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.When testing a transactional object that you intend to run under MTS, you may firstwant to test your object outside the MTS environment to simplify your testenvironment.While developing your server, you cannot rebuild the server when it is still inmemory.You may get a compiler error like,  Cannot write to DLL while executableis loaded. To avoid this, you can set the MTS package or COM+ applicationproperties to shut down the server when it is idle.To shut down the server when idle,1 In the MTS Explorer or COM+ Component Manager, right-click the MTS packageor COM+ application in which your transactional object is installed and chooseProperties.2 Select the Advanced tab.The Advanced tab determines whether the server process associated with apackage always runs, or whether it shuts down after a certain period of time.3 Change the timeout value to 0, which shuts down the server as soon as no longerhas a client to service.Cr eat i ng MTS or COM+ obj ect s 38-23I n s t a l l i n g t r a n s a c t i o n a l o b j e c t s4 Click OK to save the setting.Installing transactional objectsMTS applications consist of a group of in-process MTS objects running in a singleinstance of the MTS executive (EXE).A group of COM objects that all run in the sameprocess is called a package.A single machine can be running several differentpackages, where each package is running within a separate MTS EXE.Under COM+, you work with a similar group, called a COM+ application.In aCOM+ application, the objects need not be in-process, and there is no separateruntime environment.You can group your application components into a single MTS package or COM+application to be managed by a single process.You might want to distribute yourcomponents into different MTS packages or COM+ applications to partition yourapplication across multiple processes or machines.To install transactional objects into an MTS package or COM+ application,1 If your system supports COM+, choose Run|Install COM+ objects.If your systemdoes not support COM+ but you have MTS installed on your system, choose Run|Install MTS objects.If your system supports neither MTS nor COM+, you will notsee a menu item for installing transactional objects.2 In the Install Object dialog box, check the objects to be installed.3 If you are installing MTS objects, click the Package button to get a list of MTSpackages on your system.If you are installing COM+ objects, click the Applicationbutton.Indicate the MTS package or COM+ application into which you areinstalling your objects.You can choose Into New Package or Into New Applicationto create a new MTS package or COM+ application in which to install the object.You can choose Into Existing Package or Into Existing Application to install theobject into an existing listed MTS package or COM+ application.4 Choose OK to refresh the catalog, which makes the objects available at runtime.MTS packages can contain components from multiple DLLs, and components from asingle DLL can be installed into different packages.However, a single componentcannot be distributed among multiple packages.Similarly, COM+ applications can contain components from multiple executablesand different components from a single executable can be installed into differentCOM+ applications.Note You can also install your transactional object using the COM+ Component Manageror MTS Explorer.Be sure when installing the object with one of these tools that youapply the settings for the object that appear on the COM+ page of the Type Libraryeditor.These settings are not applied automatically when you do not install from theIDE.38-24 Dev el oper  s Gui deAd mi n i s t e r i n g t r a n s a c t i o n a l o b j e c t sAdministering transactional objectsOnce you have installed transactional objects, you can administer these runtimeobjects using the MTS Explorer (if they are installed into an MTS package) or theCOM+ Component Manager (if they are installed into a COM+ application).Bothtools are identical, except that the MTS Explorer operates on the MTS runtimeenvironment and the COM+ Component Manager operates on COM+ objects.The COM+ Component Manager and MTS Explorer have a graphical user interfacefor managing and deploying transactional objects.Using one of these tools, you can" Configure transactional objects, MTS packages or COM+ applications, and roles" View properties of components in an package or COM+ application and view theMTS packages or COM+ applications installed on a computer" Monitor and manage transactions for objects that comprise transactions" Move MTS packages or COM+ applications between computers" Make a remote transactional object available to a local clientFor more details on these tools, see the appropriate Administrator s Guide fromMicrosoft.Cr eat i ng MTS or COM+ obj ect s 38-2538-26 Dev el oper  s Gui deP a r tVPart VCreating custom componentsThe chapters in  Creating custom components present concepts necessary fordesigning and implementing custom components in C++Builder.'Cr eat i ng cus t om component sCh a p t e r39Chapter39Overview of component creationThis chapter provides an overview of component design and the process of writingcomponents for C++Builder applications.The material here assumes that you arefamiliar with C++Builder and its standard components." Visual Component Library" Components and classes" How do you create components?" What goes into a component?" Creating a new component" Testing uninstalled components" Testing installed components" Installing a component on the Component paletteFor information on installing new components, see  Installing component packageson page 10-5.Visual Component LibraryC++Builder s components are all part of a class hierarchy called the VisualComponent Library (VCL).Figure 39.1 shows the relationship of selected classes thatmake up the VCL.For a more detailed discussion of class hierarchies and theinheritance relationships among classes, see Chapter 40,  Object-orientedprogramming for component writers.The TComponent class is the shared ancestor of every component in the VCL.TComponent provides the minimal properties and events necessary for a componentto work in C++Builder.The various branches of the library provide other, morespecialized capabilities.Ov er v i ew of component c r eat i on 39-1Co mp o n e n t s a n d c l a s s e sFigure 39.1 Visual Component Library class hierarchyTObjectException TStream TPersistent TComObjectTGraphicObject TGraphic TComponent TCollection TStringsTApplication TDataSet TMenu TControl TCommonDialog TFieldTGraphicControl TWinControlTScrollingWinControl TCustomControlMost visual controlsTForminherit fromTCustomFormTWinControl.TActiveFormWhen you create a component, you add to the VCL by deriving a new class from oneof the existing class types in the hierarchy.Components and classesBecause components are classes, component writers work with objects at a differentlevel from application developers.Creating new components requires that youderive new classes.Briefly, there are two main differences between creating components and using themin applications [ Pobierz całość w formacie PDF ]