Hi Community,

I have created a C# extension in OutSystems to send Firebase Cloud Messaging (FCM) push notifications using the HTTP v1 API. The code compiles fine, but when I execute it inside OutSystems, the request times out.

Here is the method I am currently using:

/// Sends a message and returns FCM message name (projects/{pid}/messages/{id}).

public async Task SendAsync(FcmMessage message, CancellationToken ct = default)

{

    if (message is null) throw new ArgumentNullException(nameof(message));

    var url = $"https://fcm.googleapis.com/v1/projects/{_projectId}/messages:send";

    using var req = new HttpRequestMessage(HttpMethod.Post, url)

    {

        Content = new StringContent(

            JsonSerializer.Serialize(new { message }, JsonOptions),

            Encoding.UTF8,

            "application/json")

    };

    req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", await GetAccessTokenAsync(ct));

    // Basic retry for 429/5xx

    const int maxAttempts = 4;

    int attempt = 0;

    TimeSpan delay = TimeSpan.FromMilliseconds(400);

    while (true)

    {

        attempt++;

        using var toSend = req.Clone();

        using var resp = await _http.SendAsync(toSend, ct);

        string body = await resp.Content.ReadAsStringAsync(ct);

        if (resp.IsSuccessStatusCode)

        {

            using var doc = JsonDocument.Parse(body);

            return doc.RootElement.TryGetProperty("name", out var n)

                ? (n.GetString() ?? string.Empty)

                : string.Empty;

        }

        if (attempt < maxAttempts && IsTransient(resp.StatusCode))

        {

            await Task.Delay(delay, ct);

            delay = TimeSpan.FromMilliseconds(Math.Min(delay.TotalMilliseconds * 2, 4000));

            continue;

        }

        throw new FcmException((int)resp.StatusCode, body);

    }

}

This works fine when tested outside of OutSystems (in a console app), but within OutSystems it results in timeouts.

👉 Could anyone please share a working sample of a C# extension in OutSystems that sends an FCM push notification (preferably using the v1 API with OAuth2 Bearer token)?

👉 Or point out if I need to adjust how I handle HttpClient / HttpRequestMessage in the OutSystems environment?

Any guidance or code samples would be greatly appreciated.

Thanks in advance,

Kanisious Museka