How to run a report from WCF

Question

hi,
I am trying to run a report from a WCF service application, and then render it in PDF Format to a caller WPF application. But I cant get it! In more detail, this is what my app should do
1. from WPF, call a web service procedure, pass a report name, report path and parameters. Report is store at the same server where Web Service is installed
2. WCF procedure loads report, set parameters, retrieve data from DB and renders it as an array of bytes
3. WPF gets the array, save it into a PDF file, then open it.
this is the code of the WCF procedure.
    Function DownloadCRReport(codEnte As String, connString As String, reportDir As String, reportName As String, Parameters As Dictionary(Of String, Object)) As Byte() Implements IGesiService.DownloadCRReport
        Try
            Dim bytes As Byte()
            Dim infile As BinaryReader
            Dim fs As FileStream
            Dim rep As New ReportDocument
            Dim RepAddress As String
            logPath = reportDir & "log\"
            sb = New StringBuilder()
            timestamp = Now.Year.ToString & Now.Month.ToString & Now.Day.ToString & Now.Hour.ToString & Now.Minute.ToString & Now.Second.ToString
            logFileName = timestamp & "_" & reportName & ".txt"
            logFile = New StreamWriter(logPath & logFileName, FileMode.CreateNew)
            logFile.WriteLine("----
Date and time: " & Now.ToString & " -
            If My.Computer.FileSystem.FileExists(reportDir & reportName & ".rpt") = False Then
                Throw New Exception("file RPT non found in: " & reportDir)
            End If
            RepAddress = reportDir & reportName & ".rpt"
            logFile.WriteLine("rep address: " & RepAddress)
            rep.Load(RepAddress, OpenReportMethod.OpenReportByDefault)
            logFile.WriteLine("load rep")
            If rep.DataSourceConnections.Count > 0 Then
                rep.DataSourceConnections.Item(0).SetLogon("usr", "pwd")
                logFile.WriteLine("data source connection")
            End If
            For Each i In Parameters
                rep.SetParameterValue(i.Key, i.Value)
                logFile.WriteLine("param: " & i.Key & " - " & i.Value)
            Next
            Try
                fs = rep.ExportToStream(ExportFormatType.PortableDocFormat)
                logFile.WriteLine("export to stream")
                infile = New BinaryReader(fs)
                logFile.WriteLine("created binaryreader")
                bytes = infile.ReadBytes(CInt(fs.Length))
                logFile.WriteLine("render pdf. fine")
                logFile.Close()
                Return bytes
            Catch ex As Exception
                logFile.WriteLine("vbCrLf & ex.Message & vbCrLf & ex.InnerException.Message)
                logFile.Close()
                Return Nothing
            End Try
        Catch ex As Exception
            logFile.WriteLine("vbCrLf & ex.Message & "-" & vbCrLf & ex.InnerException.Message)
            logFile.Close()
            Return Nothing
        End Try
    End Function
I detected that error occurs on rep.ExportToStream(ExportFormatType.PortableDocFormat). I should point out that the same procedure works under WPF application. In the WCF server I installed CR Runtime engine for .NET framework (13.0.9.1312) and CR version for Microsoft Visual Studio (same version). Moreover, all DB operations are stored into the report, so I should not pass any dataset, just parameters.
Anyway, just to begin, I tried to call a simple report with just two string parameters and no queries, but I alwais get error ("An exception of type 'System.NullReferenceException' occurred in MyApp... Object reference not set to an instance of an object)!
How can I make it work? thanks for help

Answer 1

hi Ludek,
Im trying to change DB connection info at runtime for all of the report tables. this is the code I used in my Web Service
          Function DownloadCRReport(...)
If rep.DataSourceConnections.Count > 0 Then
   Dim conn As New ConnectionInfo
   Dim tabLogon As TableLogOnInfo
   conn.ServerName = "10.10.15.90" 'IP address of DB server
   conn.DatabaseName = "MyDB"   'Database name as set in TNSNAMES.ORA
   conn.UserID = "newuser"
   conn.Password = "newpwd"
   For Each t As Table In rep.Database.Tables
      tabLogon = t.LogOnInfo
      tabLogon.ConnectionInfo = conn
      t.ApplyLogOnInfo(tabLogon)
      logFile.WriteLine("changed logon tab. " & t.Name)
   Next
   rep.Refresh()
   logFile.WriteLine("changed data source connection")
End If
'set parameters
If Not IsNothing(Parameters) Then
   For Each i In Parameters
      rep.SetParameterValue(i.Key, i.Value)
      logFile.WriteLine("set parameter" & i.Key & " - " & i.Value)
   Next
End If
fs = rep.ExportToStream(ExportFormatType.PortableDocFormat)
          End Function
that comes to an error on rep.ExportToStream: "Unable to access database".
Running web service in debug mode, I noticed that, after t.ApplyLogonInfo(tabLogon), the new ConnectionInfo has "password" property empty. Maybe this could cause the error, or is there some mistake in the new connectioninfo?