The name server process allows a server process to register it port address with a name and type code. The name server keeps a table of equivalent host addresses so that it can translate an IP address to one on the same network as the client process.

Tunnel interactions:
The Name server may work closely with one or more tunnel processes to provide communication with processes on disjoint networks. If a request is received for a target address that is not reachable by the requesting process, the name server searches its list of tunnels for one that connects the requester's network to the target network. If an appropriate tunnel is found, the name server returns the tunnel's server port address and a gives the index of the target process entry as a process ID. The tunnel then routes the request message to the target address (resolved by an IDget request) and forwards the resulting reply to the original sender.

The Name server maintains a list of Tunnel processes. The tunnel process Registers itself with a name of "_Tunnel_<net><mask>" and a process type of lmsg::p_Tunnel. <net> and <mask> are 8-digit hex numbers giving the network address and network mask of the Target network.

Running the Name Server:
The name server process is run with the following command line:

   NameServer [-debug <level>] [-port <ip-port>] [-hosts <table>]

Where the meanings of the flags are summarized in the following table:

-debug <level>	Specifies a debug printout level. The default level (0) indicates no debugging messages are to be produced. The message volume increases with the level.
-hosts <table>	Location of the host table file.
-port <ip-port>	Specify the name service port [23456].

Name Server Inputs:

Equivalent Host Table
The "Equivalent Host" table contains a list of know hosts which are connected to more than one network. This information is used to translate the server IP address information in cases where either the target server or the client hosts are connected to more than one network. The file contains network addresses of the form <ip-address>/<net-mask>. Each line in the equivalent host file contains two or more network addresses for the same multiply connected host.

Messages:
The name server accepts messages as defined in NameMsg.hh. The following message types are handled:

AddName	The specified process name is registered. A NameStatus message is returned
FindName	The specified process name is looked up in the name server dictionary and a NameStatus message is returned.
RemoveName	The specified process name entry is removed from the name server dictionary.
NameIndex	Request for an index.
IDget	Get the name and address associated with the spcified ID.
<other>	Other message types are ignored and no reply is returned.

Signals:
Signals are used to cause asynchronous state changes.

SIGINT	Terminate cleanly.
SIGTERM	Terminate cleanly.

Name Server Outputs:

Messages:
The trigger manager accepts monitor messages as defined in NameMsg.hh. The following message types are handled:

Ack	Reply to a successful remove request.
NameStatus	Message in reply to an AddName, FindName or NameIndex request containing the name(s) and its address and type.
NAck	Reply to an unsucessful remove request.

Author:

J. Zweizig

Version:

1.0; Modified April 26, 2001