by Anthony J. Taylor
As the face of business continually changes, organizations are attempting to respond to the new technology transitions as cost-effectively as possible while maintaining their present software solutions. Many are focusing their approach to making their information interactive and are concentrating on creating or improving web-based applications as the solution for the distribution of critical corporate information.
The current trend in distributing corporate information is the increase of web-based applications as corporate intranets. Dynamic web sites are truly distributed applications and have the following benefits, which companies are beginning to realize: content-centric design, low bandwidth access, ease of distribution, low maintenance cost, and cross-platform applications.
This chapter explores web-based applications and issues related to their development. It then discusses the use of Active Server Pages and the technologies behind them. Finally, it explains how these technologies fit into the Microsoft InterDev environment and how this new Integrated Development Environment (IDE) will enable successful creation of web-based applications.
The use of web browsers has evolved dramatically in the web-based environment. Now web browsers are used not only to access the static data housed on a web server, but also to change web content interactively. Before the development of recent technologies, the flow of data was from the server to the client only. Now, however, the application client and application server have a bidirectional flow of control (see Figure 11.1).
FIG. 11.1
The bidirectional flow of control in the web-based environment is possible because
an operation is defined in a library class but implemented in a subclass in the application.
There are many benefits now that the web browser can be used as a client framework. Some benefits of a client framework include
Many companies have eagerly modified their existing applications to achieve these benefits. Web users no longer are disappointed to find stale information; they can view custom web content that responds interactively to their responses, whether they click the mouse or press a key.
As web browsers have evolved for usability as a client framework, other progressions have also occurred. The following sections briefly discuss the changes pertaining to application architecture and the transitions web developers must make.
As the application development environment evolves, the architecture needed for the new development arena has also progressed. Figures 11.2, 11.3, and 11.4 illustrate the evolution of the application architecture.
FIG. 11.2
The traditional client/server development platform was only a two-tiered environment
structure.
FIG. 11.3
Multiple user interfaces, security for business processes, and distributed processing
are a few of the many advantages to multiple-tier architecture.
Web files can not only communicate on a local network, but also can be transferred via a global network to a web browser, making management of server-side scripts and component files more difficult. Although browser-based applications appear to be the solution to client-centric information, this new environment has its pros and cons, especially with the "standards wars" taking place.
Of the many proprietary web browsers, Microsoft Internet Explorer and Netscape Navigator are the current leaders. Many Application Programming Interfaces (APIs) also are on the market today--Microsoft ISAPI, Netscape NSAPI, WebSite WSAPI, and WebSTAR W*API, just to name a few. With so many vendor products in the marketplace, delivering universally readable HTML pages with features becomes difficult.
FIG. 11.4
The web development environment uses a complex assortment of hardware.
NOTE: Despite the push for the convergence of web-based technology standards, we're beginning to see exactly the opposite. For example, Dynamic HTML standards have diverged between Microsoft and Netscape.
How can you resolve the problem, for example, of having a video file on an HTML page whose full-motion features many browsers can't view? Do you force one browser to be the standard by which every component is compatible, or do you create alternative images and file types for every web browser ever used to view a web page? These and other issues must be addressed when determining global standards for HTML, Java, Cascading Style Sheets (features and options to specify style, color, and font for HTML development), and other web-based technologies.
As a web-based application programmer, you face many issues. This paradigm is different. The new browser-based environment uses the connectionless Hypertext Transfer Protocol (HTTP), which makes maintaining state a challenge.
State is the capability to retain information. To assist with state, cookies offer some help but aren't the end-all solution. A cookie is a token file sent to a client browser but not stored on the client computer's hard disk; instead, it resides on the server. Some browsers don't support cookies, so objects that use cookie files must be supported for the browser as well.
Control logic might begin to make sense to you, but you should approach known event-driven functions differently from in the traditional client/server development arena. You also use different tools, which are sometimes more primitive in the web environment than in traditional programming environments.
