Oww Client

For a live T table on your computer (Linux or Windows) you can install oww_client.

Oww Client features

This program is based on Owwl – my Oww Library. Owwl provides a programmer's interface to the protocol used by Oww to transmit data through TCP or Unix sockets. Oww Client uses the protocol to receive weather data from one or more Oww servers. Oww Client can connect to Oww servers running locally or on another machine connected over the net. The details of your servers may be added to a pop-up list for your convenience. Units may be chosen by group (Metric, Imperial, &c) or individually (e.g. speeds in mph, but temperatures in °C). Oww Client uses Gtk+ 2. The source may be compiled on systems supporting Gtk+ 2, and binary distributions are available for Linux and Windows. Owwl (in the distribution) could be of interest to other programmers who would like to interface to Oww.

Download

Go to the oww_client download page and select the .tar.gz for Linux or the .exe for Windows.

Note that you will need to have the Gtk+ runtime environment installed (version 2.6 or later). This is common on Linux. Windows installers are available from the Gimp for Windows project.

Operation

Start oww client and point it at your (Oww) server:

Command line

oww_client yourhost.yourdomain

GUI

Run oww client (e.g. Start menu on Windows), and enter yourhost.yourdomain at the connect dialogue. You can click the "Add" button to save this for next time.

DDE Server

On Windows Oww Client now also acts as a Dynamic Data Exchange (DDE) server. Software that suuports DDE (such as LabView) may connect to Oww Client and request data. This has been developed mainly to support output from the QMC Instruments Dewar controller, which sends cryogenic temperature data using the owwl protocol. The details are as follows:

DDE Service Name: oww_client

Previously known as the application name, this is the name that Oww Client registers with DDE when it starts up.

DDE Topic Name: host name

This is the name of a host to which Oww Client is already connected. The same name should be used as was used in Oww Client's connect dialogue. So don't use yourhost in Oww Client and yourhost.yourdomain in LabView, for instance.

DDE Item: list of data fields

These are the data items you are requesting from Oww Client. They are formed from the data device name followed, optionally, by the data argument name and the unit name, separated by colons. This is not case-sensitive. If the data argument is missing, the first item is given by default, e.g. Grt voltage. If the unit name is missing, the standard metric unit is used. Unit names are as found in the Oww Client dialogue (double-click the row in the table). The items may be separated by spaces, commas, tabs or return characters - for instance, Diode1 Diode2 Grt1:V Grt1:I.

DDE Response

Oww Client responds to a DDE request with a string consisting of a tab-separated list of data values.

DDE Request Types

Data may be requested in two ways:

Normal Request

Oww Client responds immediately with the current data values.

Advice Request

This is a request to Oww Client to send the data each time there is an update, i.e. once a second with the normal servlet setup. The client (LabView) will continue to receive updates until it requests a DDE disconnect.

I have an example VI, set to connect to snap01 here: AdviseClient.vi.

See Also

• Oww
• Oww Log

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