Book Image

AWS Certified Developer - Associate Guide

By : Vipul Tankariya, Bhavin Parmar
Book Image

AWS Certified Developer - Associate Guide

By: Vipul Tankariya, Bhavin Parmar

Overview of this book

AWS Certified Developer - Associate Guide starts with a quick introduction to AWS and the prerequisites to get you started. Then, this book gives you a fair understanding of core AWS services and basic architecture. Next, this book will describe about getting familiar with Identity and Access Management (IAM) along with Virtual private cloud (VPC). Moving ahead you will learn about Elastic Compute cloud (EC2) and handling application traffic with Elastic Load Balancing (ELB). Going ahead you we will talk about Monitoring with CloudWatch, Simple storage service (S3) and Glacier and CloudFront along with other AWS storage options. Next we will take you through AWS DynamoDB – A NoSQL Database Service, Amazon Simple Queue Service (SQS) and CloudFormation Overview. Finally, this book covers understanding Elastic Beanstalk and overview of AWS lambda. At the end of this book, we will cover enough topics, tips and tricks along with mock tests for you to be able to pass the AWS Certified Developer - Associate exam and develop as well as manage your applications on the AWS platform.
Table of Contents (29 chapters)
Title Page
Credits
About the Author
Acknowledgments
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface
Index

Cross-Origin Resource Sharing (CORS)


Before understanding CORS, let us understand the significance of the same origin policy. The cross-origin policy is a critical aspect of a web application security model. In a web application security model, by default, a web browser does not allow a script file associated with a web page to access data associated on a page in a different hostname, domain, or port number. The purpose of cross-origin policy is to prevent any malicious script embedded on one page to access sensitive data on another web page.

For example, a script hosted in a page books.html on www.packtpub.com, can access the Document Object Model (DOM) of any page within the same domain, that iswww.packtpubs.com. If it tries to access DOM of a page hosted on another domain, the access is denied. Even if a page is hosted on a subdomain such as books.packtpubs.com, when it tries to access DOM of another page on projects.packtpubs.com, it is denied the access. This is a way to maintain the...