Basic principles of DLNA projection

Digital Living Network Alliance (DLNA), the Digital Home Network Alliance. DLNA is not a technology, it is a solution, it is an integration of multiple technologies and aims to build home media sharing. The DLNA contains multiple network protocols, such as http, https, and upnp, of which upnp is an important component.

DLNA mainly includes the following four products:

DMS, the abbreviation of Digital Media Server (Digital Media Server), is mainly used as a media content provider to provide content playback for DMP/DMR. DMS can control which media content is provided.

DMP, the abbreviation of Digital Media Player, can search and play the content of DMS, its function is equivalent to DMR+DMC.

The DMC, short for Digital Media Controller, searches for and controls how a DMR plays content provided by a DMS, that is, how a DMR interacts with a DMS.

DMR, short for Digital Media Renderer, plays the content provided by DMS.

Upnp Device Architecture (Upnp Device Architecture)

Upnp DA divides roles in a home network into three categories: control points, devices, and services. They communicate with each other mainly through HTTP technology. Specifications of devices and related services are disclosed to other nodes in XML.
The relationship between roles in Upnp DA is shown as follows:

The basic concepts of each role are as follows:

Root device/device, i.e., hardware device, such as computer, TV box, etc. One device can provide multiple services. However, household appliances generally contain multiple devices with different functions, so the device collection formed by the collection of multiple devices is called the root device.
The functional services provided by the device. It is divided into control service, event service and display service. A service is the smallest controllable unit (action and state) in an Upnp system.
Control point. That is, control the device, can discover and control other devices. For example, control other devices to play video, pause, etc.
In DLNA screen projection, the Android device acts as the control point. It initializes and configures the connection between the DMS and DMR devices, and does not directly participate in the actual content transmission, which is completed by the DMS and DMR.