03, 04 updates

Author: terhunej

content/modernizr/03-dual-layer/index.en.md

@@ -10,7 +10,7 @@ chapter: true
 
 Stage 3 introduces a database abstraction layer that enables your application to simultaneously interact with both MySQL and DynamoDB databases. This dual-database approach is essential for achieving zero-downtime migrations by allowing gradual transition from the legacy relational system to the modern NoSQL architecture.
 
-The abstraction layer functions as an intelligent data access facade that routes queries to appropriate databases based on configurable migration phases. This architecture pattern enables controlled, incremental migration while maintaining full application functionality throughout the transition process.
+The abstraction layer functions as an intelligent data access router which directs queries to appropriate databases based on configurable migration phases. This architecture pattern enables controlled, incremental migration while maintaining full application functionality throughout the transition process and the ability to roll-back if any issues are encountered.
 
 ## Abstraction Layer Architecture
 

content/modernizr/04-ddb-connection/index.en.md

@@ -10,7 +10,7 @@ chapter: true
 
 Stage 4 is where you actually implement the DynamoDB side of your dual database system. Think of this as installing the wiring and connections for your second database engine - you're building all the infrastructure needed to make DynamoDB work with your application.
 
-This stage focuses on creating the actual DynamoDB tables, setting up the AWS SDK connections, and implementing the data transformation logic that converts your MySQL data into DynamoDB format.
+This stage focuses on creating the actual DynamoDB tables, setting up the AWS SDK configuration, and implementing the data transformation logic that converts your MySQL data into a structure optimized for DynamoDB.
 
 ## What You'll Build
 
@@ -24,11 +24,11 @@ Each table needs to be configured with the right capacity settings, security pol
 
 You'll set up the connection between your application and DynamoDB using the AWS SDK, Setting up the DynamoDB client with proper authentication, you will connect to the proper AWS regions and make sure you configure the right information in the SDK settings for retries.
 
-At this stage you will implement the transformation logic that converts MySQL data into DynamoDB items, you will need to re-write your APIs to work with DynamoDB SDK instead of SQL, you will need to handle the difference between data types and how to flatten the relational joins into single DynamoDB items. This step requires a lot of testing and validation to make sure you don't loose any data and you always provide the same API response regardless of the method, if you retrieve the elements from the Shopping cart, you should return the list of them regardless of the Database who has them. 
+At this stage you will implement the transformation logic that converts MySQL data into DynamoDB items. You will need to re-write your APIs to work with DynamoDB SDK instead of SQL, handle the difference between data types, and flatten the relational joins into single DynamoDB items. This step requires a lot of testing and validation to make sure you don't loose any data and you always provide the same API response regardless of the method, if you retrieve the elements from the Shopping cart, you should return the list of items regardless of the Database which is storing them. 
 
 ## Test driven development
 
-All the refactoring stages, use Test Driven Development, this ensures backward compatibility and avoid changing working/existing logic. You will first create a non-working unit test, and iteratively modify the code until the unit test passes. To ensure full compatibility we provide instructions to the LLMs to re-run the Unit, Integration and End-to-end testing, every time a new functionality is added. (This is why it takes so long to complete!)
+All the refactoring stages use Test Driven Development to ensure backward compatibility and avoid changing working/existing logic. You will first create a non-working unit test, and iteratively modify the code until the unit test passes. To ensure full compatibility we provide instructions to the LLMs to re-run the Unit, Integration, and End-to-end testing every time a new functionality is added. (This is why it takes so long to complete!)
 
 ## Next Steps