location_manager

Runs on:

QNX Neutrino

Options:

None.

Description:

The location manager (location_manager) uses PPS objects to make location information available to client applications. It is automatically installed on your development host when you install the QNX Web Browser.

The following table lists how the various module types support each positioning method:

PPS objects

To interact with client applications, the location manager publishes the following PPS objects:

• /pps/services/geolocation/control — Allows an application to request location fixes, get the status of its current request, cancel positioning updates, or issue a reset to location provider modules.
• /pps/services/geolocation/status — Allows an application to monitor the status of the location manager.

Using a single positioning method

You can restrict a client application to use only a specific positioning method. To do so, set the provider and fixtype parameters as follows when issuing a location command to the /pps/services/geolocation/control object:

Control object:

A command may not work with all provider types. For instance, the reset command doesn't apply when you set the provider parameter to network.

Command and response format

To issue commands to /pps/services/geolocation/control, clients send messages in this format:

msg::command\nid::ID\ndat::{JSON_DATA}

The ID is a unique identifier; you can set it to any value you wish. The dat attribute, when required, contains parameters associated with the command.

In response, the location manager issues message in this format:

res::command\nid::ID\dat:{JSON_DATA}\nerrCode::error_code\nerr::short_desc\n
errstr::long_desc

where command and ID are the command and ID specified in the client message, JSON_DATA is JSON-encoded response data, and short_desc and long_desc are short and long string descriptions of error_code.

location command

The location command tells the location manager to provide a location fix to the client. It takes the following parameters:

Reply

The reply to the location command can include the following attributes:

Satellite array

{{sat1}, {sat2}, {sat3}, ...}

Each member of the array contains the following attributes:

cancel command

The cancel command tells the location manager to stop providing updates to the client. It takes no dat parameters.

Reply

The location manager doesn't reply to cancel commands.

status command

The status command tells the location manager to provide the status of the client's current request. It takes no dat parameters.

Reply

The reply to the status command contains the following attributes:

reset command

Reply

The location manager doesn't reply to reset commands.

Example location command

msg::location\nid::test\ndat:json:{
    "period": 1, 
    "provider":"gnss", 
    "fix_type":"best", 
    "report_sat":true,
    "report_nmea":true
}	

In response, the location manager issues a reply like the following (for the sake of brevity, some members of the satellites array have been omitted):

@control
res::location
id::test
dat:json: {
            "provider": "gnss",
            "fix_type": "gps_autonomous",
            "latitude": 45.3456098,
            "longitude": -75.8126319,
            "altitude": 60094.5,
            "altitudeAccuracy": 3181.5,
            "geoidHeight": 0,
            "heading": 0,
            "speed": 0,
            "verticalSpeed": 0,
            "ttff": 0,
            "gpsWeek": 1994,
            "gpsTow": 269966000,
            "utc": 1522205950000,
            "hdop": 7.9,
            "pdop": 15,
            "propagated": true,
            "satellites": [
              {
                "type": "GPS",
                "id": 2,
                "cno": 42,
                "ephemeris": true,
                "azimuth": 263,
                "elevation": 48,
                "tracked": true,
                "used": true,
                "almanac": true
              },
              {
                "type": "GPS",
                "id": 3,
                "cno": 19,
                "ephemeris": false,
                "azimuth": 39,
                "elevation": 11,
                "tracked": true,
                "used": false,
                "almanac": true
              },              
            ],
            "NMEA": [
              {
                "name": "GPGSV",
                "sentence": "$GLGSV,3,2,10,79,28,248,26,80,24,318,18,81,58,330,23,
                    82,16,291,19"
              },
              {
                "name": "GPGSV",
                "sentence": "$GLGSV,3,3,10,87,06,091,,88,47,066,"
              }
            ]
          }

Status object:

The location manager populates the /pps/services/geolocation/status object at startup so that applications can monitor its status.

Here is an example of the object:

@status
status:json:{
    "location_manager_location_on":true,
    "location_manager_location_gnss_on":true
}

Attributes

location_manager_location_on

location_manager_location_gnss_on