path: root/lib/orber/doc/src/ch_install.xml

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<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>1997</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>Installing Orber</title>
    <prepared></prepared>
    <responsible></responsible>
    <docno></docno>
    <approved></approved>
    <checked></checked>
    <date>1998-09-28</date>
    <rev></rev>
    <file>ch_install.xml</file>
  </header>

  <section>
    <title>Installation Process </title>
    <p>This chapter describes how to install Orber in an Erlang
      Environment.</p>

    <section>
      <title>Preparation</title>
      <p>To begin with, you must decide if you want to run Orber as a:</p>
      <list type="bulleted">
        <item><em>Single node (non-distributed)</em> - all communication with other
         Orber instances and ORB's supplied by other vendors use the OMG
         GIOP protocol.</item>
        <item><em>Multi node (distributed)</em> - all Orber nodes, within the same
        <c>domain</c>, communicate via the Erlang distribution protocol.
         For all other Orber instances, i.e. not part of the same <c>domain</c>,
         and ORB's supplied by other vendors, the OMG GIOP protocol
         is used.</item>
      </list>
      <p>Which approach to use is highly implementation specific, but a few
        things you should consider:</p>
      <list type="bulleted">
        <item>All nodes within an Orber domain should have the same
         security level.</item>
        <item>If the capacity is greater than load (volume of traffic)
         a single-node Orber might be a good solution.</item>
        <item>In some cases the distributed system architecture requires a
         single-node <term id="Orber installation"><termdef>is the structure of the ORB or ORBs as defined during the install process is called the "installation".</termdef></term>.</item>
        <item>A multi-node Orber makes it possible to load balance
         and create a more fault tolerant system. The Objects
         can also have a uniform view if you use distributed
         Mnesia tables.</item>
        <item>Since the GIOP protocol creates a larger overhead than the
         Erlang distribution protocol, the performance will be better
         when communicating with Objects within the same Orber domain
         compared with inter ORB communication (GIOP).</item>
      </list>
      <p>You also have to decide if you want Orber to store internal data using
        <c>disc_copies</c> and/or <c>ram_copies</c>. Which storage type you should
        depends if/how you intend to use Mnesia in your application. If you
        intend to use <c>disc_copies</c> you must start with creating a Mnesia
        schema, which contain information about the location of the Erlang nodes
        where Orber is planned to be run. For more background information, 
        see the Mnesia documentation.</p>
      <p>In some cases it is absolutely necessary to change the default configuration
        of Orber. For example, if two Orber-ORB's shall be able to communicate
        via GIOP, they must have a unique <c>domain</c> domain. Consult the
        <seealso marker="ch_install#config">configuration settings</seealso>
        section. If  you encounter any problems; see the chapter about 
        <em>Debugging</em> in this User's Guide.</p>
    </section>

    <section>
      <title>Jump Start Orber</title>
      <p>The easiest way to start Orber is to use <c>orber:jump_start(Port)</c>,
        which start a single-node ORB with (most likely) a unique
        domain (i.e. "IP-number:Port"). This function may only be used
        during development and testing. For any other situation, install and
        start Orber as described in the following sections.
        The listen port, i.e. iiop_port configuration parameter, is set to
        the supplied Port.</p>
      <warning>
        <p>How Orber is configured when using <c>orber:jump_start(Port)</c>
          may change at any time without warning. Hence, this operation must
          not be used in systems delivered to a customer.</p>
      </warning>
    </section>

    <section>
      <title>Install Single Node Orber</title>
      <p>Since a single node Orber communicate via the OMG GIOP protocol it is not
        necessary to start the Erlang distribution (i.e. using <c>-name/-sname</c>).</p>
      <p>If we use <c>ram_copies</c> there is no need for creating a disk based
        schema. Simply use:</p>
      <code type="none">
erl> mnesia:start().
erl> corba:orb_init([{domain, "MyRAMSingleNodeORB"}]).
erl> orber:install([node()], [{ifr_storage_type, ram_copies}]).
erl> orber:start().
      </code>
      <p>If you installation requires <c>disc_copies</c> you must begin with
        creating a Mnesia schema. Otherwise, the installation is similar
        to a RAM installation:</p>
      <code type="none">
erl> mnesia:create_schema([node()]).
erl> mnesia:start().
erl> corba:orb_init([{domain, "MyDiskSingleNodeORB"}]).
erl> orber:install([node()], [{ifr_storage_type, disc_copies},
                              {nameservice_storage_type, disc_copies}]).
erl> orber:start().
      </code>
      <p>You can still choose to store the IFR data as ram_copies, but then
        the data must be re-installed (i.e. invoke <c>orber:install/2</c>)
        if the node is restarted. Hence, since the IFR data is rather static
        you should use <c>disc_copies</c>. For more information see the
        <c>orber</c> section in the reference manual.</p>
      <p>If you do not need to change Orber's configuration you can skip
        <seealso marker="corba">orb_init/1</seealso>. 
        But, you <em>should</em> at least set the IIOP timeout parameters.</p>
    </section>

