Microservices Architecture Quiz

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Questions and Answers

What are 'dynos' in the context of this platform?

Database management systems

Physical servers for application hosting

Serverless computing components (correct)

Integration tools for continuous delivery

Which programming languages are supported by the platform?

Ruby, Python, and Java only

Only Ruby and Python

Ruby, Python, Java, Scala, Clojure, and node.js (correct)

Java, Scala, and Clojure only

What is a key feature of worker dynos?

Run computationally intensive tasks outside the web layer (correct)

Store database information persistently

Execute user HTTP requests directly

React to real-time user input immediately

What is the pricing structure for dynos?

Charged per second of usage Signup and view all the answers

Which service is NOT mentioned as part of the managed support services?

MySQL Signup and view all the answers

What is the primary advantage of decomposing a monolithic application into microservices?

Improved resilience and scalability Signup and view all the answers

Which service is responsible for sending notifications about newly available trips to drivers?

Driver Management Signup and view all the answers

What communication method can backend services use besides APIs?

Asynchronous event-based communication Signup and view all the answers

How can interfaces be organized in a microservices architecture?

By splitting interfaces for each type of client Signup and view all the answers

Which of the following options best describes how functional areas are implemented in a microservices architecture?

Functional areas are implemented as separate microservices Signup and view all the answers

What is a primary drawback of clients directly calling multiple microservices?

Increased dependency on client-side architecture Signup and view all the answers

Which platform is known for built-in support for micro-service deployment?

CloudFoundry Signup and view all the answers

What aspect of the client application must change when there is a modification in the microservices?

The client application's service calls Signup and view all the answers

What is suggested as a better approach than direct client-to-microservices communication?

Communicating through a service mesh Signup and view all the answers

What does runtime support for discovery and configuration facilitate?

Efficient management of microservices Signup and view all the answers

What is the primary function of AWS Lambdas?

To execute code in response to triggers or events Signup and view all the answers

What is a typical use case for AWS Lambdas?

Pairing with communication services like SQS or SNS Signup and view all the answers

Which of the following limitations applies to AWS Lambdas per running instance?

1,000 maximum concurrent executions Signup and view all the answers

What is the maximum execution time for an AWS Lambda function?

300 seconds Signup and view all the answers

In the provided example, which Python feature is primarily used for generating the response?

String concatenation with the format method Signup and view all the answers

What is the rationale behind not including photo resizing in the client event-response loop?

It could increase response time significantly Signup and view all the answers

Which programming languages are supported by AWS Lambdas?

Node.js, Java, Python, Go, C# Signup and view all the answers

What does Amazon S3 allow users to do?

Store and retrieve elements using unique keys Signup and view all the answers

What is a key advantage of using spatial databases in driver management systems?

They enable efficient queries for locating drivers near passengers. Signup and view all the answers

What challenge arises from the partitioned database architecture in microservices?

Difficulty in modifying multiple database entries atomically. Signup and view all the answers

Which of the following is essential to handle fault tolerance in distributed systems?

Developing interprocess or event-based communication methods. Signup and view all the answers

How does the absence of shared state in microservices affect application architecture?

It necessitates more complex communication protocols. Signup and view all the answers

What is a potential impact of faults occurring during the interaction of microservices?

Inconsistency in state across different services. Signup and view all the answers

What architectural pattern is favored for managing driver, passenger, and trip data in taxi-hailing applications?

Microservices architecture with partitioned databases. Signup and view all the answers

Which communication method is recommended for dealing with complex interactions in microservices?

RPC or event-based communication. Signup and view all the answers

Which statement best describes the complexity introduced by microservices?

It requires careful planning for interservice communication. Signup and view all the answers

What is the primary role of an API Gateway in a microservice architecture?

To serve as the sole entry point to the microservice ecosystem Signup and view all the answers

Which of the following functions is NOT typically performed by an API Gateway?

Data storage Signup and view all the answers

How many microservices does a client request typically involve when using an API Gateway?

6 to 7 Signup and view all the answers

What does the API Gateway provide to different types of clients?

Custom APIs tailored to each client type Signup and view all the answers

Which of the following is an example of how an API Gateway orchestrates microservices?

By handling client requests differently based on device type Signup and view all the answers

Which of the following best describes a primary benefit of using an API Gateway?

It simplifies load balancing across microservices. Signup and view all the answers

When can an API Gateway work with multiple microservices?

In all client requests from various devices Signup and view all the answers

What is a common communication protocol used by an API Gateway?

REST Signup and view all the answers

Which component of the architecture is directly involved with managing client authentication?

