An Add-in is a small component that enhances capability of application. It requires minimal memory resource and is used to perform specific task. Add-in is programmed for a specific larger application, and it acts as a child program after its installation.

For example, Excel, SQL (Store Procedure), and XML are the add-ins for Drone Designer.
There are two types of Add-in according to its scope:
1. Local Add-in
The scope of local add-in is limited to a particular scene/template.For example, Excel, SQL, XML, Clock and user defined variables (Integer, String, Float, etc.)
Entry in hostedaddin.xml:
<addin
dll = "BeeSys.Wasp3D.Designer.<AddIn>.dll"
alias = "<AddInClass>"
addin = "Beesys.Wasp.AddIn.<AddInHostClass>"
class = "Beesys.Wasp.AddIn.<AddInClass>"
</addin>
2. Global Add-in
The scope of global add-in is set at engine level, and it is available to all scenes/templates.
For example, Server Variable.
Entry in hostedaddin.xml:
<addin
dll = "BeeSys.Wasp3D.Designer.<AddIn>.dll"
alias = "<AddInClass>"
addin = "Beesys.Wasp.AddIn.<AddInHostClass>"
class = "Beesys.Wasp.AddIn.<AddInClass>"
global="1">
</addin>
Note:
a. Following is the path for hostedaddin.xml:
C:\Program Files\Beehive Systems Ltd\Wasp'3D\2011\Common\HostedAssemblies
b. To make an entry for global add-in, mention global="1" attribute in “addin” node in hostedaddin.xml.

Dll Requirements:
BeeSys.Wasp3D.Hosting.Interface dll from GAC
BeeSys.Wasp3D.HostingHelper dll from GAC
GFXWrpSceneGraph dll from GAC

Class Creation :
1) To create a addin, user has to create two major class:
AddInHostClass.cs
This class has to implement the followiing Interfaces and Class:
a) IWaspAddIn
b) IWaspHostWrapper
c) MarshalByRefObject

AddInClass.cs
This class has to implement the followiing interfaces:
a) IWaspAddIn
b) MarshalByRefObject
c) IWrpSceneGraph

2) User can create DataSet, DataTable and Variable type AddIn :
To Create DataSet type AddIn, user also has to implement the IWaspDataSet interface in AddInClass.cs
To Create DataTable type AddIn, user also has to implement the IWaspData interface in AddInClass.cs
To Create Variable type AddIn, user also has to implement the ISGVarService interface in AddInClass.cs

IWaspHostWrapper is used to get the 'IWaspHost' instance, which provide the services to get data from Designer like NameCreationService,ButtonCreationService etc.By NameCreationService user can provide the object name of addin and by the ButtonCreationService user can create a button at Local or Server variable pool for the object creation of Addin.

MarshalByRefObject enables access to objects across application domain boundaries in application that support remoting.

IWaspAddIn is used to create AddIn.

IWrpSceneGraph is used to get the current 'CSceneGraph' and 'CPlayoutEngine' instance for local addin and only 'CPlayoutEngine' instance for global addin.

'AddInHostClass.cs' provide the instance of class 'AddInClass.cs', which implement the AddIns Operation