Specifications

Extensibility 3-19

3-19

variable with the widget.

Each DefaultView form must have a unique name. The object’s

default property view must be called DefaultView as it is the

property view HYSYS attempts to open when the object is

instantiated, provided the functionality of the OnView method is

not overridden.

Implement the Required Methods

To implement an extension in C# or VB.NET, you must first

create a Class Library project. In the project, you must then add

a reference to the HYSYS Interoperability Library

(Aspentech.HYSYS.Interop.dll) which can be found in the root

directory of the install location for Aspen HYSYS.

Next, you must create a class that implements the required

interfaces. For example, an Extension Unit Operation must

implement the ExtensionObject interface and the

ExtensionUnitOperation interface.

The class should have the appropriate attributes from the

System.Runtime.InteropServices namespace required to

export a class to COM. These include but are not limited to

ComVisible, ClassInterface, GuidAttribute, and

ProgIdAttribute. ComVisible must be set to true;

ClassInterface is recommend to be set to AutoDispatch which

is the default; GuidAttribute represents the CLSID and will be

generated if not specified (its highly recommended that you

specify this manually); ProgIdAttribute is optional unless you

refer to this class using the ProgID in the Extension Definition.

You can register extensions on the Extensions tab of the Session

Preferences property view or using the regextn.exe command-

line executable.

A widget is an equivalent term for a control.

For more information on

extension registration

see Section 3.6 -

Registering

Extensions.