VBScript Reference Manual for InduSoft Web Studio

VBScript Reference Manual InduSoft Web Studio
Access of an object’s methods, properties and fields are made by referring to the object,
followed by a period, then the particular method, property or field of interest. E.g.
Object.Method
Object.Property
Object.Property.Item
• Dynamism
Dynamism relates to the method of allocating computer resources and definition resources
required to run an object-oriented program. There are different types, but VBScript used latebound
(late-binding) dynamic typing. This means that the VBScript engine will make the object
type determination at runtime and allocate sufficient memory at that time. Note that VBScript
and VB.NET are slightly different in their approach to dynamism, and therefore they can declare
some variables and objects in different manners (although many forms of declaration are the
same).
• Outlet Connections
At times, Objects will connect together and this connection needs to be defined. With IWS, an
example of a connection would be between a VBScript object (e.g. ADODB) and a Database
Provider (a Provider is a front-end to a database). This connection needs to be defined, and
then the connection string (of parameters) between the objects gets defined. When the need for
the connection is finished, the connection should be closed.
While a full treatment of object-oriented programming is beyond the scope of these materials, the
fundamental concepts of Objects and Classes are important to understand. VBScript supports COMbased
Objects (Component Object Module, a Microsoft standard) such as the ActiveX controls,
ADO.NET, FileSystemObject, and Microsoft Office Automation objects. VBScript also supports userdefined
classes, or Class Objects.
VBScript COM objects and VBScript Class objects differ from each other in several important respects.
These differences lead to each type of object having its unique strengths:
• VBScript classes are more flexible than VBScript COM objects. Class Objects have an abstract
subtype that encapsulates the data you want and the functions you need to work with that data.
VBScript COM objects have only basic subtypes (integer or string).
• VBScript classes are slightly more efficient than COM objects. The VBScript parser can execute
the classes' code directly instead of asking the COM object to execute a method.
• COM objects are binary modules. VBScript classes are ASCII files.
• You can use any scripting language to write COM objects. You can only use VBScript to write
VBScript classes.
• You can use COM objects from within any development environment that supports COM
automation. VBScript classes can only be used within development and runtime environments
that support VBScript (e.g IWS and Microsoft Internet Explorer).
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