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// README,v 1.19 2001/02/02 20:21:38 schmidt Exp

This directory contains files that implement a server for the TAO
Naming Service.  In addition, it contains files that run the TAO
Naming Service as a Windows NT Service.  Both of these services are
described below.

How to Run the TAO Naming Service
=================================

The following describes how to run the TAO Naming Service.

1. Syntax

        % Naming_Service [-ORBNameServicePort nsport]
                         [-o ior_output_file]
                         [-p pid_file_name]
                         [-s context_size]
                         [-t time]
                         [-f persitence_file_name]
                         [-b base_address]
			 [-m (1=enable multicast responses,0=disable(default)]
			 [-z time]

2. Optional Command-line Arguments

        -ORBNameServicePort nsport
                Multicast port for listening for requests from clients
                trying to bootstrap to a Naming Service through the
                use of multicast.  This is only used when multicast
                responding is enabled via '-m 1'.

        -o ior_output_file
                The name of the file, in which to store the IOR of the
                root Naming Service context.

        -p pid_file_name
                The name of the file, in which to store the process id
                of the Naming Service server.

        -s context_size
                Size of the hash table allocated for the root Naming
                Context (if one is created).  All contexts created
                under the root will use the same size for their hash
                tables.  The default is 1024.

        -t time
                How long (in seconds) the server should listen for
                client requests before terminating.

        -f persistence_file_name
                The name of the file to use to store/retrieve
                persistent state of the Naming Service.  Without this
                option, Naming Service is started in non-persistent
                mode.

        -b base_address
                The address used for memory mapping the file specified
                with the "-f" option above.  The value supplied with
                this option is only used when the Naming Service runs
                in persistent mode, i.e., "-f" option is present.

	-m <0|1>
                TAO offers a simple, very non-standard method for
                clients to discover the initial reference for the
                Naming Service.  However, since it can be innadequate and cause
		unexpected results if, for example, there are multiple
		naming services running on the network, the DEFAULT
		behavior is for the Naming Service to NOT RESPOND to
		such multicast queries (use the Interoperable Naming
		Service bootstrap options instead).

        -z time
                A relative round trip timeout value (in seconds) that
                the service should wait for when trying to progress an
                operation through a federated naming context before
                timing out and throwing a 'Cannot proceed' exception
                to the client. If no value is set this will never occur.

3. Environment Variables

        NameServicePort
                Multicast port for listening for requests from clients
                trying to bootstrap to a Naming Service through the
                use of multicast.  This is only used when multicast
                responding is enabled via '-m 1'.

4. Persistence

        TAO Naming Service has an optional persistence capability.  By
        default, the Naming Service is started in a non-persistent
        mode.  Supplying "-f" command-line option to the server causes
        a persistent version of the Naming Service to run.

        The file specified with the "-f" option is used to store the
        persistent state of the Naming Service, i.e., all Naming
        Contexts and their bindings.  When "-f" option is specified:

        1. If the specified file does not exist, it is created and
           used to store the state of the Naming Service.  An initial
           (root) Naming Context is also created.

        2. If the specified file exists, it is scanned and:

                a) If any inconsistency is detected in the stored
                state, or the file is not recognized by the Naming
                Service, the server exits.  (This may happen, for
                example, if a server or host crashed in the middle of
                writing a record to this file on a previous run).  A
                noncorrupted version of the file must be used instead.

                b) If the file is recognized and is ok, the state
                stored in the file becomes the current state of the
                Naming Service.

        Internally, TAO uses memory mapped file to implement
        persistence feature of the Naming Service.  A default memory
        address (ACE_DEFAULT_BASE_ADDR) is used for mapping the file.
        Alternate mapping address can be specified at compile-time by
        redefining TAO_NAMING_BASE_ADDR in tao/orbconf.h.  Alternate
        mapping address can also be specified at run-time
        with the "-b" command-line option, which takes precedence over
        TAO_NAMING_BASE_ADDR definition.
        NOTE: Naming Service stores absolute pointers in its
        memory-mapped file.  Therefore, it is important to use the
        same mapping address on each run for the same persistence file.


5. Implementation Policies

        a. Destroying Binding Iterators

                A binding iterator is destroyed when client invokes
                <destroy> operation either on the iterator itself or
                on the naming context it is iterating over.  In both
                cases, subsequent calls on the binding iterator object
                will cause OBJECT_NOT_EXIST exception.

        b. Dealing with orphaned contexts

                This implementation of the Naming Service does not
                include any form of 'garbage collection' for orphaned
                naming contexts.  It is solely the responsibility of
                clients to clean up after themselves and not leak
                server resources.  All the resources, including
                orphaned contexts, are released during the Naming
                Server shutdown.

6. Clients: ways to bootstrap to the Naming Service:

        There are several methods for a client to bootstrap to a
        Naming Service, i.e., there are several mechanisms
        <resolve_initial_references> can use when asked for
        "NameService".  In order of predictable behavior, they are:

        1. Command-line options

                The "-ORBInitRef NameService=IOR:..." or environment
                variable NameServiceIOR can be used on the client side
                to specify the object that the call to
                <resolve_initial_references> should return to the
                client.  (On the server side, -o option can be used to
                get the ior).

                Example (Unix, same host):

                        % TAO_ROOT/orbsvcs/Naming_Service -o ior_file
                        % my_client -ORBInitRef NameService=file://ior_file

                        On the first line, we start the Naming
                        Service, and output its ior to <ior_file>.  On
                        the second line, we start some client, and
                        specify the ior <resolve_initial_references>
                        should return for the Naming Service in a file
                        format.

        2. Interoperable Naming Service.

                TAO implements the standard CORBA Interoperable Naming
                Service (ING).  Therefore, most initialization options
                provided by INS can be used to bootstrap to the Naming
                Service (see TAO's releasenotes for the status of INS
                implementation).

        3. Multicast

                When started with the "respond to multicast queries"
                option turned on ('-m 1'), clients can use IP
                multicast to query for a Naming Service, and this
                instance will respond. TAO Naming Server is listening
                for client multicast requests on a specified port.  On
                the client side, <resolve_initial_references> sends
                out a multicast request on the network, trying to
                locate a Naming Service.  When a Naming Server
                receives a multicast request from a client, it replies