# Re-architecting as microservices without containers
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AWS Lambda is a serverless compute service that lets you run code without provisioning or managing servers, creating workload-aware cluster scaling logic, maintaining event integrations, or managing runtimes. Lambda runs your function only when needed and scales automatically, from a few requests per day to thousands per second. You pay only for the compute time that you consume—there is no charge when your code isn’t running. In this approach, a monolithic application is broken down into smaller services, where each service serves a single purpose. If the service isn’t constantly running, it can be implemented as a Lambda function; otherwise, the service should run in a container.

## Use cases
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You can use this migration strategy in the following scenarios:
+ You want to break your monolithic system into microservices.
+ You have the resources and time available for refactoring.
+ You can resolve all .NET Framework dependencies.
+ Your applications do not run constantly; they run for a very short period of time.

## Advantages
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This migration approach provides the following benefits, when compared with on-premises .NET applications:
+ Faster innovation because it’s easier to add new features in a microservices architecture
+ High availability and reliability
+ Increased agility and on-demand scalability
+ Independent deployment and modern CI/CD pipelines
+ Strong module boundaries and technical diversity
+ Cost savings
+ Reduced infrastructure provisioning efforts

## Disadvantages
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+ Effort and cost of refactoring
+ Potential operational complexity
+ No support for long-running applications

## AWS services
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These are some of the important AWS services that you can use to develop a microservices architecture with AWS Lambda:
+ [Amazon API Gateway](https://aws.amazon.com/api-gateway)
+ [Amazon Simple Notification Service](https://aws.amazon.com/sns) (Amazon SNS)
+ [Amazon Simple Queue Service](https://aws.amazon.com/sqs) (Amazon SQS)
+ [AWS Lambda](https://aws.amazon.com/lambda)
+ [CloudFormation](https://aws.amazon.com/cloudformation) or [AWS CDK](https://aws.amazon.com/cdk)
+ [IAM](https://aws.amazon.com/iam)
+ [Amazon S3](https://aws.amazon.com/s3)

## Tools
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AWS Professional Services offers custom tools and services to help you refactor your monolithic applications into microservices.

## Deployment decisions
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This migration and modernization approach is supported by AWS Lambda 

 ![\[Refactoring .NET applications as microservices on AWS\]](http://docs.aws.amazon.com/prescriptive-guidance/latest/modernization-net-applications/images/rearchitect-microservices.png)