Fix spellings in DEMO4-UE README file

## Demo4 Scenario Overview

The Demo4 scenario consists of one or more instances of a single Terminal application running one or more fixed or mobile terminal equipment. 

MEC-016 Service APIs "/dev_app/v1/context" and "/dev_app/v1/context/{instance}" provide the capability to instante one or more MEC applications.

MEC-016 Service APIs "/dev_app/v1/context" and "/dev_app/v1/context/{instance}" provide the capability to instantiate one or more MEC applications.

By default, there is one onboarded MEC application named onboarded-demo4, described below (see file ~/AdvantDEGE/examples/demo4-ue/src/onboarded-demo4.yaml):

```yaml

### demo4-ue

The Terminal application demo4-ue provide a simply HHTP REST APIs for MEC-016 in order to validate quickly MEC-016 support.

The Terminal application demo4-ue provide a simply HTTP REST APIs for MEC-016 in order to validate quickly MEC-016 support.

#### Check that the demo4-ue is up

The requets `GET /info/application` provides a description of the demo4-ue application.

The request `GET /info/application` provides a description of the demo4-ue application.

```sh

$ curl "http://mec-platform.etsi.org:31111/info/application" -H "accept: application/json"

{"config":"app_instance.yaml","ip":"http://demo4-ue1:80","id":"ce454f4c-16f8-4542-83d8-c8afd45bcfea","mecReady":true,"subscriptions":{"AppTerminationSubscription":{"subId":"sub-LzNr62ED50GbZL_S"},"SerAvailabilitySubscription:":{"subId":"sub-Ec2tT-tKAe_qLxI7"}},"offeredService":{"serName":"demo4","id":"2ad0e566-2054-4550-ba97-1fe1f100fff0","state":"ACTIVE","scopeOfLocality":"MEC_SYSTEM","consumedLocalOnly":true},"discoveredServices":[{"serName":"meep-dai","serInstanceId":"70bb83a5-7ec7-4ab4-b889-ca7033a5be2b","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/dev_app/v1/","version":"2.0"},{"serName":"meep-rnis","serInstanceId":"3e72aa67-ff20-4e7e-bf21-aea928a1743b","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/rni/v2/","version":"2.0"},{"serName":"meep-ams","serInstanceId":"99e8a85d-5f87-48ed-be5e-1302c18e4664","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/amsi/v1/","version":"2.0"},{"serName":"meep-loc-serv","serInstanceId":"85ddf74d-d5e7-4d6f-beb5-25e97f8b57c9","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/location/v2/","version":"2.0"},{"serName":"meep-vis","serInstanceId":"3e23a210-8b1a-4a01-bc0c-1df7d1ad6be3","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/vis/v2/","version":"2.0"},{"serName":"meep-wais","serInstanceId":"a22f614e-a5c1-4902-84d3-4361ac9e3425","consumedLocalOnly":true,"link":"http://mec-platform.etsi.org/usersb/wai/v2/","version":"2.0"}]}

```

The requets `GET /info/logs` provides some executon logs for the demo4-ue application.

The request `GET /info/logs` provides some executon logs for the demo4-ue application.

```sh

$ curl "http://mec-platform.etsi.org:31111/info/logs" -H "accept: application/json"

["5. demo4DaiAppListGET: applicationList succeed, len= 1","4. daiClient instance created","3. Subscribe to service-availability notification [201]","2. Subscribe to app-termination notification [201]","1. === Register Demo4 MEC Application [200]","0. Send confirm ready [204]"]

#### Retrieve the list of existing onboarded MEC applications

The requets `GET /dai/apps` provides the list of the onboarded MEC application.

The request `GET /dai/apps` provides the list of the onboarded MEC application.

```sh

$ curl "http://mec-platform.etsi.org:31111/dai/apps" -H "accept: application/json"

{"appList":[{"appInfo":{"appCharcs":{"bandwidth":1024,"latency":1024,"memory":1024,"storage":1024},"appDId":"onboarded-demo4","appDVersion":"v0.1.0","appDescription":"Basic HTTP Ping Pong","appLocation":[{"countryCode":"33"}],"appName":"onboarded-demo4","appProvider":"ETSI","appSoftVersion":"v0.1.0"}}]}

#### Instantiate an onboarded MEC application

The requets `POST /dai/instantiate` is used to create a new AppContext and instantiate the specified onboarded MEC application.

The request `POST /dai/instantiate` is used to create a new AppContext and instantiate the specified onboarded MEC application.

