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Outbound Integrations

Aggregator-backed providers reach out to a third-party API (Enode, OEM cloud, Tibber, …) using OAuth2 client-credentials. The SDK ships a typed-HttpClient + token-cache helper so every adapter doesn't rebuild this from scratch.

Quick start​

// Program.cs
builder.Services.AddOutboundOAuth2Client<EnodeApiClient>(
    builder.Configuration, "enode")
    .ConfigureHttpClient((sp, http) =>
    {
        var opts = sp.GetRequiredService<IOptions<EnodeOptions>>().Value;
        http.BaseAddress = new Uri(opts.ApiBaseUrl);
    });

EnodeApiClient is an ordinary typed client whose constructor takes HttpClient:

public sealed class EnodeApiClient
{
    private readonly HttpClient _http;
    public EnodeApiClient(HttpClient http) { _http = http; }

    public async Task<JsonNode?> ListChargersAsync(CancellationToken ct = default)
    {
        using var resp = await _http.GetAsync("/chargers", ct);
        resp.EnsureSuccessStatusCode();
        return await JsonNode.ParseAsync(
            await resp.Content.ReadAsStreamAsync(ct), cancellationToken: ct);
    }
    // ... etc.
}

The handler attached by AddOutboundOAuth2Client:

  1. Adds Authorization: Bearer <token> to every outgoing request,
  2. Caches the access token in process,
  3. Refreshes within RefreshSkewSeconds of expiry,
  4. On a 401 response, forces a refresh and replays the request once (the body is cloned so POST/PUT/PATCH retry cleanly).

Configuration​

{
  "Outbound": {
    "enode": {
      "TokenUrl":         "https://oauth.sandbox.enode.io/oauth2/token",
      "ClientId":         "<from secret store>",
      "ClientSecret":     "<from secret store>",
      "Scope":            null,
      "Audience":         null,
      "RefreshSkewSeconds": 60
    }
  }
}

Use dotnet user-secrets for development; in production source secrets from your secret store. The name (enode here) is both the options-binding key and the per-call cache slot — multiple integrations under the same host coexist by name.

What you get for free​

  • One IOutboundTokenProvider singleton, one cache slot per name.
  • SemaphoreSlim per name so concurrent first-time fetches don't duplicate the token call.
  • Refresh-on-401 with body cloning.
  • Standard ASP.NET resilience (timeouts, retry policies) layered via the IHttpClientBuilder returned from AddOutboundOAuth2Client.

What you don't get​

  • Refresh-token / authorization-code flows — only client-credentials. File a separate request if a probe needs interactive auth.
  • mTLS-authenticated outbound calls — separate concern; layer your own handler.

See also​