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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 th virtual section.
33 Following that is one or more <literal><target></literal>
34 elements with the identifier of each target that the virtual database
38 If multiple targets are given that has special meaning depending on the
39 filter following virt_db. If the following filter is load_balance, then
40 the load_balance filter will load balance between the targets given
41 (assuming they serve same content). If the following filter is multi,
42 then results will be merged from all targets instead.
45 The z3950_filter, on the other hand, does not support multiple targets.
48 For <literal><virtual></literal> a route may be given as
49 an attribute. This will make Metaproxy route traffic to the route
50 given. Note that virtual databases may not be combined if all
51 databases do not result in the same routing.
55 <refsect1><title>EXAMPLES</title>
57 Consider this virt_db configuration:
59 <filter type="virt_db">
61 <database>db1</database>
62 <target>localhost:9999/Default</target>
65 <database>db2</database>
66 <target>indexdata.com/gils</target>
69 <database>combined</database>
70 <target>indexdata.com/gils</target>
71 <target>localhost:9999/Default</target>
73 <virtual route="special">
74 <database>db3</database>
75 <target>indexdata.com/special</target>
80 This will offer 4 databases, <literal>db1</literal>,
81 <literal>db2</literal>, <literal>combined</literal> and
82 <literal>db3</literal>. If a Z39.50 specifies <literal>db1</literal>
83 and <literal>db2</literal> that will have same effect as specifying
84 the single database <literal>combined</literal>.
87 Since <literal>db3</literal> routes differently from the other databases,
88 this database may not be combined with the others.
92 <refsect1><title>SEE ALSO</title>
95 <refentrytitle>metaproxy</refentrytitle>
96 <manvolnum>1</manvolnum>
101 <refentrytitle>multi</refentrytitle>
102 <manvolnum>3mp</manvolnum>
105 <refentrytitle>load_balance</refentrytitle>
106 <manvolnum>3mp</manvolnum>
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