Page 288 - Open Soource Technologies 304.indd

Event Driven Programming

Data Middle Tier Client
Form
ActiveX.exe
.DLL Remoting Data DHTML
Source Report
Microsoft Visual Microsoft DCOM, Remotable Code
Database Tools Transaction ADO Recordsets
(Data View) Server Remoting UDTs
Data Access Data
ADO*, RDO, DAD Binding
Class Module
Data Environment
Creatable Recordsets
ADO Data Control
Intrinsic Data Control

Figure 13.2: Microsoft Visual Data Tools.
13.2.1 Middle Tier Components and Microsoft Transaction Server

The power of Visual Basic is also leveraged to create the middle tier components in your
application, as you make your own ActiveX DLLs and EXEs. Visual Basic now includes
enhancements that tailor applications to work with Microsoft Transaction Server.

13.3 ActiveX Data Objects (ADO)

The bridge between the data providers and data consumers is through data sources created
using Microsoft ActiveX Data Objects (ADO), which is the primary method in Visual Basic to
access data in any data source, both relational and non-relational. For backward compatibility
and project maintenance, Remote Data Objects (RDO) and Data Access Objects (DAO) are still
supported.

13.4 Data Sources and Data Controls

A graphical designer that allows you to quickly create ADO Connections and Commands to
access your data. The Data Environment designer provides a dynamic programmatic interface to
the data access objects in your project. In addition, the Data Environment provides advanced data
shaping services—the ability to create hierarchies of related data, aggregates, and automatic
groupings, all without code.
The new ADO Data control is similar to the intrinsic data control and Remote Data control, except
that it uses ADO to access data. You can now use an ADO Recordset as a data source for your
controls and objects in Visual Basic.

In Visual Basic you can now create your own data sources either as user
controls or classes, to encapsulate business rules or proprietary data structures.
The class module now features the DataSourceBehavior property and the
GetDataMember event, which allow you to configure a class as a data source.

282 LOVELY PROFESSIONAL UNIVERSITY