ASIHTTPRequest, request sent twice

Question

I´ve just started using ASIHTTPRequest for iOs and I have a small issue with it. All requests are sent twice to the server even though I only get one reply from the library to my delegate methods.

Both sync and async requests have this issue. I use Xcode 4 with ARC but have disabled it for ASIHTTPRequest by adding -fno-objc-arc as compiler flags.

Any idea what´s wrong..?

Code:

ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request startSynchronous];

NSError *error = [request error];
if (!error) {
}

Heiberg Heiberg · Accepted Answer · 2012-02-11T09:12:55

This has bitten me too. I was using a GET request to validate a multi-use voucher code on a server. When we added a rate limitation for redeeming codes some customers reported hitting the limit before they should have. Turns out that some of the validations triggered two redeems.

Your request is using the GET method.

The default behavior when using GET is to allow persistent connections (the Keep-Alive HTTP header).

When using a persistent connection your GET request might get retransmitted if something on the network looks wonky (that's a technical term) instead of the request just failing. This is usually desirable because GET requests often do not have any side effects on the server.

POST or PUT requests on the other hand default to not use a persistent connection and will not retransmit your operation, which could well be a credit card purchase or something else with significant side effects.

If you wish to prevent your ASIHTTPRequest GET sometimes sending 2 or more server requests (due to network issues outside your control) you can simply set this flag:

request.shouldAttemptPersistentConnection = NO;

This should take care of the spurious GET duplicates on the server.

ASIHTTPRequest, request sent twice

4 Answers