Post API call error handling

ServiceStack
1

Hello,

I’d like to use SS client to send WEB API calls asynchronously. My scenario is 2-tier server architecture where 2nd tier provides auditing services. I’d like at the end of the request handling in tier 1 to send audit request to tier 2 and end request handling (without waiting for results of the call to audit API of tier 2).

I’ve two questions related the scenario:

  1. What is a best practice to send a request asynchronously? Code example will be highly appreciated.
  2. What happens if the asynchronous request returns error? How should I handle it? My goal is to ignore it in worst case and log it into file in best case.

Thank you

2

What’s wrong with just calling the async ServiceClient API’s? What am I missing?

They just return .NET’s standard async Task<T> response which you handle Exceptions in a try/catch block if you’re awaiting them, otherwise you can manually chain on the Task response to subscribe to error responses. Other than our .NET C#/.NET ServiceClients docs, googling for async Exception examples returned a good article on different ways to handle Async Exceptions.

3

Does it mean that the following example will send response immediately:

client.GetAsync(new Hello { Name = "World!" })
.Error(ex => { throw ex; });

without waiting for async request from Hello API?

4

Yes calling Async methods invokes them straight away, but if you’re not going to use await you’ll also need to provide a .Success() or .ContinueWith() callback in order to access the async response.

1 Like
5

Hello Demis,

I’ve a POST request which doesn’t return a response (void). However, I cannot inherit the DTO class from IReturnVoid.

When I’m writing a code

client.PostAsync(new MyRequestDTO() { Field1 = 1, Field2 = "some text"})
.Success(r => {})
.Error(ex => Logger.Error("Failed to perform request", ex));

The compiler shows me errors:

error CS1502: The best overloaded method match for ‘ServiceStack.ServiceClientBase.PostAsync(ServiceStack.IReturnVoid)’ has some invalid arguments
error CS1503: Argument 1: cannot convert from ‘MyDTORequest’ to ‘ServiceStack.IReturnVoid’

Is inheriting from IReturnVoid is the only way to invoke the request asynchronously?

6

I’m guessing you mean you cannot implement the IReturnVoid interface. You should be able to invoke it with a string or byte[], it will just be empty, e.g:

await client.PostAsync<string>(new MyRequest { ... });