Book Image

Apex Design Patterns

By : Anshul Verma, Jitendra Zaa
Book Image

Apex Design Patterns

By: Anshul Verma, Jitendra Zaa

Overview of this book

Apex is an on-demand programming language providing a complete set of features for building business applications – including data models and objects to manage data. Apex being a proprietor programming language from Salesforce to be worked with multi tenant environment is a lot different than traditional OOPs languages like Java and C#. It acts as a workflow engine for managing collaboration of the data between users, a user interface model to handle forms and other interactions, and a SOAP API for programmatic access and integration. Apex Design Patterns gives you an insight to several problematic situations that can arise while developing on Force.com platform and the usage of Design patterns to solve them. Packed with real life examples, it gives you a walkthrough from learning design patterns that Apex can offer us, to implementing the appropriate ones in your own application. Furthermore, we learn about the creational patterns that deal with object creation mechanism and structural patterns that helps to identify the relationship between entities. Also, the behavioural and concurrency patterns are put forward explaining the communication between objects and multi-threaded programming paradigm respectively. We later on, deal with the issues regarding structuring of classes, instantiating or how to give a dynamic behaviour at a runtime, with the help of anti-patterns. We learn the basic OOPs principal in polymorphic and modular way to enhance its capability. Also, best practices of writing Apex code are explained to differentiate between the implementation of appropriate patterns. This book will also explain some unique patterns that could be applied to get around governor limits. By the end of this book, you will be a maestro in developing your applications on Force.com for Salesforce
Table of Contents (12 chapters)
Apex Design Patterns
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface

Understanding concurrency issues


In software applications, concurrency is the ability of an application to execute multiple processes simultaneously. While executing simultaneously, these processes can use shared resources and could potentially end up with data corruption or the wrong data.

We will try to understand concurrency issues using a real-life example of driving a car on a road. The following figure shows a two-lane driving road:

In the preceding figure, a car represents a process and a driving lane represents a shared resource. Driving on a straight road (without using a shared resource) is not a complex task. Complexities will arise when a driver of the car (a process) tries to change lanes (access a shared resource) and make sure that there is no chance of an accident (data loss or corruption). So, here we are trying to state that if a car (a process) runs on its own lane (not a shared resource), the possibility of data corruption is very low.

The following figure shows...