closed: release or abort.