ASP.NET Web Parts Overview
ASP.NET Web Parts is an integrated set of controls for creating Web sites that enable end users to modify the content, appearance, and behavior of Web pages directly from a browser. The modifications can be applied to all users on the site or to individual users. When users modify pages and controls, the settings can be saved to retain a user's personal preferences across future browser sessions, a feature called personalization. These Web Parts capabilities mean that developers can empower end users to personalize a Web application dynamically, without developer or administrator intervention.
Using the Web Parts control set, you as a developer can enable end users to:
Personalize page content. Users can add new Web Parts controls to a page, remove them, hide them, or minimize them like ordinary windows.
Personalize page layout. Users can drag a Web Parts control to a different zone on a page, or change its appearance, properties, and behavior.
Export and import controls. Users can import or export Web Parts control settings for use in other pages or sites, retaining the properties, appearance, and even the data in the controls. This reduces data entry and configuration demands on end users.
Create connections. Users can establish connections between controls so that, for example, a chart control could display a graph for the data in a stock ticker control. Users could personalize not only the connection itself, but the appearance and details of how the chart control displays the data.
Manage and personalize site-level settings. Authorized users can configure site-level settings, determine who can access a site or page, set role-based access to controls, and so on. For example, a user in an administrative role could set a Web Parts control to be shared by all users, and prevent users who are not administrators from personalizing the shared control.
The Web Parts control set consists of three main building blocks: personalization, user interface (UI) structural components, and actual Web Parts UI controls. For more details, see Web Parts Control Set Overview. Much of your development effort will focus on Web Parts controls, which are simply ASP.NET controls that can use the features of the Web Parts control set.
As an example of how Web Parts controls can be used to build personalizable Web pages, examine the following screen shot.
This page contains several basic elements of a Web Parts application:
Use of zones for page layout. There are two columns that can contain controls: one has the Weather and Stock Quotes controls, the other has Hotmail and News controls. These columns in Web Parts terminology are called zones--regions on a page that contain Web Parts controls. Zones exist to lay out Web Parts controls on a page, and to provide a common UI for the controls. There can be one or many zones on a page, each zone can contain one or many Web Parts controls, and each zone can have a vertical or horizontal orientation for page layout.
Web Parts controls within the zones. Each control has UI verbs (actions that a user can perform) that can appear as links, buttons, or clickable images on the control. In the preceding screen shot, notice that each control has a button in its title bar that exposes a drop-down menu. In the menus for each control are options to change details particular to that control, and other options to carry out common actions such as moving or deleting a control, and getting help. Some controls, such as the Weather control, allow users to personalize them so the controls display only information relevant to the user.
Links to enable extensive personalization. These allow users to change the content, color, and layout of the page. For instance, if users click the Add Column link, a Web Parts application could enable them to add another column to a page. Or users could click the Add Content link, which displays a catalog of controls that that they can optionally add to the page. One of those could be a stock charting control. A user could add that control to one of the zones on the page, and could then connect it to the existing Stock Quotes control to chart the stock data it contains.
You will typically work with Web Parts in one of three ways: creating pages that use Web Parts controls, creating individual Web Parts controls, or creating complete, personalizable Web applications, such as a portal.
Page developers can use visual design tools such as Microsoft Visual Studio 2005 to create pages that use Web Parts. One advantage in using a tool such as Visual Studio is that the Web Parts control set provides features for drag-and-drop creation and configuration of Web Parts controls in a visual designer. For example, you can use the designer to drag a Web Parts zone, or a Web Parts editor control, onto the design surface, and then configure the control right in the designer using the UI provided by the Web Parts control set. This can speed development of Web Parts applications and reduce the amount of code you have to write.
You can use any existing ASP.NET control as a Web Parts control, including standard Web server controls, custom server controls, and user controls. For maximum programmatic control of your environment, you can also create custom Web Parts controls that derive from the WebPart class. For individual Web Parts control development, you will typically either create a user control and use it as a Web Parts control, or develop a custom Web Parts control.
As an example of developing a custom Web Parts control, you could create a control to provide any of the features provided by other ASP.NET server controls that might be useful to package as a personalizable Web Parts control: calendars, lists, financial information, news, calculators, rich text controls for updating content, editable grids that connect to databases, charts that dynamically update their displays, or weather and travel information. If you provide a visual designer with your control, then any page developer using Visual Studio can simply drag your control into a Web Parts zone and configure it at design time without having to write additional code.
Web Application Development
Developing fully integrated and personalizable Web applications--such as a portal-- involves the most comprehensive use of Web Parts. You can develop a Web site that allows extensive user personalization of the UI and content--with features similar to MSN. Or you can even develop a packaged application that can be shipped and used by companies or fee-based ISPs that provide portal hosting services.
In a Web application scenario, you could offer a complete solution for end users to manage and personalize the application. This could include a set of Web Parts controls that provide the desired features for the site, a consistent set of themes and styles that allow end users to personalize the UI in a consistent way, catalogs of Web Parts controls from which users can select the ones they want to appear on a page, authentication services, and role-based management (for example, allowing administrative users to personalize Web Parts controls and site settings for all users).
For each part of your application, you can extend the Web Parts control set as needed to provide greater control over the environment. For example, besides authoring custom Web Parts controls for the primary UI of your pages, you might also want to develop a custom Web Parts catalog that is consistent with the look and feel of your application, and gives users more flexibility to choose how controls are added to a page. Or you could extend a zone control to provide additional UI options for the Web Parts controls it contains. You could also write a custom personalization provider to give more flexibility and control over how the personalization data is stored and managed.