#### [Abblix\.Oidc\.Server](https://www.abblix.com/en/docs/api/abblix-oidc-server 'index')
### [Abblix\.Oidc\.Server\.Features\.BackChannelAuthentication\.Interfaces](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces 'Abblix\.Oidc\.Server\.Features\.BackChannelAuthentication\.Interfaces')

## IBackChannelLongPollingService Interface

Provides signaling infrastructure for CIBA poll mode long\-polling, allowing token endpoint requests
to wait for authentication completion rather than immediately returning authorization\_pending\.

```csharp
public interface IBackChannelLongPollingService
```

Derived  
↳ [InMemoryLongPollingService](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Features.BackChannelAuthentication.InMemoryLongPollingService 'Abblix\.Oidc\.Server\.Features\.BackChannelAuthentication\.InMemoryLongPollingService')

### Remarks

This interface supports the optional long-polling feature of CIBA poll mode. When long-polling is enabled,
token endpoint requests for pending authentication requests are held open (up to a timeout) instead of
immediately returning authorization_pending. When the user completes authentication, all waiting requests
for that auth_req_id are notified and can immediately return the tokens.

<strong>Benefits of Long-Polling:</strong>
- Reduced latency: Tokens returned immediately when authentication completes (0-1 second vs 0-5 seconds)
- Reduced server load: Fewer HTTP requests (1-4 per minute vs 12 per minute with 5-second polling)
- Better user experience: Faster token delivery without constant polling overhead

<strong>Implementation Patterns:</strong>
- In-memory: Use events/TaskCompletionSource for single-server deployments
- Distributed: Use Redis Pub/Sub, SignalR, or message queue for multi-server deployments

<strong>Example Flow:</strong>

```csharp
// 1. Client requests token (status = Pending)
// 2. Server holds connection and waits
var statusChange = await longPollingSignaler.WaitForStatusChangeAsync(authReqId, timeout, cancellationToken);

// 3. Meanwhile: User authenticates on device
// 4. BackChannelDeliveryModeRouter signals change
await longPollingSignaler.NotifyStatusChangeAsync(authReqId, BackChannelAuthenticationStatus.Authenticated);

// 5. Waiting request wakes up, checks storage, returns tokens
```
### Methods

## IBackChannelLongPollingService\.NotifyStatusChangeAsync\(string, BackChannelAuthenticationStatus\) Method {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.NotifyStatusChangeAsync(string,Abblix.Oidc.Server.Features.BackChannelAuthentication.BackChannelAuthenticationStatus)}

Notifies all waiting requests that the authentication status has changed for the specified request\.
This immediately releases any long\-polling token requests waiting for this auth\_req\_id\.

```csharp
System.Threading.Tasks.Task NotifyStatusChangeAsync(string authenticationRequestId, Abblix.Oidc.Server.Features.BackChannelAuthentication.BackChannelAuthenticationStatus newStatus);
```
#### Parameters

###### `authenticationRequestId` [System\.String](https://learn.microsoft.com/en-us/dotnet/api/system.string 'System\.String') {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.NotifyStatusChangeAsync(string,Abblix.Oidc.Server.Features.BackChannelAuthentication.BackChannelAuthenticationStatus).authenticationRequestId}

The unique identifier of the authentication request that changed\.

###### `newStatus` [BackChannelAuthenticationStatus](https://www.abblix.com/en/docs/api/abblix-oidc-server/Abblix.Oidc.Server.Features.BackChannelAuthentication.BackChannelAuthenticationStatus 'Abblix\.Oidc\.Server\.Features\.BackChannelAuthentication\.BackChannelAuthenticationStatus') {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.NotifyStatusChangeAsync(string,Abblix.Oidc.Server.Features.BackChannelAuthentication.BackChannelAuthenticationStatus).newStatus}

The new authentication status \(for logging/diagnostics only\)\.

#### Returns
[System\.Threading\.Tasks\.Task](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task 'System\.Threading\.Tasks\.Task')  
A task that completes when all waiting requests have been notified\.

### Remarks
This should be called whenever authentication status changes from Pending to:
\- Authenticated \(user approved\)
\- Denied \(user rejected\)
\- Expired \(timeout occurred\)

It's safe to call this even if no requests are waiting \- it's a no\-op in that case\.

## IBackChannelLongPollingService\.WaitForStatusChangeAsync\(string, TimeSpan, CancellationToken\) Method {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.WaitForStatusChangeAsync(string,System.TimeSpan,System.Threading.CancellationToken)}

Waits for a status change notification for the specified authentication request\.
Returns immediately if a notification is received, or after timeout if no change occurs\.

```csharp
System.Threading.Tasks.Task<bool> WaitForStatusChangeAsync(string authenticationRequestId, System.TimeSpan timeout, System.Threading.CancellationToken cancellationToken=default(System.Threading.CancellationToken));
```
#### Parameters

###### `authenticationRequestId` [System\.String](https://learn.microsoft.com/en-us/dotnet/api/system.string 'System\.String') {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.WaitForStatusChangeAsync(string,System.TimeSpan,System.Threading.CancellationToken).authenticationRequestId}

The unique identifier of the authentication request to wait for\.

###### `timeout` [System\.TimeSpan](https://learn.microsoft.com/en-us/dotnet/api/system.timespan 'System\.TimeSpan') {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.WaitForStatusChangeAsync(string,System.TimeSpan,System.Threading.CancellationToken).timeout}

Maximum time to wait for a status change\.

###### `cancellationToken` [System\.Threading\.CancellationToken](https://learn.microsoft.com/en-us/dotnet/api/system.threading.cancellationtoken 'System\.Threading\.CancellationToken') {#Abblix.Oidc.Server.Features.BackChannelAuthentication.Interfaces.IBackChannelLongPollingService.WaitForStatusChangeAsync(string,System.TimeSpan,System.Threading.CancellationToken).cancellationToken}

Cancellation token to abort the wait operation\.

#### Returns
[System\.Threading\.Tasks\.Task&lt;](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1 'System\.Threading\.Tasks\.Task\`1')[System\.Boolean](https://learn.microsoft.com/en-us/dotnet/api/system.boolean 'System\.Boolean')[&gt;](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1 'System\.Threading\.Tasks\.Task\`1')  
A task that completes when either:
\- A status change notification is received \(returns true\)
\- The timeout expires \(returns false\)
\- The cancellation token is triggered \(throws OperationCanceledException\)

### Remarks
This method does NOT return the new status \- it only signals that a change occurred\.
The caller must retrieve the updated status from storage\.

Multiple callers can wait for the same auth\_req\_id simultaneously \(e\.g\., if client retries\)\.
All waiters will be notified when status changes\.