API Gateway Signup and view all the answers

Study Notes

Course Information

Course Title: Cloud Computing
Course Code: LINFO2145
Instructor: Pr. Etienne Rivière
Contact Email: [email protected]
University: Université catholique de Louvain

Announcements

Project starts this Friday
ULB students without Moodle access should provide their GitHub account to TAs in person or by email
Peer review for Quiz #1 opens after this lecture
Deadline for peer review: Before the next Wednesday's lecture
New quiz on lectures 3 and 4 available after the deadline

Course Objectives

Discuss Platform-as-a-Service (PaaS) including development environments and serverless cloud computing
Describe service-oriented architectures including classical Web services, REST APIs, microservices, API gateways and service meshs

Platform-as-a-Service (PaaS)

A cloud service model that provides developers with a managed environment for creating and deploying applications
Benefits include relief from administration and maintenance tasks like installing and maintaining OS, database servers, web servers (reduced overhead for developers)
Less flexible than Infrastructure-as-a-Service (IaaS)
Vendor lock-in is greater than with IaaS
Easier to relocate virtual machines or containers between IaaS providers compared to specific PaaS platform code

PaaS Examples

Google App Engine
Heroku
AppFog
Engine Yard
OpenShift
CleverCloud

Comparing PaaS

Comparing PaaS is more complex compared to IaaS
No longer solely focused on pricing, security features or machine performance
Factors to consider include supported programming languages, libraries, database management systems, communication features, deployment and testing support, cost and billing models

Google App Engine

Provides a complete, managed environment
Supports development tools, runtimes, libraries and Operating Systems
Primarily designed for distributed web applications
Supports Java, Ruby, Python, PHP, Go, and Node.js
Applications are designed to be small and stateless, with components that are only invoked when there's an incoming web request
Data stored in a managed database
Can include IaaS-like usage through containers with arbitrary code functions (using Kubernetes)

Google App Engine: Pricing

Billing based on actual usage per second, with a one-minute minimum charged per hour
Pricing per resource:
- vCPU: $0.0526 per core hour
- Memory: $0.0071 per GB hour
- Persistent disk $0.0400 per GB per month
Cost for outgoing traffic: $0.12 / GB
Shared Google services like caching, email, and libraries charge nothing extra

Deployment: Google App Engine

Use the Google Cloud Platform to create a new project
Use the provided SDK to test your application locally
Install the SDK for testing applications locally
Deploy via command line tool (appcfg.py)

Python (GAE) - Code Example

webapp2 : Depricated GAE web code framework
MainPage : Class to handle requests
Configuration file (YAML format) including runtime, api_version, threadsafe, handlers ,regexp, and script

Deployment: Create Project

Instructions cover the steps to create a new project on GCP.

Deployment: Uploading a Project

Steps to deploy the application using appcfg.py from the local machine.
Requires authentication and uses project IDs.

Other concepts

Discusses deployment best practices
Emphasizes considerations for using microservices, including performance and architecture choices
Illustrates architectural aspects and considerations in a Cloud Computing context (Scalability cube, Restful APIs)
Discusses communication models (one-to-one, one-to-many, synchronous, asynchronous) and implementation details
Emphasizes important considerations like service meshes, payloads, and database considerations with microservice architectures.

Platform-as-a-Service (PaaS) and portability

Discussion of portability: running applications built using GAE on a private cloud or moving to an IaaS platform for cost reasons. Introducing an open-source alternative, CapeDwarf, running on WildFly.

"Serverless" Computing

Describes serverless computing as a common form of PaaS
Highlights that code does not run directly in thin air but on actual compute resources, with the location not being managed by the user. This includes examples like AWS lambdas, Heroku.

Heroku

Discussion of Heroku's dynos (serverless components).
Details on web dynos and worker dynos. Shows execution flow diagrams for different microservice interaction strategies and the advantages and disadvantages
Describes the choice between on-demand (cheap, higher latency) and persistent (expensive, better response times)

AWS Lambdas

Discusses how this technology is a mechanism analogous to Heroku’s dynos
Describes common use cases: invoking the lambda periodically, in response to external HTTP requests or events
Details AWS Lambda limitations including memory, temporary disk usage, and execution time constraints
Illustrates Python programming example for lambda functions

Image Thumbnails

Illustrates using Amazon S3 (a key/value store) as the storage for raw images and then generating thumbnails for web display. Explains why putting thumbnail storage and creation within the main client request loop is not efficient.
Recommends storing raw images in Amazon S3 bucket and creating thumbnails separately, and then returning thumbnail URLs.

High-level architecture for AWS Lambdas

Visual representation diagram illustrating the interaction between an AWS account user, Amazon S3 buckets, an execution role, and an AWS Lambda function.

Steps for uploading images and creating thumbnails

Details the process of receiving image uploads through a channel
Highlights the use of "ObjectCreated" events

Intermediate conclusion

Discusses core design principles of PaaS and serverless models based on the idea of services
Shows how an application is formed from a set of services linked through APIs
Highlights that these services are designed to scale, and deploy in isolation, characteristics that make them compatible with cloud computing paradigms

REST Interfaces

Introduction to Representational State Transfer (REST), an architectural style for designing web applications
Explains REST general guidelines, bottom-up normalization, HTTP 1.1 and URIs

REST key features

Describes uniform interface, statelessness, client-server, and other characteristics of REST
Explains resource-based interactions, using URIs to identify "things" and representations for exchanging resource data

REST API - Uniform Interface

Describes the uniform interface within RESTful APIs that utilizes common verbs such as GET, PUT, POST, PATCH, and DELETE
Covers the role of the HTTP request method in specifying API operations
Discusses the standardization of HTTP responses, including success, error codes, etc.

