Introduction

There may be times when you need to call a library in order to get the data you desire. In my situation, I needed to call an external dll that would return data to OWS from a secure web service and doing a simple SOAP request would not cut it. Anyway , talk is cheap, lets get started..

To begin create a new Class Library in visual studio and name it (For this example I named mine DDC.OWS.QueryWebService), From here you'll want to ad references to the external dll you will be calling as well as r2i.OWS.Engine, R2i.OWS.Framework and System.Xml dlls.

(Show) Table of Contents

Now lets start writing some code:

Imports

Open up your class and add these to your imports:

Imports System.Xml

Imports System.Xml.XPath

Imports r2i.OWS.Utilities

Imports r2i.OWS

Imports r2i.OWS.Queries

Write your class in the 'Queries' Namespace and Inherit the QueryBase class from the r2i.OWS.Queries class.

Namespace

Namespace Queries

Public Class DDCQuery

Inherits QueryBase

Overrided Methods

This next part is Very Important! (well everything’s important here to get this to work, but you get the idea) This property is how OWS knows to call your dll, and change 'R2IQUERY' to whatever you wish.

Public Overrides ReadOnly Property QueryTag() As String

Get

Return "<R2IQUERY>"

End Get

End Property

Our next property will give OWS the XML format we will make our queries in. Include here any parameters you will give the query

Public Overrides ReadOnly Property QueryStructure() As String

Get

Dim s As String = ""

s &= "<R2IQUERY>" & vbCrLf

s &= " <METHODNAME></METHODNAME>" & vbCrLf

s &= " <USERID></USERID>" & vbCrLf

s &= " <CLASSID></CLASSID>" & vbCrLf

s &= "</R2IQUERY>"

Return s

End Get

End Property

As you can see our query takes a Method name, UserId, and ClassId as parameters. Now for our first function, we will create a method that will return a sorted list; this will read our parameters and store them into one location we can easily access.

Private Function GetData_XML_Method(ByRef Source As String) As SortedList

Dim srt As New SortedList

Dim strUserId As String = XMLPropertyParse_Quick(Source, "userid")

If Not strUserId Is Nothing Then

srt.Add("userId", Integer.Parse(strUserId))

End If

Dim strClassId As String = XMLPropertyParse_Quick(Source, "classid")

If Not strClassId Is Nothing Then

srt.Add("classId", Integer.Parse(strClassId))

End If

Return srt

End Function

Handling the Data

With these parts out of the way we can now create our handler that returns our data. Add this method and make the changes to the case statement to call your dll function.

Public Overrides Function Handle_GetData(ByRef Caller As Engine, ByVal isSubQuery As Boolean, ByVal Query As String, ByVal FilterField As String, ByVal FilterText As String, ByRef DebugWriter As Framework.Debugger, ByVal isRendered As Boolean, Optional ByVal timeout As Integer = -1, Optional ByVal CustomConnection As String = Nothing, Optional ByRef IsSuccessful As Boolean = True, Optional ByRef FailureMessage As String = Nothing) As System.Data.DataSet

Dim debug As Boolean = False

Dim traceDebug As Boolean = Caller.xls.enableQueryDebug_Log

Dim errorDebug As Boolean = Caller.xls.enableQueryDebug_ErrorLog

Dim thrownError As Boolean = False

Dim ds As New DataSet

Dim errorStr As String = Nothing

IsSuccessful = True

If Not DebugWriter Is Nothing Then

debug = True

Else

If traceDebug Then

If DebugWriter Is Nothing Then

DebugWriter = New r2i.OWS.Framework.Debugger

End If

Try

Dim strDebug As String = ""

Dim strMethod As String = XMLPropertyParse_Quick(Query, "methodname")

Dim settings As SortedList = GetData_XML_Method(Query)

Select Case strMethod.ToLower

Case "MethodName"

If settings.ContainsKey("userId") Then

Dim userId As Integer = CType(settings("userId"), Integer)

Handlers.DDCAssignStudentToSection.HandleRequest(userId)

End If

Case " MethodName"

If settings.ContainsKey("userId") Then

Dim userId As Integer = CType(settings("userId"), Integer)

ds = Handlers.DDCGetAddressListByUserId.HandleRequest(userId)

End If

End Select

Catch ex As Exception

EngineSingleton.Instance(Caller.Context).SortStatus(Caller.ModuleID, Caller.UserID) = Nothing

errorStr = ex.ToString

errorStr = "Error getting Dataset, DDCQUERY: " + errorStr

FailureMessage = errorStr

End Try

If Not errorStr Is Nothing Then

thrownError = True

IsSuccessful = False

If thrownError AndAlso (debug OrElse (errorDebug AndAlso thrownError) OrElse traceDebug) AndAlso DebugWriter Is Nothing Then

DebugWriter = New r2i.OWS.Framework.Debugger

End If

Try

If debug OrElse (errorDebug AndAlso thrownError) OrElse traceDebug Then

DebugWriter.AppendBlock(Caller.ModuleID, "Error", "error", False, errorStr, True)

End If

Catch ex As Exception

End Try

Else

Try

FailureMessage = ""

If debug OrElse traceDebug Then

DebugWriter.AppendHeader(Caller.ModuleID, "Tables", "tables", False)

Try

Dim dbgX As New Text.StringBuilder

Dim tbl As DataTable

For Each tbl In ds.Tables

dbgX.Append(tbl.TableName & " -  Rows: " & tbl.Rows.Count & " Columns: " & tbl.Columns.Count & " <ul>")

