/// <summary>
/// Attempts to load a RDF dataset asynchronously from the given URI using a RDF Handler
/// </summary>
/// <param name="handler">RDF Handler to use</param>
/// <param name="u">URI to attempt to get a RDF dataset from</param>
/// <param name="parser">Parser to use to parse the RDF dataset</param>
/// <param name="callback">Callback to invoke when the operation completes</param>
/// <param name="state">State to pass to the callback</param>
/// <remarks>
/// <para>
/// If the <paramref name="parser"/> parameter is set to null then this method attempts to select the relevant Store Parser based on the Content Type header returned in the HTTP Response.
/// </para>
/// <para>
/// If you know ahead of time the Content Type you can explicitly pass in the parser to use.
/// </para>
/// </remarks>
public static void Load(IRdfHandler handler, Uri u, IStoreReader parser, RdfHandlerCallback callback, Object state)
{
if (u == null)
{
throw new RdfParseException("Cannot read a RDF dataset from a null URI");
}
if (handler == null)
{
throw new RdfParseException("Cannot read a RDF dataset using a null RDF handler");
}
try
{
#if SILVERLIGHT
if (u.IsFile())
#else
if (u.IsFile)
#endif
{
//Invoke FileLoader instead
RaiseWarning("This is a file: URI so invoking the FileLoader instead");
if (Path.DirectorySeparatorChar == '/')
{
FileLoader.Load(handler, u.ToString().Substring(7), parser);
}
else
{
FileLoader.Load(handler, u.ToString().Substring(8), parser);
}
//FileLoader.Load() will run synchronously so once this completes we can invoke the callback
callback(handler, state);
return;
}
if (u.Scheme.Equals("data"))
{
//Invoke DataUriLoader instead
RaiseWarning("This is a data: URI so invoking the DataUriLoader instead");
DataUriLoader.Load(handler, u);
//After DataUriLoader.Load() has run (which happens synchronously) can invoke the callback
callback(handler, state);
return;
}
//Sanitise the URI to remove any Fragment ID
u = Tools.StripUriFragment(u);
//Setup the Request
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(u);
//Want to ask for RDF dataset formats
if (parser != null)
{
//If a non-null parser set up a HTTP Header that is just for the given parser
request.Accept = MimeTypesHelper.CustomHttpAcceptHeader(parser);
}
else
{
request.Accept = MimeTypesHelper.HttpAcceptHeader;
}
//Use HTTP GET
request.Method = "GET";
#if !SILVERLIGHT
request.Timeout = Options.UriLoaderTimeout;
#endif
if (_userAgent != null && !_userAgent.Equals(String.Empty))
{
request.UserAgent = _userAgent;
}
#if DEBUG
//HTTP Debugging
if (Options.HttpDebugging)
{
Tools.HttpDebugRequest(request);
}
#endif
request.BeginGetResponse(result =>
{
using (HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result))
{
#if DEBUG
if (Options.HttpDebugging)
{
Tools.HttpDebugResponse(response);
}
#endif
//Get a Parser and load the RDF
if (parser == null)
{
try
{
//Only need to auto-detect the parser if a specific one wasn't specified
parser = MimeTypesHelper.GetStoreParser(response.ContentType);
parser.Warning += RaiseWarning;
parser.Load(handler, new StreamParams(response.GetResponseStream()));
}
catch (RdfParserSelectionException selEx)
{
String data = new StreamReader(response.GetResponseStream()).ReadToEnd();
parser = StringParser.GetDatasetParser(data);
parser.Warning += RaiseStoreWarning;
parser.Load(handler, new TextReaderParams(new StringReader(data)));
}
}
else
{
parser.Warning += RaiseStoreWarning;
parser.Load(handler, new StreamParams(response.GetResponseStream()));
}
//Finally can invoke the callback
callback(handler, state);
}
}, null);
}
catch (UriFormatException uriEx)
{
//Uri Format Invalid