    <section>
      <title>Install RAM Based Multi Node Orber</title>
      <p>Within a domain Orber uses the Erlang distribution protocol. Hence, you
        <em>must</em> start it first by, for example, using:</p>
      <code type="none">
hostA> erl -sname nodeA
      </code>
      <p>In this example, we assume that we want to use two nodes; <c>nodeA</c> and
        <c>nodeB</c>. Since Mnesia must know which other nodes should a part
        of the distribution we either need to add the Mnesia configuration
        parameter <c>extra_db_nodes</c> or use <c>mnesia:change_config/2</c>. To 
        begin with, Mnesia must be started on all nodes before we can install
        Orber:</p>
      <code type="none">
nodeA@hostA> mnesia:start().
nodeA@hostA> mnesia:change_config(extra_db_nodes, 
                                  [nodeA@hostA, nodeB@hostB]).
      </code>
      <p>After that the above have been repeated on <c>nodeB</c> we must
        first make sure that both nodes will use the same domain name, then
        we can install Orber:</p>
      <code type="none">
nodeA@hostA> corba:orb_init([{domain, "MyRAMMultiNodeORB"}]).
nodeA@hostA> orber:install([nodeA@hostA, nodeB@hostB],
                           [{ifr_storage_type, ram_copies}]).
nodeA@hostA> orber:start().
      </code>
      <p>Note that you can only invoke <c>orber:install/1/2</c> on one of the
        nodes. Now we can start Orber on the other node:</p>
      <code type="none">
nodeB@hostB> corba:orb_init([{domain, "MyRAMMultiNodeORB"}]).
nodeB@hostB> orber:start().
      </code>
    </section>

    <section>
      <title>Install Disk Based Multi Node Orber</title>
      <p>As for RAM based multi-node Orber installations, the Erlang distribution
        must be started (e.g. erl -sname nodeA). The major difference is that
        when it is disk based a Mnesia schema must be created:</p>
      <code type="none">
nodeA@hostA> mnesia:create_schema([nodeA@hostA, nodeB@hostB]).
nodeA@hostA> mnesia:start().
      </code>
      <p>In this example, we assume that we want to use two nodes; <c>nodeA</c> and
        <c>nodeB</c>. Since it is not possible to create a schema on more than 
        one node. Hence, all we have to do is to start Mnesia (i.e. invoke 
        <c>mnesia:start()</c>) on <c>nodeB</c>.</p>
      <p>After Mnesia have been started on all nodes, you must confirm that all 
        nodes have the same domain name, then Orber is ready to be installed:</p>
      <code type="none">
nodeA@hostA> corba:orb_init([{domain, "MyDiskMultiNodeORB"}]).
nodeA@hostA> orber:install([nodeA@hostA, nodeB@hostB],
                           [{ifr_storage_type, disc_copies}]).
nodeA@hostA> orber:start().
      </code>
      <p>Note that you can only invoke <c>orber:install/1/2</c> on one of the
        nodes. Now we can start Orber on the other node:</p>
      <code type="none">
nodeB@hostB> corba:orb_init([{domain, "MyDiskMultiNodeORB"}]).
nodeB@hostB> orber:start().
      </code>
    </section>

