<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>1998</year>
      <year>2016</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
 
      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>mnesia_registry</title>
    <prepared>Dan Gudmundsson and H&aring;kan Mattsson</prepared>
    <responsible></responsible>
    <docno></docno>
    <approved></approved>
    <checked></checked>
    <date>98-04-24</date>
    <rev>A</rev>
    <file>mnesia_registry.sgml</file>
  </header>
  <module>mnesia_registry</module>
  <modulesummary>Dump support for registries in erl_interface.</modulesummary>
  <description>
    <p>This module is usually part of the <c>erl_interface</c>
      application, but is currently part of the <c>Mnesia</c>
      application.</p>
    <p>This module is mainly intended for internal use within OTP,
      but it has two functions that are exported for public use.</p>
    <p>On C-nodes, <c>erl_interface</c> has support for registry
      tables. These tables reside in RAM on the C-node, but can also
      be dumped into <c>Mnesia</c> tables. By default, the dumping
      of registry tables through <c>erl_interface</c> causes a
      corresponding <c>Mnesia</c> table to be created with
      <c>mnesia_registry:create_table/1</c>, if necessary.</p>
    <p>Tables that are created with these functions can be
      administered as all other <c>Mnesia</c> tables. They can be
      included in backups, replicas can be added, and so on.
      The tables are normal <c>Mnesia</c> tables owned by the user
      of the corresponding <c>erl_interface</c> registries.</p>
  </description>

  <funcs>
    <func>
      <name>create_table(Tab) -> ok | exit(Reason)</name>
      <fsummary>Creates a registry table in Mnesia.</fsummary>
      <desc>
        <p>A wrapper function for <c>mnesia:create_table/2</c>,
          which creates a table (if there is no existing table)
          with an appropriate set of <c>attributes</c>. The table
          only resides on the local node and its storage type is
          the same as the <c>schema</c> table on the local node,
          that is, <c>{ram_copies,[node()]}</c> or
          <c>{disc_copies,[node()]}</c>.</p>
        <p>This function is used by <c>erl_interface</c> to
          create the <c>Mnesia</c> table if it does not already
          exist.</p>
      </desc>
    </func>
    <func>
      <name>create_table(Tab, TabDef) -> ok | exit(Reason)</name>
      <fsummary>Creates a customized registry table in Mnesia.</fsummary>
      <desc>
        <p>A wrapper function for <c>mnesia:create_table/2</c>,
          which creates a table (if there is no existing table)
          with an appropriate set of <c>attributes</c>. The
          attributes and <c>TabDef</c> are forwarded to
          <c>mnesia:create_table/2</c>. For example, if the table
          is to reside as <c>disc_only_copies</c> on all nodes,
          a call looks as follows:</p>
        <code type="none">
          TabDef = [{{disc_only_copies, node()|nodes()]}],
          mnesia_registry:create_table(my_reg, TabDef)</code>
      </desc>
    </func>
  </funcs>

  <section>
    <title>See Also</title>
    <p><seealso marker="erl_interface:index">erl_interface(3)</seealso>,
      <seealso marker="mnesia:mnesia">mnesia(3)</seealso></p>
  </section>

</erlref>