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Querying GitHub Issues from Google App Script

I'm currently exploring different integrations that can be done between Google App Script and Git. This is part of a bigger attempt to integrate Git data into my project management system. I'll post more on that later. GitHub supports a number of very nice sub-systems. One of them is the GitHub Issues ticket tracking system. It's fairly robust and comes with GitHub - which means it's highly integrated out-of-the-box. Integration with Google's App Script is done via the fetchURL command and JSON object manipulation.  After a good bit of experimentation, I've settled on querying GitHub Issues with an "on open spreadsheet event" to avoid issues with Google's quota system. Essentially, Google prevents you from calling the fetchURL command more than X times (see the quota limits ) per day. That's not great if you have people actively working and changing data in a spreadsheet. Some of my other App Script routines are running thousands of times per d

Indy and HTTPS Post

I'm back to work on the HTTPS Post issue with DHL's ShipIt XML API. The problem I'm having is when I use Indy to post the xml via an HTTPS post, the response is that the file is malformed. I should mention that I'm using a relatively recent version of Indy 10. If I use FF (if you don't have it, check out the Poster add-on, let's you play with the HTTP functions using FF's libraries) it works fine. The first problem is that it's a little hard to see what FF is actually doing that is different from what Indy is doing. Enter Fiddler, stage right. Fiddler is an http proxy that captures that http information and lets you manipulate it or display the raw headers. So, pointing FF to the localhost proxy on port 8888, the headers I get are:



POST /apilandingtest.asp HTTP/1.1
Host: ecommerce.airborne.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Content-Type: text/xml
Content-Length: 1509
Pragma: no-cache
Cache-Control: no-cache



Applying a TIdLogFile to the Indy HTTP IO Intercept provides Indy's headers of:



POST /apilandingtest.asp HTTP/1.0
Content-Type: multipart/form-data; boundary=--------072108153606968
Content-Length: 1662
Host: ecommerce.airborne.com:443
Accept: text/html, */*
Accept-Encoding: identity
User-Agent: Mozilla/3.0 (compatible; Indy Library)

----------072108153606968
Content-Disposition: form-data; name="Shipment"; filename="dhl.xml"
Content-Type: text/xml



Obviously, not the same. A large part of this is because I'm using the TidMultiPartFormData class to encapsulate the data. Changing over to just a plain TStringList results in headers of :



POST /apilandingtest.asp HTTP/1.0
Content-Type: text/xml
Content-Length: 1471
Host: ecommerce.airborne.com:443
Accept: text/html, */*
Accept-Encoding: identity
User-Agent: Mozilla/3.0 (compatible; Indy Library)



but DHL still won't take the file, responding again that the XML is malformed. Looking into the log a little more, it appears as if the HTTP Post converted all CR/LF pairs into the symbol &. Sure enough, in Indy's code, there is a converter that converted CR/LF to &. Stripping CR/LF pairs out of the raw XML produces a workable solution that passes DHL's IIS server and returns the correct response. Obviously, that's a bit of a poor solution since it leaves the XML mashed together and I tend to use a text editor to review my XML data more often than an XML editor. So, with a short bit of preprocess work that converts CR/LF pairs to spaces, I now have a working Indy SSL HTTPS Post routine that DHL will accept. I've posted the code below so you won't have to go digging all over creation for a sample of Indy 10's HTTPS Post. Enjoy!



const
CR = #13;
LF = #10;
EOL = CR+LF;
xmlEOL = EOL;

type
// this is a descendant of TidLogFile, it will create a plain text file with
// information about the transfer session
TlogFile = class(TidLogFile)
protected
procedure LogReceivedData(const AText, AData: string); override;
procedure LogSentData(const AText, AData: string); override;
procedure LogStatus(const AText: string); override;
public
procedure LogWriteString(const AText: string); override;
class function buildLogLine(data, prefix: string) : string;
end;

// this ensures the output of error and debug logs are in the same format, regardless of source
class function TlogFile.buildLogLine(data, prefix: string) : string;
begin

data := StringReplace(data, EOL, RSLogEOL, [rfReplaceAll]);
data := StringReplace(data, CR, RSLogCR, [rfReplaceAll]);
data := StringReplace(data, LF, RSLogLF, [rfReplaceAll]);

result := FormatDateTime('yy/mm/dd hh:nn:ss', now) + ' ';
if (prefix <> '') then
result := result + prefix + ' ';
result := result + data + EOL;
end;

// ---------------------------------------------------------------------------

procedure TlogFile.LogReceivedData(const AText, AData: string);
begin
// ignore AText as it contains the date/time
LogWriteString(buildLogLine(Adata, '<<'));
end;

// ---------------------------------------------------------------------------

procedure TlogFile.LogSentData(const AText, AData: string);
begin
// ignore AText as it contains the date/time
LogWriteString(buildLogLine(Adata, '>>'));
end;

// ---------------------------------------------------------------------------

procedure TlogFile.LogStatus(const AText: string);
begin
LogWriteString(buildLogLine(AText, '**'));
end;