Controls might be needed to perform services for web users. When developing web-based applications, you must answer these questions before using controls within your applications:
Suppose that you want to test a web page before deployment. How would you ensure quality when the audience (possibly the global marketplace) could be using any of a variety of technology architectures? It's impossible to benchmark applications with an almost infinite amount of connectivity combinations possible.
It's clearly evident that today you must stay abreast of the web-based application environment and the technologies used. Change occurs continually, and smart programmers will be those who maintain a current knowledge of the skills necessary for web-based application development.
Hypertext Markup Language (HTML) is the method used to mark up or tag a document so that it can be distributed on the web. HTML that's not modified based on user input is referred to as static HTML.
Static HTML files that reside on the web are only as new as when the files were published. This method is fine for files that seldom change, such as annual tax statements or monthly sales reports; however, when new data is needed, the HTML files need to be published again so that web users can view the updated material. Listing 11.1 is an example of a simple HTML document.
NOTE: To create a simple HTML document, you can use your choice of many various text editors. For Listing 11.1, Microsoft Notepad was used.
<HTML> <HEAD> <TITLE>Accounting Software Support</TITLE> </HEAD> <BODY> <CENTER> <H1>Software Support Services</H1> <HR><H3>At Jones & Jones CPA, we provide quality installation, training, and customized reporting for the following accounting software packages:</H3> <BR><TABLE ALIGN=CENTER BORDER=0 WIDTH=70%><TR><TD> <A HREF="http://www.jones.com/default.htm"><IMG SRC="icon1.gif" ALT="Jones CPA Software" ALIGN="CENTER" HEIGHT=100 WIDTH=125 HSPACE=20 BORDER=0> <A HREF="http://www.cpasoft.com/index.html"><IMG SRC="icon2.gif" ALT="CPASoft Solutions" ALIGN="CENTER" HEIGHT=100 WIDTH=125 HSPACE=20 BORDER=0></TD></TR></TABLE> </CENTER> </BODY> </HTML>
ON THE WEB:For a listing of the available HTML tags, visit the World Wide Web Consortium site at http://www.w3.org or http://www.w3.org/markup/. The Microsoft Site Builder Workshop at http://www.microsoft.com/workshop/author/newhtml/default.htm might also be helpful.
As the demand for delivery of dynamic information on the web has increased, so has the technology used in web-based application development. Many web site developers are being approached to publish content on the web that can be created on demand to meet web users' expectations. Web users want content fresh, exciting, up-to-date, and tailored to their personal information needs. This new expectation requires a new web-development method--Dynamic HTML.
Microsoft Dynamic HTML is a feature of Internet Explorer 4.0 and was developed in collaboration with the World Wide Web Consortium (W3C). Figure 11.5 shows the anatomy of a web application with Dynamic HTML.
FIG. 11.5
Dynamic HTML gives users customized views of data from the database.
The old way--static HTML--is fine for data that changes as part of a regular business cycle, but today's web is extremely interactive and changes continually. To update web content as the data changes, you must use the new way--Dynamic HTML.
You can author truly dynamic web applications by using Dynamic HTML. You can change any text or graphic element on a web page without a return trip to the server by using Dynamic HTML--even if the web page has already been loaded. Web sites will be more inviting due to this flexibility.
Document Object Model (DOM) is the object model provided for HTML by Dynamic HTML. All elements in a web page are exposed as objects. You can change the look and feel of these objects at any time by modifying their attributes or applying methods. You can also state specifically how you want the positioning and style of page elements by using Cascading Style Sheets (CSS). You can use each x- and y-coordinates and z-order to position each element precisely.
CAUTION: If Dynamic HTML isn't used for a substantial change to web content, extremely slow performance will occur when an additional round-trip to the server is made to display the new text.
Download times with Dynamic HTML are actually shorter than with static HTML. You can even avoid trips to the server by using Dynamic HTML's data-binding feature. Dynamic HTML also gives you more efficiency with the use of animation and graphics. You can decide the allocation for bandwidth consumption between fetches, the consumption of bandwidth packaging, and the elements of design to optimize the users' experiences.
See Chapter 18, "Dynamic HTML," to learn more about Dynamic HTML.
