Professional ASP.NET 3.5 in C# and Visual Basic Part 91 pps

Evjen c17.tex V2 - 01/28/2008 2:58pm Page 857 Chapter 17: Portal Frameworks and Web Parts < form id="form1" runat="server" > < div > < asp:WebPartManager ID="WebPartManager1" runat="server" > < StaticConnections > < asp:WebPartConnection ID="WebPartConnection1" ConsumerID="ModifyableCalendar1" ConsumerConnectionPointID="CalendarTitleConsumer" ProviderID="TextBoxChanger1" ProviderConnectionPointID="TextBoxStringProvider" > < /asp:WebPartConnection > < /StaticConnections > < /asp:WebPartManager > < table cellpadding="3" > < tr valign="top" > < td style="width: 100px" > < asp:WebPartZone ID="WebPartZone1" runat="server" > < ZoneTemplate > < connectionControls:TextBoxChanger ID="TextBoxChanger1" runat="server" Title="Provider Web Part" / > < /ZoneTemplate > < /asp:WebPartZone > < /td > < td style="width: 100px" > < asp:WebPartZone ID="WebPartZone2" runat="server" > < ZoneTemplate > < connectionControls:ModifyableCalendar ID="ModifyableCalendar1" runat="server" Title="Consumer Web Part" / > < /ZoneTemplate > < /asp:WebPartZone > < /td > < /tr > < /table > < /div > < /form > < /body > < /html > This ASP.NET page that utilizes Web Parts contains a single two-cell table. Each cell in the table contains a single WebPartZone control — WebPartZone1 and WebPartZone2 . Before connecting the Web Parts, the new custom Web Part controls are registered in the ASP.NET page using the @Register page directive. This directive simply points to the namespace Wrox.Connection- Management . This is the namespace used by the interface and the two custom Web Part controls. Each of the custom Web Parts is placed within its own WebPartZone control. The two Web Part controls are tied together using the WebPartManager control. < asp:WebPartManager ID="WebPartManager1" runat="server" > < StaticConnections > < asp:WebPartConnection ID="WebPartConnection1" ConsumerID="ModifyableCalendar1" 857 Evjen c17.tex V2 - 01/28/2008 2:58pm Page 858 Chapter 17: Portal Frameworks and Web Parts ConsumerConnectionPointID="CalendarTitleConsumer" ProviderID="TextBoxChanger1" ProviderConnectionPointID="TextBoxStringProvider" > < /asp:WebPartConnection > < /StaticConnections > < /asp:WebPartManager > The WebPartManager server control nests the defined connection inside of the < StaticConnections > section of the declaration. The definition is actually accomplished using the WebPartConnection server control. This control takes four important attributes required in order to make the necessary connections. The first set of two attributes deals with definitions of the consumer settings. Of these, the ConsumerID attribute references the name of the control on the ASP.NET page (through its ID attribute) and the ConsumerConnectionPointID references the ID of the object working as the connection point for the consumer. Looking back, you find this is the RetrieveTitle() method shown in the following code snippet: < ConnectionConsumer("Calendar Title Consumer", "CalendarTitleConsumer") > _ Public Sub RetrieveTitle(ByVal Provider As IStringForCalendar) _myProvider = Provider End Sub The second set of attributes required by the WebPartConnection deals with the provider Web Part. The first attribute of this set is the ProviderID attribute that makes reference to the name of the control on the ASP.NET page, which is considered the provider. The second attribute, ProviderConnectionPointID is quite similar to the ConsumerConnectionPointID attribute, but the ProviderConnectionPointID attribute references the ID of the object working as the provider in the connection process. < ConnectionProvider("Provider for String From TextBox", "TextBoxStringProvider") > _ Public Function TextBoxStringProvider() As IStringForCalendar Return Me End Function Running this page gives you the results illustrated in Figure 17-25. If you type any text string in the text box in the provider Web Part on the page and click the button within this control, the Calendar control uses this String value as its value for the Caption property. This is demonstrated in Figure 17-26. As you can see from this example, you take a lot of steps to take to make this happen, but the steps aren’t too difficult. In this example, a simple String object was passed from one Web Part to another. You could, however, use the exact same process to pass more complex objects (even custom objects) or larger items such a DataSet object. Understanding the Difficulties in Dealing with Master Pages When Connecting Web Parts You should note one final consideration about dealing with connecting Web Parts on your ASP.NET pages. You might have already realized that this process gets rather difficult when you are working with ASP.NET pages that make use of the master page capability provided by ASP.NET. 858 Evjen c17.tex V2 - 01/28/2008 2:58pm Page 859 Chapter 17: Portal Frameworks and Web Parts Figure 17-25 Figure 17-26 You are allowed only a single WebPartManager control on an ASP.NET page. Many times, when you are working with master pages, it makes a lot of sense to put this control in the master page itself rather than in the content pages that make use of the master page. If you are taking this approach, it does not make much sense to start using WebPartConnection controls within the master page. You can easily have controls with the same ID on multiple content pages. If you do so, the references made within the WebPartConnection control might not be meant for these other controls. For this reason, you need to make use of the ProxyWebPartManager control. 