1xpamethod(n) SAORD Documentation xpamethod(n)
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6 XPAMethod: XPA Communication Methods
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9 XPA supports both inet and unix (local) socket communication.
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12 XPA uses sockets for communication between processes. It supports three
13 methods of socket communication: inet, localhost, and unix. In general,
14 the same method should be employed for all XPA processes in a session
15 and the global environment variable XPA_METHOD should be used to set up
16 the desired method. By default, the preferred method is "inet", which
17 is appropriate for most users. You can set up a different method by
18 typing something like:
19 setenv XPA_METHOD local # unix csh
21 XPA_METHOD=local; export XPA_METHOD # unix sh, bash, windows/cygwin
22 set XPA_METHOD=localhost # dos/windows
23 The options for XPA_METHOD are: inet, unix (or local), and localhost.
25 On Unix machines, this environment setup command can be placed in your
26 shell init file (.cshrc, .profile, .bashrc, etc.) On Windows platforms,
27 it can be placed in your AUTOEXEC.BAT file (I think!).
28 By default, inet sockets are used by XPA. These are the standard
30 Internet sockets that are used by programs such as Netscape, ftp. etc.
31 Inet sockets utilize the IP address of the given machine and a (usually
32 random) port number to communicate between processes on the same
33 machine or between different machines on the Internet. (Note that XPA
34 has an Access Control mechanism to prevent unauthorized access of XPA
35 access points by other computers on the Net). For users connected to
36 the Internet, this usually is the appropriate communication method. For
37 more information about setting up XPA communication between machines,
38 see Communication Between Machines.
39 In you are using XPA on a machine without an Internet connection, then
41 inet sockets are not appropriate. In fact, an XPA process often will
42 hang for many seconds while waiting for a response from the Domain Name
43 Service (DNS) when using inet sockets. Instead of inet sockets, users
44 on Unix platforms can also use unix sockets (also known as local
45 sockets). These sockets are based on the local file system and do not
46 make use of the DNS. They generally are considered to be faster than
47 inet sockets, but they are not implemented under Windows. Use local
48 sockets as a first resort if you are on a Unix machine that is not
49 connected to the Internet.
50 Users not connected to the Internet also can use localhost sockets.
52 These are also inet-type sockets but the IP address used for the local
53 machine is the localhost address, 0x7F000001, instead of the real IP of
54 the machine. Depending on how sockets are set up for a given platform,
55 communication with the DNS usually is not required in this case (though
56 of course, XPA cannot interact with other machines). The localhost
57 method will generally work on both Unix and Windows platforms, but
58 whether the DNS is required or not is subject to individual
59 configurations.
60 A final warning/reminder: if your XPA-enabled server hangs at startup
62 time and your XPA_METHOD is inet, the problem probably is related to an
63 incorrect Internet configuration. This can be confirmed by using the
64 unix method or (usually) the localhost method. You can use these
65 alternate methods if other hosts do not need access to the XPA server.
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68 See xpa(n) for a list of XPA help pages
69version 2.1.15 July 23, 2013 xpamethod(n)