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7 <refentry id="ref-virt_db">
9 <refentrytitle>virt_db</refentrytitle>
10 <manvolnum>3mp</manvolnum>
11 <refmiscinfo>Metaproxy Module</refmiscinfo>
15 <refname>virt_db</refname>
16 <refpurpose>Metaproxy Virtual Databases Module</refpurpose>
19 <refsect1><title>DESCRIPTION</title>
21 This filter allows one Z39.50 database to be me mapped to
22 another target; or even multiple targets.
25 The configuration of virt_db consists of zero or more
26 <literal><virtual></literal> elements each describing the
27 Z39.50 virtual database recognized.
28 The name of the database is the text content of the
29 <literal><database></literal> element which should be
30 first element inside the virtual section.
33 For Metaproxy 1.0.20 and later, the database is treated as a glob pattern.
34 This allows operators * (any number of any character) and
35 ? (any single character). The virtual sections are inspected in
36 the order given. The first matching virtual database is used.
39 Following that is one or more <literal><target></literal>
40 elements with the identifier of each target that the virtual database
44 If multiple targets are given that has special meaning depending on the
45 filter following virt_db. If the following filter is load_balance, then
46 the load_balance filter will load balance between the targets given
47 (assuming they serve same content). If the following filter is multi,
48 then results will be merged from all targets instead.
51 The z3950_filter, on the other hand, does not support multiple targets.
54 For <literal><virtual></literal> a route may be given as
55 an attribute. This will make Metaproxy route traffic to the route
56 given. Note that virtual databases may not be combined if all
57 databases do not result in the same routing.
61 <refsect1><title>EXAMPLES</title>
63 Consider this virt_db configuration:
65 <filter type="virt_db">
67 <database>db1</database>
68 <target>localhost:9999/Default</target>
71 <database>db2</database>
72 <target>indexdata.com/gils</target>
75 <database>combined</database>
76 <target>indexdata.com/gils</target>
77 <target>localhost:9999/Default</target>
79 <virtual route="special">
80 <database>db3</database>
81 <target>indexdata.com/special</target>
84 <database>*</database><!-- default -->
85 <target>localhost:9999</target>
90 This will offer 4 databases, <literal>db1</literal>,
91 <literal>db2</literal>, <literal>combined</literal> and
92 <literal>db3</literal>. If a Z39.50 specifies <literal>db1</literal>
93 and <literal>db2</literal> that will have same effect as specifying
94 the single database <literal>combined</literal>.
97 Since <literal>db3</literal> routes differently from the other databases,
98 this database may not be combined with the others.
102 <refsect1><title>SEE ALSO</title>
105 <refentrytitle>metaproxy</refentrytitle>
106 <manvolnum>1</manvolnum>
111 <refentrytitle>multi</refentrytitle>
112 <manvolnum>3mp</manvolnum>
115 <refentrytitle>load_balance</refentrytitle>
116 <manvolnum>3mp</manvolnum>
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