WebRequest fails with "414 Request URI too long" in ASP.NET application

Question

We have an ASP.NET application that requests an SSRS 2005 report in HTML format after passing the parameters for the report as a WebRequest. The application only fails when a report with a large number of multi-select parameters is requested, throwing a "414: Request URI too long" error at the webRequest.GetResponse() line.

The code used to make the request is:

HttpWebRequest webRequest = null;
HttpWebResponse webResponse = null;
string webRequestURL = _ReportManager.GetRSUrl(reportID); //this passes the report link on the SSRS server

//make the request

Byte[] bytes = Encoding.UTF8.GetBytes("xml_doc=" + HttpUtility.UrlEncode(webRequestURL));

webRequest = (HttpWebRequest)WebRequest.Create(webRequestURL);
webRequest.Method = "POST";
webRequest.ContentLength = bytes.Length;
webRequest.Timeout = Configuration.WebRequestTimeOut;

RSExecution2005.ReportExecutionService rsE = new RSExecution2005.ReportExecutionService();
rsE.Url = Configuration.ReportExecutionServiceUrl2005;
rsE.Credentials = System.Net.CredentialCache.DefaultCredentials;
webRequest.Credentials = rsE.Credentials;

Stream reqStream = null;
reqStream = webRequest.GetRequestStream();
reqStream.Write(bytes, 0, bytes.Length);
reqStream.Close();

webResponse = (HttpWebResponse)webRequest.GetResponse();

As the report fails on the server side, I have looked into IIS and ReportServer properties to increase the maxUrl, maxRequestLength, MaxQueryString, etc. in terms of bytes (as per this article) but the application still throws an error. I have tried this in the web.config files and directly on the IIS manager.

The reporting server version in 2005 and it is hosted on Windows Server 2008, which is running IIS 7.

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On David Lively's advise I tried requesting the URI by putting the parameters in the body. This works for smaller requests, but still fails for large multi-select parameters. The amended code is as follows:

HttpWebRequest webRequest = null;
HttpWebResponse webResponse = null;
string webRequestURL = _ReportManager.GetRSUrl(reportID); //this passes the report link on the SSRS server

string postData = string.Empty;
string URIrequest = string.Empty;
URIrequest = webRequestURL.Substring(0, webRequestURL.IndexOf("&"));
int requestLen = webRequestURL.Length;
int postDataStart = webRequestURL.IndexOf("&") + 1;
postData = webRequestURL.Substring(postDataStart, (requestLen - postDataStart));

Byte[] bytes1 = Encoding.UTF8.GetBytes(postData);

webRequest = (HttpWebRequest)WebRequest.Create(URIrequest);
                webRequest.Method = "POST";
                webRequest.ContentType = "application/x-www-form-urlencoded";
                webRequest.ContentLength = bytes1.Length;
                webRequest.Timeout = Configuration.WebRequestTimeOut;

RSExecution2005.ReportExecutionService rsE = new RSExecution2005.ReportExecutionService();
rsE.Url = Configuration.ReportExecutionServiceUrl2005;
rsE.Credentials = System.Net.CredentialCache.DefaultCredentials;
webRequest.Credentials = rsE.Credentials;

Stream reqStream = webRequest.GetRequestStream();
reqStream.Write(bytes1, 0, bytes1.Length);
reqStream.Close();
webResponse = (HttpWebResponse)webRequest.GetResponse();

Even though the requestURI of the webRequest does not store parameters, it seems that the GetReponse() function adds the parameters to the 'address' property of the webRequest. could this be the problem? if so, how can it be fixed.

Answer 1

Is it possible for you to use POST variables instead of GET? That way, there are no limits that I'm aware of, as all of your data will be sent in packets instead of HTTP headers.

Actually it looks like you might be using POST from what's in your code. Can you look in the server logs to verify the URI that is causing this to fail? If you're sending POST data, the request uri shouldn't be an issue unless it's unrelated to the data you're POSTing.