859 Evjen c17.tex V2 - 01/28/2008 2:58pm Page 860 Chapter 17: Portal Frameworks and Web Parts Suppose you have a master page with a WebPartManger control. In this case, the WebPartManager control can be rather simple, as shown here: < asp:WebPartManager ID="WebPartManager1" runat="server" > < /asp:WebPartManager > With this WebPartManager control on your .master page, you ensure this single instance manages the Web Parts contained in each and every content page making use of this particular master page. Next, if a content page making use of this master page is attempting to connect some Web Parts, you must place a ProxyWebPartManger control on the content page itself. This instance of the ProxyWeb- PartManager is where you define the connections for the Web Parts on this particular content page. This is illustrated in the following code snippet: < asp:ProxyWebPartManager ID="ProxyWebPartManager1" runat="server" > < StaticConnections > < asp:WebPartConnection ID="WebPartConnection1" ConsumerID="ModifyableCalendar1" ConsumerConnectionPointID="CalendarTitleConsumer" ProviderID="TextBoxChanger1" ProviderConnectionPointID="TextBoxStringProvider" > < /asp:WebPartConnection > < /StaticConnections > < /asp:ProxyWebPartManager > Summary This chapter introduced you to the WebPartManager, WebPartZone, and the WebPart controls. Not only do these controls allow for easy customization of the look-and-feel of either the Web Parts or the zones in which they are located, but also the framework provided can be used to completely modify the behavior of these items. This chapter also showed you how to create your own custom Web Part controls. Creating your own controls was always one of the benefits provided by ASP.NET, and this benefit has been taken one step further with the capability to now create Web Part controls. Web Part controls enable you to take advan- tage of some of the more complex features that you do not get with custom ASP.NET server controls. You may find the Portal Framework to be one of the more exciting features of ASP.NET 3.5; you may like the idea of creating completely modular and customizable Web pages. End users like this feature, and it is quite easy for developers to implement. Just remember that you do not have to implement every feature explained in this chapter; with the framework provided, however, you can choose the functionality that you want. 860 Evjen c18.tex V2 - 01/28/2008 3:01pm Page 861 HTML and CSS Design with ASP.NET When HTML was first introduced by Tim Berners-Lee, it was intended to be a simple way for researchers using the Internet to format and cross-link their research documents. At the time, the Web was still primarily text-based; therefore, the formatting requirements for these documents were fairly basic. HTML needed only a small handful of basic layout concepts such as a title, paragraph, headers, and lists. As the Web was opened up to the general public, graphical browsers were introduced, and as requirements for formatting Web pages continued to expand, newer ver- sions of HTML were introduced. These newer versions expanded the original capabilities of HTML to accommodate the new, rich graphical browser environment, allowing table layouts, richer font styling, images, and frames. While all of these improvements to HTML were helpful, HTML still proved to be inadequate for allowing developers to create complex, highly stylized Web pages. Therefore, in 1994 a new tech- nology called Cascading Style Sheets was introduced. CSS served as a complementary technology to HTML, giving developers o f Web pages the power they needed to finely control the style of their Web pages. As the Web has matured, CSS has gained popularity as developers realized that it has significant advantages over standard HTML styling capabilities. Unlike HTML, which was originally con- ceived as primarily a layout mechanism, CSS was conceived from the beginning to provide rich styling capabilities to Web pages. The cascading nature of CSS makes it easy to apply styles with a broad stroke to an entire application, and only where necessary override those styles. CSS makes is easy to externally define Web site style information, allowing for a clear separation of Web page style and structure. CSS also allows developers to greatly reduce the file size of a Web page, which translates into faster page load times and reduced bandwidth consumption. While the point of this chapter