Using a Web service data source

You can use a Web service as the data source for a DataWindow having any of the following DataWindow presentation styles:

Support for a Web service data source is not available for RichText and OLE presentation styles, and it is only available in the Enterprise edition of PowerBuilder.

After you select a supported DataWindow presentation style from the DataWindow tab of the New dialog box, you select a data source for the DataWindow.

When you select Web Service as the data source and click Next, the DataWindow wizard opens a page that prompts you to select a WSDL file. The file you select should be in a publicly accessible location for all members of the development team. You can enter the URL to a WSDL, ASMX, or XML file, or you can browse a mapped drive for these types of files.

The Choose WSDL File page of the DataWindow wizard also lets you name the assembly file that the wizard will create. The assembly file serves as an interface between the DataWindow and the Web service. If you do not name the assembly file, the wizard will select a name for you based on the name of the WSDL file entry.

The next step to access a Web service data source is to select a service described in the WSDL, and then one of its public methods. You must then select a parameter for the DataWindow to use as the result set for the method.

A DataWindow typically obtains its data from an array of structures. Because a Web service method can pass an array of structures in one of its arguments rather than in a return value, the wizard prompts you to select one of the method’s arguments or its return value as the designated result set for the method. If you want data for a single row and column only, you can select a parameter that has a simple datatype. You can also select a parameter that is an array of simple datatypes rather than an array of structures.

You complete the wizard as you would when using any other type of data source for your DataWindow. After you complete the wizard, the DataWindow displays in the DataWindow painter. However, there is no equivalent to the SQL painter for a DataWindow with a Web service data source. For this type of DataWindow, you cannot select Design>Data Source from the DataWindow painter menu to change selected columns or modify the DataWindow syntax.

The DataWindow can also use a Web service data source that has structures for parameters, as long as the structures are composed of the simple datatypes that can be mapped to DataWindow datatypes. An array of structures can be mapped to n rows with x columns where n is the size of the array and x is the number of members in the structure. Nested structures are not supported.

For a Web service that you create from a PowerBuilder nonvisual object, a result set must be passed by reference, but it cannot be passed in a method return value. You must use a method argument to pass the result set and then select that argument in any DataWindow object that uses the method as its data source.

A parameter passed by reference is a bidirectional [IN,OUT] parameter by definition. The Web Service DataWindow wizard lets you select a Web service method [OUT] or [IN,OUT] parameter, instead of the method return value, to pass a result set to a DataWindow object. However, the parameter you select cannot be used for both a return value and a retrieval argument by the same DataWindow object.

In the Web Service DataWindow, some database or transaction-related functions and events are not supported and meaningless because the Web Service DataWindow has no direct relation to the database. The following functions cannot be used with the Web Service DataWindow: GetSQLPreview, GetSQLSelect, SetSQLPreview, SetSQLSelect, SetTrans, and SetTransObject.

The DBError event is also not supported for the Web Service DataWindow. Instead, you can use the WSError error event to handle errors during retrieve, insert, or update operations.

Some Web services support or require a user ID and password, and other session-related properties like firewall settings. The WSConnection object can provide this information for your DataWindow connections.

You use an instance of the WSConnection object to connect to a Web service by calling the SetWSObject method.

The following code instantiates a WSConnection object with user-related and authentication information, then sets the object as the connection object for a Web service data source:

int ii_return

wsconnection ws_1

ws_1 = create wsconnection

ws_1.username = "johndoe"

ws_1.password = "mypassword"

ws_1.endpoint = "myendpoint"

ws_1.authenticationmode = "basic"

ws_1.usewindowsintegratedauthentication = true

ii_return = dw_1.setwsobject (ws_1)

For more information about setting properties for a Web service connection, see WSConnection and SetWSObject in the online Help.