| | | PAN filter |
The "panfilter" ("pan" stands for Product Arrival Notification and it is a term borrowed from the Unisys prodman manual), is one mecahnism for notifying another computer or computers when a particular file is received.
The panfilter was developed for nbsp and then it was merged with npemwin. The main motivation for enabling this in nbsp is to support a setup in which one or several computers wait for a message indicating that a particular product file has been received and saved in the spool directory by nbsp, so they can go and get it for further special processing. The nbsp computer can export by NFS, http or other means the spool directory, and the client computers can read just the file or request it by http or whatever have been set up. Similar setups can be used with npemwin as well.
There can be various form of notification, but at the moment the only one implemented is a UDP transmission. The panfilter has an "rc" file "panfilter.rc" where the rules for deciding what files to send and to whom are defined. When a given file is received and it matches a rule, the panfilter sends the client computer(s) a message containing the wmo header, the awips id if it is in the file, and the name of the file. With that information the client computer can construct the appropriate path or url to get the file and do what it wants with it.
The file "panfilter.rc-ex" contains more detailed explanations and examples, and the files "npemwinudpread.pl" and "npemwinudpread.tcl" (in the npemwin documentation directory "/usr/local/share/doc") are two simple udp reader examples.
| | | PAN filter |