throw new RdfException("Unable to load from the given URI '" + u.ToString() + "' since it's format was invalid, see inner exception for details", uriEx);
}
catch (WebException webEx)
{
#if DEBUG
if (Options.HttpDebugging)
{
if (webEx.Response != null)
{
Tools.HttpDebugResponse((HttpWebResponse)webEx.Response);
}
}
#endif
//Some sort of HTTP Error occurred
throw new WebException("A HTTP Error occurred resolving the URI '" + u.ToString() + "', see innner exception for details", webEx);
}
}
/// <summary>
/// Loads RDF data using an RDF Handler from a data: URI
/// </summary>
/// <param name="handler">RDF Handler</param>
/// <param name="u">URI to load from</param>
/// <remarks>
/// Invokes the normal <see cref="UriLoader">UriLoader</see> instead if a the URI provided is not a data: URI
/// </remarks>
/// <exception cref="UriFormatException">Thrown if the metadata portion of the URI which indicates the MIME Type, Character Set and whether Base64 encoding is used is malformed</exception>
public static void Load(IRdfHandler handler, Uri u)
{
if (u == null)
{
throw new RdfParseException("Cannot load RDF from a null URI");
}
if (handler == null)
{
throw new RdfParseException("Cannot read RDF into a null RDF Handler");
}
if (!u.Scheme.Equals("data"))
{
//Invoke the normal URI Loader if not a data: URI
#if !SILVERLIGHT
UriLoader.Load(handler, u);
#else
UriLoader.Load(handler, u, (_, _1) => { }, null);
#endif
return;
}
String mimetype = "text/plain";
bool mimeSet = false;
bool base64 = false;
String[] uri = u.AbsolutePath.Split(',');
String metadata = uri[0];
String data = uri[1];
//Process the metadata
if (metadata.Equals(String.Empty))
{
//Nothing to do
}
else if (metadata.Contains(';'))
{
if (metadata.StartsWith(";"))
{
metadata = metadata.Substring(1);
}
String[] meta = metadata.Split(';');
for (int i = 0; i < meta.Length; i++)
{
if (meta[i].StartsWith("charset="))
{
//OPT: Do we need to process the charset parameter here at all?
//String charset = meta[i].Substring(meta[i].IndexOf('=') + 1);
}
else if (meta[i].Equals("base64"))
{
base64 = true;
}
else if (meta[i].Contains('/'))
{
mimetype = meta[i];
mimeSet = true;
}
else
{
throw new UriFormatException("This data: URI appears to be malformed as encountered the parameter value '" + meta[i] + "' in the metadata section of the URI");
}
}
}
else
{
if (metadata.StartsWith("charset="))
{
//OPT: Do we need to process the charset parameter here at all?
}
else if (metadata.Equals(";base64"))
{
base64 = true;
}
else if (metadata.Contains('/'))
{
mimetype = metadata;
mimeSet = true;
}
else
{
throw new UriFormatException("This data: URI appears to be malformed as encountered the parameter value '" + metadata + "' in the metadata section of the URI");
}
}
//Process the data
if (base64)
{
StringWriter temp = new StringWriter();
foreach (byte b in Convert.FromBase64String(data))
{
temp.Write((char)((int)b));
}
data = temp.ToString();
}
else
{
data = Uri.UnescapeDataString(data);
}
//Now either select a parser based on the MIME type or let StringParser guess the format
try
{
if (mimeSet)
{
//If the MIME Type was explicitly set then we'll try and get a parser and use it
IRdfReader reader = MimeTypesHelper.GetParser(mimetype);
reader.Load(handler, new StringReader(data));
}
else
{
//If the MIME Type was not explicitly set we'll let the StringParser guess the format
IRdfReader reader = StringParser.GetParser(data);
reader.Load(handler, new StringReader(data));
}
}
catch (RdfParserSelectionException)
{
//If we fail to get a parser then we'll let the StringParser guess the format
IRdfReader reader = StringParser.GetParser(data);
reader.Load(handler, new StringReader(data));
}
}