Oleg Sych - ASP.NET Dynamic Data Unleashed

Oleg Sych

800 East 96th Street, Indianapolis, Indiana 46240 USA

ASP.NET Dynamic Data Unleashed

Copyright 2012 by Pearson Education, Inc.

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ISBN-13: 978-0-6723-3565-5

ISBN-10: 0-672-33565-4

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First Printing: May 2012

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Oleg Sych has been working as a professional software engineer since 1993, building distributed enterprise applications since 2000, and leading development teams since 2002. Between 2009 and 2011, Oleg received several MVP awards from Microsoft in C# and Visual Studio ALM categories. His professional interests include agile software architecture and development process. In his spare time, Oleg is trying to learn how to ski, play tennis, and raise teenage boys.

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Most of the web applications that exist today work with data. From a simple guest book page on a personal website, to a large product catalog of an online retailer, to customer relationship management (CRM) and enterprise resource planning (ERP) systemsapplications help people work with data. Working with data means dealing with CRUD. Every database application must allow users to Create, Read (or Retrieve), Update, and Delete records. A product catalog will not be functional unless users can add new products to the catalog, search for and retrieve existing products, update product information, and delete discontinued products from the catalog. Of course, a product catalog rarely exists by itself; it is usually a part of a larger e-commerce system, which has to support all CRUD operations not only for products, but also for customers, suppliers, shipping companies, orders, and more.

Implementing each type of CRUD operation requires some form of presentation, business, and data access logic. Implementing them in your applications usually requires a lot of repetition. Data access logic for products is similar to data access logic for customers, as well as suppliers and shipping companies. You write SQL or .NET code (or both) to insert, select, update, and delete database records. Presentation logic for products is also similar to presentation logic for customers, suppliers, and shipping companies. You create ASP.NET pages with text boxes, drop-down lists, validation controls, links, and buttons. What truly distinguishes the different types of entities is their purposethe business logic they represent. The Product entity has attributes such as description, price, picture, and rules that define how to validate product names, what to do when a new product is added to the catalog, or when an existing product is discontinued. The Customer entity has different attributesfirst name, last name, credit card numbersand rules that define what to do when a customer changes his billing address or requests to close his account.

Understanding the business logic, a developer can usually figure out how to implement the required data access and presentation logic. The resulting application might not look very pretty, but it will perform its business function. The ASP.NET framework provided all building blocks required for implementing database applications, and although it made web developers a lot more productive, it offered little assistance with the repetitive coding of CRUD operations and made it easy for them to fall into the trap of code reuse by copy and paste. It is unfortunate that a typical ASP.NET application has numerous web pages full of validators and code-behind files where data access code is intermixed with business logic.

There are many techniques for reducing code duplication. In ASP.NET, user controls are an excellent way to extract common presentation logic and reuse it in multiple pages. Patterns, such as Domain Model and Active Record (Fowler, 2002), can be used to encapsulate business and data access logic in application code. Some developers also choose to use stored procedures and implement this logic in database code instead. Separation of the business and data access code from the presentation code allows you to reuse it in multiple web pages without duplication. However, implementing business and data access layers requires more forethought, expertise, and commitment from developers. To be effective, these techniques must be introduced in the application architecture early. Retrofitting them to an existing application requires a lot of refactoring (Fowler, et al., 1999) and can be very costly. It is not unusual for such a refactoring effort to be longer than the initial application implementation itself.