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diff --git a/xpa/doc/pod/xpamethod.pod b/xpa/doc/pod/xpamethod.pod new file mode 100644 index 0000000..038ac4e --- /dev/null +++ b/xpa/doc/pod/xpamethod.pod @@ -0,0 +1,99 @@ +=pod + +=head1 NAME + + + +B<XPAMethod: XPA Communication Methods> + + + +=head1 SYNOPSIS + + + + + +XPA supports both inet and unix (local) socket communication. + + + +=head1 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: B<inet>, B<unix> (or +B<local>), and B<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, B<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 B<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 B<localhost> +sockets. These are also inet-type sockets but the IP address used for +the local machine is the B<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 B<inet>, the problem probably is +related to an incorrect Internet configuration. This can be confirmed +by using the B<unix> method or (usually) the B<localhost> +method. You can use these alternate methods if other hosts do not need +access to the XPA server. + + + +=head1 SEE ALSO + + + +See xpa(n) for a list of XPA help pages + + + +=cut |