HTTP verbs - Semantics

Explains how different HTTP verbs are used
Describes GET as a read-only operation and POST, PUT, PATCH and DELETE for creating, replacing, updating and deleting items respectively

HTTP verbs - Example usage

Provides examples of how HTTP verbs work in the context of resources (ex: a list of students or a specific student)

Design effective & safe APIs

Discusses importance of resource naming, consistency, idempotent usage of API, rate limits, and secure access with example use cases

HTTP responses

Discusses HTTP response codes and their uses to identify the status of a request or message sent to a server.
Explains how those codes are grouped in five families with various intended uses and meanings.

JSON

Describes JSON (JavaScript Object Notation)
Highlights its use as a common data format in modern applications, being human-readable and machine-parseable

Constraint 2 - Statelessness

Discusses the lack of session state stored on the server during interactions with RESTful interfaces. Explains why this approach is well suited to a Cloud environment and how it enables scalability.

Interest of REST APIs

Explains the benefit of using REST APIs in an elastic and scalable system and in terms of portability, clarity, and implementation

REST Maturity Model

Details Richardson's model for REST APIs, outlining various maturity levels (0-3)

Example of RESTful APIs (OpenStack)

Illustrates a platform (OpenStack) API using GET/POST/PUT/DELETE examples for launching VMs, creating/editing/removing images, etc.

Example of OpenStack API use

Covers specific examples of calls using curl instructions to interact with a real system (OpenStack)

Microservices

Describes micro services, an architecture focusing on small, interconnected services
Explains that each micro-service is implemented as a single functionality
Defines important considerations to be mindful of when implementing microservices including: independent databases, separate deployment for new/old service, and different languages/frameworks
Uses example of a taxi-hailing application

Monothic vs. Microservices Application Structure

Presents diagrams describing typical architectures for an application before (monolithic) and after (microservices) implementing design principles, and presents the differences in complexity

Advantages of a monolith

Shows the benefits of a monolithic architecture from a developer's perspective (simplicity of deployment + tooling support - IDEs, etc.) and the advantages of a shared programming language, or how to deploy.

Monothic Hell (1 & 2)

Shows the disadvantages or limitations to a monolith from the view point of a developer (complexity in scaling up, adding features and maintenance) and a DevOps/Operations person (complexity in deployment time, scaling and resource allocation)

Microservices Communication

Highlights the various strategies used to communicate between microservices such as synchronous and asynchronous communication styles, direct from client and through API Gateways, or through message driven architectures

API Gateways

Explains that a specific microservice will act as the sole entry point into your system (an API Gateway)
Discusses how API gatekeeps knowledge of the inner system's architecture
Explains the benefits of using API gateways, including encapsulation and centralized control of communication

Interaction Styles

Highlights "one-to-one" interactions where each client request generates a processing instance by just one service
Describes "one-to-many" interactions where a single request gets handled by several services
Discusses synchronous (blocking, fast) and asynchronous communication modes (non-blocking)

Mixing Interaction Styles

Shows a visual representation of how to implement various interactions styles in order to communicate between several microservices
Discusses synchronous, event-based interactions, and how these are applied in scenarios

Synchronous Request/Response

Explores using REST over HTTP and the overhead added, emphasizing better, more efficient approaches such as RPC and other options (Thrift) for data communication between services. Explains how these communication technologies offer different levels of direct communication
Shows how Thrift can be utilized as a language-neutral solution

Asynchronous communication, event-based

Discusses client-service communication where events are triggered by clients.
Explains that once the event has been sent, the client does not wait for feedback or a response, but continues its execution and receives feedback via events or messages.
Explains the role of communication channels in asynchronous event-based communication
Explains the use of message brokers

Payload formats

Discusses various payload formats for exchanging data, such as JSON, XML, structured binary formats (Protocol Buffers and Avro)

Service Meshes

Explains the concept with use cases and details on how a service mesh can help maintain performance consistency while handling communication between microservices
Highlights the benefits in cloud deployments and management of different instances and nodes
Explains the use cases and describes various concepts used in microservices implementation

Conclusion

Summarizes the benefits of using PaaS and microservices in the Cloud, including features such as serverless computing, well-suited implementation for operations tasks, compatibility with containers, and various benefits from a scalability perspective.

Additional resources

Lists supplementary learning materials, including videos by industry experts, and ebooks

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Description

Test your knowledge on microservices architecture and dynos management in cloud platforms. This quiz covers topics like programming languages, pricing structures, and communication methods within microservices. Perfect for developers looking to deepen their understanding of modern application deployment techniques.