```sh

$ curl -X POST "http://mec-platform.etsi.org:31111/dai/instantiate" -H "accept: application/json"

{"appAutoInstantiation":true,"appInfo":{"appDId":"onboarded-demo4","appDVersion":"v0.1.0","appDescription":"Basic HTTP Ping Pong","appName":"onboarded-demo4","appProvider":"ETSI","appSoftVersion":"v0.1.0","appPackageSource":"appPackageSource1","userAppInstanceInfo":[{"appInstanceId":"20","appLocation":{"countryCode":"33"},"referenceURI":"https://mec-platform.etsi.org/usersb/onboarded-demo4"}]},"appLocationUpdates":true,"associateDevAppId":"04e71585-87c7-4d2e-b913-538cf1ef","callbackReference":"http://demo4-ue1:80","contextId":"20"}

```

Note that, in the response:

- The field "contextId" indicates the identifier to be used to [terminate the instance](#terminate-an-existing-instance-of-onboarded-mec-application),

- The field "contextId" indicates the identifier to be used to [terminate the instance](#terminate-an-existing-instance-of-onboarded-mec-application).

- The field "referenceURI" indicates the URL to the new instance of the onboarded MEC application, see clause [Ping request](#ping-request]).

#### Ping request

The requets `GET /onboarded-demo4/ping/{appcontextid}` is the ping/pong request to send to the instance of the onboarded MEC application [onboarded-demo4](#onboarded-demo4).

The request `GET /onboarded-demo4/ping/{appcontextid}` is the ping/pong request to send to the instance of the onboarded MEC application [onboarded-demo4](#onboarded-demo4).

```sh

$ curl "http://mec-platform.etsi.org/usersb/onboarded-demo4/ping/20" -H "accept: application/json"

"pong"

#### Terminate an existing instance of onboarded MEC application

The requets `DELETE /dai/delete/{appcontextid}` terminates the instance of the specified onboarded MEC application.

The request `DELETE /dai/delete/{appcontextid}` terminates the instance of the specified onboarded MEC application.

```sh

$ curl -X DELETE "http://mec-platform.etsi.org:31111/dai/delete/20" -H "accept: application/json"

#### application location availability task

The requets `POST /dai/availability/{appcontextid}` provides the location availability for the specified instance of the onboarded MEC application.

The request `POST /dai/availability/{appcontextid}` provides the location availability for the specified instance of the onboarded MEC application.

```sh

$ curl -X POST "http://mec-platform.etsi.org:31111/dai/availability/20" -H "accept: application/json"

#### Postman workspace

The code below is the the Postman workspace equivalent to the cUrl requests above.

The code below is the the Postman workspace equivalent to the curl requests above.

```json

{

### onboarded-demo4

The MEC application onboarded-demo4 is a basic HTTP REST API "Ping/Pong" application. When it recieves an HTTP GET /ping request, it replies with 200 OK "pong".

The goal of thos application is just to validate the support of MEC-016 Service APIs.

The goal of this application is just to validate the support of MEC-016 Service APIs.

## Using Demo4

### Preamble (reserved to MEC Sandbox administrator)

Before to use Demo4, the configuration files '~/AdvantDEGE/examples/demo4-ue/src/onboarded-demo4.yaml' and '~/AdvantEDGE/examples/demo4-ue/src/onboarded-demo/onboarded-demo-test1.json' and the binariy folders shall be copied into the folder /var/lib/docker/volumes/meep-dai/_data/ (required to use sudo command). This is the descriptor of the onboarded MEC application [onboarded-demo4](#onboarded-demo4).

Before using Demo4, the configuration files '~/AdvantDEGE/examples/demo4-ue/src/onboarded-demo4.yaml' and '~/AdvantEDGE/examples/demo4-ue/src/onboarded-demo/onboarded-demo-test1.json' and the binariy folders shall be copied into the folder /var/lib/docker/volumes/meep-dai/_data/ (required to use sudo command). This is the descriptor of the onboarded MEC application [onboarded-demo4](#onboarded-demo4).

**_Note_** For the MEC Sandbox platform, the configuration files and the binariy folders shall be copied into the folder /var/lib/docker/volumes/<sandbox network name>/_data (e.g. /var/lib/docker/volumes/meep-4g-5g-wifi-macro-mec016-1/_data)

$ ./build-demo4-ue.sh --rebuild_dai

```

NOTE: Binary files are created in ./bin/ folder

NOTE: Binary files are created in ./bin/ folder.

#### Dockerize demo applications

Demo Application binaries must be dockerized (containerized) as container images in the Docker registry. This step is necessary every time the demo binaries are updated.

Therefore, the following steps need to be done prior to running Demo4 application instances.

#### Obtain demo binaries

Use the same procedure described above for Demo4 with AdvantEDGE.

- Use the same procedure described above for Demo4 with AdvantEDGE.

#### Create work directory for demo4-ue instance

Create a work directory of your choice on the system (e.g. ~/tmp/demo4) and copy the files ~/AdvantEDGE/examples/demo4-ue/src/demo-server/demo4-ue-config.yaml and ~/AdvantEDGE/examples/demo4-ue/bin/demo-server/demo-server.

- Create a work directory of your choice on the system (e.g. ~/tmp/demo4) and copy the files ~/AdvantEDGE/examples/demo4-ue/src/demo-server/demo4-ue-config.yaml and ~/AdvantEDGE/examples/demo4-ue/bin/demo-server/demo-server.

	The structure should look like this:

			\____ demo-server

	```

Update the configuration file demo4-ue-config.yaml accordingly and launcg the demo application:

Update the configuration file demo4-ue-config.yaml accordingly and launch the demo application:

```sh

$ ./demo-server ./demo4-ue-config.yaml