Chapter 6: Platform as a Service

Question 1

What are the three PaaS Value Propositions?

Answer 1

1. Maintenance
   - Hardware maintenance
   - OS patches
   - Middleware updates
2. Availability
   - Application/service will be available despite maintenance/outages
3. Scalability
   - Application/service will scale to thousands of concurrent users

Question 2

What is the COST of Scalability?

Answer 2

COST: Configuration that Outperforms a Single Thread
-> When to use scalable systems is an important decision
(Flink quickly outperforms the local implementations)

Question 3

PaaS vs. IaaS

Answer 3

● PaaS offers higher abstraction level compared to IaaS
■ Less development/maintenance effort
■ Less flexibility, high provider dependence

Question 4

PaaS Abstraction Levels.

Answer 4

■ Execution environments (like on Heroku)
■ Databases
■ Distributed processing
■ Domain-specific workbenches (like SageMaker)
■ Complete services (like Rekognition)*

Question 5

Explain Serverless Computing.

Answer 5

Serverless computing is a cloud execution model. The provider runs the server-side and dynamically manages
the resources. Enabled by high-level PaaS offerings.

Question 6

Explain BaaS.

Answer 6

■ Backend as a Service
♦ Use cloud database, authentication, etc. as backend to a rich client app
♦ Often used for mobile apps

Question 7

Explain FaaS.

Answer 7

■ Function as a Service
● Motivation: Run backend code without managing server resources and/or long-running applications
● Architecture: Stateless, ephemeral, event-triggered
● Automatic horizontal scaling

Question 8

When does Serverless Computing makes sense?

Answer 8

■ Platform services that don’t live long

■ Platform services where you don’t think about scaling

Question 9

Name an implication of Serverless Architecture.

Answer 9

Less Ops to worry about at the expense of flexibility.

Question 10

What are the pros and cons of Serverless Architecture?

Answer 10

● Good:
■ Less application code, reduced development effort
■ Possibly less costs
■ Cloud operator probably better at implementing default
tasks than application developer
● Bad:
■ Monitoring becomes more complex
■ Security needs to be handled at all the services
■ Additional complexity through managing the different cloud services

Question 11

Summary PaaS/FaaS.

Answer 11

● Managed platforms allow developers to focus more on their applications and less on operations
■ PaaS: in addition to the infrastructure, the entire runtime is managed as well, yet users typically still allocate and scale resources
■ FaaS: users only write and upload their functions, provider manages allocation and scaling of resources