Update in Visual Basic .NET

Drawer PDF417 in Visual Basic .NET Update

Update
Paint PDF 417 In VB.NET
Using Barcode generator for Visual Studio .NET Control to generate, create PDF417 image in VS .NET applications.
www.OnBarcode.com
Scanning PDF417 In VB.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
The Update() method is more complex. This is because Update() handles BusinessBase and CommandBase subclasses differently from other objects. The specific DataPortal_XYZ method to be invoked varies based on the base class of the business object. This complicates the process of retrieving the MethodInfo object: Dim method As MethodInfo Dim methodName As String If TypeOf obj Is CommandBase Then methodName = "DataPortal_Execute" ElseIf TypeOf obj Is Core.BusinessBase Then Dim tmp As Core.BusinessBase = DirectCast(obj, Core.BusinessBase) If tmp.IsDeleted Then methodName = "DataPortal_DeleteSelf" Else If tmp.IsNew Then methodName = "DataPortal_Insert" Else methodName = "DataPortal_Update" End If End If Else methodName = "DataPortal_Update" End If method = MethodCaller.GetMethod(obj.GetType, methodName)
Generate EAN-13 In Visual Basic .NET
Using Barcode generator for .NET Control to generate, create EAN 13 image in .NET applications.
www.OnBarcode.com
Printing ANSI/AIM Code 39 In Visual Basic .NET
Using Barcode generation for .NET framework Control to generate, create Code 39 Extended image in .NET framework applications.
www.OnBarcode.com
CHAPTER 4 s DATA ACCESS AND SECURITY
ECC200 Creator In Visual Basic .NET
Using Barcode printer for VS .NET Control to generate, create ECC200 image in Visual Studio .NET applications.
www.OnBarcode.com
Encode Matrix 2D Barcode In Visual Basic .NET
Using Barcode creation for Visual Studio .NET Control to generate, create Matrix Barcode image in VS .NET applications.
www.OnBarcode.com
The same GetMethod() call is used as in Fetch() and Delete(), but the name of the method is determined based on the type and state of the business object itself. If the business object is a subclass of CommandBase, then the method name is DataPortal_Execute. For any other objects that don t inherit from BusinessBase, the method name is DataPortal_Update. If the business object is a subclass of BusinessBase, however, the object s state becomes important. If the object is marked for deletion, then the method name is DataPortal_DeleteSelf. If the object is new, the name is DataPortal_Insert; otherwise, it is DataPortal_Update. Once the MethodInfo object has been retrieved, the rest of the code is essentially the same as in the other three methods. Now let s discuss the two remaining classes that set up an appropriate transaction context.
Code 128 Code Set A Generator In Visual Basic .NET
Using Barcode generation for .NET Control to generate, create Code 128A image in VS .NET applications.
www.OnBarcode.com
MSI Plessey Creator In Visual Basic .NET
Using Barcode generator for Visual Studio .NET Control to generate, create MSI Plessey image in Visual Studio .NET applications.
www.OnBarcode.com
Csla.Server.ServicedDataPortal
PDF-417 2d Barcode Printer In Java
Using Barcode maker for BIRT reports Control to generate, create PDF 417 image in Eclipse BIRT applications.
www.OnBarcode.com
PDF417 Reader In VS .NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
The ServicedDataPortal has one job: to create a distributed COM+ transactional context within which SimpleDataPortal (and thus the business object) will run. When a call is routed through ServicedDataPortal, a distributed transactional context is created, ensuring that the business object s DataPortal_XYZ methods run within that context. Normally, to run within a COM+ distributed transaction, an object must inherit from System. EnterpriseServices.ServicedComponent. This is a problem for typical business objects, since you don t usually want them to run within COM+, and no one likes all the deployment complexity that comes with a ServicedComponent. ServicedDataPortal allows business objects to avoid this complexity. It does inherit from ServicedComponent, and includes the appropriate Enterprise Services attributes to trigger the use of a distributed transaction. But it turns out that when a ServicedComponent running in a transactional context calls a normal .NET object, that object also runs in the transaction. This is true even when the normal .NET object doesn t inherit from ServicedComponent. The use of this concept is illustrated in Figure 4-11.
