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Npemwin is a separate program, that can used stand-alone or in conjuction with an Nbsp server. Npemwin can connect to a list of EMWIN servers, or to a NOAAPort Nbsp server or to a directly attached serial (WX12/13) device. It saves all the files received in a directory based on file type and WFO ID. Extensive facilities allow to call a script for each complete file received for post-processing (alarms/notifications, database insertion, and others). It can in turn serve any number of byte blaster clients, including of course other instances of Npemwin itself, and it can relay the data by ldm and nntp.

Byteblaster Npemwin

Npemwin can be used independently of nbsp. In that mode, it can connect to any number of byte blaster servers or to a directly attached emwin serial (WX12/13) device. In any case, it will serve the data to any number of byte blaster clients, including other instances of npemwin itself, and it can relay the data by ldm and nntp.

It can be configured to register itself with the NWS master host to be advertised as a ``public'' server and appear in the list of available servers. It has no hard-coded limits to the number of clients it can serve. The number can be limited in the run-time configuration file if desired. Clients can be dennied or allow access through the tcpwrappers /etc/hosts.allow file. When used in this way npemwin tries to imitate ``bug for bug'' the behaviour of a regular BB server, as seen by either the BB clients, the BB servers or the master host.

It has a built-in web server for monitoring the internal state of the server as well as displaying the files received using any web browser. To show what it looks like our test web server is open at

That version is configured to run with nntp, gempak and ldm. The nntp gateway can be accessed by pointing the news client to
at the standard nntp port.

The following are some of the more important features.

Noaaport Emwin

Nbsp has a built-in emwin-like server. That is, the files received from the noaaport stream can be sent through the network to clients using the byte blaster protocol used by the emwin system. Nevertheless, emwin client programs must be prepared to receive data at a much larger rate than was available using the traditional emwin system. This means in particular that most of the popular emwin client programs must be revised and updated to to be usable with a noaaport-based emwin server. A short paper ``ENGINE.FRM-doc.pdf'' written by Jose F. Nieves and Ray Weber, posted in the files section of the noaaport yahoo groups, explains and documents the results of some of the experiments that we have carried out along these lines. The original paper and support files are available from this site as well.

ENGINE.FRM and byteengn.exe

We took those steps further in two ways. First we revised slightly the modifications required to the ENGINE.FRM file, to be more systematic, but the changes are minimal. In addition to that file, for those that cannot compile the program themselves we are also making available the resulting compiled executable byteengn.exe. This program can be used in place of the original and it will make the Weathernode program able to get the data from an nbsp server. A noaaport (nbsp-based) emwin server is running on

which developers or anybody can use for testing purposes.

In general it is not a good the idea to let many clients connect to the nbsp noaaport server. This is the raison d'entre of the program npemwin which, in this role, is meant to sit between the noaaport server and the emwin clients. npemwin is a typical unix daemon, whose job is to connect as a client to the noaaport server, and then serve the emwin clients in the standard way. The idea is that npemwin is installed in a different computer, so that emwin clients connect to it, and only npemwin connects to the noaaport server so that it is perturbed as little as possible.

For practical purposes, it makes no difference to an emwin client whether it is connecting directly to nbsp or to npemwin, in fact it cannot distinguish between the two. In either case the modifications to the ENGINE.FRM file of the byteengn.exe program are required.