NAME

       XPAMethod -  XPA Communication Methods

SYNOPSIS

       XPA supports both inet and unix (local) socket communication.

DESCRIPTION

       XPA uses sockets for communication between processes. It supports three methods of socket communication:
       inet, localhost, and unix. In general, the same method should be employed for all XPA processes in a
       session and the global environment variable XPA_METHOD should be used to set up the desired method. By
       default, the preferred method is "inet", which is appropriate for most users. You can set up a different
       method by typing something like:

         setenv XPA_METHOD local              # unix csh
         XPA_METHOD=local; export XPA_METHOD  # unix sh, bash, windows/cygwin
         set XPA_METHOD=localhost             # dos/windows

       The options for XPA_METHOD are: inet, unix (or local), and localhost. On Unix machines, this environment
       setup command can be placed in your shell init file (.cshrc, .profile, .bashrc, etc.) On Windows
       platforms, it can be placed in your AUTOEXEC.BAT file (I think!).

       By default, inet sockets are used by XPA. These are the standard Internet sockets that are used by
       programs such as Netscape, ftp. etc. Inet sockets utilize the IP address of the given machine and a
       (usually random) port number to communicate between processes on the same machine or between different
       machines on the Internet. (Note that XPA has an Access Control mechanism to prevent unauthorized access
       of XPA access points by other computers on the Net). For users connected to the Internet, this usually is
       the appropriate communication method. For more information about setting up XPA communication between
       machines, see Communication Between Machines.

       In you are using XPA on a machine without an Internet connection, then inet sockets are not appropriate.
       In fact, an XPA process often will hang for many seconds while waiting for a response from the Domain
       Name Service (DNS) when using inet sockets. Instead of inet sockets, users on Unix platforms can also use
       unix sockets (also known as local sockets). These sockets are based on the local file system and do not
       make use of the DNS. They generally are considered to be faster than inet sockets, but they are not
       implemented under Windows. Use local sockets as a first resort if you are on a Unix machine that is not
       connected to the Internet.

       Users not connected to the Internet also can use localhost sockets. These are also inet-type sockets but
       the IP address used for the local machine is the localhost address, 0x7F000001, instead of the real IP of
       the machine. Depending on how sockets are set up for a given platform, communication with the DNS usually
       is not required in this case (though of course, XPA cannot interact with other machines).  The localhost
       method will generally work on both Unix and Windows platforms, but whether the DNS is required or not is
       subject to individual configurations.

       A final warning/reminder: if your XPA-enabled server hangs at startup time and your XPA_METHOD is inet,
       the problem probably is related to an incorrect Internet configuration. This can be confirmed by using
       the unix method or (usually) the localhost method. You can use these alternate methods if other hosts do
       not need access to the XPA server.

SEE ALSO

       See xpa(7) for a list of XPA help pages