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diff --git a/xpa/doc/method.html b/xpa/doc/method.html new file mode 100644 index 0000000..d85fc89 --- /dev/null +++ b/xpa/doc/method.html @@ -0,0 +1,90 @@ +<!-- =defdoc xpamethod xpamethod n --> +<HTML> +<HEAD> +<TITLE>XPA Communication Methods</TITLE> +</HEAD> +<BODY> + +<!-- =section xpamethod NAME --> +<H2><A NAME="xpamethod">XPAMethod: </A>XPA Communication Methods</H2> + +<!-- =section xpamethod SYNOPSIS --> +<H2>Summary</H2> +<P> +XPA supports both inet and unix (local) socket communication. + +<!-- =section xpamethod DESCRIPTION --> +<H2>Description</H2> +<P> +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: +<PRE> + setenv XPA_METHOD local # unix csh + XPA_METHOD=local; export XPA_METHOD # unix sh, bash, windows/cygwin + set XPA_METHOD=localhost # dos/windows +</PRE> +The options for XPA_METHOD are: <B>inet</B>, <B>unix</B> (or +<B>local</B>), and <B>localhost</B>. 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!). + +<P> +By default, <B>inet</B> 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 <A HREF="./acl.html">Access Control</A> 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 +<A HREF="./inet.html">Communication Between Machines</A>. + +<P> +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</B> 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. + +<P> +Users not connected to the Internet also can use <B>localhost</B> +sockets. These are also inet-type sockets but the IP address used for +the local machine is the <B>localhost</B> 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. + +<P> +A final warning/reminder: if your XPA-enabled server hangs at startup +time and your XPA_METHOD is <B>inet</B>, the problem probably is +related to an incorrect Internet configuration. This can be confirmed +by using the <B>unix</B> method or (usually) the <B>localhost</B> +method. You can use these alternate methods if other hosts do not need +access to the XPA server. + +<!-- =section xpamethod SEE ALSO --> +<!-- =text See xpa(n) for a list of XPA help pages --> +<!-- =stop --> + +<P> +<A HREF="./help.html">Go to XPA Help Index</A> + +<H5>Last updated: September 10, 2003</H5> +</BODY> +</HTML> |