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ASP.NET PDF Viewer using C#, VB/NETddlListA.Attributes.Add("onchange", "populateListB();"); The other part of the static page you need to modify is the script code in the head of the page. The JavaScript function can stay as is. You ll need to generate the data structures that precede this function in the HTML. You ll dynamically generate this in the code-behind, and then use a PlaceHolder to inject it into the output stream. Here s the entire server-side block of markup for the head element: <head runat="server"> <title>Pool Halls</title> <asp:PlaceHolder Runat=server ID=plScript /> <script language=javascript> function populateListB() { itemarray = listsB[document.all.ddlListA.selectedIndex]; valuearray = valuesB[document.all.ddlListA.selectedIndex]; ctlListB = document.all.ddlListB; for (i=ctlListB.options.length; i>0; i--) {ctlListB.options[i] = null;} for (i=0; i<itemarray.length; i++) {ctlListB.options[i] = new Option(itemarray[i],valuearray[i]);} } </script> </head> Notice that your PlaceHolder is declared outside of the client-side script block. An element declared with the runat=server attribute within a client-side script block will not be recognized during server-side page processing. Not only is it unavailable during server-side processing, but it also will get left in the script block, causing a JavaScript error on the client. For this reason, when you generate JavaScript on the server, you ll wrap it in your own script element and inject the entire block into the output using your PlaceHolder. You ll bind your lists to XML. The cities will be bound to a simple list: <Cities> <City>New York</City> <City>Los Angeles</City> <City>Chicago</City> <City>Houston</City> <City>Philadelphia</City> <City>Minneapolis</City> </Cities> excel 2010 free barcode font, barcode fonts for excel 2007, how to make barcodes in excel 2003, generate barcode in excel 2003, free barcode software for excel, excel formula barcode check digit, free barcode addin for excel 2013, barcode generator for excel 2010, barcode macro excel, download barcode macro for excel,I discuss this alternative mainly to explain why the proxy authentication feature was invented in the first place. In this approach, the application presents to the database the actual end user s password. This works fine for client/server applications that need to support a small number of dedicated connections for a relatively small user-community. In the context of a three-tier web application, however, this approach has the following drawbacks: Most application servers today have built-in authentication mechanisms, such as the use of a central directory service for storing user credentials, which obviate the need for applications to know or use the database password of the end user account. It is not uncommon for the same user to access different applications running on the application server. If each application has a different database account for the user, the user would have to sign on separately whenever he wants to switch to a new application. The single sign-on feature available in most application servers today is designed to solve this problem. Using single sign-on, the user authenticates once to the application server and is able to access multiple applications hosted on the application server without logging into each one of them separately. Figure 15-3 illustrates this concept. Applying the .NET Design Guidelines to F# Figure 15-3. A user accesses multiple applications but authenticates (or signs on) only once to the application server using the single sign-on feature. Security is undermined if the application stores the end user s password. For example, if the application code has the password, then it is trivial to extract the passwords in many cases (e.g., using the strings utility found in most UNIX operating system variants). Every time there is a change in a user s password in the database, all applications that access the username and password have to be modified as well, leading to maintenance problems. The second list will be bound by client-side script. The XML structure you ll use to generate this client-side script code contains simple pool hall name and address information: <PoolHall> <Name>Amsterdam Billiard Club</Name> <Address>210 E 86th St</Address> <City>New York</City> <State>NY</State> <Phone>212-570-4545</Phone> <id>1</id> </PoolHall> You ll bind the list and generate the code by trapping the page s Load event. First you pop open the XML doc and bind the list of cities: DataSet ds = new DataSet(); ds.ReadXml(Server.MapPath("PoolHalls.xml")); ddlListA.DataTextField = "City_text"; ddlListA.DataSource = ds.Tables[1]; ddlListA.DataBind(); Next comes the dynamic generation of the client script code. Specifically, you re generating the arrays that are used from within the populateListB method. The client-side script needs to look like this: listsB = new Array; valuesB = new Array; listsB[0] = new Array; listsB[0][0] = "A J Billiard Parlor"; listsB[0][1] = "Campus Room"; listsB[0][2] = "Champion Billiards"; valuesB[0] = new Array; valuesB[0][0] = "33"; valuesB[0][1] = "34"; valuesB[0][2] = "35"; listsB[1] = new Array; listsB[1][0] = "Amsterdam Billiard Club"; listsB[1][1] = "Bernardos Billar and Cafeteria"; listsB[1][2] = "Billiard Club"; listsB[1][3] = "Broadway Billiard Cafe"; valuesB[1] = new Array; valuesB[1][0] = "0"; valuesB[1][1] = "1";
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