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98 lines
3.8 KiB
Markdown
98 lines
3.8 KiB
Markdown
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# Introduction to OpenMTC
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## Using OpenMTC for IoT/M2M applications
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OpenMTC provides an implementation of the [oneM2M standard](http://www.onem2m.org/).
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This allows you to develop new or test existing IoT/M2M applications, create
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your own IoT/M2M infrastructure, or extend an existing one.
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## How is data represented in an OpenMTC-based system?
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In an OpenMTC system, all entities are represented as **resources**. Resources
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are either:
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* **Containers** consisting of other containers (subcontainer) or content instances
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* **Content Instances** holding actual values
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This results in a hierarchical **resource tree** with content instances as leafs.
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Each resource within the resource tree is uniquely addressable by an unique identifier (URI).
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### Example
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Lets assume you have a ZigBee device providing informations about the current
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temperature and its battery status. This will result in the following resource
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tree:
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![Resource Tree](pics/example_resource_tree.png "Resource Tree")
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## How to access and provide data from/to an OpenMTC-based system?
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OpenMTC provides mechanisms to create, change, update, and delete
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resources in the resource tree. Therefore, an application is needed
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that will use one of the following two approaches:
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* **A REST API** (external interface)
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* **The OpenMTC SDK** (internal interface)
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Using the *REST API*, it is possible to provide your application logic
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by just using your preferred HTTP client.
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In addition, it is also possible to use the *OpenMTC SDK* to write your application. Common
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problems, like how to create a subscription that will notify your
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application whenever a particular resources are changed or have a new
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content instance available, are easily to be solved, using the SDK.
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## How to structure your OpenMTC-based IoT system?
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Using OpenMTC, it is possible to create your own IoT/M2M infrastructure.
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Consider an IoT system that collects data from different sensors, in
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different field domains, and automatically distributes the data to
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central nodes of multiple field domains.
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![Example OpenMTC Architecture](pics/openmtc-archtecture-overview.png "Example OpenMTC
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Architecture")
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With OpenMTC you would setup an **OpenMTC Gateway** for every field domain. All
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oneM2M devices within this field domain would register themself with the
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gateway. Non-oneM2M devices would need an **Interworking Proxy**
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inbetween to translate to oneM2M.
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The gateways are registered at an **OpenMTC Backend** within the infrastructure domain.
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**OpenMTC Applications** could either connect directly to the gateways or the backend to provide/collect data.
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### Application (AE)
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An application is provided by you and others to access data within the OpenMTC-based IoT system.
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An example for an application is the server part of Graphical User Interface (GUI), that allows to
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visualize data stored in the resource tree.
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Another example would be an application using device data to do some analytics
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and providing the results within the resource tree.
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#### Interworking Proxy (IPE)
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A special kind of application -- in a matter of speaking -- is an IPE.
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An IPE allows to translate data from a non-oneM2M domain to a oneM2M
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domain.
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An example for an IPE could be an application that reads out sensor
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values from your sensor device by using a vendor-specific binary
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interface and translates it to oneM2M.
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### OpenMTC Gateway
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A software node that is central to a particular small field domain
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that allows to collect data from various IPEs. A local application
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can access the resource tree, via the OpenMTC Gateway.
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It is possible to create a hierarchy of OpenMTC Gateways. This
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allows to travel data from one part in your IoT system to another
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one.
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### OpenMTC Backend
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If you need a central software node within the infrastructure domain,
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the OpenMTC Backend is the exact choice. Usually, it acts as the
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root node within a hierarchy of OpenMTC Gateways.
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