NxTera with PowerBuilder

How to connect the database using Middleware NxTera in Pow开发者_Python百科erBuilder?

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.

In NXTera (as in Entera), you connect to the database with a data access server. A data access server is one three types of servers that can be created in NXTera: functionality, data access and transaction server. A data access server provides access to the database via RPC by transforming the SQL into RPC calls within the data access server. Data access servers come in 7 flavors: ora_start (Oracle), syb_start (Sybase), db2_start (DB2), ifx_start (Informix), eda_start (EDA), ing_start (Ingres) and mysql_start (MySQL). An eighth db_start is generic for Windows: cli_start (SQLserver, et al.) You would not be required to use the DataWindow since you are calling an RPC directly from the PB client. This solution maintains the separation of Presentation layer logic from Business logic from database logic.