Exception Suppression Mechanism (Silent Handling)

When initiating an HTTP remote request, you may encounter the following exceptions:

The target host is unreachable
The request is canceled
The request times out
Other network exceptions

By default, these exceptions interrupt program execution. Although developers usually use try/catch for exception handling, in some scenarios we prefer that exceptions silently return null without interrupting the flow. To that end, the framework provides flexible exception suppression functionality.

Suppress all request exceptions

var httpResponseMessage = httpRemoteService.SendAsync(HttpRequestBuilder.Post("https://furion.net/")    .SuppressExceptions());  // Suppress all exceptions

When an exception occurs during the request, execution is not interrupted; instead null is returned, i.e. the value of httpResponseMessage is null.

In some scenarios, while suppressing exceptions, we still want to capture the exception information (for example, to write it to a log) without interrupting the normal execution of the program. In this case, you can use the SetOnRequestFailed callback:

HttpRequestBuilder.Post("https://furion.net/")    .SuppressExceptions()    .SetOnRequestFailed((exception, responseMessage) =>     // Note: responseMessage may be null    {        Console.WriteLine(exception.Message);    });

This method allows you to safely handle error information after an exception has been suppressed, and is suitable for log recording, monitoring, or other error response logic.

Suppress only specific types of exceptions

The framework also supports suppressing only specific types of exceptions. For example, you can suppress only timeout exceptions and request cancellation exceptions:

var httpResponseMessage = httpRemoteService.SendAsync(HttpRequestBuilder.Post("https://furion.net/")    .SuppressExceptions([typeof(TimeoutException), typeof(TaskCanceledException)]));  // Suppress timeout and cancellation exceptions

Disable exception suppression configuration

To restore the default behavior (i.e. interrupt the program when an exception occurs), you can explicitly disable exception suppression:

var httpResponseMessage = httpRemoteService.SendAsync(HttpRequestBuilder.Post("https://furion.net/")    .SuppressExceptions(false);  // Restore default configuration

This configuration is equivalent to not calling SuppressExceptions(); when any exception occurs, program execution will be interrupted.

Notes

When exception suppression is enabled, note the following:

Override rule
When SuppressExceptions() or related configurations are called multiple times, only the last call takes effect.
Priority between status code checking and exception suppression
Even if EnsureSuccessStatusCode() is configured, suppressed exceptions still return null and do not trigger the status code checking logic.
Priority of exception suppression
Exception suppression takes priority over status code checking. If both status code checking and exception suppression are enabled, exception suppression takes effect first.
Request interceptors still work
If exceptions are captured via SetOnRequestFailed(ex, res) or other request handling mechanisms, interceptors or callbacks will still be invoked even when the exception is suppressed.
Advice on choosing exception types
Carefully choose the exception types to suppress based on the specific business scenario, to avoid masking potential problems by over-suppressing exceptions.
Automatic suppression log output
When an exception is successfully suppressed, the framework automatically outputs a Warning-level log (for example, "An exception occurred but was suppressed by SuppressExceptionPipelineHandler.") to aid troubleshooting.