  </section>

  <section>
    <title>Configuration</title>
    <marker id="config"></marker>
    <p>It is essential that one configure Orber properly, to avoid, for example,
      malicious attacks and automatically terminate IIOP connections no longer
      in use. An easy way to extract information about Orber's configuration
      parameters is to invoke the operation
      <seealso marker="orber">orber:info/1/2</seealso>.
      Orber offer the following configuration parameters:</p>
    <table>
      <row>
        <cell align="center" valign="middle"><em>Key</em></cell>
        <cell align="center" valign="middle"><em>Range</em></cell>
        <cell align="center" valign="middle"><em>Default</em></cell>
      </row>
      <row>
        <cell align="left" valign="middle">domain</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">"ORBER"</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_port</cell>
        <cell align="left" valign="middle">integer() >= 0</cell>
        <cell align="left" valign="middle">4001</cell>
      </row>
      <row>
        <cell align="left" valign="middle">nat_iiop_port</cell>
        <cell align="left" valign="middle">integer() > 0 | {local, integer(), [{integer(), integer()}]}</cell>
        <cell align="left" valign="middle">The same as <c>iiop_port</c></cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_out_ports</cell>
        <cell align="left" valign="middle">0 | {integer(),integer()}</cell>
        <cell align="left" valign="middle">0</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_max_fragments</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_max_in_requests</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_max_in_connections</cell>
        <cell align="left" valign="middle">integer() > 0</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_backlog</cell>
        <cell align="left" valign="middle">integer() > 0</cell>
        <cell align="left" valign="middle">5</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_packet_size</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ip_address</cell>
        <cell align="left" valign="middle">string() | {multiple, [string()]}</cell>
        <cell align="left" valign="middle">All interfaces</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ip_address_local</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">Defined by the underlying system</cell>
      </row>
      <row>
        <cell align="left" valign="middle">nat_ip_address</cell>
        <cell align="left" valign="middle">string() | {multiple, [string()]} |  {local, string(), [{string(), string()}]}</cell>
        <cell align="left" valign="middle">The same as <c>ip_address</c></cell>
      </row>
      <row>
        <cell align="left" valign="middle">objectkeys_gc_time</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">giop_version</cell>
        <cell align="left" valign="middle">{1,0} | {1,1} | {1,2}</cell>
        <cell align="left" valign="middle">{1,1}</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_setup_connection_timeout</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_connection_timeout</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_in_connection_timeout</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_out_keepalive</cell>
        <cell align="left" valign="middle">true | false</cell>
        <cell align="left" valign="middle">false</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_in_keepalive</cell>
        <cell align="left" valign="middle">true | false</cell>
        <cell align="left" valign="middle">false</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_timeout</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">interceptors</cell>
        <cell align="left" valign="middle">{native, [atom()]}</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">local_interceptors</cell>
        <cell align="left" valign="middle">{native, [atom()]}</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">orbInitRef</cell>
        <cell align="left" valign="middle">[string()] | undefined</cell>
        <cell align="left" valign="middle">undefined</cell>
      </row>
      <row>
        <cell align="left" valign="middle">orbDefaultInitRef</cell>
        <cell align="left" valign="middle">string() | undefined</cell>
        <cell align="left" valign="middle">undefined</cell>
      </row>
      <row>
        <cell align="left" valign="middle">orber_debug_level</cell>
        <cell align="left" valign="middle">0 - 10</cell>
        <cell align="left" valign="middle">0</cell>
      </row>
      <row>
        <cell align="left" valign="middle">flags</cell>
        <cell align="left" valign="middle">integer() >= 0</cell>
        <cell align="left" valign="middle">0</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_acl</cell>
        <cell align="left" valign="middle">[{atom(), string()}] | [{atom(), string(), [string()]}]</cell>
        <cell align="left" valign="middle">[]</cell>
      </row>
      <row>
        <cell align="left" valign="middle">secure</cell>
        <cell align="left" valign="middle">no | ssl</cell>
        <cell align="left" valign="middle">no</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_generation</cell>
        <cell align="left" valign="middle">2 | 3</cell>
        <cell align="left" valign="middle">2</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_port</cell>
        <cell align="left" valign="middle">integer() >= 0</cell>
        <cell align="left" valign="middle">4002</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_accept_timeout</cell>
        <cell align="left" valign="middle">integer() > 0 | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_backlog</cell>
        <cell align="left" valign="middle">integer() > 0</cell>
        <cell align="left" valign="middle">5</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_ip_address_local</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">Defined by the underlying system</cell>
      </row>
      <row>
        <cell align="left" valign="middle">nat_iiop_ssl_port</cell>
        <cell align="left" valign="middle">integer() > 0 | {local, integer(), [{integer(), integer()}]}</cell>
        <cell align="left" valign="middle">The same as <c>iiop_ssl_port</c></cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_cacertfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_certfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_verify</cell>
        <cell align="left" valign="middle">0 | 1 | 2</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_depth</cell>
        <cell align="left" valign="middle">integer()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_password</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_keyfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_ciphers</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_server_cachetimeout</cell>
        <cell align="left" valign="middle">integer() | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_cacertfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_certfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_verify</cell>
        <cell align="left" valign="middle">0 | 1 | 2</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_depth</cell>
        <cell align="left" valign="middle">integer()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_password</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_keyfile</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_ciphers</cell>
        <cell align="left" valign="middle">string()</cell>
        <cell align="left" valign="middle">-</cell>
      </row>
      <row>
        <cell align="left" valign="middle">ssl_client_cachetimeout</cell>
        <cell align="left" valign="middle">integer() | infinity</cell>
        <cell align="left" valign="middle">infinity</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_out_keepalive</cell>
        <cell align="left" valign="middle">true | false</cell>
        <cell align="left" valign="middle">false</cell>
      </row>
      <row>
        <cell align="left" valign="middle">iiop_ssl_in_keepalive</cell>
        <cell align="left" valign="middle">true | false</cell>
        <cell align="left" valign="middle">false</cell>
      </row>
      <tcaption>Orber Configuration Parameters</tcaption>
    </table>
    <br></br>
    <br></br>
    <p><em>Comments on the table 'Orber Configuration Parameters':</em></p>
    <taglist>
      <tag><em>domain</em></tag>
      <item>Since Orber domains, they are supposed to communicate via IIOP,
      <em>MUST</em> have unique names, communication will
       fail if two domains have the same name. The domain name <em>MAY NOT</em>
       contain <c>^G</c> (i.e. <c>\007</c>).</item>
      <tag><em>iiop_port</em></tag>
      <item>If set to 0 the OS will pick any vacant port. 
            <br></br>
<em>Note:</em>On a UNIX system it is preferable to
       have a IIOP port higher than 1023, since it is not recommended to 
       run Erlang as a root user.</item>
      <tag><em>nat_iiop_port</em></tag>
      <item>The value is either an integer or <c>{local, DefaultNATPort, [{Port, NATPort}]}</c>. See also
      <seealso marker="ch_install#firewall">Firewall Configuration</seealso>.</item>
      <tag><em>iiop_out_ports</em></tag>
      <item>When set to 0 any available port will be used. 
       If a range is specified, Orber will only
       use the local ports within the interval when trying to connect to
       another ORB (Orber acts as a client ORB). If all ports are in use
       communication will fail. Hence, it is <em>absolutely necessary</em> to
       set <c>iiop_connection_timeout</c> as well. Otherwise, connections
       no longer in use will block further communication. If one use, for
       example, <c>erl -orber iiop_out_ports "{5000,5020}"</c>, Orber
       will only use port 5000 to 5020 when connecting.
       If communicating via SSL, make sure you use a version that supports
       the local <c>{port, Port}</c> option. See also
      <seealso marker="ch_install#firewall">Firewall Configuration</seealso>.</item>
      <tag><em>iiop_max_fragments</em></tag>
      <item>Limits the number of IIOP fragments allowed per request.</item>
      <tag><em>iiop_max_in_requests</em></tag>
      <item>Limits the number of concurrent incoming requests per incoming connection.</item>
      <tag><em>iiop_max_in_connections</em></tag>
      <item>Limits the number of concurrent incoming connections.</item>
      <tag><em>iiop_backlog</em></tag>
      <item>Defines  the maximum length the queue of pending incoming
       connections may grow to.</item>
      <tag><em>iiop_packet_size</em></tag>
      <item>Defines the maximum size of incoming requests.
       If this limit is exceeded, the connection is closed.</item>
      <tag><em>ip_address</em></tag>
      <item>This option is used if orber only should 
       listen on a specific ip interface on a multi-interface host or if
       exported IOR:s should contain multiple components. The value is
       the IPv4 or IPv6 address as a string or <c>{multiple, IPList}</c>.
       The latter requires that the object is available via the all IP addresses
       found in the list.</item>
      <tag><em>ip_address_local</em></tag>
      <item>This option defines the default local interface Orber will
       use when connecting to another ORB via IIOP, i.e., Orber act as the
       client side ORB. The value is a IPv4 or IPv6 address as a string.
       It is possible to override <c>ip_address_local</c> by defining
      <c>iiop_acl</c> or passing the Orber generic <c>interface</c> Context.
       If this option is not used, the underlying OS will choose which interface to
       use. For more information, see the
      <seealso marker="ch_install#interfaces">Interface Configuration</seealso>
       section.</item>
      <tag><em>nat_ip_address</em></tag>
      <item>The value is the ip address as
       a string (IPv4 or IPv6), <c>{multiple, IPList}</c> or 
      <c>{local, DefaultNATIPAddress, [{IPAddress, NATIPAddress}]}</c>. See also
      <seealso marker="ch_install#firewall">Firewall Configuration</seealso>.</item>
      <tag><em>objectkeys_gc_time</em></tag>
      <item>This option should be set if objects are started
       using the option <c>{persistent, true}</c>.
       The value is <c>integer()</c> seconds.</item>
      <tag><em>giop_version</em></tag>
      <item>Defines the default GIOP protocol version.</item>
      <tag><em>iiop_setup_connection_timeout</em></tag>
      <item>The value is an integer (seconds) or the atom infinity. 
       This option is only valid for client-side 
       connections. If this option is set, attempts to connect to other ORB's
       will timeout after the given time limit. Note, if the time limit is large
       the TCP protocol may timeout before the supplied value.</item>
      <tag><em>iiop_connection_timeout</em></tag>
      <item>The value is an integer (timeout in seconds between 0 and 1000000) 
       or the atom infinity. This option is only valid for client object 
       connections, i.e., will have no effect on server connections. Setting this
       option will cause client connections to be terminated, if and only if,
       there are no pending requests. If there are a client still waiting for
       a reply, Orber will try again after the given seconds have passed. The main
       purpose for this option is to reduce the number of open connections; it is,
       for example, not necessary to keep a connection, only used once a day,
       open at all time.</item>
      <tag><em>iiop_in_connection_timeout</em></tag>
      <item>The same as for <c>iiop_connection_timeout</c>. The only difference is
       that this option only affects incoming connections (i.e. Orber act as
       server-side ORB).</item>
      <tag><em>iiop_out_keepalive</em></tag>
      <item>Enables periodic transmission on a connected socket, when no other 
       data is being exchanged. If the other end does not respond, the 
       connection is considered broken and will be terminated. 
       When enabled the SO_KEEPALIVE socket level option is set.</item>
      <tag><em>iiop_in_keepalive</em></tag>
      <item>The same as for <c>iiop_out_keepalive</c>. The only difference is
       that this option only affects incoming connections.</item>
      <tag><em>iiop_timeout</em></tag>
      <item>The value is an integer (timeout in seconds between 0 and 1000000) 
       or the atom infinity. This option is only valid on the client side.
       Setting this option, cause all intra-ORB requests to timeout and
       raise a system exception, e.g. <c>TIMEOUT</c>, if no replies are delivered
       within the given time limit.</item>
      <tag><em>interceptors</em></tag>
      <item>If one set this parameter, e.g.,
      <c>erl -orber interceptors "{native, ['myInterceptor']}"</c>,
       Orber will use the supplied interceptor(s) for all inter-ORB 
       communication. <c>'myInterceptor'</c> is the module name of the
       interceptor. For more information, see the interceptor chapter
       in the User's Guide and the Reference Manual.</item>
      <tag><em>local_interceptors</em></tag>
      <item>If defined, its value will be
       used when activating local interceptors via
      <seealso marker="ch_install#flags">Orber Environment Flags</seealso>.
       If not defined, but the flag is set, Orber will use the value of
       the <c>interceptors</c> parameter.</item>
      <tag><em>orbInitRef</em></tag>
      <item>Setting this option, e.g., 
      <c>erl -orber orbInitRef [\"NameService=corbaloc::host.com/NameService\"]</c>, 
       will alter the location from where <c>corba:resolve_initial_references(Key)</c> 
       tries to find an object matching the given Key. The keys will also appear when
       invoking <c>corba:list_initial_services()</c>. This variable overrides
      <c>orbDefaultInitRef</c></item>
      <tag><em>orbDefaultInitRef</em></tag>
      <item>If a matching Key for <c>orbInitRef</c> is not
       found, and this variable is set, it determines the location from where 
      <c>orber:resolve_initial_references(Key)</c> tries to find an object 
       matching the given Key. Usage:
      <c>erl -orber orbDefaultInitRef \"corbaloc::host.com\"</c>.</item>
      <tag><em>orber_debug_level</em></tag>
      <item>The range is 0 to 10.
       Using level 10 is the most verbose configuration.
       This option will generate reports, using the <c>error_logger</c>,
       for abnormal situations. It is not recommended to use this option
       for delivered systems since some of the reports is not to be considered
       as errors. The main purpose is to assist during development.</item>
      <tag><em>flags</em></tag>
      <item>No flags are activated in the default case.
       The available configuration settings are described in
      <seealso marker="ch_install#flags">Orber Environment Flags</seealso>.</item>
      <tag><em>iiop_acl</em></tag>
      <item>This option must be activated by setting 
      <seealso marker="ch_install#flags">Orber Environment Flags</seealso> parameter.
       The value of this parameter shall be a list of <c>[{Direction, Filter}]</c> 
       and/or <c>[{Direction, Filter, [Interfaces]}]</c>. The <c>Direction</c>, 
      <c>tcp_in</c>, <c>ssl_in</c>, <c>tcp_out</c> or <c>ssl_out</c>, determines if
       the Access Control List (ACL) applies to incoming or outgoing connections
       and IIOP or IIOP over SSL. The <c>Filter</c> uses a extended format of 
       Classless Inter Domain Routing (CIDR). For example, <c>"123.123.123.10"</c> limits
       the connection to that particular host, while <c>"123.123.123.10/17"</c> allows
       connections to or from any host equal to the 17 most significant bits. Orber
       also allow the user to specify a certain port or port range, for example,
      <c>"123.123.123.10/17#4001"</c> and <c>"123.123.123.10/17#4001/5001"</c>
       respectively. IPv4 or none compressed IPv6 strings are accepted.      <br></br>

