chore(binding-opcua) fix application/octet-stream encoding/decoding #…

[erossignon]

…1400

[codecov]

Codecov Report

❌ Patch coverage is 63.76812% with 50 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.41%. Comparing base (3325e12) to head (92fcbd8).
⚠️ Report is 32 commits behind head on master.

Files with missing lines	Patch %	Lines
...ackages/binding-opcua/src/opcua-protocol-client.ts	29.57%	50 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1449      +/-   ##
==========================================
- Coverage   77.58%   77.41%   -0.17%     
==========================================
  Files          79       84       +5     
  Lines       15331    15989     +658     
  Branches     1445     1519      +74     
==========================================
+ Hits        11894    12378     +484     
- Misses       3414     3585     +171     
- Partials       23       26       +3     

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[danielpeintner]

I think the general problem with the current code is that it right away decodes the data on the wire. It should first get the data raw and afterwards the ContentSerdes decodes the data.

[danielpeintner]

Take a look at CoAP for example where the readResource call returns the raw data

node-wot/packages/binding-coap/src/coap-client.ts

Lines 59 to 75 in 8dc6ed8

	public async readResource(form: CoapForm): Promise<Content> {
	const req = await this.generateRequest(form, "GET");
	debug(`CoapClient sending ${req.statusCode} to ${form.href}`);
	return new Promise<Content>((resolve, reject) => {
	req.on("response", (res: ObserveReadStream) => {
	debug(`CoapClient received ${res.code} from ${form.href}`);
	debug(`CoapClient received Content-Format: ${res.headers["Content-Format"]}`);
	// FIXME does not work with blockwise because of node-coap
	const contentType = (res.headers["Content-Format"] as string) ?? form.contentType;
	resolve(new Content(contentType, Readable.from(res.payload)));
	});
	req.on("error", (err: Error) => reject(err));
	req.end();
	});
	}

Afterwards the configured ContentSerdes deals with the actual content and whether the "byte stream" is JSON, CBOR or anything else..

The same should happen with OPC UA....

[erossignon]

the current code is that it right away decodes the data
In fact this code is where the encoding takes palce;( not decoding)

[danielpeintner]

I tried to test the PR with a simple example and I think it does not work as expected. Maybe I am just not understanding it properly.

As mentioned in #1400 OPC-UA seems to work fine until I add contentType.

Note: FYI, not adding any contentType at all would mean JSON which is not the case for OPC UA I believe.

If I add
"contentType": "application/octet-stream"
in a form the codec tries to do work... which has been done already.

Also, it seems that the according code hasn't changed in that regard.

Try to add "contentType": "application/octet-stream" in a simple TD and you will get something like.

throw new Error(`application/octet-stream only supports primitive types (boolean, integer, number, string) - got ${form.type}`);
                          ^

Error: application/octet-stream only supports primitive types (boolean, integer, number, string) - got undefined

[erossignon]

I tried to test the PR with a simple example and I think it does not work as expected. Maybe I am just not understanding it properly.

As mentioned in #1400 OPC-UA seems to work fine until I add contentType.

Note: FYI, not adding any contentType at all would mean JSON which is not the case for OPC UA I believe.

If I add "contentType": "application/octet-stream" in a form the codec tries to do work... which has been done already.

Also, it seems that the according code hasn't changed in that regard.

Try to add "contentType": "application/octet-stream" in a simple TD and you will get something like.

throw new Error(`application/octet-stream only supports primitive types (boolean, integer, number, string) - got ${form.type}`);
                          ^

Error: application/octet-stream only supports primitive types (boolean, integer, number, string) - got undefined

Could you provide an example of things that reproduce what you're doing. That would be easier to grasp . My understanding should be clearly available in the new unit test added. May be I missed your specific case.