REST API Overview

Authorize a web application

Web applications are built using a server-side framework, which runs on a private server to secure communication with the authorization server. This ensures that the application's source code or configuration remains inaccessible to the public and allows for using a client secret.

NOTE: Your client credentials carry many privileges, so be sure to keep them secure!

Do not put your client credential information (clientid, client secret or access tokens) in publicly accessible code where they can be discovered.
Store them in a safe place on the backend (server).

Authorization code flow

Web applications can use the OAuth 2.0 Authorization Code Flow to enable data owners to authorize third-party apps to access user data. This flow includes features like customer login and consent handling to obtain authorization from the resource owner.

The following steps provide an overview of the process.

The application makes a request to the authorization server endpoint.
The end-user provides their authentication information and consents for the application to access resources on their behalf.
The authorization server returns an authorization code to the Redirect URI specified when creating the application.
The application uses the authorization code to obtain an access token from the authorization server.
The application uses the access token to call the API on behalf of the user.

sequenceDiagram
    participant ro as Resource Owner
    participant app as Application
    participant as as Authorization Server
    participant api as iTwin API

    ro->>+app: Connect to application
    app->>+as: Request authorization code
    as->>ro: Redirect to login and consent
    ro->>as: Sign in and consent
    as->>-app: Authorization code
    app->>+as: Exchange authorization code for an access_token
    as->>as: Validate client_id, client_secret, scope and redirect_uri
    as->>-app: Granted access token
    app->>-ro: Signed in

    ro->>+app: Perform action
    app->>+api: API request with the access token
    api->>-app: API response
    app->>-ro: Render content

Set up authorization for your app

The following steps outline how to implement the authorization code flow in your application. Once you have registered your app, you can begin to obtain the access token.

When the user opens the web app, redirect them to the authorization server endpoint, https://ims.bentley.com/connect/authorize. This will provide a login screen to the end user for authentication. The request for an authorization code requires the following parameters:

Parameter
Description
response_type
Set to code to indicate that an authorization code is needed.
client_id
The ID of the app you created. If you forgot the ID, find it on the My Apps page. Locate your app in the list, and the Client ID is in the same-named column.
redirect_uri
The callback URL you entered when registering your application. The returned authorization code is sent to this URL. In this case, the callback URL must be https://developer.bentley.com/redirect-tutorial.
scope
Add the itwin-platform scope assigned to your app during registration. When requesting a refresh token, include the scope offline_access. Separate multiple scopes with a space. Your end user will consent to the app accessing this information on their behalf during the login process.
state
(Optional) Used by the client to maintain state between a request and a callback. Recommended to prevent cross-site request forgery. The authorization server includes this value when redirecting the user-agent to the client.
The user signs in to authenticate and consents for the application to access resources on their behalf. This page is managed by the Bentley authorization server and does not require any implementation in your application.

Once authenticated, the Bentley authorization server returns an authorization code to the Redirect URI registered with your application. Extract the code in the response from the redirect_uri.

https://example-rediect-uri?code=<code>

NOTE: Authorization codes are time-sensitive. If your code expires, send a new request to the authorization server for a new code.
Exchange the authorization code for an access token, by sending a request to the token endpoint.

POST https://ims.bentley.com/connect/token

The authorization request requires the following parameters:

client_id

Identification generated during application creation. Found in the My Apps page or in the first step if generated during the tutorial.

client_secret

Secret created during application creation.

grant_type

Set to authorization_code Indicates the type of grant being used. This tells the service you are exchanging the code for a token.

code

This is the authorization code returned in the previous request.

redirect_uri

The callback URL you entered when registering your application. This URL must match the URL provided in the initial request.

The authorization server confirms the information sent in the request and returns an access token. Bentley's authorization server completes this step. There is no implementation needed in your application. A successful response includes the access_token, an expiry of 3600 seconds, and a refresh_token. Tokens are Bearer type, which must be specified in your API calls.
Use the access token to call the API. Tokens are added to the Authorization header with Bearer type in subsequent requests. Successfully sending a request to an API requires the end user to have the correct account permissions. Use the Access Control API to ensure your user can access the required resources.

Authorization request example

https://ims.bentley.com/connect/authorize?response_type=code&client_id=<client_id>&redirect_uri=<redirect_uri>&scope=<scope>&state=<state>

Token request example

curl https://ims.bentley.com/connect/token -X POST --data-urlencode grant_type=authorization_code --data-urlencode code=<authorization_code> --data-urlencode client_id=<client_id> --data-urlencode client_secret=<client_secret> --data-urlencode redirect_uri=<redirect_uri> --data-urlencode scope=<scope>