QR Code Generator In C#
Using Barcode generation for .NET Control to generate, create Quick Response Code image in VS .NET applications.
www.OnBarcode.com
Code128 Recognizer In Visual Basic .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Figure 4-11. Using ServicedDataPortal to wrap a business object in a transaction
Drawing Data Matrix In Java
Using Barcode drawer for Android Control to generate, create Data Matrix image in Android applications.
www.OnBarcode.com
Decoding USS Code 128 In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Once the transactional context is established by ServicedDataPortal, all normal .NET objects invoked from that point forward run within the same context. ServicedDataPortal itself inherits from System.EnterpriseServices.ServicedComponent, and includes some key attributes:
Scan UPC-A Supplement 5 In C#
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
QR Decoder In .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
CHAPTER 4 s DATA ACCESS AND SECURITY
Barcode Creation In .NET
Using Barcode printer for Reporting Service Control to generate, create Barcode image in Reporting Service applications.
www.OnBarcode.com
Making GS1 128 In Java
Using Barcode drawer for Java Control to generate, create EAN / UCC - 14 image in Java applications.
www.OnBarcode.com
<Transaction(TransactionOption.Required)> _ <EventTrackingEnabled(True)> _ <ComVisible(True)> _ Public Class ServicedDataPortal Inherits ServicedComponent Implements IDataPortalServer The <Transaction()> attribute specifies that this object must run within a COM+ transactional context. If it is called by another object that already established such a context, this object will run within that context; otherwise, it will create a new context. The <EventTrackingEnabled()> attribute indicates that this object will interact with COM+ to enable the spinning balls in the Component Services management console. This is only important (or even visible) if the data portal is running within COM+ on the server meaning that the EnterpriseServicesProxy is used by the client to interact with the server. The <ComVisible()> attribute makes this class visible to COM, which is a requirement for any class that is to be hosted in COM+. Because ServicedDataPortal inherits from ServicedComponent, the Csla.dll assembly itself must be configured so it can be hosted in COM+. Because the assembly already includes the Csla. Server.Hosts.EnterpriseServicesPortal class, all the necessary configuration already exists. This was discussed earlier in the chapter. The class also implements the IDataPortalServer interface, ensuring that it implements the four data methods. Each of these methods has another Enterprise Services attribute <AutoComplete()>: <AutoComplete(True)> _ Public Function Create( _ ByVal objectType As System.Type, _ ByVal criteria As Object, _ ByVal context As Server.DataPortalContext) As Server.DataPortalResult _ Implements Server.IDataPortalServer.Create Dim portal As New SimpleDataPortal Return portal.Create(objectType, criteria, context) End Function The <AutoComplete()> attribute is used to tell COM+ that this method will vote to commit the transaction unless it throws an exception. In other words, if an exception is thrown, the method votes to roll back the transaction; otherwise, it votes to commit the transaction. This fits with the overall model of the data portal, which relies on the business object to throw exceptions in case of failure. The data portal uses the exception to return important information about the failure back to the client. ServicedDataPortal also relies on the exception to tell COM+ to roll back the transaction. Notice how the Create() method simply creates an instance of SimpleDataPortal and delegates the call to that object. This is the same as Csla.Server.DataPortal did for manual transactions; except in this case, SimpleDataPortal and the business object are wrapped in a distributed transactional context. The other three data methods are implemented in the same manner.
Print UCC - 12 In None
Using Barcode encoder for Online Control to generate, create UPC-A Supplement 5 image in Online applications.
www.OnBarcode.com
Creating UPC A In None
Using Barcode generator for Word Control to generate, create UPC Symbol image in Microsoft Word applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.