CODEWITHSUNDEEP
http
toyknight
toyknight

Reputation: 33

Can HTTP request fail half way?

I am talking about only one case here.

client sent a request to server -> server received it and returned a response -> unfortunately the response dropped.

I have only one question about this.

As I want to sync status between client/server and want 100% accuracy no matter how poor the network is, the answer to this question can greatly affect the client's 'retry on failure' strategy.

Any comment is appreciated.

Upvotes: 1

Views: 695

Answers (2)

blendenzo
blendenzo

Reputation: 653

Yes, the situation you have described is possible and occurs regularly. It is called "packet loss". Since the packet is lost, the response never reaches the client, so no response code could possibly be received. Web browsers will display this as "Error connecting to server" or similar.

HTTP requests and responses are generally carried inside TCP packets. If a TCP packet carrying the HTTP response does not arrive in the expected time window, the request is retransmitted. The request will only be retransmitted a certain number of times before a timeout error will occur and the connection is considered broken or dead. (The number of attempts before TCP timeout can be configured on both the client and server sides.)

Upvotes: 2

IMSoP
IMSoP

Reputation: 97898

Is this case even possible?

Yes. It's easy to see why if you picture a physical cable between the client and the server. If I send a request down the cable to the server, and then, before the server has a chance to respond, unplug the cable, the server will receive the request, but the client will never "hear" the response.

If it's possible then what should the response code be, or will client simply see it as read timeout?

It will be a timeout. If we go back to our physical cable example, the client is sitting waiting for a response that will never come. Hopefully, it will eventually give up.

It depends on exactly what tool or library you're using how this is wrapped up, however - it might give you a specific error code for "timeout" or "network error"; it might wrap it up as some internal 5xx status code; it might raise an exception inside your code; etc.

Upvotes: 0

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