Microsoft Internet Information Server (IIS) is designed to expand the I-net by providing a development platform where you can perform secure, high-speed information publishing. IIS is Microsoft's web server and a product of the Windows NT Server package. Active Server Pages (ASP) allows server-side scripting and the capability to add interactivity to the standard HTML file.
ASP files allow you to develop web-based applications in virtually any language. ASP also offers you an opportunity to create web solutions independent of the type of web browser used.
The mixture of IIS and ASP might be the solution you've searched for. For additional detailed information on the combination of these two technologies, see Chapter 13, "An Inside Look at Active Server Pages and Internet Information Server."
With ASP, you can execute scripts on the server side versus the client side, which allows the web server to do all the script's processing work. Because the script is generated on the server side, the usual worry of capabilities on the client-side server is now eliminated.
An ASP is basically a text file with an extension of .asp. When requested by a web browser, an ASP script instance is generated. The server then reads and executes the commands from top to bottom. The result of the browser request is personalized content, formatted on the server and then sent to the browser.
The primary benefits of ASP are as follows:
Figure 11.6 shows the anatomy and use of ASP in a web-based application environment. You can find more information on the use of ASP in Chapter 13.
As you see in Figure 11.6, ASP files are used to create dynamic content with Microsoft's COM platform. Third-party controls (or your own controls) can be used to extend the web-based application functionality. In Figure 11.6, when the client connects to a site containing an ASP file, the web server takes the web client request and dynamically interprets the Active Server Page objects and scripting into HTML, which is then presented to the client. The significance of the default.asp file is that it's the home web page for the web site being requested.
To create an ASP file, you first create a static HTML page. For example:
<HTML> <BODY BGCOLOR="#ffffff"> <H1>Hello!</H1> </BODY> </HTML>
Next, change the extension of the file from .htm to .asp, so the page will be recognized by the ASP engine on the server as a scripting page to be parsed. Then, add the ASP scripting as shown in boldface in the following listing. The variable =Now will display the current time in the output of the following example:
<HTML> <BODY BGCOLOR="#ffffff"> <H1>Hello!</H1> <H1>The Time is: <% =Now %> </H1> </BODY> </HTML>
FIG. 11.6
With Active Server Pages, companies can mix ActiveX scripting and ActiveX Server
Components for the creation of web-based applications.
Providing useful, organized information to web users can differentiate a company from its competitors. Information can be a powerful tool, and by allowing web access to important information and presenting it so that users can easily understand it, organizations can leverage this power. For example, companies that provide web users access to a database of parts, a sales catalog, or information on a legacy system will have a strong advantage over companies that don't.
Today's web users want access to all data, as well as the capability to combine different types of data. This is desirable, of course, but information systems department leaders want to meet this need without relocating the data from its original source.
IIS provides database connectivity by using ActiveX Data Objects (ADO), an ASP component. ADO provides access to any data source compatible with Open Database Connectivity (ODBC). Some popular databases include Microsoft Access and SQL Server, as well as Sybase, Informix, and Oracle. If you're already familiar with DAO/RDO, you'll find a short learning curve for ADO. Another benefit of ADO is the capability to use ADO with any development language (C/C++, Visual Basic, VBScript, Java, and more).
ADO provides high-level, language-neutral programming objects, and OLE DB (object linking and embedding database) is the component architecture that allows all types of data to be accessed with no need to relocate the data. OLE DB interfaces expose resident functionality and don't force data to be in a relational database format. Figure 11.7 shows the use of ADO and OLE DB interfaces.
FIG. 11.7
When you use a combination of ADO and OLE DB interfaces, data access can be simple
and functional.
Notice in Figure 11.7 that OLE DB offers a higher degree of functionality. Depending on the functionality desired, however, a combination of ADO and OLE DB might be suitable. An example of this would be the use of OLE DB to access nonrelational data, such as spreadsheets or electronic mail, and the use of ADO for accessing relational data, such as SQL Server. OLE DB is the cornerstone of Microsoft's Universal Data Access strategy.
