Core Metadata

Introduction

The Core Metadata contains the information about the devices and sensors and how to communicate with them. This information is used by the other services such as Core Data, Core Command, etc.

Specifically, Core Metadata has the following capabilities:

• Manages information about the devices that are connected to and operated by Edge Xpert
• Accesses to the type and organization of data reported by the devices
• Accesses to how to control these devices

Although Core Metadata has this information, it does not perform the following activities:

• It is not responsible for the actual data collection from the devices, which is performed by Device Services and Core Data
• It is not responsible for issuing commands to the devices, which is handled by Core Command and the Device Services

Data Models

To understand Core Metadata, it is important to know the Edge Xpert data objects that manage it. Metadata stores its information in a local persistence database.by default, Redis is used, but a database abstraction layer allows other databases to be used as well.

Device Profile

Device profiles define general characteristics of devices, the data they provide, and the way they can be controlled. Think of a device profile as a template for a device type or classification. For example, a device profile for BACnet thermostats provides general characteristics for the types of data a BACnet thermostat sends, such as current temperature and humidity. It also defines what types of commands or actions Edge Xpert can send to the BACnet thermostat. Examples include actions that set the cooling or heating point. Device profiles are usually defined in YAML or JSON files and uploaded to Edge Xpert. See below for more details.

Device Profile Details

Metadata device profile object model

name: "BAC-9001"
manufacturer: "KMC"
model: "BAC-9001"
labels:
    - "B-AAC"
description: "KMC BAC-9001 BACnet thermostat"

name: Temperature
description: "Get the current temperature"
isHidden: false

name: ActiveCoolingSetpoint
description: "The active cooling set point"
isHidden: false

-
    name: Temperature
    description: "Get the current temperature"
    isHidden: false
    attributes:
        { type: "analogValue", instance: "1", property: "presentValue", index: "none"  }
-
    name: ActiveCoolingSetpoint
    description: "The active cooling set point"
    isHidden: false
    attributes:
        { type: "analogValue", instance: "3", property: "presentValue", index: "none"  }

name: Temperature
description: "Get the current temperature"
attributes:
    { type: "analogValue", instance: "1", property: "presentValue", index: "none"  }
properties:
    valueType: "Float32"
    readWrite: "R"
    units: "Degrees Fahrenheit"

Device

Data about actual devices is another type of information that the Core Metadata stores and manages. Each device managed by Edge Xpert Foundry registers with Core Metadata (via its owning Device Service). Each device must have a unique name associated to it.

Metadata stores information about a device (such as its address) against the name in its database. Each device is also associated to a device profile. This association enables Core Metadata to apply knowledge provided by the device profile to each device. For example, a thermostat profile would say that it reports temperature values in Celsius. Associating a particular thermostat (the thermostat in the lobby for example) to the thermostat profile allows Core Metadata to know that the lobby thermostat reports temperature value in Celsius.

Device Service

Metadata also stores and manages information about the Device Services. Device Services serve as Edge Xpert's interfaces to the actual devices and sensors.

Device Services are other microservices that communicate with devices via the protocol of that device. For example, a Modbus Device Service facilitates communications among all types of Modbus devices. Examples of Modbus devices include motor controllers, proximity sensors, thermostats, and power meters. Device Services simplify communications with the device for the rest of Edge Xpert.

When a Device Service starts, it registers itself with Core Metadata. When Edge Xpert provisions a new devices the device gets associated to its owning Device Service. That association is also stored in Core Metadata.

Metadata Device, Device Service and Device Profile Model

Metadata's Device Profile, Device and Device Service object model and the association between them

Device Provisioning

A device needs to be onboarded into a Device Service so that the Device Service knows the location of the device and how to communicate with it. This process is called device provisioning.

There are two parts to device provisioning:

• A device profile is added to Edge Xpert. The device profile contains information about the resources and commands that are available for that device
• A device connection is added to Edge Xpert. This specifies the physical addressing information of the device such as its IP-address or port number

Once these two requirements are met, Edge Xpert will be able to communicate with the device.

Device provisioning can be done in two ways:

1. Static Provisioning
2. Dynamic Provisioning

Static Provisioning

All of the Device Services support static provisioning of devices. For static provisioning the device profile and the connection information for the device is known before onboarding the device. First, the device profile is added to Edge Xpert and then the device can be added. These steps can be performed using the Edge Xpert REST APIs or the Edge Xpert Manager UI.

Dynamic Provisioning

Some Device Services support dynamic provisioning using automatic discovery. The Device Service is provided with the necessary information about where to look and general parameters for a device (or devices). While the Device Service is running, it will continually scan (on a configurable schedule) for new devices as specified by the discovery parameters. When it finds a device that matches these parameters it will automatically create and register device profiles for those devices, and automatically onboard the devices to the Edge Xpert platform.

The configuration about how and where to look for discoverable devices is specified by an Edge Xpert Provision Watcher.

Provision Watcher

A provision watcher is specific configuration information provided to a Device Service and then stored by Core Metadata. The provision watcher is given identifiers which are a map of key value pairs that identify the type of protocol and the specific locations and parameters used in the discovery scanning process. For example, this can include MAC addresses and/or IP addresses.

In addition to providing details about what devices to look for during a scan, a provision watcher may also contain “blocking” indentifiers, which define parameters about devices that should not be automatically provisioned if they are found. This allows the scope of a device scan to be narrowed or allows specific devices to be avoided. Examples of how this is used can be found in Automatic Discovery

Metadata's provision watcher object model

Data Dictionary

Configuration Properties

Please refer to the general Common Configuration documentation for configuration properties common to all services. Below are only the additional settings and sections that are not common to all Edge Xpert Services.