Click here to close now.

Welcome!

Microsoft Cloud Authors: Liz McMillan, Elizabeth White, Pat Romanski, Jaynesh Shah, Carmen Gonzalez

Related Topics: Microsoft Cloud

Microsoft Cloud: Article

Master Pages in ASP.NET 2.0

Simplify reuse and maintenance

Since the advent of Web development, Web developers have sought a way to provide a consistent look and feel across the Web application. This pursuit has resulted in different custom solutions. With the introduction of master pages in ASP.NET 2.0, Microsoft has finally brought the support to the framework level and has given the developers what they have been asking for. Master pages, as the name suggests, allow the developer to define the layout in a single page and easily apply the layout to multiple pages across the Web site, thereby ensuring a consistent appearance. This article looks at how we use master pages with the help of some examples. We will also look at some of the new features that are available in ASP.NET 2.0.

Master Pages
Master pages allow the developer to take a compartmentalized approach while developing Web sites. It allows the developer to move standardized layouts like header, footer, navigation, or any other content that is common over multiple pages to the master page. Content that is specific to a particular page can be defined in content pages that we will see in the next section. Master pages are transparent to the users and when a request is made to the URL of the content page, ASP.NET merges the content of the content page with that of the master page and renders the resulting page. Unlike ordinary ASPX pages, a Web server does not serve a master page and if a user makes a request to the master page, the server returns an error message (see Figure 1).

Master pages are like any other ASP.NET pages with a couple of exceptions. They are identified by a .master file extension. Listing 1 (the code is online at www.sys-con.com/dotnet/source.cfm) is an example of a simple master page. Note that instead of the familiar page directive <%@Page%> in a normal ASPX page, the master page has a <%@Master %> directive. Master pages define ContentPlaceholder controls that act as placeholders where content from the content page will be inserted. ContentPlaceholder control is specific to master pages and cannot be declared in a content page. In this example we have defined one ContentPlaceholder control identified as ContentPlaceholder1. A master page can define zero to any number of ContentPlaceholder controls.

Content Pages
The content page is the actual page that a user will request from the server. Content pages are like typical ASPX pages and have a .ASPX extension. However, they differ from an ordinary ASPX page in two ways. The first difference is that a content page has to be associated with a master page, which is done by setting the MasterPageFile attribute in the page directive. Second, all of the content in a Web page must be defined inside a new content control. Any content that is defined outside the content control results in an error. The content control in turn has to be mapped to the Contentplaceholder controls that have been defined in the Master page. Listing 2 shows a content page that refers to Sample.master as its master page. In this example the content page defines a content control called Content1. This content control in turn is mapped to the ContentPlaceholder ContentPlaceHolder1 of the master page by setting the ContentPlaceHolderID.

Sequence of Events
Just like regular ASPX pages, master pages and content pages have events that are fired during the page life cycle. They can also have user controls that need to be initialized. The list below shows the sequence of events in a content page that references a master page.

  1. Controls in the master page are initialized
  2. Controls in the content page are initialized
  3. Master page is initialized
  4. Content page is initialized
  5. Content page loads
  6. Master page loads
  7. Master page controls load
  8. Content page controls load
Creating a Master Page and a Content Page
Now that we have seen what a master page and a content page are, let's see how to create a master and content page using Visual Studio .NET 2005 Beta. Visual Studio allows us to add master pages by choosing an item of type Master Page in the Add New Item option. It also gives us the option to have a code behind page associated with the master page and also select the language of the page. In Figure 2, I add a master page called MyMaster1.master using the Add New Item dialog.

To the master page that I just created, I have added an image, footer, and two content placeholders. Each of the ContentPlaceholder controls that has been added has a unique ID which will be referred to by the content page to insert its content. Listing 3 shows the markup and Figure 3 shows the design view of the master page that I have created. Any content page that uses this master page will automatically inherit the image, the heading, and the footer.