ON THE WEB:For more information on database connectivity, the following URLs might be helpful:
- See http://www.microsoft.com/ado/ for information on ActiveX Data Objects.
- Visit http://www.microsoft.com/data/ to see what the industry is doing in the area of OLE DB. It's also possible to download the v1.1 SDK and register as an OLE DB Developer.
- For ODBC information, refer to http://www.microsoft.com/odbc/.
The Usenet newsgroups at microsoft.public.oledb and microsoft.public.odbc also might be beneficial.
Components, or objects, have altered the method of software development and use of systems forever. A business problem can be solved now by reusable software components. Any object can be modified without altering the other objects contained in a framework, or the interaction between them. Initial programming efforts remain intact and can be reused repeatedly in various ways.
Web components vary in their ease-of-use and application. Each has specific attributes for a particular function, and it's important to match the correct technology with the task needed.
It's not enough to have components themselves. They must exist in a distributed, open environment that permits their execution in a plug-and-play fashion--an environment that truly enables the reality of dynamic reengineering.
To insert a component into a standard HTML document, you use the <OBJECT> tag. Here is a brief example:
<OBJECT CLASSID="" DATA="" CODEBASE="" ID="" TYPE=""> <PARAM NAME=" " VALUE=" "> </OBJECT>
Companies are migrating to a component-based environment--not just for the sake of using new technology, but because they see component use and reuse as a solution to their critical business problems. Components are suited for the distributed systems environment because both the data and business logic are housed within objects, allowing them to be located anywhere within a distributed network.
When you're creating interactive web-based applications, many components are available to assist you. The following sections describe several of the available technologies.
ActiveX is a group of technologies provided by Microsoft that allows you to create active content for the World Wide Web. ActiveX makes interactive web creation faster and easier. Using ActiveX technology will make the Internet more productive and useful.
ActiveX is a product of the Microsoft object linking and embedding (OLE) technology. Some might wonder if ActiveX is a new name for OLE because they're both based on the Component Object Model (COM). Although they appear similar, they provide different services to web developers.
OLE refers only to the technology that allows users to build multiple documents through object linking and embedding. OLE is optimized for desktop application integration and end-user usability, whereas ActiveX is optimized for size and speed to allow controls to respond interactively to events by being embedded in a web-based architecture. All ActiveX and OLE technologies are built on the COM-provided foundation.
See Chapter 4, "Using Microsoft's Object Technologies," for more information on ActiveX technologies and COM.
COM is the method that allows two separate software application components to access each other's services. With COM, a software application component applies its functionality as one or more COM objects. Each COM object supports one to many interfaces, which in turn might support one to many methods.
The elements of ActiveX include client and server technologies, as follows:
| Control | Description |
| Animated | Uses the Microsoft Windows animation common control to display |
| Button | various frame sequences of an AVI, depending on the button state. |
| Chart | Enables drawing of various chart types with different styles. |
| Gradient | Shades the area with a range of colors, displaying a transition from onespecified color to another. |
| Label | Displays given text at any specified angle. It can also render the text alonguser-defined curves. |
| Marquee | Scrolls, slides, or bounces uniform resource locators (URLs) within a user-defined window. |
| Menu | Displays a menu button or a pull-down menu. This control acts like a tri-state button when no menu items are specified or displays a pull-down menu when one or more menu items are specified. It can also display a pop-up menu if the Pop-up method is used. |
| Pop-up Menu | Displays a pop-up menu whenever the Pop-up method is called and firesa click event when a menu item is selected. |
| Pop-upWindow | Displays specified HTML documents in a pop-up window. You can usethis control to provide ToolTips or previews of links. |
| Preloader | Downloads the specified URL and puts it in the cache. The control is invisible at runtime and starts downloading when enabled. |
| Stock Ticker | Continuously displays changing data. The control downloads the URLspecified at regular intervals and displays that data. The data can be in textor XRT format. |
| Timer | Invokes an event periodically. It's invisible at runtime. |
| View Tracker | Generates OnShow and OnHide events whenever the control falls withinor out of the viewable area. |
ON THE WEB:For information about additional ActiveX controls, visit www.microsoft.com/activex/gallery.
