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It is very convenient to access the gpsd from web apps with asynchronous request ?POLL; But there are problems:
First, the AIS data not available by ?POLL; request.
Second, the data other them time-position-velocity (from GNSS reciever, in general) may not be included to ?POLL; request.
The reason is that gpsd collect data during "epoch" from one GNSS fix recive to another. But "epoch" for AIS and instruments data is longer. So this data is not available for the ?POLL; request that returns the data collected during gpsd epoch in request moment.
Details and discussion see:
https://lists.nongnu.org/archive/html/gpsd-users/2020-04/msg00093.html
https://lists.nongnu.org/archive/html/gpsd-users/2021-06/msg00017.html
But this is a some strange software. Because the same functionality is present actually in gpsd: it collects a stream of data, aggregates it, and gives structured data on demand. The difference in the lifetime of the data. In gpsdPROXY it can be set explicitly and separately by data type.
I believe that such functionality must be in gpsd. But there is no such thing.
As a side, you may use gpsdPROXY to collect data from sources that do not have data lifetime control. For example, from VenusOS where there are no instruments data reliability control, or from SignalK, where there it timestamp at least.
Other side effect is storing MOB data and calculate of collision capabilities for AIS targets.
But you can just use gpsdPROXY as websocket proxy to gpsd.
However, currently the gpsdPROXY is actually a back-end for GaladrielMap. As such, it has many features poor described in the documentation.
This code is written without the use of AI, "best practices," OOP and IDE.
This cache/proxy daemon collect AIS and all TPV data from gpsd or other source during the user-defined lifetime and gives them by ?POLL; request of the gpsd protocol.
So data from AIS stream and instruments such as echosounder and wind meter become available via ?POLL; request.
In addition, you may use ?WATCH={"enable":true,"json":true} stream, just like from original gpsd.
Also it is a data multiplexer, collecting various data from various sources to provide them to clients in unify interface.
You can specify multiple addresses and ports to connect to, for example, in ipv4 and ipv6 networks.
Normally, the gpspPROXY works with gpsd on the same or the other machine. In this case, the data is the most complete and reliable.
The gpsdPROXY can work in VenusOS v2.80~38 or above. Or get data from any version via LAN. To do this, you need to enable "MQTT on LAN" feature. On VenusOS remote console go Settings -> Services -> MQTT on LAN (SSL) and Enable.
- VenusOS does not provide depth and AIS services.
- The data provided by VenusOS are not reliable enough, so be careful.
The gpsdPROXY can get data from Signal K local or via LAN. If it possible, gpsdPROXY find Signal K by yourself via zeroconf service or jast on standard port.
Indeed, SignalK can be used from gpsdPROXY only local. Via LAN it's odd.
The gpsdPROXY tries to determine the possibility of a collision according to the adopted simplified collision model based on the specified detection distance and the probability of deviations from the course.
Output collisions data contains a list of mmsi and position of vessels that have a risk of collision. The GaladrielMap highlights such vessels on the map and indicates the direction to them on self cursor.
For the Collision detector to work correctly, you must specify the boat parameters in params.php.
The gpsdPROXY supports the exchange of "man overboard" information between connected clients. Output MOB data contains a GeoJSON-like object with MOB points and lines.
In addition, there is a support for AIS Search and Rescue Transmitter (SART) messages AIS-MOB and AIS-EPIRB as a local MOB alarm. Besides, the netAIS alarm and MOB messages also supported.
In response to the command ?WPT={"action":"start","wayFileName":"fileName.gpx"}; the gpsdPROXY loads the file fileName.gpx and searches for a <rte> object with the text "current" in the <cmt> field. If this, the gpsdPROXY finds the <wpt> closest to the current position in this <rte>, and makes it the current waypoint.
The gpsdPROXY makes sure that the current position is no further than the specified distance from the waypoint and, when it is reached, determines the next waypoint.
The result is given to clients subscribed to the "WPT" messages as object {"class" : "WPT"}.
You can cancel following with the command ?WPT={"action":"cancel"};
Control: ?WPT={"action":"nextWPT"};, ?WPT={"action":"prevWPT"};
If the file fileName.gpx does not contain a <rte> object with the text "current" in the <cmt> field, then will take the <wpt>'s, starting from the one marked as "current" if it is. If there are no <wpt>'s, the last <rte> will be used.