is not to convince you that CSS is the best solution for styling your Web site, it will help you understand how you can leverage these technologies in your ASP.NET- based Web applications. It will start with a brief overview of CSS and how it works with HTML, and then move into creating Web s ites in Visual Studio using HTML and CSS. Finally, you look at how you can use ASP.NET and CSS together. Evjen c18.tex V2 - 01/28/2008 3:01pm Page 862 Chapter 18: HTML and CSS Design with ASP.NET Caveats While this chapter includes a lot of great information about HTML and CSS, and how you can use them in conjunction with ASP.NET and Visual Studio 2008, there are several caveats you should be aware of. First, because there is no way that a single chapter can begin to cover the entire breadth of HTML and CSS, if you are looking for an in-depth discussion of these topics, you can check out the Wrox title Beginning CSS: Cascading Style Sheets for Web Design, 2nd Edition, by Richard York (Wiley Publishing, Inc., 2007). Second, because CSS is simply a specification, it is up to each browser vendor to actually interpret and implement that specification. As is so often the case in Web development, each browser has its own quirks in how it implements (or sometimes does not implement) different CSS features. While the samples in this chapter were tested on Internet Explorer 7, you should make sure to thoroughly test your Web sites in multiple browsers on multiple platforms in order to ensure that your CSS is rendering appropriately in each browser you are targeting. Finally, the DOCTYPE you use in your Web pages can influence how the browser applies the CSS styles includes in your Web page. You should understand how different DOCTYPES influence the browser’s rendering process in your Web page. HTML and CSS Overview From the beginning of the Web, continuing to today, HTML serves as the primary mechanism for defin- ing the content blocks of your Web page, and is the easiest way to define the layout of your Web page. HTML includes a variety of layout tags you can use, including Table, List, and Grouping elements. You can combine these elements to create highly complex layouts in your Web page. Figure 18-1 illustrates a single Web page that defines a basic layout using a variety of HTML elements. While this layout is interesting, it lacks all but the most basic styling. To solve this problem, many devel- opers would be tempted to start adding HTML-based formatting tags. For example, if I wanted to change the font and color of the text in the first paragraph, I might change its HTML to something like this: <font face="Arial" Color="Maroon"> In fact, in the early days of Web design tools, this is what most of them generated when the user added styling to their Web pages, and for a while, using Font tags looks like a great solution to the problem of styling your Web pages. Web developers and designers quickly learned, however, that using the Font tag quickly leads to a mess of spaghetti HTML, with font tags being splattered throughout the HTML. Imagine that if, in the previous example, you not only wanted to set the control and color, but some of the work needed to be bold, others needed to be a different color or font face, some a different font size, some underlined, and some displayed as superscript. Imagine how many font tags you would need then and how it would increase the weight of the Web page and decrease its maintainability. Using Font tags (and other style-related tags) meant that there was no longer a clear and clean separation between the structure and content of the Web page, but instead both were mashed together into a single complex document. 862 Evjen c18.tex V2 - 01/28/2008 3:01pm Page 863 Chapter 18: HTML and CSS Design with ASP.NET Figure 18-1 Introducing CSS The introduction of CSS to the Web development and design world brought it back to a clean and elegant solution for styling Web pages. CSS meant a style could be defined in a single location for the entire Web site, and simply referenced on the elements requiring the style. Using CSS brought back the logic separation between Web page content and the styles used to display it. Creating Style Sheets Like HTML, CSS is an interpreted language. When a Web page request is processed by a Web server, the server’s response can include style sheets, which are simply collections of CSS instructions. The style sheets can be included in the servers’ response in three different ways: through external style sheet files, internal style sheets embedded directly in the Web page, or inline styles sheets. External Style Sheets External Style Sheets are collections of CSS styles stored outside of the Web pages that will use t hem — generally files using the .css extension. Visual Studio makes it simple to add external style sheet files to your application by including a Style Sheet file template in the Add New Item dialog box, as shown in Figure 18-2. 