Microsoft Internet Explorer 3.0 and higher supports Java applets. Of the many variations of IDE tools for Java development, Visual Studio 97's Visual J++, Sun Microsystems' Java JDK, and Borland's Latte are a few of the development environments available on the web.
See Chapter 7, "Creating Components with Visual J++."
ON THE WEB:For more information on the Java development environments mentioned in this chapter, see these web sites:
- Borland Latte: http://www.borland.com/jbuilder/latte/
- Microsoft Visual J++: http://www.microsoft.com/visualJ/
- Sun's Java JDK: http://www.sun.com/software/Dev-progs/PR/JDK.html
A platform-specific program called a virtual machine executes an applet. The Microsoft Virtual Machine--available on 32-bit Windows, Macintosh, and Windows 3.1--has been highly acclaimed by the media and developers as the safest, fastest, most functional, and most reliable pure Java on the market.
Java also works with ActiveX, which opens up a vast number of combinations between the two technologies. By extending Java with ActiveX, you can create reusable components. Also thanks to ActiveX technology, you can enhance Java applets with multimedia effects, highly tune performance, and use a wide variety of objects, including ActiveX controls, ActiveX documents, and ActiveX scripting. You can use these applets as building blocks for web applications.
Java is an object-oriented language that you can integrate with the existing client/server infrastructure. Java is similar to the C++ programming language, except that it doesn't have pointers, contains a different method for garbage collection, and is extremely strict regarding its object orientation. Sun Microsystems developed Java to be independent of the platform being used.
When using Java class libraries, you can create specific use-class libraries or purchase commercially developed class libraries.
To call a Java applet, you use a simple HTML tag:
<APPLET CODE="Name.Class" HEIGHT=500 WIDTH=500> </APPLET>
TIP: Java applets from earlier alpha versions might not execute on newer Java-supporting web browsers. Check the HTML source code to determine whether the applet will execute. The older Java versions used the <APP> tag; newer versions use the <APPLET> tag.
Visual Basic, Scripting Edition (VBScript) is a fast, small, lightweight interpreted language used in web browsers and applications designed to work with ActiveX controls and other embedded objects in HTML documents. Although it's a direct subset of Microsoft Visual Basic, VBScript doesn't include the capability of directly accessing or performing file input/output (I/O) with the underlying operating system.
NOTE: Now, only Microsoft Internet Explorer fully supports VBScript.
ActiveX objects are crucial to productive VBScript coding. When VBScript authors use these controls, web applications provide a quality appearance to web users.
VBScript authors can dynamically manage the outcome of an ActiveX control placed directly on the web page. Code that responds to animate object events can now be created with VBScript.
VBScript procedures are coded either between the <HEAD> and </HEAD> tags or between the <BODY> and </BODY> tags. The code must always be wrapped in <SCRIPT> tags. To ensure that the browser correctly executes the code as VBScript and not another language, make sure that the LANGUAGE indicator is set to equal either VBScript or VBS.
The use of VBScript within an HTML document file is given in the following example, with the actual VBScript code in boldface:
<HTML> <HEAD> <TITLE></TITLE> <SCRIPT LANGUAGE = "VBScript"> <!-- VBScript code is inserted here --> </SCRIPT> </HEAD> <BODY> <SCRIPT LANGUAGE = "VBS"> <!-- VBScript code can also be inserted here. --> </SCRIPT> </BODY> </HTML>
TIP: When including your VBScript code within the <BODY> section, always embed the source with HTML comment tags (<!-- and -->) to ensure that the code is hidden from browsers that aren't compatible with VBScript.
ON THE WEB:For more information about VBScript, visit www.microsoft.com/vbscript.
Microsoft's JScript is a scripting language similar to VBScript in its use. Like VBScript, JScript is used to add interactivity and intelligence to web-based documents and doesn't produce standalone applets. Now, only Microsoft Internet Explorer fully supports JScript.
