EncDotNet.S100.Samples.Ais

This console sample streams live AIS vessel positions from aisstream.io and prints each vessel as it's added, updated or removed. It shows the AIS dynamic feature source, AisDynamicFeatureSource, without a UI.

Prerequisites

Run the sample

  1. Set the ENCDOTNET_AIS_STREAM_KEY environment variable to your API key:

    export ENCDOTNET_AIS_STREAM_KEY=<your-key>

  2. From the repository root, run the sample:

    dotnet run --project samples/EncDotNet.S100.Samples.Ais

    The sample subscribes to the whole world and prints:

    Connected to aisstream.io, listening on world. Press Ctrl+C to exit.

  3. Press Ctrl+C to stop. The sample prints how many vessels it saw.

To keep the subscription small, and within aisstream.io's fair-use limits, pass a bounding box as minLat,minLon,maxLat,maxLon in decimal degrees. For example, for San Francisco Bay:

dotnet run --project samples/EncDotNet.S100.Samples.Ais -- 37.4,-123.0,38.2,-122.0

If the environment variable isn't set, the sample prints how to set it and exits with code 1.

Output

Each line starts with a marker:

Marker Meaning
+ The first message from a vessel.
Two spaces An update for a vessel already seen.
- A vessel removed because it sent no message for 6 minutes.

A line shows the vessel ID, the feature kind, the position, the speed over ground and the course over ground:

+ ais:367123450  vessel.ais.cargo       37.7785,-122.3850 SOG= 12.4kn COG=270°

How it works

The sample connects three layers, described in the AIS source design note:

AisStreamIoMessageSource       driver: the aisstream.io WebSocket connection
  ↓ IAisMessageSource
AisDynamicFeatureSource        keeps one feature per MMSI, ages out old targets
  ↓ IDynamicFeatureSource
Program.cs                     prints each Changed event to the console

The driver is in EncDotNet.S100.DynamicSources.Ais.Drivers.AisStreamIo. Program.cs subscribes to the source's Changed event and reads CurrentFeatures for the added and updated vessels.

SoundCharts uses the same AisDynamicFeatureSource for its AIS overlay. To turn it on, open Settings > Vessels, select Enable AIS overlay, and enter your API key or set the same environment variable. The change takes effect when you restart SoundCharts.

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