Pro Grammatically SSRS Report Generation in C#

public void RenderSSRSReport(string whereFilter)
{
    string reportPath = string.Empty;
    string historyID = null;
    string deviceInfo = null;
    string extension = null;
    string encoding = null;
    string mimeType = null;
    string[] streamIDs = null;
    string format = "pdf";
    Byte[] result;
    FileStream stream = null;
    try
    {
        ReportExecution2005.Warning[] warnings = null;
        ExecutionInfo execInfo = new ExecutionInfo();
        TrustedUserHeader trusteduserHeader = new TrustedUserHeader();
        ExecutionHeader execHeader = new ExecutionHeader();
        ServerInfoHeader serviceInfo = new ServerInfoHeader();
        ReportExecution2005.ReportParameter[] _parameters = null;
        ParameterValue[] _ParameterValue = null;
        reportPath = ConfigurationManager.AppSettings["SSRSReportPath"];
        ReportExecutionServiceSoapClient rsExec = new ReportExecutionServiceSoapClient();
        rsExec.ClientCredentials.Windows.AllowedImpersonationLevel = System.Security.Principal.TokenImpersonationLevel.Impersonation;
        rsExec.LoadReport(trusteduserHeader, reportPath, historyID, out serviceInfo, out execInfo);
        execHeader.ExecutionID = execInfo.ExecutionID;
        //If you have any parameters then use this code block
        if (whereFilter != "")
        {
            _parameters = execInfo.Parameters;
            _ParameterValue = new ParameterValue[1];
            _ParameterValue[0] = new ParameterValue();
            _ParameterValue[0].Name = _parameters[0].Name;
            _ParameterValue[0].Value = whereFilter.Split('=').LastOrDefault().Trim();
            rsExec.SetExecutionParameters(execHeader, null, _ParameterValue, "en-us", out execInfo);
        }
        rsExec.Render(execHeader, null, format, deviceInfo, out result, out extension, out mimeType, out encoding, out warnings, out streamIDs);
        rsExec.Close();
        rsExec = null;
        stream = File.OpenWrite(PDFFilePath);
        stream.Write(result, 0, result.Length);
        stream.Close();
        stream.Dispose();
        stream = null;
    }
    catch (Exception)
    {
        if (stream != null)
        {
            stream.Close();
            stream.Dispose();
            stream = null;
        }
    }
}