The most uncomplicated method of starting WF and keeping it running is to start WF when the website application starts up.

This can lead to the application start up time to increase depending on the number of running workflows.

To do this, you need to setup a global.asax file and on application start up start the necessary WF components.

Sample:

<%@ Application Language="VB" %>

<script runat="server">

    Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
        Dim workflowRuntime As System.Workflow.Runtime.WorkflowRuntime = New System.Workflow.Runtime.WorkflowRuntime("WorkflowRuntime")
        Application("WorkflowRuntime") = workflowRuntime

        Dim typeProvider As System.Workflow.ComponentModel.Compiler.TypeProvider = New System.Workflow.ComponentModel.Compiler.TypeProvider(workflowRuntime)
        typeProvider.AddAssembly(GetType(ASM.Web.WF.WIM.AuthorizationsWF).Assembly)
        workflowRuntime.AddService(typeProvider)
       
        ' Add the external data service

        ' Add custom manual charge service
        'requestService = New RequestService()
        'dataService.AddService(requestService)
       
        '  Should only be run when changes are made to the tracking profile.
        CreateAndInsertTrackingProfile()

        workflowRuntime.StartRuntime()
    End Sub
   
    Sub Application_End(ByVal sender As Object, ByVal e As EventArgs)
        Dim workflowRuntime As System.Workflow.Runtime.WorkflowRuntime = Application("WorkflowRuntime")
        workflowRuntime.StopRuntime()
    End Sub
   
    Sub CreateAndInsertTrackingProfile()
        Dim trackingProfile As Workflow.Runtime.Tracking.TrackingProfile = New Workflow.Runtime.Tracking.TrackingProfile()

        Dim activityTrackPoint As Workflow.Runtime.Tracking.ActivityTrackPoint = New Workflow.Runtime.Tracking.ActivityTrackPoint()
        Dim activityTrackingLocation As Workflow.Runtime.Tracking.ActivityTrackingLocation = New Workflow.Runtime.Tracking.ActivityTrackingLocation(GetType(Workflow.ComponentModel.Activity))
        activityTrackingLocation.MatchDerivedTypes = True
       
        Dim activityExecutionStatuses As Collections.Generic.IEnumerable(Of Workflow.ComponentModel.ActivityExecutionStatus) = CType(System.Enum.GetValues(GetType(Workflow.ComponentModel.ActivityExecutionStatus)), Collections.Generic.IEnumerable(Of Workflow.ComponentModel.ActivityExecutionStatus))
        For Each activityExecutionStatus As Workflow.ComponentModel.ActivityExecutionStatus In activityExecutionStatuses
            activityTrackingLocation.ExecutionStatusEvents.Add(activityExecutionStatus)
        Next

        activityTrackPoint.MatchingLocations.Add(activityTrackingLocation)
       
        Dim workflowDataTrackingExtract As System.Workflow.Runtime.Tracking.WorkflowDataTrackingExtract = New System.Workflow.Runtime.Tracking.WorkflowDataTrackingExtract()
        workflowDataTrackingExtract.Member = "FileEventArgs"

        activityTrackPoint.Extracts.Add(workflowDataTrackingExtract)
       
        trackingProfile.ActivityTrackPoints.Add(activityTrackPoint)
        trackingProfile.Version = New Version("1.0.0.1")

        Dim workflowTrackPoint As Workflow.Runtime.Tracking.WorkflowTrackPoint = New Workflow.Runtime.Tracking.WorkflowTrackPoint()
        Dim workflowTrackingLocation As Workflow.Runtime.Tracking.WorkflowTrackingLocation = New Workflow.Runtime.Tracking.WorkflowTrackingLocation()
       
        Dim trackingWorkflowEvents As Collections.Generic.IEnumerable(Of Workflow.Runtime.Tracking.TrackingWorkflowEvent) = CType(System.Enum.GetValues(GetType(Workflow.Runtime.Tracking.TrackingWorkflowEvent)), Collections.Generic.IEnumerable(Of Workflow.Runtime.Tracking.TrackingWorkflowEvent))
        For Each trackingWorkflowEvent As Workflow.Runtime.Tracking.TrackingWorkflowEvent In trackingWorkflowEvents
            workflowTrackingLocation.Events.Add(trackingWorkflowEvent)
        Next

        workflowTrackPoint.MatchingLocation = workflowTrackingLocation
        trackingProfile.WorkflowTrackPoints.Add(workflowTrackPoint)
       
        InsertTrackingProfile(trackingProfile)
    End Sub

    Sub InsertTrackingProfile(ByVal trackingProfile As Workflow.Runtime.Tracking.TrackingProfile)
        Dim profile As String = SerializeTrackingProfile(trackingProfile)
       
        Using sqlCommand As New Data.SqlClient.SqlCommand()
            sqlCommand.CommandType = System.Data.CommandType.StoredProcedure
            sqlCommand.CommandText = "dbo.UpdateTrackingProfile"
            sqlCommand.Connection = New Data.SqlClient.SqlConnection(ConfigurationManager.ConnectionStrings.Item("SharedConnectionString").ConnectionString)

            Dim typeFullName As Data.SqlClient.SqlParameter = New Data.SqlClient.SqlParameter()
            typeFullName.ParameterName = "@TypeFullName"
            typeFullName.SqlDbType = System.Data.SqlDbType.NVarChar
            typeFullName.SqlValue = GetType(ASM.Web.WF.WIM.AuthorizationsWF).ToString()
            sqlCommand.Parameters.Add(typeFullName)

            Dim assemblyFullName As Data.SqlClient.SqlParameter = New Data.SqlClient.SqlParameter()
            assemblyFullName.ParameterName = "@AssemblyFullName"
            assemblyFullName.SqlDbType = System.Data.SqlDbType.NVarChar
            assemblyFullName.SqlValue = GetType(ASM.Web.WF.WIM.AuthorizationsWF).Assembly.FullName
            sqlCommand.Parameters.Add(assemblyFullName)

            Dim versionId As Data.SqlClient.SqlParameter = New Data.SqlClient.SqlParameter()
            versionId.ParameterName = "@Version"
            versionId.SqlDbType = System.Data.SqlDbType.VarChar
            versionId.SqlValue = trackingProfile.Version.ToString()
            sqlCommand.Parameters.Add(versionId)

            Dim trackingProfileXml As Data.SqlClient.SqlParameter = New Data.SqlClient.SqlParameter()
            trackingProfileXml.ParameterName = "@TrackingProfileXml"
            trackingProfileXml.SqlDbType = System.Data.SqlDbType.NVarChar
            trackingProfileXml.SqlValue = profile
            sqlCommand.Parameters.Add(trackingProfileXml)

            sqlCommand.Connection.Open()
            Try
                sqlCommand.ExecuteNonQuery()
            Catch e As Data.SqlClient.SqlException
                Dim s As String
                s = e.Message
            End Try
        End Using
    End Sub

    Function SerializeTrackingProfile(ByVal trackingProfile As Workflow.Runtime.Tracking.TrackingProfile) As String
        Dim trackingProfileSerializer As Workflow.Runtime.Tracking.TrackingProfileSerializer = New Workflow.Runtime.Tracking.TrackingProfileSerializer()
        Dim stringWriter As IO.StringWriter = New IO.StringWriter(New StringBuilder(), System.Globalization.CultureInfo.InvariantCulture)
        trackingProfileSerializer.Serialize(stringWriter, trackingProfile)
        Return stringWriter.ToString()
    End Function
           
    Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
        ' Code that runs when an unhandled error occurs
       
    End Sub

      
</script>