[SOLVED] Support to read images via OPC UA with eclipse milo

Support to read images via OPC UA with eclipse milo

I just found in the OPCUA specification that images are supported (BMP, GIF, JPG and PNG) (see link). I also went through the org.eclipse.milo.opcua.stack.core.Identifiers and I see that types exist to handle those image formats:

    public static final NodeId ImageBMP = init(2000);
    public static final NodeId ImageGIF = init(2001);
    public static final NodeId ImageJPG = init(2002);
    public static final NodeId ImagePNG = init(2003);

The question is, has milo currently support for reading those image formats via OPCUA? Any example of how to do it?

Thanks!

Solution

You just read the Value attribute like any other VariableNode.

The result will be a ByteString. Those NodeIds you found are the ids of alias/simple DataTypes that inherit from ByteString and serve as a hint to what the contents of the ByteString will be.

It’s up to you to turn the bytes into an image after that - it doesn’t have anything to do with OPC UA or Milo at that point. You’ll probably want to look at the ImageIO API.