Distributed Systems Fundamentals Questions

1. Fallacies.md

Fallacy #1. The network is reliable

• Why the pattern Client-Response might cause some troubles?
• What are distributed objects?
• How we can solve this problem?

Fallacy #2. Latency isn't a problem

• How many calls do you do between services before replying a syncronous call to the end user?
• Which pattern is more common in your application? Remote calls or messages?
• Do you use ORM? Which's the difference between lazy-loading and eager-loading?

Fallacy #3. Bandwidth isn't a problem.

• Why Fallacy #3 balances Fallacy #2?
• Which is your services network bandwidth?
• Is Gb Internet a lot? How it effects the TCP? and Serialization?
• We are doing microservices, what happens if we add 10 more to your tribe? and 100? how does it affects the riability?
• How Circuit Breakers relate to Fallacy #2 and #3?
• Domain Models / Domain Boundaries / Domain Driven Deisgn relates?
• Are we splitting batch jobs from high-priority APIs? Low priority networks vs high priority networks
• Why Udi says, the business cannot affort a monolithic solution, why he says that?

Fallacy #4. The Network is Secure.

• Are you plugging into your laptop random USBs you find in the street?
• Are you oversharing in your social networks?
• Are you familiar with Thread Modelling?
• Are we in a secure network in our home office?
• Are you using VPN when working in a shared wifi like a cafeteria?
• Do you know about OWAP Top 10?
• Are you doing security meanwhile you are developing? or you do it later?
• Are our cryptographic algorithms strong enough for the next 10 years?

Book Recommendation: Secure by Design.

Fallacy #5. The network topology won't change

• Do you know what's a discovery system and why it's used for?
• Which are the discovery systems we are using today?
• Do we have hardcoded addresses?
• Are you familiar with multicast protocol?
• Are you running performance tests?

Fallacy #6. The admin will know waht to do

• How many configurations do your service have?
• Do you know what they all do?
• Are you sure what will happen if you change a configuration?
• Do you have documentation of your configuration?
• How does this relates to DevOps?
• Are your systems High Availability?
• Do you have High Availablity with Blue-Green Deployment but the code isn't backward compatible?
• Apple is a crap.
• Are you able to deploy your systems meanwhile someone else is doing a demo? Or they tell you to not deploy?
• Are you overusing logging?

Fallacy #7. Transport cost isn't a problem

• How this logical decoupling relates to microservices?
• Do you agree that doing the things the right way is more expensive?
• Udi says logical monolithic design is evil instead of monolithic deployments. Why?
• Should the logical and phisical design be 1 to 1?
• Is the Data Transport constant?
• Do we know from how much time we can effort our systems? Are you concerned about this?

Fallacy #8. The network is homogeneous?

• Did you have integration problems before?
• Did you have different ways to serialize JSON?
• Did you used default values without talking to the domain experts because it was easier?
• Which has been the last time that you had an integration problem? How did you solve it?

Fallacy #9. The system is atomic

• Could you identify a distributed logic system deployed in a monolithic way vs a monolithic system depolyed distributed?
• How easy is to spot code coupling cross systems?
• Do you have a monolithic data architecture?
• Are you designing your data boundaries so you don't need to do joins?
• What are the Entity Services?

Fallacy #10. The system is finished

• Have you been in a project without realising you're in a project?
• Are you working in a "maintenance" project?
• Where are the most senior people in the team? Are they working in the early beginning or on the maintenance part of the system?
• In how mainly rewrites have you been in?
• Is it faster to rewrite from scratch rather make a small feature meanwhile dealing with legacy code?
• Is maintenance concept applicable to software?
• Viablility vs Maintainablity

Fallacy #10. Towards a better development

• Are you receiving requirements or workarounds?
• Are you prototyping to understand what they need?
• Are we a team or a group of individuals?

Fallacy #11. Business logic can be should be centralized

• Validation Logic Reimplementation. What happens when the rules change? Did you forget this scenario once? What did you did to solve it?
• Are you drawing the dependencies between code? Is it ugly?
• Are we using the Git to support changes our our business rules?

2. Coupling.md

Coupling in Application: Afferent and Efferent

• What's coupling? Which kind's of coupling exists?
• Do we agree that a class without coupling is useless?
• When you said in the past that something was coupled, which kind of coupling you were more concerned about?
• Were you able to relate the kind of coupling which the kind of class we had in our code base?
• Are you concerned by the amount dependencies with the logging library?
• Are we coupling to stable things or volatile things?
• Is the code analysis we are doing help us manage the coupling?
• Are you aware of the coupling in your system?

Coupling in System: Platform, Temporal and Spatial

• Are you making coupling explicit? Is it easy accessible?
• Are we hidding the coupling?
• What is Platform Coupling? What's run time coupling?
• Are we sharing a contract and schema, or classes or types?
• What's temporal coupling? Can you detect temporal coupling in your system?
• What's Sepecial Coupling?
• Do we have hidden coupling?

Coupling Solutions: Platform

• How many options possible for interoperability do you know?
• What does an schema solve?
• Which are the transfer protocols you know?

Coupling Solutions: Temporal and Spatial

• Do you have syncronous blocking request response queries between services?
• Are you one of the 5 people that should be writing multithread code?
• Are you using async await in your code?
• Are you aware of what deadlocks, lifelocks, data races could imply in your code?
• How could you remove the temporal coupling and still get the data from service B?
• Did you do use Cache to solve multiple request to other services?
• In which place you put the cache?
• Are you familiar with subscribe solutions?
• What means that Pub/Sub requires a single source of truth?
• What is a Source of Truth?
• What is a good event? What they should be facts?
• When to do Pub/Sub? When not to use Pub/Sub?
• What happens when two entities need to be consistency transactionally but they are in two different systems?
• Document based routing, how does that relate with Special Coupling?
• How many dimensions we have in coupling? Why we cannot have small degree of all types of coupling?