Why should you care?

You care about this when Payment API goes down for 30 seconds and you do not want Order to hang forever or crash.

See it live — copy this example

Create a Web API project (dotnet new webapi), paste the code, then run dotnet run.

builder.Services.AddHttpClient<IPaymentClient>()
    .AddPolicyHandler(Policy.Handle<HttpRequestException>()
        .WaitAndRetryAsync(3, i => TimeSpan.FromSeconds(Math.Pow(2, i))))
    .AddPolicyHandler(Policy.TimeoutAsync<HttpResponseMessage>(TimeSpan.FromSeconds(5)));

Run Example »

This lesson uses terminal or setup steps. Run commands on your computer — the live editor appears on coding lessons.

What happened?

• The example shows Fallback Mechanisms wired into Identity Service.
• Read each line, run it locally, then change one setting and observe what breaks or improves.
• That is how teams learn in production too — small experiments, not big bang rewrites.

Try it yourself

1. Open or create the ShopNest project area for Identity Service.
2. Apply the Fallback Mechanisms pattern from the lesson example.
3. Run dotnet build && dotnet run (or docker compose up when the lesson uses containers).
4. Change a string or number in the example and run again — predict the output first.
5. Break the code on purpose (remove a semicolon), read the compiler error, then fix it.

Remember

Fallback Mechanisms connects to Identity Service in ShopNest Cloud-Native. Practice by editing the example yourself — do not only read. Move on when you can explain this topic in your own words without looking.

Real-world: Swiggy order → restaurant → rider flow

When a customer confirms food order, events notify restaurant prep and rider dispatch. No single 30-second HTTP chain.

Outcome: Restaurant promos deploy without taking down payment processing.