How to connect the database using Middleware NxTera in PowerBuilder?
The whole point of middleware like NxTera is to not allow a client like PowerBuilder to connect directly to the database. Instead the client must call services (CORBA, SOAP, Java Web Services) offered by the middleware to obtain and manipulate data.
Starting with PB 11 Enterprise, the DataWindow can use a Web Service as a data source. In NxTera you would have SOAP web services to retrieve, and if desired to insert, delete, and update. You would create the DataWindow with a Web Service data source, and optionally specify the web services for Insert, Delete, and Update. See the PowerBuilder User's Guide for details. The chapters are "Defining DataWindow Objects" and "Controlling Updates in DataWindows".
Web Service Data Sources are only available in the Enterprise edition. If you're not using Enterprise, you would have to define proxies for the web services, call the web service to retrieve the data yourself, copy the data into the DataWindow, and handle Insert, Update, and Delete yourself. We retrieve data this way for some non-updatable DataWindows because the web service doesn't return data as an array of structures suitable for the DataWindow.