How to develop OPC Servers with .NET ?
||Advosol offers toolkits and components that support the development of OPC DA servers and XML DA web services. The application specific server part can be developed as a .Net assembly using Visual Basic .Net or C#. All COM Interop respecively web services handling is done in the generic server.
The same customization plug-in assembly can be used with the DANSrv OPC DA server and the XDARap and UDAWeb XML DA web services.
The same customization plug-in assembly can be used with the server running in 32-bit or 64-bit mode.
Access to a mix of OPC DA and XML DA servers is further supported by gateways. The characteristics of OPC DA / XML DA servers and gateways is outlined below:
Native COM respectively XML DA servers with the same customization plug-in
Having a native solution for either COM based OPC DA or web service based OPC DA or web service based XML DA simplifies usage and configuration and offers best performance. However only one type, either OPC DA or XML DA can be installed.
The COM server doesn't need any web service features and the XML DA server is a native web service, not using any COM features. The rather complex Windows security configuration is minimized and each server is performance optimized for it's environment.
With this approach a device cannot be accessed simultanously from OPC DA and XML DA clients. The servers use the same customization plug-in but they run either as a COM server or as a web service and cannot access the same customization instance. Each server runs it's own customization plug-in instance and for some devices it may not be possible to run multiple instances at the same time.
The UDAWeb Universal Data Access web service combines toolkit and gateway features and supports simultanous access to multiple OPC DA and XML DA servers.
Server with gateway or wrapper
The device can be accessed simultanously from OPC DA and XML DA clients.
Only one customization plug-in instance is running for device access and OPC DA and XML DA clients can simultanously access the device.
Best performance is typically achieved by running an OPC DA server and supporting XML DA access through a gateway (wrapper). If remote access is required then the better solution is to have an XML DA server and a gateway at the remote OPC DA client location.
The gateways require no programming and only a simple configuration.