Develop a client application with the IoT SDK

This section shows you how to create a client application for a thing, named Gopher. The thing is manually registered in AM and authenticated with a username/password authentication flow. For more information about the IoT SDK API, refer to the Go package documentation.

Develop the application

These steps assume that you have installed the required software and cloned the things GitHub repository:

Create a directory structure for your Go project:
```
mkdir -p things/cmd/gopher
```
Create an empty project file (main.go ):
```
cd things
touch cmd/gopher/main.go
```

Open main.go in a text editor, and add the following code:

package main

import (
    "github.com/ForgeRock/iot-edge/v7/pkg/builder"
    "github.com/ForgeRock/iot-edge/v7/pkg/callback"
    "log"
    "net/url"
)

func main() {
    amURL, err := url.Parse("http://am.localtest.me:8080/openam")
    if err != nil {
        log.Fatal(err)
    }
    _, err = builder.Thing().
        ConnectTo(amURL).
        InRealm("/").
        WithTree("Example").
        HandleCallbacksWith(
            callback.NameHandler{Name: "Gopher"},
            callback.PasswordHandler{Password: "5tr0ngG3n3r@ted"}).
        Create()
    if err != nil {
        log.Fatal(err)
    }
    log.Println("Gopher successfully authenticated.")
}

Create a Go module:

go mod init example.com/things && go mod tidy
go: creating new go.mod: module example.com/things
go: to add module requirements and sums:
        go mod tidy
go: finding module for package github.com/ForgeRock/iot-edge/v7/pkg/callback
go: finding module for package github.com/ForgeRock/iot-edge/v7/pkg/builder
go: found github.com/ForgeRock/iot-edge/v7/pkg/builder in github.com/ForgeRock/iot-edge/v7 v7.4.0
go: found github.com/ForgeRock/iot-edge/v7/pkg/callback in github.com/ForgeRock/iot-edge/v7 v7.4.0

This step creates a go.mod file that specifies your project dependencies and versions.

Build an executable for your client application:
```
go build example.com/things/cmd/gopher
```
This step builds an executable gopher application in the things directory.

Run the application

Before you can run the application, you must register an identity for Gopher in AM:

Get an admin SSO token from AM:

curl \
--header 'X-OpenAM-Username: amAdmin' \
--header 'X-OpenAM-Password: changeit' \
--header 'Content-Type: application/json' \
--header 'Accept-API-Version: resource=2.0, protocol=1.0' \
--request POST \
'http://am.localtest.me:8080/openam/json/authenticate'
{
 "tokenId": "qGAzvBw20z5…AAA.*",
 "successUrl": "/openam/console",
 "realm": "/"
}

Save the tokenId returned in this request as a variable, for example:

export tokenId=qGAzvBw20z5…AAA.*
echo $tokenId
qGAzvBw20z5…AAA.*

curl \
--header 'Content-Type: application/json' \
--header 'Accept-Api-Version: resource=4.0, protocol=2.1' \
--cookie "iPlanetDirectoryPro=${tokenId}" \
--data '{
    "userPassword": "5tr0ngG3n3r@ted",
    "thingType": "device"
}' \
--request PUT \
"http://am.localtest.me:8080/openam/json/realms/root/users/Gopher"
{
  "_id": "Gopher",
  "_rev": "-1",
  "realm": "/",
  "username": "Gopher",
  "uid": [
    "Gopher"
  ],
  "universalid": [
    "id=Gopher,ou=user,dc=openam,dc=forgerock,dc=org"
  ],
  "objectClass": [
    "iplanet-am-managed-person",
    "inetuser",
    "fr-iot",
    "sunFMSAML2NameIdentifier",
    "inetorgperson",
    "devicePrintProfilesContainer",
    "iplanet-am-user-service",
    "iPlanetPreferences",
    "pushDeviceProfilesContainer",
    "forgerock-am-dashboard-service",
    "organizationalperson",
    "top",
    "kbaInfoContainer",
    "person",
    "sunAMAuthAccountLockout",
    "oathDeviceProfilesContainer",
    "webauthnDeviceProfilesContainer",
    "iplanet-am-auth-configuration-service",
    "deviceProfilesContainer"
  ],
  "dn": [
    "uid=Gopher,ou=people,dc=openam,dc=forgerock,dc=org"
  ],
  "inetUserStatus": [
    "Active"
  ],
  "cn": [
    "Gopher"
  ],
  "sn": [
    "Gopher"
  ],
  "thingType": [
    "device"
  ],
  "createTimestamp": [
    "20200831103235Z"
  ]
}

Run the executable to authenticate your application to AM:

./gopher
2020/09/01 11:09:49 Gopher successfully authenticated.