Question 216215 in ASP.NET Question posted in
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Asp.net – Creating Polly retry policy creation for HTTP Transient exception

I am trying to implement polly retry for a method for http transient exception but i am stuck on issues
here is the situation

CustomResponse response = getResponse(CustomRequest request)

getResponse has 2 implemtation one using wcf another using API (These2 implementation are in separate class)

If succeed i will get a response of my output type CustomResponse
Or it will throw exception such as serviceNotAvailable or Internal server error

I tried writing this below policy

Policy. handle<httpRequestException>()
.Or<TimeOutexception()
.Or<BadRequestException>()

But i am not able to get one for service not available and internal server error

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2

Answers


  1. 0

    What you’ll need to do is wire it up yourself. Here is an example with SQL and Win23 Errors, some errors such as Connection Failures I don’t retry, others I return true in order to retry. Change this code to tap into the HttpRequestException in a similar way to this SqlException and Win32Exception:

    .Handle<SqlException>(e => SqlHelper.ShouldRetryOn(e))
.Or<TimeoutException>()
.OrInner<Win32Exception>(Win32Helper.ShouldRetryOn)


public static bool ShouldRetryOn(Exception ex)
{
    StringBuilder sb = new();
    if (ex is SqlException sqlException)
    {
        foreach (SqlError err in sqlException.Errors)
        {
            switch (err.Number)
            {




public static bool ShouldRetryOn(Win32Exception ex)
{
    switch (ex.NativeErrorCode)
    {
        // Timeout expired
        case 0x102:
            return true;
        // Semaphore timeout expired
        case 0x121:
            return true;
        default:
            return false;
    }
}

    Alternatively tap into Pollys in built WaitAndRetry for Http calls HttpPolicyExtensions.HandleTransientHttpError().WaitAndRetryAsync

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  2. 0

    The Handle and Or builder methods help you to define trigger for exceptions.

    The HandleResult and OrResult builder methods help you to define trigger based on the response/result object.

    Policy
  .HandleResult<CustomResponse>(res => res.StatusCode == HttpStatusCode.ServerInternalError)
  .Or<HttpRequestException>()
  .Or<TimeOutexception()
  .Or<BadRequestException>()

    OR

    Policy
  .Handle<HttpRequestException>() 
  .OrResult<CustomResponse>(res => res.StatusCode == HttpStatusCode.ServerInternalError)
  .Or<TimeOutexception()
  .Or<BadRequestException>()

    The above code samples assumed that the StatusCode is accessible through the CustomResponse object.

    These samples can be easily extended to trigger for multiple statuscodes.

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