JScript resembles the programming language Java but has a few exceptions, as are obvious from the following comparisons:
| JScript is | Java is |
| An interpreted language | Compiled to bytecode before execution on client |
| Object-based, lacks classes and inheritance | Object-oriented, uses classes with inheritance |
| Embedded code in HTML | Applet codes separate from HTML |
| Loose typing with variable data types not declared | Strong typing with variable data declared |
| Object references checked at runtime | Object references must exist at compile time |
| Secure, can't write to hard disk | Secure, can't write to hard disk |
Because Internet Explorer programmers can code in JScript or VBScript, you must use the LANGUAGE parameter to specify which language is used. In the following example, HTML is extended to enable the dispatching of an event to a JScript user-defined function by the name of callthis():
<INPUT TYPE=BUTTON NAME=mybutton VALUE="Click on Me" onclick="callthis();"LANGUAGE="JavaScript">
Another alternative is to extend the <SCRIPT> tag itself, as in the following example:
<FORM>
...
<INPUT TYPE=BUTTON NAME=mybutton VALUE="Click on Me">
<SCRIPT FOR="mybutton" EVENT="onClick" LANGUAGE="JavaScript">
alert("Hello");
</SCRIPT>
...
</FORM>
With the addition of the FOR and EVENT attributes in the preceding example, Internet Explorer developers can bind a script to a defined object (here, the mybutton button), which is the source associated with an event (in this case, the onclick event). The result of the example would be an alert or pop-up window that displays the word Hello when users click the mybutton button.
ON THE WEB:For additional assistance with JScript, visit www.microsoft.com/jscript.
Although many server-based components have already been discussed in this chapter, two others are worth mentioning: Common Gateway Interface (CGI) and Internet Server Application Programming Interface (ISAPI). You can create these two server-side extensions in many ways, depending on the programming language and extension used.
Common Gateway Interface (CGI) CGI has maintained its long-standing place as a standard in web interactivity. CGI scripts allow the creation of applications in many different languages. Although web users can view only the CGI submission, many processes take place to produce the result:
You can create CGI applications in any executable or interpreted programming language that allows access to operating system environment variables: standard input (stdin) and standard output (stdout). History shows the Perl language is popular for this purpose; however, many other languages, such as C, awk, and REXX, have also been used in the creation of CGI applications.
NOTE: If an interpreted language is used, the corresponding interpreter must be available when IIS starts the CGI extension application.
If server-side extensions are created by using Perl, there's now an alternative to implementing them as CGI applications. An independent software vendor and HIP, Inc., have combined to create an interpreter for Perl that's available as an ISAPI application. Legacy and Perl scripts can now be executed without the CGI spawning process, which eliminates much overhead.
ON THE WEB:For more information on Perl, visit HIP's web site at http://www.HIP.com.
Internet Server Application Programming Interface (ISAPI) ISAPI extensions are filters and applications that you can use to create active web-based applications. An Internet filter is a dynamic link library (DLL) that resides on an HTTP server to filter the data traffic that travels to and from the server. You can activate additional processes, such as clicking HTML links or completing an HTML form, by implementing ISAPI extensions into a web page. These extensions are DLL applications that an HTTP server can load and call. ISAPI applications vary from CGI applications in that they have access to the same resources as the server and are executed in the identical address space as the HTTP server. Figure 11.8 shows the relationship between ActiveX server-side extensions and IIS.
FIG. 11.8
The overhead with ISAPI extensions is much lower than with CGI applications because
ISAPI extensions can be preloaded, can unload DLLs that haven't been called for a
period of time, and don't require the creation of additional processes.
ISAPI filters are templates that you can use to request data dynamically. There can be a level of complexity with ISAPI filters versus ISAPI applications. ISAPI filters require knowledge of the underlying technology executing the template request. With ISAPI applications, however, little or no previous knowledge of the underlying technology is required because the application is used to dynamically create the content.
With ISAPI applications, you're limited by the functionality provided. The trade-off between ISAPI filters and applications depends on the primary reason for their utilization--ease-of-use versus flexibility. The filter is an in-process control, whereas the application is out-of-process and requires more overhead than a DLL.