Dim col As DataColumn

For Each col In tbl.Columns

dbgX.Append("<li>" & col.ColumnName & " " & col.DataType.ToString & "</li>")

dbgX.Append("</ul> ")

DebugWriter.Append(dbgX.ToString)

Catch ex As Exception

End Try

DebugWriter.AppendFooter(False)

End If

Catch ex As Exception

End Try

End If

If Not isSubQuery Then

Try

'Handle custom paging if required here

If Not ds Is Nothing AndAlso ds.Tables.Count > 0 Then

If Caller.xls.enableCustomPaging = True Then

'CHECK FOR TABLE 1 COLUMN 0 ROW 0

If ds.Tables.Count > 1 Then

'WE HAVE OUR TABLE

If ds.Tables(1).Rows.Count > 0 Then

'WE HAVE OUR ROW

Try

If Not IsDBNull(ds.Tables(1).Rows(0).Item(0)) Then

Caller.TotalRecords = ds.Tables(1).Rows(0).Item(0)

Else

Caller.TotalRecords = ds.Tables(0).Rows.Count

End If

Catch ex As Exception

End Try

Else

Caller.TotalRecords = ds.Tables(0).Rows.Count

End If

Else

Caller.TotalRecords = ds.Tables(0).Rows.Count

End If

Else

Caller.TotalRecords = ds.Tables(0).Rows.Count

End If

'VERSION: 1.8.1 - Now sets the TotalPages value

If Caller.TotalRecords > 0 Then

If Caller.RecordsPerPage > 0 Then

Caller.TotalPages = Math.Ceiling(CDbl(Caller.TotalRecords) / CDbl(Caller.RecordsPerPage))

Else

Caller.TotalPages = 1

End If

Else

Caller.TotalPages = 0

End If

Else

Caller.TotalRecords = 0

Caller.TotalPages = 0

End If

Catch ex As Exception

thrownError = True

If thrownError AndAlso (debug OrElse (errorDebug AndAlso thrownError) OrElse traceDebug) AndAlso DebugWriter Is Nothing Then

DebugWriter = New r2i.OWS.Framework.Debugger

End If

If debug OrElse errorDebug OrElse traceDebug Then

DebugWriter.AppendBlock(Caller.ModuleID, "Exception", "exception", False, ex.ToString, True)

End If

End Try

End If

Try

If (errorDebug AndAlso thrownError) OrElse traceDebug Then

If Not debug Then

DebugWriter.AppendHeader(Caller.ModuleID, "Statistics", "statistics", False)

DebugWriter.Append("<ul>")

DebugWriter.Append("<li>ModuleId " & Caller.ModuleID & "</li>")

DebugWriter.Append("<li>TabId " & Caller.TabID & "</li>")

DebugWriter.Append("<li>TabModuleId " & Caller.TabModuleID & "</li>")

DebugWriter.Append("<li>Filter " & Caller.xls.filter & "</li>")

DebugWriter.Append("<li>Filter Field " & FilterField & "</li>")

DebugWriter.Append("<li>Filter Text " & FilterText & "</li>")

DebugWriter.Append("<li>Current Page " & (Caller.PageCurrent + 1) & "</li>")

DebugWriter.Append("<li>Page Size " & Caller.RecordsPerPage & "</li>")

DebugWriter.Append("<li>Total Records " & Caller.TotalRecords & "</li>")

DebugWriter.Append("<li>Form <ol>" & Caller.ShowForm("<li>", "</li>") & "</ol></li>")

DebugWriter.Append("<li>Session <ol>" & Caller.ShowSession("<li>", "</li>") & "</ol></li>")

DebugWriter.Append("<li>Cookies <ol>" & Caller.ShowCookies("<li>", "</li>") & "</ol></li>")

DebugWriter.Append("<li>ViewState <ol>" & Caller.ShowViewState("<li>", "</li>") & "</ol></li>")

DebugWriter.Append("</ul>")

DebugWriter.AppendFooter(False)

If (errorDebug AndAlso thrownError) OrElse traceDebug Then

If traceDebug Then

'Controller.AddLog(Caller.ConfigurationID, Caller.UserID, "Automated Debug - Trace", DebugWriter.ToString, Caller.Session.SessionID)

ElseIf (errorDebug AndAlso thrownError) Then

'Controller.AddLog(Caller.ConfigurationID, Caller.UserID, "Automated Debug - Query Error", DebugWriter.ToString, Caller.Session.SessionID)

End If

If Not debug Then

DebugWriter.Close()

DebugWriter = Nothing

End If

Catch ex As Exception

End Try

Return ds

End Function

Now also note that your dll MUST return data in a dataset if you are expecting back data. Otherwise it is completely fine to have method calls that don’t return data.

Conclusion

At this point you can build your library and add this wrapper to the bin folder in dnn. From here remember what the dll’s name is, we need to edit the openwebstudio.config file.

Find the Queries node in this document and Add this:

Where R2IQuery is the root node of the xml query call,

DDC.OWS.QueryWebSrvice.Queries.DDCQuery is the path to the class with the query,

And DDC.OWS.QueryWebService is the dll name.

Save the config file.

Now whenever you want to use this and call your library in OWS, do a query template or a simple query and include parameters in your query structure:

</R2IQUERY>

That’s it!

Calling an external dll from OWS

By Kevin Schreiner

Introduction

Imports

Namespace

Overrided Methods

Handling the Data

Conclusion