       The list of <c>Interfaces</c>, IPv4 or IPv6 strings, may only contain 
      <em>one</em> address for outgoing connections. For incoming connections,
       the <c>Interfaces</c> list may contain several IP strings. If set for
       outgoing connections, and access is granted, Orber will use that local
       interface when connecting to the server-side ORB. For incoming connections,
       the client-side ORB is required to use one of the listed interfaces locally.
       If it fail to do so, access will be denied. The module 
      <seealso marker="orber_acl">orber_acl</seealso> provides operations for
       evaluating the access control for filters and addresses. See also the
      <seealso marker="ch_install#interfaces">Interface Configuration</seealso>
       and
      <seealso marker="ch_install#firewall">Firewall Configuration</seealso>
       chapters.</item>
      <tag><em>secure</em></tag>
      <item>Determines the security mode Orber will use, which is either 
      <c>no</c> if it is an insecure domain or the type of security 
       mechanism used. Currently, per default, Orber is compliant with
      <c>CSIv1</c> level 0, which means IIOP via SSL/TLS. 
       The security chapter later in this manual describes how to get security
       in Orber and how the options are used.</item>
      <tag><em>ssl_generation</em></tag>
      <item>Defines which SSL version, i.e. available API, is installed. The
      default value, <c>2</c>, refers to SSL-3.1 or later, but earlier than SSL-4.0.
      If set to <c>3</c> SSL-4.0, or later, must be available. Currently it not possible
      to use <c>1</c>, it is only reserved for future use.</item>
      <tag><em>iiop_ssl_port</em></tag>
      <item>If set, the value must be an
       integer greater than zero and not equal to <em>iiop_port</em>.</item>
      <tag><em>iiop_ssl_accept_timeout</em></tag>
      <item>The value is an integer (timeout in seconds) or the atom infinity and
       determine how long the SSL handshake may take. This option should
       be set to avoid if a client never initiate the handshake.</item>
      <tag><em>iiop_ssl_backlog</em></tag>
      <item>Defines  the maximum length the queue of pending incoming
       connections may grow to.</item>
      <tag><em>iiop_ssl_ip_address_local</em></tag>
      <item>This option defines the default local interface Orber will
       use when connecting to another ORB via IIOP SSL, i.e., Orber act as the
       client side ORB. The value is a IPv4 or IPv6 address as a string.
       It is possible to override <c>iiop_ssl_ip_address_local</c> by defining
      <c>iiop_acl</c> or passing the Orber generic <c>interface</c> Context.
       If this option is not used, the underlying OS will choose which interface to
       use. For more information, see the
      <seealso marker="ch_install#interfaces">Interface Configuration</seealso>
       section.</item>
      <tag><em>nat_iiop_ssl_port</em></tag>
      <item>If set, the value must be an integer greater than zero or 
      <c>{local, DefaultNATPort, [{Port, NATPort}]}</c>. See also
      <seealso marker="ch_install#firewall">Firewall Configuration</seealso>.</item>
      <tag><em>ssl_server_cacertfile</em></tag>
      <item>the file path to a server side CA certificate.</item>
      <tag><em>ssl_server_certfile</em></tag>
      <item>The path to a file containing a chain of PEM encoded certificates.</item>
      <tag><em>ssl_server_verify</em></tag>
      <item>The type of verification used by SSL during authentication of the
       other peer for incoming calls.</item>
      <tag><em>ssl_server_depth</em></tag>
      <item>The SSL verification depth for outgoing calls.</item>
      <tag><em>ssl_server_password</em></tag>
      <item>The server side key string.</item>
      <tag><em>ssl_server_keyfile</em></tag>
      <item>The file path to a server side key.</item>
      <tag><em>ssl_server_ciphers</em></tag>
      <item>The server side cipher string.</item>
      <tag><em>ssl_server_cachetimeout</em></tag>
      <item>The server side cache timeout.</item>
      <tag><em>ssl_client_cacertfile</em></tag>
      <item>The file path to a client side CA certificate.</item>
      <tag><em>ssl_client_certfile</em></tag>
      <item>The path to a file containing a chain of PEM encoded certificates.</item>
      <tag><em>ssl_client_verify</em></tag>
      <item>The type of verification used by SSL during authentication of the
       other peer for outgoing calls.</item>
      <tag><em>ssl_client_depth</em></tag>
      <item>The SSL verification depth for incoming calls.</item>
      <tag><em>ssl_client_password</em></tag>
      <item>The client side key string.</item>
      <tag><em>ssl_client_keyfile</em></tag>
      <item>The file path to a client side key.</item>
      <tag><em>ssl_client_ciphers</em></tag>
      <item>The client side cipher string.</item>
      <tag><em>ssl_client_cachetimeout</em></tag>
      <item>The client side cache timeout.</item>
      <tag><em>iiop_ssl_out_keepalive</em></tag>
      <item>Enables periodic transmission on a connected socket, when no other 
       data is being exchanged. If the other end does not respond, the 
       connection is considered broken and will be terminated. 
       When enabled the SO_KEEPALIVE socket level option is set. Requires that
       the installed SSL version support the <em>keepalive</em> option
       and that the <em>ssl_generation</em> points to this version.</item>
      <tag><em>iiop_ssl_in_keepalive</em></tag>
      <item>The same as for <c>iiop_ssl_out_keepalive</c>. The only difference is
       that this option only affects incoming connections.</item>
    </taglist>
    <p>It is possible to invoke operations using the extra timeout parameter:</p>
    <pre>
erl> module_interface:function(ObjRef, Timeout, ..Arguments..).
erl> module_interface:function(ObjRef, [{timeout, Timeout}], ..Arguments..).
erl> module_interface:function(ObjRef, ..Arguments..).    </pre>
    <p>The extra Timeout argument will override the configuration parameter 
      <c>iiop_timeout</c>. It is, however, not possible to use <c>infinity</c>
      to override the Timeout parameter. The Timeout option is also valid for 
      objects which resides within the same <term id="Orber domain"><termdef>A domain containing several Erlang nodes, which are communicating  by using the Erlang internal format. An Orber domain looks as one ORB from the environment.</termdef></term>.</p>
    <p>The <c>iiop_setup_connection_timeout</c>, <c>iiop_timeout</c>,
      <c>iiop_connection_timeout</c> and <c>iiop_in_connection_timeout</c>
      variables should be used. The specified values is implementation specific, 
      i.e., WAN or LAN, but they should range from 
      <c>iiop_setup_connection_timeout</c> to <c>iiop_connection_timeout</c>.</p>
    <p>To change these settings in the configuration file, the
      <c>-config</c> flag must be added to the erl command. See the
      Reference Manual 
      <em>config(4)</em> for further information. The values can also
      be sent separately as
      options  to the Erlang node when it is started, see the Reference
      Manual 
      <em>erl(1)</em> for further information. </p>

