/// <summary>
/// Internal Helper Method which executes the HTTP Requests against the Sparql Endpoint.
/// </summary>
/// <param name="target">Uri to make Request to.</param>
/// <param name="postData">Data that is to be POSTed to the Endpoint in <strong>application/x-www-form-urlencoded</strong> format.</param>
/// <param name="accept">The Accept Header that should be used.</param>
/// <returns>HTTP Response.</returns>
private HttpWebResponse ExecuteQuery(Uri target, String postData, String accept)
{
// Expect errors in this function to be handled by the calling function
// Set-up the Request
HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(target);
// Use HTTP GET/POST according to user set preference
httpRequest.Accept = accept;
if (!postData.Equals(string.Empty))
{
httpRequest.Method = "POST";
httpRequest.ContentType = MimeTypesHelper.Utf8WWWFormURLEncoded;
using (var writer = new StreamWriter(httpRequest.GetRequestStream(), new UTF8Encoding(Options.UseBomForUtf8)))
{
writer.Write(postData);
writer.Close();
}
}
else
{
if (HttpMode.Equals("AUTO"))
{
httpRequest.Method = postData.Equals(string.Empty) ? "GET" : "POST";
}
else
{
httpRequest.Method = HttpMode;
}
}
ApplyRequestOptions(httpRequest);
Tools.HttpDebugRequest(httpRequest);
HttpWebResponse httpResponse = (HttpWebResponse)httpRequest.GetResponse();
Tools.HttpDebugResponse(httpResponse);
return(httpResponse);
}
/// <summary>
/// Internal method which builds the Query Uri and executes it via GET/POST as appropriate.
/// </summary>
/// <param name="sparqlQuery">Sparql Query.</param>
/// <param name="acceptHeader">Accept Header to use for the request.</param>
/// <returns></returns>
private HttpWebResponse QueryInternal(String sparqlQuery, String acceptHeader)
{
// Patched by Alexander Zapirov to handle situations where the SPARQL Query is very long
// i.e. would exceed the length limit of the Uri class
// Build the Query Uri
StringBuilder queryUri = new StringBuilder();
queryUri.Append(Uri.AbsoluteUri);
bool longQuery = true;
if (HttpMode.Equals("GET") ||
HttpMode.Equals("AUTO") && sparqlQuery.Length <= LongQueryLength && sparqlQuery.IsAscii())
{
longQuery = false;
try
{
queryUri.Append(!Uri.Query.Equals(string.Empty) ? "&query=" : "?query=");
queryUri.Append(HttpUtility.UrlEncode(sparqlQuery));
// Add the Default Graph URIs
foreach (string defaultGraph in _defaultGraphUris)
{
if (defaultGraph.Equals(string.Empty))
{
continue;
}
queryUri.Append("&default-graph-uri=");
queryUri.Append(HttpUtility.UrlEncode(defaultGraph));
}
// Add the Named Graph URIs
foreach (string namedGraph in _namedGraphUris)
{
if (namedGraph.Equals(string.Empty))
{
continue;
}
queryUri.Append("&named-graph-uri=");
queryUri.Append(HttpUtility.UrlEncode(namedGraph));
}
}
catch (UriFormatException)
{
if (HttpMode.Equals("GET"))
{
throw;
}
longQuery = true;
}
}
// Make the Query via HTTP
HttpWebResponse httpResponse;
if (HttpMode.Equals("AUTO") && (longQuery || queryUri.Length > 2048) || HttpMode == "POST")
{
// Long Uri/HTTP POST Mode so use POST
StringBuilder postData = new StringBuilder();
postData.Append("query=");
postData.Append(HttpUtility.UrlEncode(sparqlQuery));
// Add the Default Graph URI(s)
foreach (String defaultGraph in _defaultGraphUris)
{
if (defaultGraph.Equals(String.Empty))
{
continue;
}
postData.Append("&default-graph-uri=");
postData.Append(HttpUtility.UrlEncode(defaultGraph));
}
// Add the Named Graph URI(s)
foreach (String namedGraph in _namedGraphUris)
{
if (namedGraph.Equals(String.Empty))
{
continue;
}
postData.Append("&named-graph-uri=");
postData.Append(HttpUtility.UrlEncode(namedGraph));
}
httpResponse = ExecuteQuery(Uri, postData.ToString(), acceptHeader);
}
else
{
// Make the query normally via GET
httpResponse = ExecuteQuery(UriFactory.Create(queryUri.ToString()), String.Empty, acceptHeader);
}
return(httpResponse);
}
