OPOS and Microsoft .NET

An Microsoft .NET application wishing to utilize retail devices has at least two available approaches.

OPOS via COM Interop

Microsoft .NET's COM interoperability support allows straightforward integration of the OPOS Common Control Objects into .NET applications.  One can directly reference COM objects, and Visual Studio will build the required interoperability layer.

Alternatively, available below are OPOS CCO interoperability assemblies created by the Microsoft TLBIMP utility.  All use the "POS.Devices" namespace, and the class names are consistent with the CCO names.  Creating an instance of the class will instantiate the corresponding OPOS CCO, after which time one may call OPOS methods and properties, plus add handlers for events.

A typical .NET POS application will include the following in its software stack.  Ensure that all of these components are installed, plus registered and/or configured as needed:

• Application.
   
• OPOS for .NET Assembly.  The application references and creates an instance of the assembly's device class.  Creating this class causes an instance of the corresponding OPOS Common Control Object to be created.  Adding event handlers to this class will hook into the Control Object's events.
   
• OPOS Common Control Objects.  The Common Control Object lives for as long as the assembly's device class that created it.  (The registered CCO version must be greater or equal to the OPOS for .NET Assembly.)
   
• OPOS Service Object.  When the application calls the OPOS for .NET Assembly device class' Open(DeviceName) method, it calls the Control Object's Open method, which looks for the DeviceName in the registry to find and instantiate the appropriate Service Object.  (You can manually browse the registry beginning at the key HKLM\SOFTWARE\OLEforRetail\ServiceOPOS to find the valid device names.)
  
  The service object must be acquired from the hardware vendor, and must be installed and configured using instructions from the vendor.  Most vendor's configuration utilities offer a test option (which often run the OPOS CheckHealth API).  During setup, you should try it to make sure that the Service Object is set up and working with the hardware before adding the additional software layers.

The pre-built assemblies plus a sample application may be found below.

POS for .NET

Microsoft's Point of Service for .NET is currently at version 1.12.  Excerpting from its home documentation page, POS for .NET "is a class library that enables POS developers to apply Microsoft .NET technologies in their products. It provides a simple and consistent interface for.NET Framework applications to interact with POS devices, a set of interfaces and classes created to help Vendors write applications for common devices such as Cash Drawers or Line Displays, and support for Windows Plug and Play functionality."

To download, search this page for "POS for .NET".  The POS for .NET v1.12 download page states that its supported operating systems are "Windows Embedded for Point of Service; Windows Server 2003 Service Pack 1; Windows Vista Business; Windows Vista Enterprise; Windows XP Service Pack 2".

The UnifiedPOS specification contains an appendix that describes the POS for .NET relationship to UnifiedPOS.

OPOS Assemblies for .NET

The complete set of OPOS Assemblies are available in a ZIP file, or they may be installed via the CCO 1.13.001 Windows Installer file.  A simple test program is also available.

• OPOS for .NET Assemblies 1.13.000
  This ZIP file contains the following:
  • One assembly for each of the OPOS device types. As an example, the filename of the POSPrinter assembly is "POS.Devices.OPOSPOSPrinter.dll".  In addition, for compatibility with applications built against the 1.12.000 assemblies, a publisher policy assembly for each device type.
  • An assembly containing the OPOS constants.
  • A "readme" file.
  • Two batch files to assist developers in adding or removing the assemblies from the Global Assembly Cache (GAC), if desired.
• OPOS for .NET Assemblies 1.12.000
  This ZIP file contains the same set of files, but for UnifiedPOS 1.12.
• POSPrinter1 Application
  This ZIP file contains a C# test application project.  It was built against the 1.12.000 OPOS for .NET Assemblies.

A screenshot of the POSPrinter1 sample application follows, followed by the NCR Emulator Service Object which was used for this run. The following activities occur while running it:

• Application startup: Instantiate the OPOS POSPrinter assembly's class and wire the StatusUpdateEvents. Display the OPOS Common Control Object's ControlObjectDescription and ControlObjectVersion properties.
• Open: When this button is pressed, the application calls the Open and ClaimDevice methods, and sets the DeviceEnabled property. After opening the device, the application displays the ServiceObjectDescription and ServiceObjectVersion properties.
• Print: When this button is pressed, the application calls the PrintNormal method to print on the receipt station.
• On the emulator, update the Receipt Station's paper status to "Empty".  A StatusUpdate event is fired; value 24 = PTR_SUE_REC_EMPTY.
• Print when out-of-paper: The print fails with ResultCode 114 = OPOS_E_EXTENDED. (The ResultCodeExtended is not output by this program, but would be 203 = OPOS_EPTR_REC_EMPTY.)

The following screen shots are from Visual Studio 2008, with the POSPrinter1 solution loaded. The Solution Explorer shows the references, including references to the POSPrinter and OPOS Constants assemblies:

The Object Browser shows the classes and interfaces in the OPOSPOSPrinter assembly:

Last updated: 2010-06-26

Web Site navigation aids:  Table-of-Contents.  Search.

Send mail to webmaster@monroecs.com with questions or comments about this web site.
Copyright © 2009 Monroe Consulting Services, Inc.