Now that we have created the master page, let's go ahead and create a content page using the Add New Item option in Visual Studio .NET 2005 Beta (see Figure 4). A content page is just an ordinary Web form and Visual Studio .NET 2005 Beta does not have a special type called content page. When we create the content page, the Add New Item dialog, however, gives us the option to select the master page that will be referenced by the Web form. Once we select this option, Visual Studio presents us with a dialog box that lists all the master pages in the Web site (see Figure 5). Figure 6 shows the design view of the content page that we have just created. You will notice that all the master page content is grayed out and cannot be edited. Listing 4 shows the markup of the content page we just created. The only editable portion in the content page is between the <asp:Content> tags. Each of these content tags is linked to ContentPlaceholder of the master page by setting the ContentPlaceHolderID for the content control. In Listing 4, Content1 is mapped to ContentPlaceholder1 of the master page and Content2 is mapped to ContentPlaceholder2 of the master page. Content control in turn can contain other controls. In this example I have added some text in each of the content tags. Figure 7 shows the browser rendering of the content page.

Nesting Master Pages
Master pages can be nested and can have one master page refer to another as its master. Nested master pages are very useful while designing Web sites with different sections where each individual section has to have its own layout and at the same time be consistent with the overall appearance of the Web site. For example, in a corporate Web site we could have a master page that could define the global menu and a master page for each department that would define the departmental menu. Nesting the department master page and the corporate master page would allow us to combine the two menus. Visual Studio .NET 2005 Beta, however, does not provide designer support for nested master pages.

Let's look at how to create a nested master page with the help of an example. Listing 5 shows the parent master page, ParentMaster.master. This parent master page is then referred to by the child master page (see Listing 6). As you can see, the child master page is not very different from the parent master page. They have the same .master extension; however, the child master page has a content control that is mapped to the ContentPlaceHolder control defined in the parent master page. The child master page can also define ContentPlaceHolder controls of its own to display content of the content page that refers to this page as its master. The child master page in our example defines a content control that is mapped to ContentPlaceHolder1 of the master page. It defines a Contentplaceholder control of its own ChildContentPlaceHolder1 to which the content page will map its content. Listing 7 is the content page that refers to the child master page as its master page. Figure 8 shows the rendering of the content page that uses nested master pages.

Configuring a Site to Use Master Pages
Instead of giving the master attribute in the page directive of each and every page in a Website, ASP.NET 2.0 gives you the option to set the master page in the Web.config file. This is very useful in large Web sites as it gives the developers the flexibility to make the change at one place and apply it across the site. The code snippet below shows how to set the master page in the web.config file:

<system.web>
<pages masterPageFile="MyMaster1.master" />
</system.web>

A couple of things need to be pointed out about setting master pages through the web.config file. First, if the content page has a master page explicitly set in its page directive, that master page assumes precedence over the one set in the web.config file. If there are multiple master page settings in different web.config files, the master page setting in the immediate folder overrides the other setting similar to how in an application with multiple sub- folders, the setting of the web config in the immediate folder takes precedence over the others.

Accessing Master Page Controls from Content Pages
The developer may need to access the controls in the master page for many reasons. One could be to display a value that is relevant to the content page. ASP.NET 2.0 gives you multiple options to achieve this. The first step is to get a reference to the master page. In a content page, the Master property returns the reference to the master page. Once we have obtained the reference to the master page, it is now possible to refer to the controls of the master page. We will look at two approaches. The first approach is early binding, where the control is declared as a public property in the master page. Listing 8 shows the master page where we first expose the text of control Label2 as a public property LabelText. We then access and set the value of LabelText in the page load event of the content page as shown in Listing 9. Another thing to point out is the strong typed reference to the Master page using the <%@masterType%> directive in the Content page. This explicitly casts the value of the master property to the master page object which in our case is AccessMasterProperties.

The second approach is the late binding approach. Here we make use of the familiar FindControl method. We get a reference to a label control in the master page and change the text value from the content page. We search for the label by its ID which in this case is Label1 and then cast it to a label control and set the value for the text.

