10/11: Microservices

Question 1

What is a microservice

Answer 1

A microservice is a small application that can be
deployed independently, scaled independently,
and tested independently, and that has a single
responsibility - a single reason to change and/or a
single reason to be replaced.

Question 2

what is a saga?

Answer 2

transactions are broken down into collections of sub-transactions called sagas
each subtransaction has a subtransaction that undos it
the saga guarantees either all of the transactions complete
or none
A FAILUREMANAGEMENT PATTERN FR DISTRIBUTED DATABASED

Question 3

why are microservs good?

Answer 3

can be written in different languages
scales well
can scale based on what you need
loose coupling

Question 4

what are key issues in MSs?

Answer 4

• How to decompose the application into services
  • How to maintain data consistency
  • How to implement queries

Question 5

what are the essential traits of MSs

Answer 5

isolation
autonomicity
single responsiblity - do one thing and do it well
exclusive state
mobility

Question 6

what is event sourcing?

Answer 6

similar to journaling in OS

keep a log of events. allows the log to be replayed in the event of a crash

Question 7

what is xyz partitioning

Answer 7

x is more machines
y is diff mahcines do diff tasks
z is diff machines work on diff data

Question 8

what is CQRS

Answer 8

Command Query Responsibility Segregation
seperates the read and write model from each other, decouples the writes and the responses to the writes
allows us to scale reads and writes independantly of each other

Question 9

what is Polyglot persistence

Answer 9

Polyglot Persistence is a fancy term to mean that when storing data, it is best to use multiple data storage technologies, chosen based upon the way data is being used by individual applications or components of a single application. Different kinds of data are best dealt with different data stores. In short, it means picking the right tool for the right use case.

Question 10

what is continous delivery

Answer 10

is a software development discipline where you build software in
such a way that the software can be released to product at any
time
continuously integrating the software, building executables,
• running automated tests on those executables to detect
problems
• pushing the executables into increasingly production-like
environments to ensure the software will work in production

Question 11

what are the issues of mciroservices

Answer 11

increased complexity that comes with a distributed system
requires thorough automated testing
high level of automation required