// ---------------------------------------------------------------------------

procedure TlogFile.LogWriteString(const AText: string);
begin
// protected --> public
inherited;
end;

// ---------------------------------------------------------------------------

//this will use an https post to push the data
procedure TDHLShipment.sendFile;
const testURL = 'https://some url that accepts data'; //replace this with the url of where you will be sending the data or send it as a param
logFileName = 'j:\winprog\main\http.log'; //the logfile name if you use the logging
var
plainData : TStringList; //this is the unencoded data
// formData : TIdMultiPartFormDataStream; //I've left this in just in case you want to see how the multi-part works
HTTP : TidHTTP; //going to need the HTTP object
SSLIO : TIdSSLIOHandlerSocketOpenSSL; //going to need the SSL object
response : TStringList; //this will catch the response from the server
logFile : TLogFile; //this is the logfile and is optional but handy for debuging

//this is because the plainData TStringList may contain CR/LF pairs. If so, HTTP Post will convert those pairs to & which, in my specific case, kills the data.
procedure ConvertCRLFToSpace;
begin
if plainData.Count > 1 then
// convert CR/LF pairs to spaces
plainData.Text := StringReplace(Trim(plainData.Text), sLineBreak, ' ',[rfReplaceAll]);
end;

begin
// formData := TIdMultiPartFormDataStream.Create; //if you wanted to send multi-part data, use this instead
plainData := TStringList.Create; //My specific case wants stripped down headers and no multipart functionality
try
// formData.AddFile('Shipment', 'dhl.xml', 'text/xml'); //you can add a lot more detail about the file with the multi part data stream
plainData.LoadFromFile('dhl.xml'); //or you can just load up the plain file
Http:=TidHTTP.Create(nil); //create the HTTP instance
try
SSLIO:=TIdSSLIOHandlerSocketOpenSSL.Create(nil); //create the SSL handler
SSLIO.SSLOptions.Method := sslvSSLv3; //set the SSL mode
HTTP.ReadTimeout := 10000; //depending on size of upload, you may need to adjust these
HTTP.ConnectTimeout := 10000;
HTTP.IOHandler := SSLIO; //assign the SSL handler to the HTTP IO Handler or you won't be able to interact with SSL servers
HTTP.Request.Contenttype := 'text/xml'; //I'm doing XML, set the content type appropriate to your data type. If you used the multi-part, you probably don't need this
HTTP.HTTPOptions := []; //no options
logFile := TLogFile.Create(nil); //create the log file
logFile.FileName:=logFileName; //set the default log file name - NOTE: you could get fancy with this, but I normally don't use it
logFile.Active:=true; //activate the log file (creates the file and intializes everything)
HTTP.IOHandler.Intercept := logFile; //set the logFile to the intercept of the IOHandler to capture the events
response:=TStringList.Create; //create the string list to catch the server's response
try
try
ConvertCRLFToSpace; //clean up the CR/LFs so the data doesn't get funky (you may not need this)
response.Text := HTTP.Post(testURL, plainData); //post the data to the URL and place the response in the response string list
except on EIdOSSLCouldNotLoadSSLLibrary do //if we have an SSL problem, this is going to be when it shows
ShowMessage('An error occurred loading the SSL '+ //provide a little clue although, as I mentioned yesterday, you may need to change the SSL loader to get good error messages
'libraries. Please make sure you '+
'have installed the OpenSSL '+
'libraries from http://www.'+
'openssl.org/related/binaries.html.');
end;
response.SaveToFile('response.xml'); //save the server's response (or process it or whatever you're going to do)
ShowMessage('Sent successfully. Response='+#13#10+response.Text); //tell the user it worked
finally
response.Free; //free the response
end;
finally
Http.free; //free the http object
end;
finally
plainData.Free; //free the data
//formData.Free;
end;

end;

Comments

That tip on the CR/LF pairs solved a problem we had. Thanks a bunch!
Anonymous said…
Wonderful post. Thanks for sharing the code. This got us out of a bind.
Marshall Fryman said…
Glad it helped. It took me a while to track down all the information I needed to diagnose the problem. I tend to post on anything that I had to spend a lot of time researching so it's an easy reference for everyone.
James said…
This comment has been removed by the author.
Anonymous said…
Many thanks for this tip!

I have been trying to use TIdHTTP to invoke an IBM Webshpere SOAP service for many months, but could never get it to work.

Using this article, I finally have TIdHTTP working!

Many thanks!

Keith
CNB said…
The CRLF to & behavior is documented in the manual. Under "TIdCustomHTTP.Post" it says: "When ASource is a TStrings instance, Post will replace all occurrences of the End-Of-Line (EOL) character in ASource with the value '&' prior to transfer to the HTTP server. When ASource is a TStream instance, no preprocessing of the stream content is performed." The clean solution, in my opinion, if possible, would be to place your data in a TStream before sending, not a TStringList.

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