Dynamically Changing Master Pages
ASP.NET 2.0 allows the developer to change the master page associated with a content page dynamically at run-time. This is very useful if the developer would like to give the users the flexibility of choosing the master pages. The master page for a content page can be set programmatically by assigning a value to the MasterPagefile property of the page. However, this dynamic assignment can be done only in the preinit event of the content page since this is the earliest event that occurs in the page execution life cycle. If we attempt to set the master page file in events like pageload, it would result in an exception. Listing 10 shows an example where we have a dropdown list with the available master pages. On clicking the button we redirect the response to the same page and pass the value of the master page to be set as a request string. The MasterPagefile is then set in the preinit event.

Device-Specific Master Pages
ASP.NET 2.0 pages and controls have built-in support that enables them to automatically render appropriate content depending on the browser and the device that has requested the page. Master pages also support similar behavior. We can create a master page specifically for a device or a browser and in the content page instead of binding to a single master page. We can bind them to number of master pages, each of them specific to a particular device. The binding is qualified with the device name. Listing 11 shows a content page that is bound to two master pages, one for Internet explorer and another for mozilla. The Internet Explorer master page is prefixed with ie and the one for Mozilla is prefixed with Mozilla. These browser prefixes are defined in the browsercaps section of the machine.config file. Depending upon the browser requesting the page, the content page is bound to the appropriate master page. Figures 9 and 10 show the rendering of the content page when it is requested through the two different browsers, Mozilla and Internet Explorer. As you see, ASP.NET 2.0 has automatically chosen the appropriate master page.

Conclusion
In this article we looked at the concept of master pages and saw how they allow the developer to easily create reusable page layouts. It also greatly simplifies maintenance as it is now possible to make changes at one place and propagate them throughout the Web site. I am sure that this feature will have a significant impact on how ASP.NET applications are built in the future.

More Stories By Jeevan Murkoth

Jeevan Murkoth is a Microsoft Certified Solutions Developer (MCSD) in .NET (Early Achiever) and a Microsoft Certified Application Developer (MCAD) in .NET. He currently consults for Tennessee Valley Authority and lives in Chattanooga, TN. He has an MS in Management Information Systems from Texas Tech University.

Comments (1) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
Mujtaba Syed 12/14/04 03:48:48 PM EST

Nice article.

