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Data Management and Exchange 787
Technologies for communication
trol is usually defined as a stand-alone object that doesn’t necessarily have an application behind it. For purposes of this manual, the words “object” or “embedded object” applies to either a component object or an ActiveX control.
A component object is an identifiable part of a larger program that provides a particular func- tion or group of related functions; it is roughly equivalent to a Java applet. ActiveX controls can be created using one of several languages or development tools, or with scripting tools. In implementation, an ActiveX control is a dynamic link library (DLL) module. It runs in what is known as a container, an application program that uses COM program interfaces.
OLE (Object Linking and Embedding) is Microsoft’s framework for a compound document technology for combining text, sound, animations, controls and so forth into a document. Each object is an independent program component that can interact with the user and communicate with other objects.
Whereas OLE provides services for the compound document that users see on their display; COM provides the underlying services of interface negotiation, life cycle management (deter- mining when an object can be removed from the system), licensing, and event services (putting an object into service as the result of an event that has happened to another object.)
ExtendSim supports embedding of COM/OLE objects and ActiveX controls in two places in the application:
• At the worksheet/model level, where they can be included as a container object and be manipulated much like blocks and other types of worksheet objects.
• Attheblockdialoglevel,wheretheycanbeinsertedintoaspecialtypeofdialogitemcalled an embedded object.
The Gantt Chart (Plotter library) uses an embedded ActiveX control. The Read and Write blocks (Value library) uses OLE/COM to communicate with other applications. ExtendSim also has many OLE/COM functions to facilitate ActiveX controls and COM objects.
☞ ExtendSim can be a container for objects embedded using the Insert Object menu command or through ModL programming. It also has ModL functions to support its use as either an OLE automation client or server.
ADO (Windows only)
ActiveX Data Objects (ADO) is a method for exchanging information with various databases on Windows-based computers. ADO sends an entire table of information at one time, provid- ing high-speed data interchange. The ExtendSim ADO interface allows you to communicate with Access, SQL Server, and MySQL.
The interface is implemented as a Component Object Mode (COM) DLL. A set of ModL func- tions for accessing the DLL can be found in the ADO DBFunctions include file. These func- tions bundle a set of COM calls that perform specific ADO actions such as creating a table or transferring data. The Structured Query Language (SQL) is used to manipulate and select the data in the ADO database. SQL commands can be sent to the external database through the ADO interface.
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