Added an introduction page for DMI

docs/concept/device/dmi.md

@@ -3,4 +3,71 @@ title: Device Management Interface
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-tbd...
+## What is DMI?
+
+DMI (Device Management Interface): Integrate device management interfaces to enhance KubeEdge's capabilities. Develop a cloud-native platform for the comprehensive digital twin management of devices, including both device management and data.
+
+* Cloud Native: Treat devices as k8s (Kubernetes) resources to generate virtual digital twins, allowing for simulation based on k8s.
+* Device Management: Manage the lifecycle of devices as you would manage pods, simplifying operations for users.
+* Device Operations: There are two entry points for device operations, with interactive control capabilities on k8s (human-machine, machine-machine), and device interactive control capabilities are also provided to deployments.
+* Device Data: Edge-side deployments can access corresponding data, and device data is uploaded to the cloud in certain situations.
+
+
+
+## Features
+
+DMI has the following features：
+
+
+
+
+## Architecture
+
+* Decouple the device management layer from the device business data layer.
+* Microservice the device data, "Device as a Service."
+* Help developers focus on the development of business applications themselves.
+* Reduce the possibility of cloud-edge channel congestion and improve system availability.
+* Provide a more flexible and unified standardized approach to device management.
+
+
+
+![sedna_arch](/img/dmi/dmi-architecture.png)
+
+
+### Component
+DMI consists of the following components：
+
+#### Management Plane
+* Separate management plane data from business plane data.
+  * Management plane data is stored in KubeEdge's ETCD, which has less frequent changes.
+  * Business plane data is directly exported to data processors via the data plane.
+* The management plane data includes:
+  * Metadata
+  * Attributes
+  * Configurations
+  * Status
+  * Lifecycle 
+* Device Information Management:
+  * Cached in KubeEdge's SQLite database
+  * Mapped using a combination of node and protocol
+  * Initialized through the return values of the registration interface
+  * Devices are added or removed through the device interface to the Mapper
+* The Mapper implements a REST access method using gRPC and Unix Domain Sockets (UDS).
+
+#### Data Plane
+1. Edge-side applications access device data through **REST Service**.
+2. Cloud-side applications access device data through **REST Service**.
+3. The mapper pushes data to edge-side applications by configuring the **REST destination address**.
+4. The mapper pushes data to cloud-side applications by configuring the **REST destination address**.
+5. The mapper pushes data to an edge-side database by configuring the **destination address**.
+6. The mapper pushes data to an MQTT broker by configuring the **destination address**.
+7. Edge-side applications subscribe to device data via **MQTT broker topics**.
+8. Cloud-side applications subscribe to device data via **MQTT broker topics**.
+9. After processing the data, edge-side applications upload the results to the cloud.
+
+#### Interface Implementation
+* The system is divided into two separate interfaces: the **upstream** and the **downstream**.
+  *  The **upstream interface** is used by the Mapper to access Edgecore, register the Mapper, and report device status, utilizing a common Unix Domain Socket (UDS) at `/etc/kubeedge/dmi.sock`.
+  * The **downstream interface** is for Edgecore to access the Mapper to perform CRUD (Create, Read, Update, Delete) operations on devices, using a UDS specific to each Mapper.
+
+