    <section>
      <marker id="flags"></marker>
      <title>Orber Environment Flags</title>
      <p>The <c>Environment Flags</c> allows the user to activate debugging
        facilities or change Orber's behavior. The latter may result in that
        Orber is no longer compliant with the OMG standard, which may be necessary
        when communicating with a non-compliant ORB.</p>
      <table>
        <row>
          <cell align="left" valign="middle"><em>Hexadecimal Value</em></cell>
          <cell align="left" valign="middle"><em>OMG Compliant</em></cell>
          <cell align="left" valign="middle"><em>Description</em></cell>
        </row>
        <row>
          <cell align="left" valign="middle">0001</cell>
          <cell align="left" valign="middle">no</cell>
          <cell align="left" valign="middle">Exclude CodeSet Component</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0002</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Local Typechecking</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0004</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Use Host Name in IOR</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0008</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Enable NAT</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0020</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Local Interceptors</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0080</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Light IFR</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0100</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Use IPv6</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0200</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">EXIT Tolerance</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0400</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Enable Incoming ACL</cell>
        </row>
        <row>
          <cell align="left" valign="middle">0800</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Enable Outgoing ACL</cell>
        </row>
        <row>
          <cell align="left" valign="middle">1000</cell>
          <cell align="left" valign="middle">yes</cell>
          <cell align="left" valign="middle">Use Current Interface in IOR</cell>
        </row>
        <tcaption>Orber Environment Flags</tcaption>
      </table>
      <p>Any combination of the flags above may be used and changes the
        behavior as follows:</p>
      <list type="bulleted">
        <item><em>Exclude CodeSet Component</em> - instruct Orber to exclude
         the CodeSet component in exported IOR:s. When activated, no
         negotiating regarding character and wide character conversions 
         between the client and the server will occur. This flag will,
         most likely, cause problems if your IDL specification contains
         the data types wchar and/or wstring.</item>
        <item><em>Local Typechecking</em> -
         If activated, parameters, replies and raised exceptions
         will be checked to ensure that the data is correct. If an error
         occurs, the <c>error_logger</c> is used to generate reports.
         One <em>MAY NOT</em> use this option for delivered systems due
         to the extra overhead. Since this option activates typechecking
         for all objects generated on the target node, it is also possible
         to use the option <c>{local_typecheck, boolean()}</c>, when
         invoking <c>oe_create/2</c>, <c>oe_create_link/2</c>,
        <c>corba:create/4</c> or <c>corba:create_link/4</c>, to override
         the configuration parameter.</item>
        <item><em>Use Host Name in IOR</em> - normally Orber inserts the IP-number
         in IOR:s when they are exported. In some cases, this will cause
         the clients to open two connections instead of one.</item>
        <item><em>Enable NAT</em> - if this flag is set, it is possible to use
         the NAT (Network Address Translation) configuration parameters
         (<c>nat_iiop_port</c>, <c>nat_iiop_ssl_port</c> and 
        <c>nat_ip_address</c>).</item>
        <item><em>Local Interceptors</em> - use interceptors for local
         invocations.</item>
        <item><em>Light IFR</em> - if the IFR is not explicitly used and this 
         flag is set, Orber will use a minimal IFR to reduce memory usage
         and installation time.</item>
        <item><em>Use IPv6</em> - when this option is activated, Orber will use
        <c>IPv6</c> for inter-ORB communication.</item>
        <item><em>EXIT Tolerance</em> - servers will survive even though the
         call-back module caused an EXIT.</item>
        <item><em>Enable Incoming ACL</em> - activates access control for incoming
         connections.</item>
        <item><em>Enable Outgoing ACL</em> - activates access control for outgoing
         connections.</item>
        <item><em>Use Current Interface in IOR</em> - when set, Orber will add
         the interface the request came via to exported local IOR:s.</item>
      </list>
      <p>Invoking the operation
        <seealso marker="orber">orber:info/1/2</seealso> will display the currently
        set flags in a readable way.</p>
    </section>
  </section>

