xpaaccess(1) [debian man page]
xpaaccess(1) SAORD Documentation xpaaccess(1) NAME
xpaaccess - see if template matches registered XPA access points SYNOPSIS
xpaaccess [-c] [-h] [-i nsinet] [-m method] [-n] [-t sval,lval] [-u users] -v <template> [type] OPTIONS
-c contact each access point individually -h print help message -i access XPA point on different machine (override XPA_NSINET) -m override XPA_METHOD environment variable -n return number of matches instead of "yes" or "no" -t [s,l] set short and long timeouts (override XPA_[SHORT,LONG]_TIMEOUT) -u [users] XPA points can be from specified users (override XPA_NSUSERS) -v print info about each successful access point -V print info or error about each access point --version display version and exit DESCRIPTION
xpaaccess returns "yes" to stdout (with a return error code if 1) if there are existing XPA access points that match the template (and optional access type: g,i,s). Otherwise, it returns "no" (with a return error code of 0). If -n is specified, the number of matches is returned instead (both to stdout and in the returned error code). If -v is specified, each access point is displayed to stdout instead of the number of matches. By default, xpaaccess simply contacts the xpans name server to find the list of registered access points that match the specified template. It also checks to make sure the specified types are supported by that access point. This is the fastest way to determine available access points. However, an access point might registered but not yet available, if, for example, the server program has not entered its event loop to process XPA requests. To find access points that are guaranteed to be available for processing, use the -c (contact) switch. With this switch, xpaaccess contacts each matching XPA server (rather than the name server) to make sure the registered access point really is ready for processing. In this mode, if an access point is registered but not available, xpaaccess will pause for a period of time equal to the XPA_LONG_TIMEOUT, in order to give the server a chance to ready itself. By default, this timeout is 30 seconds. You can shorten the time of delay using the -t "short,long" switch. For example, to shorten the delay time to 2 seconds, use: xpaaccess -c -t "2,2" ds9 The first argument is the short delay value, and is ignored in this operation. The second is the long delay timeout. Note also that the default xpaaccess method (no -c switch) does not check access control (acls) but rather only checks whether the access point is both registered with the xpans name server and provides the specified type of access. In other words, the default xpaaccess could return 'yes' when you might not actually have access. This mode also always returns 'yes' for the xpans name server itself, regardless of whether the name server is active. The -c (contact) switch, which contacts the access point directly, can and does check the access con- trol (only for servers using version 2.1 and above) and also returns the real status of xpans. SEE ALSO
See xpa(7) for a list of XPA help pages version 2.1.14 June 7, 2012 xpaaccess(1)
Check Out this Related Man Page
xpa(7) SAORD Documentation xpa(7) NAME
XPA - Public Access to Data and Algorithms SYNOPSIS
This document is the Table of Contents for XPA. DESCRIPTION
The XPA messaging system provides seamless communication between many kinds of Unix programs, including X programs and Tcl/Tk programs. It also provides an easy way for users to communicate with XPA-enabled programs by executing XPA client commands in the shell or by utilizing such commands in scripts. Because XPA works both at the programming level and the shell level, it is a powerful tool for unifying any analysis environment: users and programmers have great flexibility in choosing the best level or levels at which to access XPA services, and client access can be extended or modified easily at any time. A program becomes an XPA-enabled server by defining named points of public access through which data and commands can be exchanged with other client programs (and users). Using standard TCP sockets as a transport mechanism, XPA supports both single-point and broadcast mes- saging to and from these servers. It supports direct communication between clients and servers, or indirect communication via an interme- diate message bus emulation program. Host-based access control is implemented, as is as the ability to communicate with XPA servers across a network. XPA implements a layered interface that is designed to be useful both to software developers and to users. The interface consists of a library of XPA client and server routines for use in C/C++ programs and a suite of high-level user programs built on top of these libraries. Using the XPA library, access points can be added to Tcl/Tk programs, Xt programs, or to Unix programs that use the XPA event loop or any event loop based on select(). Client access subroutines can be added to any Tcl/Tk, Xt, or Unix program. Client access also is supported at the command line via a suite of high-level programs. Choose from the following topics: o Introduction to XPA [xpaintro(7)] o Access Point Names and Templates [xpatemplate(7)] o Getting Common Information About Access Points [xpacommon(7)] o Communication Methods [xpamethod(7)] o Communication Between Hosts [xpainet(7)] o Distinguishing Users [xpausers(7)] o XPA User Programs o xpaget: get data and info [xpaget(1)] o xpaset: send data and info [xpaset(1)] o xpainfo: send info alert [xpainfo(1)] o xpaaccess: get access point info [xpaaccess(1)] o xpamb: message bus emulation [xpamb(1)] o xpans: the XPA name server [xpans(1)] o XPA Server Routines o XPANew: define a new access point [xpanew(3)] o XPACmdNew: define a new command access point [xpacmdnew(3)] o XPACmdAdd: add a command [xpacmdadd(3)] o XPACmdDel: delete a command [xpacmddel(3)] o XPAInfoNew: define an info access point [xpainfonew(3)] o XPAFree: free an access point [xpafree(3)] o XPAMainLoop: event loop for select server [xpamainloop(3)] o XPAPoll: poll for XPA events [xpapoll(3)] o XPACleanup: release reserved XPA memory [xpacleanup(3)] o XPA Server Macros: accessing structure internals [xpamacros(3)] o XPA Race Conditions: how to avoid them [xparace(3)] o XPA Out of Memory (OOM) errors [xpaoom(3)] o XPA Client Routines o XPAOpen: open a persistent client connection [xpaopen(3)] o XPAClose: close persistent client connection [xpaclose(3)] o XPAGet: get data [xpaget(3)] o XPASet: send data or commands [xpaset(3)] o XPAInfo: send an info alert [xpainfo(3)] o XPAGetFd: get data and write to an fd [xpagetfd(3)] o XPASetFd: read data from and fd and send [xpasetfd(3)] o XPANSLookup: look up an access point [xpanslookup(3)] o XPAAccess: get access info [xpaaccess(3)] o The XPA/Xt Interface: Xt interface to XPA [xpaxt(7)] o The XPA/Tcl Interface: Tcl interface to XPA [xpa(3tcl)] o Tailoring the XPA Environment o Environment Variables [xpaenv(7)] o Access Control [xpaacl(7)] o Miscellaneous o Where to Find Example/Test Code o User Changes Between XPA 1.0 and 2.0 o API Changes Between XPA 1.0 and 2.0 o What Does XPA Stand For, Anyway? version 2.1.14 June 7, 2012 xpa(7)