863 Evjen c18.tex V2 - 01/28/2008 3:01pm Page 864 Chapter 18: HTML and CSS Design with ASP.NET Figure 18-2 Once the Style Sheet is created by Visual Studio, it’s easy to insert new styles. Visual Studio even gives you CSS IntelliSense when working with styles in the document, as shown in Figure 18-3. Figure 18-3 External style sheets are linked into Web pages using the HTML < link > tag. A single Web page can contain multiple style sheet references, as shown in Listing 18-1. 864 Evjen c18.tex V2 - 01/28/2008 3:01pm Page 865 Chapter 18: HTML and CSS Design with ASP.NET Listing 18-1: Using external style sheets in a Web page <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>CSS Inheritance Sample</title> <link href="SampleStyles.css" rel="stylesheet" type="text/css" /> </head> <body> <form id="form1" runat="server"> <div>Lorum Ipsum</div> </form> </body> </html> You can add multiple link tags to a single Web page in order to link several different style sheets into the page. You can also use the CSS import statement directly in your style sheet to actually link multiple style sheets together. @import url("layout.css"); Using the import statement has t he advantage that you can alter the style sheets linked together without having to modify every Web page in your site. Instead, you can simply link each page to a master external style sheet, which in turn will use the import statement to link in other external style sheets. Note that older browsers may not understand this syntax and will simply ignore the command. Using external style sheets in your Web site offers several advantages. First, because external style sheets are kept outside of the Web pages in your site, it is easier to add a link tag to all of your Web pages rather than trying to manage the styles directly in each page. This also makes maintenance easier because, should you decide to update the style of your Web site in the future, you have a single location in which styles are kept. Finally, using external style sheets can also help the performance of your Web site by allowing the browser to take advantage of its caching capabilities. Like other files downloaded by the browser, the style sheets will be cached on the client once they have been downloaded. Internal Style Sheets Internal style sheets are collections of CSS styles that are stored internally in a single Web page. The styles are located inside of the HTML < style > tag, which is generally located in the < head > section of the Web page. An example of internal style sheets is shown in Listing 18-2. Listing 18-2: Using internal style sheets in a Web page <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>CSS Inheritance Sample</title> <style type="text/css"> Continued 865 Evjen c18.tex V2 - 01/28/2008 3:01pm Page 866 Chapter 18: HTML and CSS Design with ASP.NET div { font-family:Arial; } </style> </head> <body> <form id="form1" runat="server"> <div>Lorum Ipsum</div> </form> </body> </html> It is important when you create internal style sheets that when you create style blocks, you make sure to include the type attribute with the style tag so the b rowser knows how to properly interpret the block. Additionally, as with external style sheets, Visual Studio also gives you IntelliSense support to make it easy for you to add properties. Inline Styles Inline styles are CSS styles that are applied directly to an individual HTML element using t he element’s Style attribute which is available on most HTML elements. An example of inline styles is shown in Listing 18-3. Listing 18-3: Using inline styles in a Web page <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>CSS Inheritance Sample</title> </head> <body> <form id="form1" runat="server"> <div style="font-family:Arial;">Lorum Ipsum</div> </form> </body> </html> CSS Rules Regardless of how they are stored, once CSS styles are sent f rom the server to the client, the browser is responsible for parsing the styles and applying them to the appropriate HTML elements in the Web page. If a style is stored in either an external or internal style sheet, the styles will be defined as a CSS rule. Rules are what the browser uses to determine what styling to apply, and to what HTML elements it should. Inline styles do not need to be defined as a rule because they are automatically applied to the element they are included with. Therefore, the browser does not need to select the elements to apply it to. 866 . cell in the table contains a single WebPartZone control — WebPartZone1 and WebPartZone2 . Before connecting the Web Parts, the new custom Web Part controls are registered in the ASP. NET page using. technologies in your ASP. NET- based Web applications. It will start with a brief overview of CSS and how it works with HTML, and then move into creating Web s ites in Visual Studio using HTML and CSS. Finally,. HTML element using t he element’s Style attribute which is available on most HTML elements. An example of inline styles is shown in Listing 18 -3. Listing 18 -3: Using inline styles in a Web page <!DOCTYPE