+# Construct an opaque identifier from its components. Although it's
+# trivial, this is needed in so many places that it really needs to be
+# factored out.
+#
+# This is the converse of _parse_target_string() in IRSpy.pm, which
+# should be renamed and moved into this package.
+#
+sub irspy_make_identifier {
+ my($protocol, $host, $port, $dbname) = @_;
+
+ die "irspy_make_identifier(" . join(", ", map { "'$_'" } @_).
+ "): wrong number of arguments" if @_ != 4;
+
+ die "irspy_make_identifier(): protocol undefined" if !defined $protocol;
+ die "irspy_make_identifier(): host undefined" if !defined $host;
+ die "irspy_make_identifier(): port undefined" if !defined $port;
+ die "irspy_make_identifier(): dbname undefined" if !defined $dbname;
+
+ return "$protocol:$host:$port/$dbname";
+}
+
+
+# Returns the opaque identifier of an IRSpy record based on the
+# XPathContext'ed DOM object, as returned by irspy_xpath_context().
+# This is doing the same thing as irspy_make_identifier() but from a
+# record rather than a set of parameters.
+#
+sub irspy_record2identifier {
+ my($xc) = @_;
+
+ ### Must be kept the same as is used in ../../../zebra/*.xsl
+ return $xc->find("concat(e:serverInfo/\@protocol, ':',
+ e:serverInfo/e:host, ':',
+ e:serverInfo/e:port, '/',
+ e:serverInfo/e:database)");
+}
+
+
+# Transforms an IRSpy opqaue identifier, as returned from
+# irspy_make_identifier() or irspy_record2identifier(), into a YAZ
+# target-string suitable for feeding to ZOOM. Before we introduced
+# the protocol element at the start of the identifier string, this was
+# a null transform; now we have to be a bit cleverer.
+#
+sub irspy_identifier2target {
+ my $res = _irspy_identifier2target(@_);
+ #carp "converted ID '@_' to target '$res'";
+ return $res;
+}
+
+sub _irspy_identifier2target {
+ my($id) = @_;
+
+ confess "_irspy_identifier2target(): id is undefined"
+ if !defined $id;
+
+ my($protocol, $target) = ($id =~ /(.*?):(.*)/);
+ if (uc($protocol) eq "Z39.50" || uc($protocol) eq "TCP") {
+ return "tcp:$target";
+ } elsif (uc($protocol) eq "SRU") {
+ return "sru=get,http:$target";
+ } elsif (uc($protocol) eq "SRW") {
+ return "sru=srw,http:$target";
+ }
+
+ warn "_irspy_identifier2target($id): unrecognised protocol '$protocol'";
+ return $target;
+}
+
+
+# Modifies the XML document for which $xc is an XPath context by
+# inserting or replacing the values specified in the hash %$data. The
+# keys are fieldnames, which are looked up in the register
+# $fieldsByKey to determine, among other things, what their XPath is.
+