  <section>
    <title>Firewall Configuration</title>
    <marker id="firewall"></marker>
    <p>Firewalls are used to protect objects from clients in other networks or 
      sub-networks, but also to restrict which hosts internal objects may connect to
      (i.e. <c>inbound protection</c> and <c>outbound protection</c>). A firewall
      can limit access based on:</p>
    <list type="bulleted">
      <item><em>Transport Level</em> - performs access control decisions based on
       address information in TCP headers.</item>
      <item><em>Application Level</em> - understands GIOP messages and the specific
       transport level inter-ORB Protocol supported e.g. IIOP.</item>
    </list>
    <p>This section describes how to configure a <c>Transport Level</c> firewall. It
      must have prior knowledge of the source to destination mappings, and
      conceptually has a configuration table containing tuples of the form: 
      <c>({inhost:inport}, {outhost:outport})</c>. If there are no port restrictions
      it is rather easy to configure the firewall. Otherwise, we must consider the
      following alternatives:</p>
    <list type="bulleted">
      <item><em>Incoming Requests</em> - Orber only uses the port-numbers specified 
       by the configuration parameters <em>iiop_port</em> and 
      <em>iiop_ssl_port</em>. Other ORB's may use several ports but it should
       be possible to change this behavior. Consult the other ORBs 
       documentation.</item>
      <item><em>Outgoing Requests</em> - Most ORB's, Orber included,
       ask the OS to supply a vacant local port when connecting to the
       server-side ORB. It is possible to change this behavior when using
       Orber (i.e. set the configuration parameter <em>iiop_out_ports</em>).</item>
    </list>
    <warning>
      <p>Using the option <c>iiop_out_ports</c> may result in that Orber runs out of
        valid ports numbers. For example, other applications may steal some of the
        ports or the number of concurrent outgoing connections to other ORBs may be 
        higher than expected. To reduce, but not eliminate, the risk you should use 
        <c>iiop_connection_timeout</c>.</p>
    </warning>
    <p>Firewall configuration example:</p>
    <pre>
# "Plain" IIOP
To: Orber-IPNo:(iiop_port)     From: ORB-IPNo:X
To: ORB-IPNo:Z                 From: Orber-IPNo:(iiop_out_ports | Any Port)

