121. Explain the concept of states in ASP.NET.
State is quite an innovative concept in Web development because it eliminates the drawback of losing state data due to reloading of a Web page. By using states in a Web application, you can preserve the state of the application either at the server or client end. The state of a Web application helps you to store the runtime changes that have been made to the Web application. For example, as already described earlier, a change in the data source of the Web application might be initiated by a user when he/she selects and saves some products in the shopping cart.
If you are not using states, these changes are discarded and are not saved. You may think that the whole concept of storing states is optional. However, under certain circumstances, using states with applications is imperative. For example, it is necessary to store states for Web applications, such as an e-commerce shopping site or an Intranet site of a company, to keep track of the requests of the users for the items they have selected on the shopping site or the days requested for vacation on the Intranet site.
122. Can we validate a DropDownList by RequiredFieldValidator?
Yes, we can validate a DropDownList by RequiredFieldValidator. To perform this validation, we have to set the InitialValue property of RequiredFieldValidator control.
123. List the features of the Chart control.
The following are the features of the Chart control:
- Bounds a chart with any data source.
- Simple manipulation of chart data, such as copying, merging, grouping, sorting, searching, and filtering.
- Support many statistical and financial formulas for data analysis.
- Provide advanced chart outlook, such as 2-D, 3-D, lighting, and perspective.
- Support events and customizations.
- Includes interactivity with Microsoft AJAX.
- Supports AJAX Content Delivery Network (CDN).