/// <summary>
/// Provides the data of a Url given it's unique ID. It transparently undertakes the
/// decompression of the data stored in the database for the given Url.
/// </summary>
/// <param name="urlID">The ID of the Url</param>
/// <returns>The Url's data as a string, or an empty string if the operation fails.</returns>
/// <exception cref="ArgumentOutOfRangeException">Thrown if a negative value is given for Url ID.</exception>
/// <exception cref="CWException">If the given Url's data cannot be found in the database.</exception>
public string ProvideUrlData(int urlID)
{
if (urlID <= 0)
{
throw new ArgumentOutOfRangeException("urlID");
}
string retVal = string.Empty;
try
{
if (!ConnectToDatabase())
{
if (!ConnectToDatabase())
{
throw new CWDBConnectionFailedException();
}
}
SqlCommand cmd = new SqlCommand("cw_select_url_data", dbcon);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("@url_id", SqlDbType.Int);
cmd.Parameters[0].Value = urlID;
DataSet ds = new DataSet();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(ds);
da.Dispose();
cmd.Dispose();
if (ds.Tables[0].Rows.Count == 0)
{
ds.Dispose();
throw new CWException("The data for the specified Url are not available.");
}
else
{
DataRow dr = ds.Tables[0].Rows[0];
byte [] data = (byte [])dr[1];
int original_length = (int)dr[3];
CompressionUtils.DecompressToString(data, out retVal);
ds.Dispose();
//if(retVal.Length != original_length)
//{
// //log("Warning: Invalid string length of decompressed data.");
//}
}
}
catch (Exception e)
{
throw e;
}
finally
{
DisconnectFromDatabase();
}
return(retVal);
}
/// <summary>
/// Selects a random Url to extract words from.
/// </summary>
/// <param name="UrlID">The ID of the selected Url.</param>
/// <param name="data">The data of the selected Url.</param>
private void SelectUrlForWordExtraction(out int UrlID, out string data)
{
UrlID = 0;
data = String.Empty;
try
{
try
{
dbcon.Open();
}
catch
{}
if (dbcon.State == ConnectionState.Closed)
{
//log a message
return;
}
SqlCommand cmd = new SqlCommand("cw_select_url_for_word_extraction", dbcon);
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandTimeout = settings.DBActionTimeout;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
da.Fill(ds);
da.Dispose();
cmd.Dispose();
dbcon.Close();
if (ds.Tables.Count == 0)
{
return;
}
UrlID = (int)ds.Tables[0].Rows[0][0];
byte [] buffer = (byte [])ds.Tables[0].Rows[0][1];
CompressionUtils.DecompressToString(buffer, out data);
ds.Dispose();
}
catch
{
if (dbcon.State != ConnectionState.Closed)
{
try
{
dbcon.Close();
}
catch
{}
}
GC.Collect();
}
}