# IIOP via SSL
To: Orber-IPNo:(iiop_port)     From: ORB-IPNo:X
To: Orber-IPNo:(iiop_ssl_port) From: ORB-IPNo:Y
To: ORB-IPNo:Z                 From: Orber-IPNo:(iiop_out_ports | Any Port)
    </pre>
    <p>If the communication take place via a
      <seealso marker="ch_install#firewall_nat">TCP Firewall with NAT</seealso>
      (Network Address Translation), we must activate this behavior and define
      the external address and/or ports.</p>
    <marker id="firewall_nat"></marker>
    <image file="firewall_nat.gif">
      <icaption>
TCP Firewall With NAT</icaption>
    </image>
    <p>Using NAT makes it possible to use different host data for different network
      domains. This way we can share Internet Protocol address resources or
      obscure resources. To enable this feature the 
      <seealso marker="ch_install#flags">Enable NAT</seealso> flag must be set and
      <c>nat_iiop_port</c>, <c>nat_iiop_ssl_port</c> and <c>nat_ip_address</c>
      configured, which maps to <c>iiop_port</c>, <c>iiop_ssl_port</c> and 
      <c>ip_address</c> respectively. Hence, the firewall must be configured to
      translate the external to the internal representation correctly. If these NAT parameters 
      are assigned a single port number or IP address, only those will be used when
      an IOR is exported to another ORB. When <c>ip_address</c> is set to 
      <c>{multiple, [IPAddress]}</c>, <c>nat_ip_address</c> should be configured in the same 
      way, so that each NAT IP address can be translated to a valid address by the firewall.
      If objects are supposed to be accessible via different interfaces and port, see also
      <seealso marker="ch_install#interfaces">Interface Configuration</seealso>, 
      the options <c>{local, DefaultNATIPAddress, [{IPAddress, NATIPAddress}]}</c> and/or
      <c>{local, DefaultNATPort, [{Port, NATPort}]}</c> shall be used. The default NAT IP address
      and port, should be translated to the value of <c>ip_address_local</c> and the default 
      listen port by the firewall. If the IP address and/or port is not found in the list,
      the default values will be inserted in the IOR. The firewall must be able to translate
      these correctly.</p>
    <p>If it is necessary to limit the access to an ORB within a secure network,
      but other applications running on the same host may not be blocked out,
      one can use a <em>Application Level</em> firewall or Orber Access Control 
      List (ACL). The latter makes it possible for the user to define which hosts
      may communicate, either as server or client, with Orber. This is achieved by
      defining the configuration parameter
      <seealso marker="ch_install#config">iiop_acl</seealso>. The Classless Inter
      Domain Routing (CIDR) <c>Filter</c> determines which peer interfaces and 
      ports the other ORB may use.</p>
    <table>
      <row>
        <cell align="left" valign="middle"><em>Filter</em></cell>
        <cell align="left" valign="middle"><em>Peer Interface(s)</em></cell>
        <cell align="left" valign="middle"><em>Peer Port(s)</em></cell>
      </row>
      <row>
        <cell align="left" valign="middle">"10.1.1.1"</cell>
        <cell align="left" valign="middle">10.1.1.1</cell>
        <cell align="left" valign="middle">any</cell>
      </row>
      <row>
        <cell align="left" valign="middle">"10.1.1.1/8"</cell>
        <cell align="left" valign="middle">10.0.0.0-10.255.255.255</cell>
        <cell align="left" valign="middle">any</cell>
      </row>
      <row>
        <cell align="left" valign="middle">"10.1.1.1/8#4001"</cell>
        <cell align="left" valign="middle">10.0.0.0-10.255.255.255</cell>
        <cell align="left" valign="middle">4001</cell>
      </row>
      <row>
        <cell align="left" valign="middle">"10.1.1.1/8#4001/5001"</cell>
        <cell align="left" valign="middle">10.0.0.0-10.255.255.255</cell>
        <cell align="left" valign="middle">4001-5001</cell>
      </row>
      <tcaption>Orber ACL Filters</tcaption>
    </table>
    <p>Orber ACL, also allows the user to define which local interface(s) may be used,
      but will not detect <c>spoofing</c>. The operation
      <seealso marker="orber_acl">orber_acl:match/2/3</seealso> makes it easy to
      verify whether access would be granted or not. For example, if Orber would
      be started with the ACL <c>[{tcp_out, "10.1.1.1/8#4001/5001"}]</c>, then 
      <c>orber_acl:match/2</c> would behave as follows:</p>
    <code type="none">
erl> orber_acl:match({11,1,1,1}, tcp_out).
false

