Posted in July 2008

Design Patterns are an essential tool for any object orientated programmer who wants to take his/her skills to the next level. Understanding the specifics of Design Pattern practices and methodologies will help developers uncover reoccurring patterns in software development and give them the tools to apply the correct solution.

For every difficulty encontered during application development, chances are this problem was encountered before (and solved). Design Patterns represent key programming practices that have been proven to get the job done in the most efficient, reusability and extensibility. This greatly increases efficiency of code and helps to break an application down into loosely compelled manageable chucks.

As a .Net developer you may have used some of these patterns without even knowing. A design patterns name captures the basic concepts that govern its use and a common practice is to include the pattern name in the name of the object that implements it.

You may have come across the following names while working with the .Net framework:

• Proxy
• Adapter
• Command
• Factory

The deeper your understanding of Design Patterns the more you’ll be to understand the .Net framework and how it can leverage you applications.

Main Design Patterns Concepts

• Use interface inheritance over concrete base class inheritance
• Create loosely coupled objects to promote code reuse by keeping object small and specialised
• Defer / Delegate responsibility to specialised objects using composition

Choosing the correct pattern
The best way to decide which pattern is fit for the jobs it to break down your development specification into each requirement. If these requirement exhibit certain characteristics that relate to a design pattern then apply it. E.g. If you application is responsible for monitoring a file system and reporting changes back to a number of objects you are most-likely to implement the Observer pattern.

Summary
Once you have gained an understanding of object orientated concepts you should be ready to tackle Design Patterns. You will be surprised how many patterns that are already familiar to you and how much the put things into perspective. You’ll also find that the more you learn, the more you’ll see application development from a different perspective (almost like seeing the Matrix!!). To truly understand the benefits of Design Patterns you have to apply them to your application development. This will improve your object reuse and make future program changes less painful!

List of Design Patterns LINK:

• Adapter Pattern
• Command Pattern
• Composite Pattern
• Decorator Pattern
• Factory Pattern
• Flyweight Pattern
• Intepreter
• Model-View-Controller
• Null Pattern
• Observer-Observable
• Singleton
• State Pattern
• Strategy Pattern
• Template Pattern
• Union Pattern
• Visitor Pattern

There are many tools on the market for creating application for mobile phones and portable devices. This blog post investigates the technologies necessary for creating Microsoft related ASP.Net mobile applications.

Window Mobile (OS)
Window mobile is a compact operating system for mobile devices. These devices include Pocket PCs, Smartphones, Portable Media Centres and on-board computers for cars. Windows Mobile has been designed to be similar aesthetic to Vista and is currently at version 6.1 with a new release scheduled for 2010.

.Net Compact Framework
The .Net compact framework is a scaled sown version of the .Net Framework and uses some of the same class libraries with a few additional libraries designed specifically for mobile devices. This can be integrated with Visuals Studio 2003, 2005 and 2008 to develop impressive mobile windows form based and web based applications.

ASP.Net Mobile Controls and the Microsoft Internet Toolkit
Developing applications for mobile devices can be a challenging as there are certain limitations, which include:

• Different mark-up languages for PDAs, Cell phones or Japanese phones.
• Devices have a varying number or display lines, horizontal/vertical orientation and screen colours.
• Different network connectivity
• Capabilities, display resolution and ability to make phone calls.

All these factors must be taken into consideration when developing applications for mobile devices.

This is where the Microsoft Internet toolkit comes in, as it addresses these issues so that developers can build one mobile web application that delivers the appropriate mark-up for a wide range of mobile devices.

The mobile toolkit contains:

• Mobile web form controls which are similar to ASP.Net controls as the generate mark-up code
• Mobile Internet Designer which integrates with Visual Studio .Net IDE to provide a web application design environment
• Browser Capabilities which makes it possible to run ASP.Net functionality on mobile devices
• Quick Start Tutorial with sample code
• Developer Documentation
• Device adapter code samples

Using a combination of the Windows Mobile operating system, .Net Compact Framework, and the Microsoft Internet Toolkit applications can be written to run on a wide range of mobile devices in a similar manor to that of regular browser base applications.

Summary
These are the three basic tools that are necessary to start building applications that target mobile devices.
Mobile devices are becoming increasingly popular as people continually want to stay connected when they are away from their desk. Microsoft has developed a cohesive little package of products that integrate well together and provide an infrastructure similar to their full blown application development environment. This will hopefully encourage developers to venture into the world of mobile application development.