Русское описание

gpsd2websocket

version 0

Access to gpsd data via the websocket protocol from webapps.
The main goal is to simplify the creation of web applications using Global Navigation Satellite System receivers. The front-end application doesn't need to worry about the data accuracy or the connectivity of the sensors — it receives only reliable information.
It is a lightweight proxy server, written in pure PHP without using third-party libraries. The server runs on any platform that has a basic PHP implementation, and is very resource-free.

Features

• The gpsd2websocket communicates with a separately running gpsd in the usual way, so you can run gpsd in the way you want in the configuration you require.
• The user application can connect to the gpsd2websocket using either the websocket or tcp socket protocol.
• The user application can only retrieve data from the required gpsd data classes.
• The user application may not receive the specified class data from certain gpsd devices.
• The user application is not required to follow any communication protocol and can be dumb - just connect.
• However, a user application can specify connection parameters using commands similar to the gpsd protocol commands.
• Any number of gpsd2websocket instances can be running simultaneously, each with its own configuration.

Demo

located in demo/ directory

On the same computer:

• Run the gpsd with a real GNSS receiver or with a simulator.
• Run the php gpsd2websocket.php
• Open demo/index.html in the browser.

Install

Just copy files gpsd2websocket.php and fCommon.php to any dir. Optionally, copy and modify params.php.

Usage

Run

php gpsd2websocket.php [--params=params.php] [any parameters]
When running without parameters, all parameters are taken from the included params.php file, if present.
You can specify your own configuration file. Explicitly specified in command line parameters take precedence over parameters from a file.
Command line parameters:
--params=params.php The parameters file name. Default params.php
--gpsdProxyHost=host To the gpsd2websocket connection host. The square brackets [] on ipv6 address is required. Default [::]
--gpsdProxyPort=port To the gpsd2websocket connection port. Default 3839.
--dataSourceHost=host The instruments data source, gpsd host. Default localhost.
--dataSourcePort=port The instruments data source, gpsd port. Default 2947.
--gpsdProxyTimeouts="{json string}" Timeouts for gpsd data types, after which the data are considered obsolete. See params.php for defaults.
--dontUseDevices="{json string}" gpsd devices black list. In order not to use this data from this device. For example: {"TPV":["tcp://192.168.10.10:3800"],"AIS":[gpsd://192.168.10.10:2947#tcp://localhost:2222]}. Default empty.
--defaultSubscribe="TPV,ATT" Default returned gpsd data classes. All list: TPV, ATT, SKY, TOFF, PPS, OSC, AIS. Default "TPV,ATT".
--boatInfo="{json string}" Vehacle description. Some vessel characteristics to correct some data parameters. Default empty.
--noClientTimeout=30 sec., disconnect from gpsd on no any client present. 0 to disable. Default 30sec.
--noRealTime="AIS,SKY" A list of gpsd classes that do not have to be given to clients immediately. Default "AIS,SKY".
-h --help short help

Connect

The client application should access the gpsd2websocket in the usual way:

let webSocket = new WebSocket("ws://"+gpsdProxyHost+":"+gpsdProxyPort);

webSocket.onopen = ...

webSocket.onmessage = ...

webSocket.onclose = ...

webSocket.onerror = ...

, see demo/index.html for example.
Immediately after the connection is established, the client program will start receiving data according to the gpsd2websocket configuration.
When connecting via a tcp socket, you should send a string \n\n to start receiving data.

Data format

The gpsd2websocket sends the data in JSON format as described in the gpsd documentation for {"scaled";true,"split24":true} mode, except:

• All data (include AIS) in SI units:

• Speed in m/sec
• Location in degrees
• Angles in degrees
• Draught in meters
• Length in meters
• Beam in meters

• undefined values (include AIS) is null
• No 'second' field, but has 'timestamp' as unix time
• No 'depth' value in the TPV class data, this value is only present in class ATT data
• No 'temp' value in the TPV class data, this value is only present in class ATT data
• No any wind value in the TPV class data, this values is full present in class ATT data
• No 'wtemp' value in the TPV class data, this value is only present in class ATT data
• The AIS class contain only:

{"class":"AIS",
"ais":{
	"vessel_mmsi":{
		...
		vessel data
		...

The data format is the same as in gpsdPROXY.

Data control

The client program can send commands to the gpsd2websocket similar to gpsd commands:
?DEVICES; Returns a device list object
?WATCH={}; This tells the gpsd2websocket to stop/start sending data or change the data conditions. The parameters can be as follows:

"subscribe" - specify which data classes should be received. List of classes: TPV, ATT, SKY, TOFF, PPS, OSC, AIS.
For example: ?WATCH={"subscribe":"TPV,AIS"};

"dontUseDevices" - specify which data classes from which devices should NOT be received.
For example: ?WATCH={"dontUseDevices":{"ATT":["gpsd://192.168.10.10:2947#tcp://localhost:2222"],"AIS":["tcp://192.168.10.10:3800"]}}

"enable" - true/false, start/stop sending data

?POLL;, ?POLL={}; This stop (default) WATCH mode and requests the relevant data once. The parameters can be "subscribe" and "dontUseDevices". Unlike gpsd, you can ?POLL={"subscribe":"AIS"};

Any other commands and parameters are ignored. Commands can be sent at any time and in any order.

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