erl> orber_acl:match({10,1,1,1}, tcp_out).
true

erl> orber_acl:match({11,1,1,1}, tcp_out, true).
{false,[],0}

erl> orber_acl:match({10,1,1,1}, tcp_out, true).
{true,[],{4001,5001}}
    </code>
    <p>Only if the returned boolean is true the extra return values makes a 
      difference. In the example above, <c>{true,[],{4001,5001}}</c> means that
      Orber may connect to <c>"10.1.1.1"</c>, using any local interface,
      if the server-side ORB listens for incoming connect requests on a port
      within the range 4001-5001. Note, invoking the <c>orber_acl:match/2/3</c>
      operation, will not result in a connect attempt by Orber. The reason for 
      this, is that this function may be used on a live node as well as in test
      environment. Hence, if a local interface is currently not available or no 
      server-side ORB available via the given host/port(s), will not be detected
      by Orber.</p>
  </section>

  <section>
    <title>Interface Configuration</title>
    <marker id="interfaces"></marker>
    <p>In many cases it is sufficient to simply configure the underlying OS which
      local interfaces shall be used for all applications. But, in some cases
      it is required, due to, for example, the firewall configuration, that different
      local interfaces are used for different applications. Some times, it is even
      necessary to use a specific interface for a single CORBA object. This section
      describe how one can alter this in different ways.</p>
    <p>The default behavior is that Orber lets the OS configuration decide which interface
      will be added in IOR:s exported to another ORB and the local interface used
      when connecting to another ORB (Orber act as client side ORB). The latter can be
      overridden by setting the configuration parameters <c>iiop_ssl_ip_address_local</c>
      and/or <c>ip_address_local</c>, which will affect IIOP via SSL and IIOP 
      respectively. These parameters can be overridden by using the Orber generic 
      <c>interface</c> Context or defining an ACL (Access Control List). The latter
      always takes precedence if a local interface is included (e.g. 
      <c>[{tcp_out, "10.0.0.0/8", ["10.0.0.1"]}]</c>). If the interface is excluded
      (e.g. <c>[{tcp_out, "10.0.0.0/8"}]</c>), the interface chosen will, in the following
      order, be determined by
      <c>#'IOP_ServiceContext'{}</c>, <c>ip_address_local/iiop_ssl_ip_address_local</c> or
      the configuration of the underlying system.</p>
    <p>Adding the interface context, for generated stubs/skeletons, is done in the 
      following way:</p>
    <code type="none">
Ctx = #'IOP_ServiceContext'{context_id = ?ORBER_GENERIC_CTX_ID, 
                            context_data = {interface, "10.0.0.1"}},
'CosNaming_NamingContext':resolve(NS, [{context, [Ctx]}], Name),
    </code>
    <p>It is also possible to add the context to 
      <c>corba:string_to_object/2, corba:resolve_initial_references/2, corba:resolve_initial_references_remote/3,  corba:list_initial_services_remote/2, corba_object:not_existent/2,  corba_object:non_existent/2</c> and <c>corba_object:is_a/3</c>. 
      The operations exported by <c>corba_object</c> are affected
      if the supplied IOR is external. The function <c>corba:string_to_object/2</c>
      might require the interface context if a <c>corbaloc</c> or a <c>corbaloc</c>
      string is passed (See the
      <seealso marker="ch_naming_service#interop_ns">INS</seealso> chapter),
      while <c>corba:resolve_initial_references_remote/3</c> and
      <c>corba:list_initial_services_remote/2</c> always connect to another ORB and
      it might be necessary to add the context.
      The remaining <c>corba</c> operations are affected if calls are re-directed
      by setting the <c>orbInitRef</c> and/or <c>orbDefaultInitRef</c> configuration
      parameters. For more information, see the Reference Manual for each module.</p>
    <p>Configuring which interface(s) that shall be used when exporting an IOR to
      another ORB, is determined by <c>nat_ip_address</c>, setting the flag 
      <seealso marker="ch_install#flags">16#1000</seealso>
      and <c>ip_address</c>, in that order. Orber listens for incoming connections
      either via all interfaces or the interface defined by <c>ip_address</c>. It is
      also possible to add and remove extra listen interfaces by using
      <c>orber:add_listen_interface/2/3</c> and <c>orber:remove_listen_interface/1</c>.
      In this case one should set the 16#1000 flag and, if necessary, set the
      configuration parameters
      <c>{local, DefaultNATIPAddress, [{IPAddress, NATIPAddress}]}</c> and/or
      <c>{local, DefaultNATPort, [{Port, NATPort}]}</c>.</p>
  </section>
</chapter>