CoreDeviceAdapter v0.4.0: LineBasedMessageParser incompatible with protobuf binary messages

[tylerkron]

Summary

CoreDeviceAdapter v0.4.0 uses LineBasedMessageParser which is designed for text-based protocols (like SCPI responses) but cannot parse binary protobuf messages sent by DAQiFi devices after initial command exchange.

Current Behavior

• CoreDeviceAdapter successfully connects to devices and sends SCPI commands
• Device responses after initial SCPI commands are binary protobuf messages
• LineBasedMessageParser cannot parse these binary messages, so MessageReceived events never fire
• Device initialization fails to complete due to lack of response processing

Root Cause

The CoreDeviceAdapter uses LineBasedMessageParser (see LineBasedMessageParser.cs) which:

• Expects text messages terminated by line endings (CRLF)
• Uses UTF-8 encoding to convert bytes to strings
• Cannot handle binary protobuf data that contains null bytes and non-text content

Expected Behavior

CoreDeviceAdapter should support both:

1. Text-based SCPI command responses (current functionality)
2. Binary protobuf message parsing for device status and data messages

Proposed Solution

Add support for protobuf message parsing in CoreDeviceAdapter by either:

1. Creating a CompositeMessageParser that can handle both text and protobuf formats
2. Adding a ProtobufMessageParser alongside LineBasedMessageParser
3. Making the message parser configurable in CoreDeviceAdapter constructor

Impact

This limitation prevents Phase 2 integration of CoreDeviceAdapter in daqifi-desktop application. Current workaround is using Phase 1 approach (existing transport + Core 0.4.0 ScpiMessageProducer).

Device Communication Flow

1. SCPI Commands (text-based): DEVICE:ON, DEVICE:FORMAT PROTOBUF → LineBasedMessageParser works
2. Device Status Responses (binary protobuf): DaqifiOutMessage with device metadata → LineBasedMessageParser fails
3. Data Streaming (binary protobuf): Continuous measurement data → LineBasedMessageParser fails

Test Case

// This should work but currently fails:
var adapter = new CoreDeviceAdapter(transport);
adapter.MessageReceived += (sender, args) => {
    // This event never fires for protobuf responses
    Console.WriteLine($"Received: {args.Data}");
};
adapter.SendAsync("DEVICE:INFO"); // Response is protobuf, not parsed

Priority

High - Required for Phase 2 CoreDeviceAdapter integration in daqifi-desktop v0.4.1

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