If you are using EAServer as the component server, you can deploy a custom component that uses methods of the generic server component interface. You can also write a server component with its own DataWindow methods for use with EAServer or COM+.
You can use a custom component to enhance:
Maintainability Keep connection information on the server by specifying values for transaction properties.
Performance Specify the source file and DataWindow object on the server so that the DataWindow object is loaded when the component instance is created, resulting in fewer method calls from server-side scripts in the Web page. You can also improve performance by having your custom component maintain its state.
For information about changing the state property of a custom component, see “Maintaining state on the server”.
Scalability Specify the source file and DataWindow object and use EAServer instance pooling so that the component is reused and loading the DataWindow object occurs only once.
Contention between the DataWindow painter and EAServer
If you are working in the DataWindow painter and testing the
same PBL in EAServer, your PBL
might be locked when the EAServer component
loads the DataWindow. To avoid this, disable instance pooling for
the component in EAServer Manager.
After you have finished testing and editing the DataWindow object,
you can enable instance pooling.
Instance pooling provides better performance in a production environment when a component instance can be reinitialized and reused for multiple clients.
For information on creating a custom component that uses the generic Web DataWindow interface, see “Creating a custom server component in EAServer” or “Deploying DataWindow objects to the component server”.
For full control of Web generation and the state of the DataStore object that holds the DataWindow definition and data, you can write your own custom class user object in PowerBuilder and deploy it as an EAServer or COM component. Using a custom component that includes only the processing you need can reduce the size of the client control returned to the Web client.
The source code for the generic component is available in PBDWRMT.PBL in the PowerBuilder code examples directory so that you can examine or reuse it. You can modify or add to the code in this PBL or start from scratch, using the sample PBL as a model for your own component.
Mixed-case method names
The methods of the generic EAServer component
use mixed-case names and all the examples in this section use mixed
case. If you write your own server component, the methods of the EAServer component you generate
are all lowercase. However, you can change the case of the method
names in the IDL file for your component after it is deployed to EAServer. When you use your own
component, you must generate and compile stubs for the component,
and you must do this after you make any changes to the IDL.
Your server component will use methods on a DataStore object to retrieve data and return the data and state to the client as HTML. To get the HTML and JavaScript that represents the state, data, and presentation of the DataWindow object, use the Describe method:
ls_html = ds_1.Describe("DataWindow.Data.HTML");
To update the HTML according to user actions, use the SetHTMLAction method:
li_rtn = ds_1.SetHTMLAction(arg_action, arg_context);
SetHTMLAction restores the state of the DataStore based on the context passed in as an argument and then changes the state based on the passed action.
For more information about SetHTMLAction, see the DataWindow Reference or online Help. For information about working with DataStore objects, see Chapter 4, “Using DataStore Objects”.
If you create your own server component and deploy it to EAServer, you must also generate and compile the stubs. For information on generating and compiling stubs, see the EAServer documentation.
