private async Task <bool> DeduplicatedTokenExchangeIdAsync(ITurnContext turnContext, CancellationToken cancellationToken)
{
// Create a StoreItem with Etag of the unique 'signin/tokenExchange' request
var storeItem = new TokenStoreItem
{
ETag = (turnContext.Activity.Value as JObject).Value <string>("id")
};
var storeItems = new Dictionary <string, object> {
{ TokenStoreItem.GetStorageKey(turnContext), storeItem }
};
try
{
// Writing the IStoreItem with ETag of unique id will succeed only once
await _storage.WriteAsync(storeItems, cancellationToken).ConfigureAwait(false);
}
catch (Exception ex)
// Memory storage throws a generic exception with a Message of 'Etag conflict. [other error info]'
// CosmosDbPartitionedStorage throws: ex.Message.Contains("pre-condition is not met")
when(ex.Message.StartsWith("Etag conflict", StringComparison.OrdinalIgnoreCase) || ex.Message.Contains("pre-condition is not met"))
{
// Do NOT proceed processing this message, some other thread or machine already has processed it.
// Send 200 invoke response.
await SendInvokeResponseAsync(turnContext, cancellationToken : cancellationToken).ConfigureAwait(false);
return(false);
}
return(true);
}
/// <summary>
/// Determines if a "signin/tokenExchange" should be processed by this caller.
///
/// If a token exchange is unsuccessful, an InvokeResponse of PreconditionFailed is sent.
/// </summary>
/// <param name="turnContext"><see cref="ITurnContext"/> for this specific activity.</param>
/// <param name="cancellationToken"><see cref="CancellationToken"/> for this specific process.</param>
/// <returns>True if the bot should continue processing this TokenExchange request.</returns>
public async Task <bool> ShouldProcessTokenExchange(ITurnContext turnContext, CancellationToken cancellationToken)
{
if (turnContext.Activity.Name != SignInConstants.TokenExchangeOperationName)
{
throw new InvalidOperationException("Only 'signin/tokenExchange' invoke activities can be procssed by TokenExchangeHelper.");
}
if (!await this.ExchangedTokenAsync(turnContext, cancellationToken).ConfigureAwait(false))
{
// If the TokenExchange is NOT successful, the response will have already been sent by ExchangedTokenAsync
return(false);
}
// If a user is signed into multiple Teams clients, the Bot might receive a "signin/tokenExchange" from each client.
// Each token exchange request for a specific user login will have an identical Activity.Value.Id.
// Only one of these token exchange requests should be processe by the bot. For a distributed bot in production,
// this requires a distributed storage to ensure only one token exchange is processed.
// This example utilizes Bot Framework IStorage's ETag implementation for token exchange activity deduplication.
// Create a StoreItem with Etag of the unique 'signin/tokenExchange' request
var storeItem = new TokenStoreItem
{
ETag = (turnContext.Activity.Value as JObject).Value <string>("id")
};
var storeItems = new Dictionary <string, object> {
{ TokenStoreItem.GetStorageKey(turnContext), storeItem }
};
try
{
// Writing the IStoreItem with ETag of unique id will succeed only once
await _storage.WriteAsync(storeItems, cancellationToken).ConfigureAwait(false);
}
catch (Exception ex)
// Memory storage throws a generic exception with a Message of 'Etag conflict. [other error info]'
when(ex.Message.StartsWith("Etag conflict"))
{
// CosmosDbPartitionedStorage throws: ex.Message.Contains("pre-condition is not met")
// Do NOT send this message on to be processed, some other thread or machine already has processed it.
// TODO: Should send 200 invoke response here???
return(false);
}
return(true);
}