Exchange app

The Exchange app synchronizes Eliona asset bookings with Microsoft Exchange servers.

Exchange app

Eliona app for Microsoft Exchange booking integration

Create a room list in Exchange, make these rooms available in Eliona as bookable assets, and allow users to book the rooms directly through Eliona.

Configuration of Exchange Web Services (EWS)

Follow these steps for Exchange Online and hybrid installations where user emails are stored in Exchange Online. For an on-premises Exchange Server installation or a hybrid configuration with on-premises primary accounts, skip this chapter and obtain only the NTLM credentials and the EWS API URL.

Please note that EWS for Exchange Online will be discontinued on October 1, 2026. This does not affect on-premises Exchange servers and hybrid configurations. Further details about the discontinuation can be found in the Exchange Team Blog.

Application registration in Microsoft Entra

To configure EWS with the Exchange app, follow the steps below to register it in Microsoft Entra.

1. Application registration

Navigate to Entra and select App registrations, then select Register an app. You must enter the application details.

2. Permission configuration

Application authentication (impersonation)

For application authentication that supports impersonation:

• Go to API permissions.

• Add the permission full_access_as_app and grant admin consent.

Here is an example of the required configuration in the application manifest:

"requiredResourceAccess": [
    {
        "resourceAppId": "00000002-0000-0ff1-ce00-000000000000",
        "resourceAccess": [
            {
                "id": "dc890d15-9560-4a4c-9b7f-a736ec74ec40",
                "type": "Role"
            }
        ]
    }
]

3. Generating secrets for authentication

To authenticate the application:

• Navigate to Certificates & secrets in Entra.

• Select New client secret.

• Store the generated secret securely, as it is required to authenticate the application with Microsoft services.

Configuring impersonation via PowerShell

To configure impersonation and other settings that are not available in the Entra portal, you must use PowerShell. Note that an online PowerShell console is not available without a subscription. Local PowerShell installations on Windows, Linux, or macOS can manage these configurations:

• Make sure the necessary PowerShell modules for managing Exchange are installed.

• Use scripts to configure impersonation rights or other Exchange-specific settings.

PowerShell scripts for configuring impersonation

1. Connect to Exchange Online PowerShell:

$UserCredential = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $Session -DisableNameChecking

1. Assigning impersonation rights:

New-ManagementRoleAssignment –Name:impersonationAssignmentName –Role:ApplicationImpersonation –User:serviceAccount

1. Checking impersonation rights:

Get-ManagementRoleAssignment –RoleAssignee serviceAccount –Role ApplicationImpersonation –RoleAssigneeType User

Replace serviceAccount with the name of your service account or user that will perform impersonation.

Disconnecting the PowerShell session

Remember to close the PowerShell session once your configuration tasks are complete:

Remove-PSSession $Session

Installation

The Exchange app is installed via the App Store in Eliona.

Assets

The Exchange app automatically creates all rooms in the configured room list. Once the room is created in Eliona, it remains there even if it is removed from the room list (but bookings will no longer be synchronized). A room can be renamed or deleted independently in Eliona. Whenever a new room is added to the room list, it is created in Eliona.

Configuration

The Exchange app is configured by defining one or more authentication credentials:

Attribute	Description
clientID	ClientID obtained in the Entra Admin Center. (Only for OAuth authentication)
clientSecret	ClientSecret obtained in the Entra Admin Center. (Only for OAuth authentication)
tenantID	ID of the Exchange Online organization (Only for OAuth authentication)
ewsURL	URL of the EWS API (only for NTLM authentication)
username	NTLM username (only for NTLM authentication)
password	NTLM password (only for NTLM authentication)
serviceUserUPN	Email address of the service user (for querying rooms, creating anonymous bookings, ...)
roomListUPN	Email of the room list containing the rooms to be synchronized. CAC will be disabled if left empty.
bookingAppURL	URL of the booking app. Use the one from the example below.
enable	Flag to enable or disable fetching this configuration.
refreshInterval	Interval in seconds for room discovery.
requestTimeout	API request timeout in seconds
projectIDs	List of Eliona project IDs for which this app should collect data. For each project ID, all assets will be created automatically in Eliona.

The configuration is done using a corresponding JSON structure. As an example, the following JSON structure can be used to define an endpoint for app permissions:

{
  "clientId": "01234567-89ab-cdef-0123-456789abcdef",
  "clientSecret": "random-cl13nt-s3cr3t",
  "tenantId": "01234567-89ab-cdef-0123-456789abcdef",

  "ewsURL": "https://outlook.office365.com/EWS/Exchange.asmx",
  "username": "username",
  "password": "password",

  "serviceUserUPN": "[e-mail]",
  "roomListUPN": "[e-mail]",

  "bookingAppURL": "http://booking:3000/v1",
  "enable": true,
  "refreshInterval": 60,
  "requestTimeout": 120,
  "projectIDs": [
    "10"
  ]
}

Configurations can be created in Eliona using this structure under Apps > Exchange app > Settings For this, select the /configs endpoint with the POST method.

Once configuration is complete, the app starts continuous asset creation. When all detected rooms have been created, the user is informed via Eliona's notification system.

Booking synchronization

If the Exchange app and the booking app are configured correctly, bookings are synchronized bidirectionally between the Exchange server and Eliona. Bookings in Eliona must be made on the assets created by continuous asset creation. Changes and cancellations from either the Exchange server or Eliona are also synchronized with the other service.

If an error occurs during synchronization from Eliona to Exchange (typically when the room does not accept the invitation), the user is informed about the problem using Eliona notifications and the booking in Eliona is canceled.

If the booking is made by a user without an Exchange account (or an ad-hoc booking), the booking is made by the service user.

Booking time

When creating or deleting a booking from Eliona, the booking becomes visible in Outlook within a few seconds. Changes in Outlook are synchronized every refreshInterval seconds with Eliona.

Recurring events

Recurring events can be created in Outlook. All occurrences are passed on to Eliona and synchronized. Users in Eliona can cancel specific occurrences.

Note that there is a limit to how far in advance resources can be booked. The limit can be configured in Exchange administration for the resources.

Booking multiple assets

While the booking frontend does not allow booking multiple assets at the same time

to book, Outlook does allow this. The app synchronizes the multiple booking in Eliona and the event can be changed or canceled.