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<cref>
  <header>
    <copyright>
      <year>1998</year><year>2009</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
      compliance with the License. You should have received a copy of the
      Erlang Public License along with this software. If not, it can be
      retrieved online at http://www.erlang.org/.
    
      Software distributed under the License is distributed on an "AS IS"
      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
      the License for the specific language governing rights and limitations
      under the License.
    
    </legalnotice>

    <title>erl_global</title>
    <prepared>Gordon Beaton</prepared>
    <responsible>Gordon Beaton</responsible>
    <docno></docno>
    <approved>Gordon Beaton</approved>
    <checked>Gordon Beaton</checked>
    <date>980703</date>
    <rev>A</rev>
    <file>erl_global.sgml</file>
  </header>
  <lib>erl_global</lib>
  <libsummary>Access globally registered names</libsummary>
  <description>
    <p>This module provides support for registering, looking
      up and unregistering names in the Erlang Global module. For more
      information, see the description of Global in the reference manual.</p>
    <p>Note that the functions below perform an RPC using an open file
      descriptor provided by the caller. This file descriptor must 
      not be used for other traffic during the global operation or the 
      function may receive unexpected data and fail.</p>
  </description>
  <funcs>
    <func>
      <name><ret>char **</ret><nametext>erl_global_names(fd,count)</nametext></name>
      <fsummary>Obtain list of Global names</fsummary>
      <type>
        <v>int fd;</v>
        <v>int *count;</v>
      </type>
      <desc>
        <p>Retrieve a list of all known global names.
          </p>
        <p><c><![CDATA[fd]]></c> is an open descriptor to an Erlang connection.
          </p>
        <p><c><![CDATA[count]]></c> is the address of an integer, or NULL. If
          <c><![CDATA[count]]></c> is not NULL, it will be set by the function to
          the number of names found.
          </p>
        <p>On success, the function returns an array of strings, each
          containing a single registered name, and sets <c><![CDATA[count]]></c> to
          the number of names found. The array is terminated
          by a single NULL pointer. On failure, the function returns
          NULL and <c><![CDATA[count]]></c> is not modified.
          </p>
        <note>
          <p>It is the caller's responsibility to free the array
            afterwards. It has been allocated by the function with a
            single call to <c><![CDATA[malloc()]]></c>, so a single <c><![CDATA[free()]]></c> is
            all that is necessary.</p>
        </note>
      </desc>
    </func>
    <func>
      <name><ret>int</ret><nametext>erl_global_register(fd,name,pid)</nametext></name>
      <fsummary>Register a name in Global</fsummary>
      <type>
        <v>int fd;</v>
        <v>const char *name;</v>
        <v>ETERM *pid;</v>
      </type>
      <desc>
        <p>This function registers a name in Global.
          </p>
        <p><c><![CDATA[fd]]></c> is an open descriptor to an Erlang connection.
          </p>
        <p><c><![CDATA[name]]></c> is the name to register in Global.
          </p>
        <p><c><![CDATA[pid]]></c> is the pid that should be associated with
          <c><![CDATA[name]]></c>. This is the value that Global will return when
          processes request the location of <c><![CDATA[name]]></c>.
          </p>
        <p>The function returns 0 on success, or -1 on failure.</p>
      </desc>
    </func>
    <func>
      <name><ret>int</ret><nametext>erl_global_unregister(fd,name)</nametext></name>
      <fsummary>Unregister a name in Global</fsummary>
      <type>
        <v>int fd;</v>
        <v>const char *name;</v>
      </type>
      <desc>
        <p>This function unregisters a name from Global.
          </p>
        <p><c><![CDATA[fd]]></c> is an open descriptor to an Erlang connection.
          </p>
        <p><c><![CDATA[name]]></c> is the name to unregister from Global.
          </p>
        <p>The function returns 0 on success, or -1 on failure.</p>
      </desc>
    </func>
    <func>
      <name><ret>ETERM *</ret><nametext>erl_global_whereis(fd,name,node)</nametext></name>
      <fsummary>Look up a name in global</fsummary>
      <type>
        <v>int fd;</v>
        <v>const char *name;</v>
        <v>char *node;</v>
      </type>
      <desc>
        <p><c><![CDATA[fd]]></c> is an open descriptor to an Erlang connection.
          </p>
        <p><c><![CDATA[name]]></c> is the name that is to be looked up in Global.
          </p>
        <p>If <c><![CDATA[node]]></c> is not NULL, it is a pointer to a buffer
          where the function can fill in the name of the node where
          <c><![CDATA[name]]></c> is found. <c><![CDATA[node]]></c> can be passed directly to
          <c><![CDATA[erl_connect()]]></c> if necessary.
          </p>
        <p>On success, the function returns an Erlang Pid containing the address
          of the given name, and node will be initialized to
          the nodename where <c><![CDATA[name]]></c> is found. On failure NULL will be
          returned and <c><![CDATA[node]]></c> will not be modified.</p>
      </desc>
    </func>
  </funcs>
</cref>

