Socket Error when using MWS SubmitFeed in Delphi using TIdHTTP

Question

I am building an application in Delphi 2006 to integrate with Amazon's MWS API but am getting Socket Error 10061 Connection Refused.

Here is my Delphi code:

// pull out url end point - in my case mws-eu.amazonservices.com:443
url := '';
url := getOption('URL');
if url='' then LogMessage('DEV','No Amazon URL in INI file! ', true);

request := TStringList.Create;

// add standard required fields
//request.Add('Marketplace='+getOption('Marketplace')); 
request.Add('Action='+action);
request.Add('AWSAccessKeyId='+getOption('AWSAccessKeyId'));
//request.Add('MWSAuthToken='+getOption('MWSAuthToken')); 

//request.Add('Merchant='+getOption('SellerId'));
request.Add('SellerId='+getOption('SellerId'));
request.Add('SignatureMethod='+getOption('SignatureMethod')); // HmacSHA256
request.Add('SignatureVersion='+getOption('SignatureVersion')); // 2

request.Add('Version='+getOption('Version')); // not sure where this comes from or whether its common to all calls ?? Version=2009-01-01

// add request specific params (these are sent in to this function)
for loop := 0 to params.Count-1 do
begin
request.Add(paramsloop);
end;

// add timestamp
d:=Now;
dt:=FormatDateTime('yyyy-mm-dd"T"hh:mm:ss"Z"',d);
request.Add('Timestamp='+dt);

// call our custom sort method
LogMessage('DEV','Before='+request.GetText, false);
request.CustomSort(StringListCompareLogical);
LogMessage('DEV','After='+request.GetText, false);

// encode the params as per MWS
stringResult:=MWSEncodeParams(request);
LogMessage('DEV','result:'+stringResult, false);

stringToSign := 'POST' + char(10);
stringToSign := stringToSign + url + char(10);
stringToSign := stringToSign + '/' + char(10);
stringToSign := stringToSign + stringResult;

LogMessage('DEV','stringToSign:'+stringToSign, false);

// call sha method in DLL encrypter
uPugwash.getSH256_HMAC(getOption('SecretKey'),stringResult,True,Signature);
// add result to request as signature
request.Add('Signature='+Signature);
stringResult:=stringResult+'&Signature='+Signature;

// call md5 method in DLL encrypter
uPugwash.getMD5(requestBody,true,MD5) ;

LogMessage('DEV','output signature: '+Signature, true);
LogMessage('DEV','output md5: '+MD5, true);
lHTTP := TIdHTTP.Create(nil);

lIOHandler:=TIdSSLIOHandlerSocketOpenSSL.Create(nil);
lIOHandler.Port := 443; // lIOHandler.Port := 25;

try
lHTTP.IOHandler := lIOHandler;
lHTTP.ConnectTimeout:=5000;
lHTTP.HandleRedirects := True;
lHTTP.ReadTimeout := 20000;
lHTTP.Request.Method := 'POST';
lHTTP.Request.AcceptCharSet := 'UTF-8';
lHTTP.Request.ContentType := 'text/xml';
//lHTTP.Request.ContentType:='application/x-www-form-urlencoded';
lHTTP.Request.ContentEncoding := 'utf-8';
lHTTP.Request.UserAgent := 'POS Amazon Web Integration/'+getOption('posVersion')+' (Language=Delphi/2006; Customer='+getOption('Customer')+')';
lHTTP.Request.Host := url;
lHTTP.Request.CustomHeaders.Add('X-Amazon-User-Agent: '+lHTTP.Request.UserAgent);
lHTTP.Request.CustomHeaders.Add('Content-MD5: '+MD5);
lHTTP.Request.Accept:='text/plain, */*';
lHTTP.ProtocolVersion:=pv1_1;
lHTTP.HTTPOptions:=lHTTP.HTTPOptions+hoKeepOrigProtocol-hoForceEncodeParams;

RBody := TStringStream.Create(requestBody); // this is my feed xml
RBody.Seek(0,0);

LogMessage('DEV','request body:'+requestBody, false);
LogMessage('DEV','request url:'+stringResult, false);

fullURL := 'https://'+url+'?'+stringResult; // this is url with required parameters on end
LogMessage('DEV','fullURL:'+fullURL, false);

// make actual call
rawResp := lHTTP.POST(fullURL,RBody); // falls over here with socket exception

I have presumed above that the normal params are sent in the url and the xml is sent in the body.

Any pointers to where I may be going wrong would be much appreciated.

Thank you!

Answer 1

I've been struggling with Indy and Amazon web services a lot too. The particular error you are getting is winsock error :

WSAECONNREFUSED
10061
Connection refused.No connection could be made because the target computer actively refused it. This usually results from trying to connect to a service that is inactive on the foreign host—that is, one with no server application running.

Acoording to my experience the error may happen due to several things:

1. Wrong server adress or wrong port - check the url and the port for the service. Make sure they are correct(I am no expert in MWS so can't help you with that)

2. Some firewall on the client side is blocking the request - try to disable all kinds of firewall and try requesting again

3. A very unstable internet connection on the client side can cause this error

All in all, I wouldn't encourage you to use Indy as I've seen it fail in many situations. I found out that the WinHTTP API altough a little bit more complex is way more stable.

Hope that some of this helps.