Linux, PHP<8. The cretinous decisions made at PHP 8 do not allow the gpsdPROXY to work at PHP 8, and I do not want to follow these decisions.
Just copy files to any dir and configure.
See params.php
A simple authorization system is designed to divide users into those who have access to all features and those whose possibilities are limited.
The limitations are that there is no access to the next commands:
CONNECTUPDATEWPT
You can specify a list of addresses or/and subnets from which full access is allowed (white list) or, conversely, a list of addresses and subnets from which full access is prohibited (black list). See params.php for details.
$ php gpsdPROXY.php
Connect to the daemon on host:port from params.php by gpsd protocol via BSD socket or websocket.
gpsdPROXY daemon checks whether the instance is already running, and exit if it.
Added some new parameters for commands:
- "subscribe":"TPV[,AIS[,ALARM,[WPT]]]" parameter for ?POLL and ?WATCH={"enable":true,"json":true} commands.
This indicates to return TPV or AIS or ALARM data only, or a combination of them. Default - all.
For example:?POLL={"subscribe":"AIS"}return class "POLL" with "ais":[], not with "tpv":[]. - "minPeriod":"", sec. for WATCH={"enable":true,"json":true} command. Normally the data is sent at the same speed as they come from sensors. Setting this allow get data not more often than after the specified number of seconds. For example:
WATCH={"enable":true,"json":true,"minPeriod":"2"} sends data every 2 seconds.
New commands:
?CONNECT={"host":"","port":""};Requires you to connect to the specified address as to gpsd.?UPDATE={"updates":""};Getting data in gpsd format.?WPT={"action":"start","wayFileName":"fileName.gpx"};WPT control.?WPT={"action":"cancel"};?WPT={"action":"nextWPT"};?WPT={"action":"prevWPT"};
The output same as described for gpsd, exept:
-
The DEVICES response of the WATCH command include one device only: the daemon self. So no need to merge data from similar devices -- the daemon do it.
-
sky array in POLL object is empty.
-
The AIS object does not contain scaled and device fields, it contains the ais array only:
ais:{mmsi:{}}with value as described in AIS DUMP FORMATS section, 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 is null
- No 'second' field, but has 'timestamp' as unix time.
- The 'depth' value from the TPV class data is also present in the ATT class data
- The 'temp' value from the TPV class data is also present in the ATT class data
- The all wind values from the TPV class data is also present in the ATT class data
- The 'wtemp' value from the TPV class data is also present in the ATT class data
In the future, all these values will remain only in the data of the ATT class.
- The AIS class contain only:
{"class":"AIS",
"ais":{
"vessel_mmsi":{
...
vessel data
...
- Added ALARM array to MOB and collisions.
let webSocket = new WebSocket("ws://"+gpsdProxyHost+":"+gpsdProxyPort);
webSocket.onopen = function(e) {
console.log("spatialWebSocket open: Connection established");
};
webSocket.onmessage = function(event) {
let data;
data = JSON.parse(event.data);
switch(data.class){
case 'VERSION':
console.log('webSocket: Handshaiking with gpsd begin: VERSION recieved. Sending WATCH');
webSocket.send('?WATCH={"enable":true,"json":true,"subscribe":"TPV,AIS,ALARM","minPeriod":"0"};');
break;
case 'DEVICES':
console.log('webSocket: Handshaiking with gpsd proceed: DEVICES recieved');
break;
case 'WATCH':
console.log('webSocket: Handshaiking with gpsd complit: WATCH recieved.');
break;
case 'TPV':
console.log('webSocket: recieved TPV.');
break;
case 'ATT':
console.log('webSocket: recieved ATT.');
break;
case 'AIS':
console.log('webSocket: recieved AIS.');
break;
case 'ALARM':
for(const alarmType in data.alarms){
switch(alarmType){
case 'MOB':
console.log('webSocket: recieved MOB alarm.');
break;
case 'collisions':
console.log('webSocket: recieved collision alarm.');
break;
};
};
break;
};
};
webSocket.onclose = function(event) {
console.log('webSocket closed: connection broken with code '+event.code+' by reason ${event.reason}');
};
webSocket.onerror = function(error) {
console.log('webSocket error');
};
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