Monolothic

Notes:

• A company may have more than one monolith

• A monolith means a big heavy app

Pros:

• Knowledge Sharing

• Easier dependency management

• Easier version management

• Easier to track breakages across different projects

• Easier to know what team is doing at a glance

Cons:

• Harder to split code ownership

• Harder to define responsibilities

• Monolithic codebases can easily become a mess

  • No strong conventions

  • Can be harder to deploy

• Increased complexity on codebase

• Harder to distinguish responsibility of the codebase

Examples:

• Facebook

  • Only WWW is a monolithic app

Resources:

• ​David R. Maclver: Why you should use a single repository for all your company’s projects​

  • It is impossible for your code to get out of sync with itself

  • Any change can be considered and reviewed as a single atomic unit

  • Refactoring to modularity becomes cheap

Questions:

• When should you break down a monolithic app?

• When should you unbundle a monolith?

Non-Monolothic

Examples:

• Amazon

  • Lots of data duplication

Common in:

• Microservices (typically)

• FaaS / Serverless

Microservices

Pros:

• Lighter weight deployments

Cons:

• Many repositories

  • Complex

• Poor knowledge sharing

• Orchestration

Requires:

• Service Discovery

• Event Bus

  • Pub/Sub

Good for:

• Services that can't exist in a FaaS environment

  • AWS Lambda Limitations

  • • Execution time. AWS has a limit of 15 minutes

    • Storage space

    • Uploads of 50mb zip

    • ​https://docs.aws.amazon.com/lambda/latest/dg/limits.html​

When to use microservices?

• Reusable functionality across different services

  • Can exist as a library; or micro service

• Isolate small piece of code for:

  • Improved quality

  • Predictable releases

  • Security

• When you want to create a black box

• Reduce transparency

• If it can exist as it’s own product

• Things which can’t exist in a FaaS

Questions to ask:

• When should you bundle a microservice?

• When should you unbundle a microservice?

• When should you break down a monolothic app into a microservice?

• When does a microservice become a monolithic app?

• If your goal is to keep it as a Single Responsiblity Principle

  • Why not just use a FaaS architecture?

FaaS (Functions as a Service) / Serverless

Pros:

• DevOps is not required

• Reduce security footprint

• Isolated

• Pay for what you use

Cons:

• Harder debugging

• Increased complexity on infrastructure

Good for:

• Teams with poor devops

When to use FaaS?

• Unpredictable demands

  • Competing faaa products (Ec2) can leveraged auto scaling

• Small work loads that don’t require an always on machine

• Isolated processes

Examples:

• Low traffic url shortener https://github.com/aizatto/url-shortener/​