Visual InterDev is an IDE that allows you to create web-based applications by using multiple and varied development languages and technologies. You can build I-net applications with the visual development and database tools and features included in Visual InterDev.
Microsoft created Visual InterDev in response to the generally immature web-application development tools and utilities, which often consist merely of text editors. A typical Visual InterDev-created web-based application consists of server-side scripts developed by using VBScript or any ActiveX-scripting-supported language. The scripts, which use server-side runtime ActiveX components, sometimes perform complex processing but usually provide system services or implement business rules.
Visual InterDev might or might not provide all the design tools and features you want, but it's extensible. This means that design-time controls (ActiveX controls that have been extended with a new COM-based interface) can be used for the design of the web-based application, but when the application is executed from a script, users don't view the control. Users view only the output, produced in the form of HTML text and script code.
Visual InterDev allows the use and sharing of projects and components from multiple development tools. Visual InterDev allows the creation of web-based applications that integrate components and business processes that use not only simple server-side scripts, but also Visual C++, Visual FoxPro, Visual Basic, Visual J++, and a multitude of third-party development tools that integrate with Visual InterDev.
Visual InterDev contributes web-to-database connectivity and high-end visual database design tools. Database components in Visual InterDev include the following:
Visual InterDev provides database wizards that direct you through the creation of data-bound HTML forms. The Data Form Wizard automatically generates the required complex HTML and ActiveX server scripting to bind a web page to the database.
Various design-time controls for database access are also included in Visual InterDev. An example of a design-time control is the Microsoft Data Command control. With this control, an ODBC database connection is selected, and the Visual InterDev Query Designer then visually builds a query against that database connection.
The Query Designer helps you by working with any ODBC data source and visually constructing complex SQL statements. It helps you generate the correct DML (Data Manipulation Language) code for INSERT, UPDATE, SELECT, and DELETE queries.
In addition to providing a live connection to each database, Data View depicts each connection used by the web-based application, enabling you to work directly with the connections within the Visual InterDev IDE. Detailed information--such as objects and their properties within each database, field types, key structures, stored procedures, and table definitions--are provided through Data View, which works with the Query Designer and Database Designer to provide the administration, maintenance, and development of databases.
You can use Database Designer and Database Administrator to create new SQL Server 6.5 databases and to modify the properties and structure of existing databases. With a couple of clicks, you can perform difficult database administration tasks. You use a syntax-colored source editor when editing SQL Server and Oracle stored procedures.
Visual InterDev provides integrated source management for users of Microsoft Visual SourceSafe 5.0. This is extremely helpful when multiple developers are working on web applications in a team-based setting, as explicit check-in and check-out procedures are used for all files in the application environment.
Visual InterDev includes a set of wizards to perform a variety of common tasks, such as creating web projects and data-bound HTML forms. The wizards can be a starting point from which you can customize the finished web application.
CAUTION: If you make changes to a wizard-created application and then execute the wizards again, your initial changes will be lost.
In addition to the developer tools, a basic set of multimedia management and editing tools are included in Visual InterDev. Microsoft Media Manager allows you to manage and track content, Microsoft Music Producer enables you to create custom audio tracks for web pages, and Microsoft Image Composer allows you to manipulate and edit images.
See Chapter 14, "Developing Active Content with Visual InterDev."
See Chapter 16, "Visual InterDev Design-Time Controls."
ON THE WEB:For more information on Visual InterDev, visit the Microsoft Visual InterDev web site at http://www.microsoft.com/vinterdev.
In this chapter, you learned about web-based applications and the technologies that create and deploy them. You also saw a diagram of a sample web-based application and the components used. Also, you learned how easy it can be to apply Active Server Pages to your I-net applications by using the features available in the newly introduced IDE by Microsoft: Visual InterDev.
No matter which technologies and methods you choose for your web-site creation, one fact remains: The dynamic content you develop will increase the effectiveness of your web-based applications and allow the right information to be delivered to the right users.
For more information on web-based application topics covered in this chapter, see the following chapters:
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