/capture-admin/agents/{agent_name}/capabilities.json: When only one capability, returns an object, otherwise an array

[felix-itz]

Hi, we're still on Opencast 14. I noticed that if /capture-admin/agents/{agent_name}/capabilities.json is only one, properties-response.properties.item is an object, whereas if it is multiple, it is an array:

For instance one:

{"properties-response":{"properties":{"item":{"key":"capture.device.names","value":"Auto A,Auto B"}}}}

Multiple:

{"properties-response":{"properties":{"item":[{"key":"capture.device.names","value":"Presentation Recorder: presentation/source"},{"key":"capture.device.Presentation Recorder: presentation/source.version","value":"8.1.4"},{"key":"capture.device.Presentation Recorder: presentation/source.mode","value":1}]}}}

Is this still an issue in the current Opencast and if so, is this by intention?

[mtneug]

Most probably yes and there are a ton of other endpoints that behave similar to this. This is more or less default Java / JAX-RS behavior and probably not an issue between Java codebases that use the same stack. But this is a pain in the neck to deal with for everything else...

[mtneug]

For the record, take a look at the following code:

opencast/modules/capture-admin-service-impl/src/main/java/org/opencastproject/capture/admin/endpoint/CaptureAgentStateRestService.java

Lines 292 to 297 in b2648e9

	PropertiesResponse r = new PropertiesResponse(service.getAgentCapabilities(agentName));
	if ("json".equals(type)) {
	return Response.ok(r).type(MediaType.APPLICATION_JSON).build();
	} else {
	return Response.ok(r).type(MediaType.TEXT_XML).build();
	}

And the PropertiesResponse class:

opencast/modules/common/src/main/java/org/opencastproject/util/PropertiesResponse.java

Lines 35 to 53 in b2648e9

	@XmlType(name = "properties-response", namespace = "http://common.opencastproject.org")
	@XmlRootElement(name = "properties-response", namespace = "http://common.opencastproject.org")
	@XmlAccessorType(XmlAccessType.FIELD)
	public class PropertiesResponse {
	@XmlJavaTypeAdapter(HashtableAdapter.class)
	private Properties properties;
	public PropertiesResponse() {
	}
	public PropertiesResponse(Properties properties) {
	this.properties = properties;
	}
	public Properties getProperties() {
	return this.properties;
	}
	}

We use standard annotations and don't switch return types.

BTW this being part of the capture agent API will probably never change as this is implemented in "hardware" (well there is still firmware software, but how often is that updated...).

[felix-itz]

This is more or less default Java / JAX-RS behavior

I guess Plugins should deal with that more consistently.

But this is a pain in the neck to deal with for everything else...

A pity for the plugin authors.