Update usage-demo3.md

  - User context relocation request registration

  - MEC Assisted state transfer subscriptions & notifications

## Using Demo3 with AdvantEDGE

To use Demo3 as an AdvantEDGE scenario container:

- Build & dockerize Demo3 server & frontend

- Import the provided scenario _demo3-scenario.yaml_

- Create a sandbox & deploy Demo3 scenario

### Scenario composition

## Demo3 Scenario Overview

The Demo3 scenario consists of two instances of a single MEC application running on two different mec platforms

- MEC Application instance 1 on MEC Platform _mep1_ with coverage area: _zone1_

- MEC Application instance 2 on MEC Platform _mep2_ with coverage area: _zone2_

**NOTE:** To view terminal movement on a map, you must first provision maps in AdvantEDGE as described

[here](https://interdigitalinc.github.io/AdvantEDGE/docs/overview/features/gis/#map-provisioning)

##### Demo server

### Demo server

Demo server is a web server that interacts with the _Application Enablement_ & _Application Mobility_ services

and maintains MEC Application instance state such as:

- Application readiness

- Mobility & termination subscriptions

- Terminal device contexts (counters that continue to increment even with MEC application mobility)

##### Demo frontend

### Demo frontend

The frontend is an instance-specific dashboard that provides MEC application information.

It provides controls to:

- Register/Deregister the MEC application instance

- Add/Remove terminal devices to track for Edge application mobility

### Obtain demo binaries

## Using Demo3 with AdvantEDGE

To use Demo3 as an AdvantEDGE scenario container:

- Build & dockerize Demo3 server & frontend

- Import the provided scenario _demo3-scenario.yaml_

- Create a sandbox & deploy Demo3 scenario

##### Build from source

### Build from source

To build _demo-frontend_ & _demo-server_ from source code:

```

_**NOTE:** Binary files are created in ./bin/ folder_

##### Optionally use pre-built binaries (from GitHub release)

### Optionally use pre-built binaries (from GitHub release)

```

# Get bin folder tarball from desired release

cd ~/AdvantEDGE/examples/demo3

- Configure Demo3 application instances

- Start Demo3 application instances

### Configuring application instances

Demo3 does not have prior knowledge or configuration information of the MEC services offered by the MEC platform.

Therefore, the following steps need to be done prior to running Demo3 application instances.

##### Obtain demo binaries

### Obtain demo binaries

Use the same procedure described above for Demo3 with AdvantEDGE.

##### Create work directories for each Demo3 MEC application instance

### Create work directories for each Demo3 MEC application instance

Create work directories of your choice on the system of your choosing; we'll use `~/demo3-mep1` and `~/demo3-mep2` for

this example and create a folder named `static` inside each one of the folders.

notifications sent by the ETSI MEC Sandbox can be received by demo applications. If the system is behind a firewall,

ports will need to be opened._**

##### Copy demo-server to working directories

### Copy demo-server to working directories

For each application instance, copy the following files to the working directories:

- Server executable (`/AdvantEDGE/examples/demo3/bin/demo-server/demo-server`)

- Template configuration file (`/AdvantEDGE/examples/demo3/demo3-config.yaml`)

               ├── index.html

```

##### Create application instances in the MEC Sandbox

### Create application instances in the MEC Sandbox

Login via the [ETSI MEC Sandbox](https://try-mec.etsi.org/) frontend.

Deploy either of teh dual-MEP scenarios. Note that the _dual-mep-short-path_ network scenario will trigger

Create two Application Instance IDs called `demo3`, one on _mep1_ and one on _mep2_ respectively.

##### Edit application instance configuration files

### Edit application instance configuration files

For each application instance, edit the copied template configuration file with instance-specific configuration values.

The resulting configuration should look like this:

port: ''                    # the port number that demo3 is listening on for incoming traffic

```

##### Start Demo3 instances

### Start Demo3 instances

Start the demo3 instances `./demo3-server demo3-config.yaml`

After starting the servers, the frontend can be accessed at `<your-ip-address>:<your-port>`