@ThingsExpo Stories
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile devices as well as laptops and desktops using a visual drag-and-drop application – and eForms-buildi...
While great strides have been made relative to the video aspects of remote collaboration, audio technology has basically stagnated. Typically all audio is mixed to a single monaural stream and emanates from a single point, such as a speakerphone or a speaker associated with a video monitor. This leads to confusion and lack of understanding among participants especially regarding who is actually speaking. Spatial teleconferencing introduces the concept of acoustic spatial separation between conference participants in three dimensional space. This has been shown to significantly improve comprehe...
There will be 150 billion connected devices by 2020. New digital businesses have already disrupted value chains across every industry. APIs are at the center of the digital business. You need to understand what assets you have that can be exposed digitally, what their digital value chain is, and how to create an effective business model around that value chain to compete in this economy. No enterprise can be complacent and not engage in the digital economy. Learn how to be the disruptor and not the disruptee.
The enterprise market will drive IoT device adoption over the next five years. In his session at @ThingsExpo, John Greenough, an analyst at BI Intelligence, division of Business Insider, will analyze how companies will adopt IoT products and the associated cost of adopting those products. John Greenough is the lead analyst covering the Internet of Things for BI Intelligence- Business Insider’s paid research service. Numerous IoT companies have cited his analysis of the IoT. Prior to joining BI Intelligence, he worked analyzing bank technology for Corporate Insight and The Clearing House Pay...
SYS-CON Events announced today that MetraTech, now part of Ericsson, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Ericsson is the driving force behind the Networked Society- a world leader in communications infrastructure, software and services. Some 40% of the world’s mobile traffic runs through networks Ericsson has supplied, serving more than 2.5 billion subscribers.
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal an...
The Domain Name Service (DNS) is one of the most important components in networking infrastructure, enabling users and services to access applications by translating URLs (names) into IP addresses (numbers). Because every icon and URL and all embedded content on a website requires a DNS lookup loading complex sites necessitates hundreds of DNS queries. In addition, as more internet-enabled ‘Things' get connected, people will rely on DNS to name and find their fridges, toasters and toilets. According to a recent IDG Research Services Survey this rate of traffic will only grow. What's driving t...
The Internet of Things promises to transform businesses (and lives), but navigating the business and technical path to success can be difficult to understand. In his session at @ThingsExpo, Sean Lorenz, Technical Product Manager for Xively at LogMeIn, demonstrated how to approach creating broadly successful connected customer solutions using real world business transformation studies including New England BioLabs and more.
The world is at a tipping point where the technology, the device and global adoption are converging to such a point that we will see an explosion of a world where smartphone devices not only allow us to talk to each other, but allow for communication between everything – serving as a central hub from which we control our world – MediaTek is at the heart of both driving this and allowing the markets to drive this reality forward themselves. The next wave of consumer gadgets is here – smart, connected, and small. If your ambitions are big, so are ours. In his session at @ThingsExpo, Jack Hu, D...
17th Cloud Expo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterprises are using some form of XaaS – software, platform, and infrastructure as a service.
The recent trends like cloud computing, social, mobile and Internet of Things are forcing enterprises to modernize in order to compete in the competitive globalized markets. However, enterprises are approaching newer technologies with a more silo-ed way, gaining only sub optimal benefits. The Modern Enterprise model is presented as a newer way to think of enterprise IT, which takes a more holistic approach to embracing modern technologies.
The true value of the Internet of Things (IoT) lies not just in the data, but through the services that protect the data, perform the analysis and present findings in a usable way. With many IoT elements rooted in traditional IT components, Big Data and IoT isn’t just a play for enterprise. In fact, the IoT presents SMBs with the prospect of launching entirely new activities and exploring innovative areas. CompTIA research identifies several areas where IoT is expected to have the greatest impact.
There's no doubt that the Internet of Things is driving the next wave of innovation. Google has spent billions over the past few months vacuuming up companies that specialize in smart appliances and machine learning. Already, Philips light bulbs, Audi automobiles, and Samsung washers and dryers can communicate with and be controlled from mobile devices. To take advantage of the opportunities the Internet of Things brings to your business, you'll want to start preparing now.
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at @ThingsExpo, Robin Raymond, Chief Architect at Hookflash, will walk through the shifting landscape of traditional telephone and voice services ...
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Architect for the Internet of Things and Intelligent Systems at Red Hat, described how to revolutioniz...
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, and physical persons. In the IoT vision, every new "thing" - sensor, actuator, data source, data con...
All major researchers estimate there will be tens of billions devices - computers, smartphones, tablets, and sensors - connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades. With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo, June 9-11, 2015, at the Javits Center in New York City. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be
The 4th International Internet of @ThingsExpo, co-located with the 17th International Cloud Expo - to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA - announces that its Call for Papers is open. The Internet of Things (IoT) is the biggest idea since the creation of the Worldwide Web more than 20 years ago.
SYS-CON Events announced today that O'Reilly Media has been named “Media Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York City, NY. O'Reilly Media spreads the knowledge of innovators through its books, online services, magazines, and conferences. Since 1978, O'Reilly Media has been a chronicler and catalyst of cutting-edge development, homing in on the technology trends that really matter and spurring their adoption by amplifying "faint signals" from the alpha geeks who are creating the future. An active participa...
We’re entering a new era of computing technology that many are calling the Internet of Things (IoT). Machine to machine, machine to infrastructure, machine to environment, the Internet of Everything, the Internet of Intelligent Things, intelligent systems – call it what you want, but it’s happening, and its potential is huge. IoT is comprised of smart machines interacting and communicating with other machines, objects, environments and infrastructures. As a result, huge volumes of data are being generated, and that data is being processed into useful actions that can “command and control” thi...