Release 10.1A: OpenEdge Development:
Progress Dynamics Web Development Guide

> ## Client-side data management

> User interface data, application data, and messages are stored and managed on the client to minimize network traffic to the server.

> ##### UI data

> User interface data is stored with UI objects. For example, if a menu object contains multiple levels, the data for all levels is stored on the client. Therefore, when a user expands a menu selection, the response is immediate. The user does not have to wait for the event to be sent to a server for processing and updating.

> ##### Application data

> WebDataObjects (WDOs) are used on the client side for managing application data. WDOs are proxies for server-side SDOs and are written in JavaScript. They provide a performance advantage when data manipulation can be performed on the client. For example, after doing a query and receiving all the records in the Customer table, you might want to perform a sort based on balance due. Instead of requesting another query and sort from the server, you can do a local sort on the data that you already have on the client.

> WDOs use a WebBusinessObject (WBO) for communication with the server. There is only one WBO per page, but there can be many WDOs associated with it. Both the WBO and WDOs exist within the Hidden Frame of the default HTML layout page (`default.htm`). For more information about `default.htm`, see the "Default HTML file" section.

> ##### Messages

> An Info object is available to store and display messages. Messages are usually loaded immediately after login and can be displayed in a window area or in a pop-up. Therefore, a user error or some other condition can generate a local response rather than a network call to a Web server. Messages are displayed in the Message Frame of the default HTML layout page (`default.htm`). For more information about `default.htm`, see the "Default HTML file" section.

> Also see the "Information (info)" section.

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