How to resolve ASP.NET core web API 2 mins timeout issue

Introduction

We are in the new world of microservices and cross-platform applications which will be supported for multiple platforms and multiple heterogeneous teams can work on the same application. I like ASP.NET Core by the way its groomed to support modern architecture and adhere to the software principles. I am a big fan of dot net and now I become the craziest fan after seeing the sophisticated facility by dot net core to support infrastructure level where we can easily perform vertical and horizontal scaling. It very important design aspect is to keep things simple and short and by the way, RESTFul applications are build and it is a powerful mantra for REST-based application and frameworks. Some times we need to overrule some principles and order to handle some situations. I would like to share my situation of handling HTTP long polling to resolve the ASP.Net core 2 mins issue.

What is HTTP Long polling?

In the RESTFul term, when a client asks for a query from the server, the server responds to the request, and then it will terminate.  Our client frameworks designed in the way to handle resilient situations where it can wait for some limited amount of time to get the server response and if not it will throw the timeout error. It is applicable for HTTP Client in our ASP.NET Core web API.

But In some situations, the server needs some extra time to respond to the client request where we need to open the HTTP Connection active irrespective of framework-specific time. This is called HTTP Long polling.

What is the issue with HTTP Long Polling in ASP.NET Core?

To meet my requirement I dragged to the situation of the Long polling in one of my ASP.NET Core applications. I was clueless to resolve the following issue where it always fails for 2 mins wherein case I need a lot more time to sustain the request.  I got this weird error

“502 - Web server received an invalid response while acting as a gateway or proxy server”

I tried almost all possible ways to resolve but whenever I hit the button merely 2 mins my request fails and throws the error wherein I need to standby a little more long time.

Approach 1 – Connection HTTP Header

This Issue gives me a little more opportunity to learn about Connection HTTP Header. Let me share my thoughts.  By default in c#, the HTTP Client Header object Connection key has Keep-Alive as value.

What is HTTP Keep-Alive?

Consider that we are visiting a site, By default, the browser will create a new HTTP Connection for each resource for the page we are visiting. This will increases the page load time of your site and this is the main performance hindrance. Microsoft used their mantra to reduce the page load time or API load time by using Keep-Alive value to the connection key in Http Client key object. by the way, It will create only one HTTP Connection object and all subsidiary requests will use the same object and so we gain performance.

I thought of using this to enable HTTP Long Pooling in my application. But I got no luck. My Application throws an error immediately after 2 mins. I was clueless at this movement.

Approach 2 – IIS Connection Timeout

I just tried with increasing Connection Time to 3600 secs in my IIS Connection settings where my site is hosted.

Now also I got no luck.

Approach 3 – Kestral Request Time out

I got to know that the IIS does not affect any of the settings that I made. This is a strange thing for me because I resolved time out problems in ASP.NET by adjusting values in IIS. What’s new in ASP.NET Core? These things make me more interested in learning the hosting modal of ASP.NET core.

Our Thala mantra “Never ever give up!!!”

I need to solve the Long Polling where my client is crushing me to get the solution. With the energy of our thala mantra, I started learning the hosting modal. I would like to share a few things which I learned

Kestral Web Server

It is the cross-platform hosting modal where we can host our ASP.NET Core application in IIS, Nginx, and Apache web servers. This is the cross-cutting model which helps us host our application in all platform that .NET  Core supports.

By default, ASP.NET Core application is having out process hosting modal wherein the IIS server will act as Reverse Proxy/Gateway to the ASP.NET Core Kestral web server. In simple words, the application will request the IIS Server and it will forward the request to the kestrel web server and so settings made in IIS has no effect on my changes.

Important Note

Kestral web server has default HTTP time out of 2 mins and so we can’t sustain the HTTP Long Polling.

If we increase the HTTP time out of  Kestral then we can sustain the HTTP Long polling in ASP.NET Core applications and this will be applicable only for out process hosting modal. I did the following on the Web. Config of my application which resolves my 2 mins timeout issue

<?XML version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
</handlers>
<aspNetCore requestTimeout="01:00:00" processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
</system.webServer>
</configuration>

We need to clean publish to apply these changes properly in the webserver.

Conclusion

I guess this article could help fellow developers like me who are trying to resolve the same kind of issue. Please share if you have different thoughts so that I could furnish this article which would help others.