[Requests] Response to RFC on SensorThings API standard for Internet of Things

Simon Jirka jirka at 52north.org
Fri Jul 17 08:26:42 EDT 2015


Here are some comments on the SensorThings API:

PART A

1. Evaluator:
        Simon Jirka
        52°North Initiative for Geospatial Open Source Software GmbH
        Martin-Luther-King-Weg 24
        48155 Münster, Germany
        E-Mail: jirka at 52north.org

        Christoph Stasch
        52°North Initiative for Geospatial Open Source Software GmbH
        Martin-Luther-King-Weg 24
        48155 Münster, Germany
        E-Mail: c.stasch at 52north.org

2. Submission: OGC SensorThings API Part 1: Sensing [OGC 15-078]

PART B

1. Requirement: General
2. Section number: Introduction
3. Criticality: Minor
4. Comments/justifications for changes: In the introduction we have
read the following sentence: „the SensorThings API is designed
specifically for resource-constrained IoT devices“. As the
SensorThings API is relying upon REST, which implies the HTTP
protocol, this might be difficult to understand. Many IoT devices
might not have contiuous HTTP connections available. We recommend to
discuss this in more detail in the introduction.

1. Requirement: General
2. Section number: Document wide
3. Criticality: Minor
4. Comments/justifications for changes: We recommend further
discussion how the SensorThings API relates to the SWE standards. For
example: Could the JSON encoding for observations presented in this
document be specified as an additional encoding of O&M? Similarly, the
sensing profile is very similar to the SOS interface standard. Would
it be useful to define the REST API of the sensing profile as an
additional binding of SOS (in a dedicated specification document)?
This could be useful beyond IoT use cases.

1. Requirement: Req 12
2. Section number: 8.3.7
3. Criticality: Minor
4. Comments/justifications for changes: The JSON encoding is using
several elements of O&M, e.g. sampling and result time. As the
SensorThings API is meant as a lightweight standard, could a property
such as the result time, which might only be relevant for subset of
use cases, be made optional?

1. Requirement: General
2. Section number: 9.4
3. Criticality: Minor
4. Comments/justifications for changes: The query entity sets appear
to be applicable to several OGC standards. In order to develop REST
bindings for these standards, would it make sense to define them in a
separate document, e.g OWS Common for REST endpoints?

1. Requirement: General
2. Section number: 14
3. Criticality: Minor
4. Comments/justifications for changes: The chapter describing how the
SensorThings API and MQTT could be coupled is a bit unclear and hard
to understand. Please provide an overview of typical application
patterns and illustrate the communication flows that you have in mind.


Best regards
Christoph and Simon


-- 
Dr. Simon Jirka
52°North Initiative for Geospatial Open Source Software GmbH
Martin-Luther-King-Weg 24
48155 Münster, Germany
E-Mail: jirka at 52north.org
Fon: +49-(0)-251-396371-31
Fax: +49-(0)-251-396371-11
http://52north.org/
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