Lecture 9

Question 1

What is architecture in terms of software development?

Answer 1

Architecture: Designing a solution to a problem according to given constraints

Question 2

What is architecture style in terms of software development?

Answer 2

Architectural Style: General principles informing the creation of an architecture

Architectural styles inform and guide the creation of architectures

Question 3

What is a distributed system?

Answer 3

A distributed system involves multiple entities talking to one another in some way, while also performing their own operations

Question 4

What is Software Oriented Architecture (SOA)?

Answer 4

SOA is a way of developing distributed systems by combining stand-alone, reusable, loosely-coupled services.

SOA defines an architecture which usually consists of the following roles and the contracts between those
roles

Service Service Requestor Service provider–Publish–>Service

Question 5

How did we use to write software?

Answer 5

Monoliothic Architechture many components but….
One database
A single deployment unit
A single language/technology

Question 6

What is a service?

Answer 6

SOA centres around the concept of decomposing
business problems into services.

Service = Business Capability

Question 7

What are the principles of SOA?

Answer 7

Standardized service contract
service reusability
service discoverability
service composability
service loose coupling
Service abstraction
service statelessness
service autonomy

Question 8

How can SOA be realised?

Answer 8

SOA can be realised through a variety of technologies

Question 9

Describe the 3 evolutions of SOA

Answer 9

Evolution of SOA

1. SOAP-based web services
2. RESTful web services
3. Microservices

Question 10

What is a SOAP-based web service?

Answer 10

Based on international standards

Service interfaces is exposed through WSDL documents

Message exchange using SOAP

Client code may be generated from WSDL description

Question 11

What is a RESTful web service?

Answer 11

Representative State Transfer (REST)

Everything is a resource

Resources are identified by URIs and their state is manipulated through HTTP operations GET, POST, PUT, DELETE

Rather a set of architectural principals, than a standard

Question 12

SOAP-based services: drawbacks

Answer 12

Inefficient
Overly general
Heaveywieght

Question 13

SOAP vs REST web services

Answer 13

Independence – SOAP is language, and transport independent, while REST must use HTTP

Efficiency – REST can use smaller messaging formats, while SOAP requires XML for all of its messages

Environment – SOAP works well in a distributed environment, while REST assumes a direct point-to-point collaboration

Dynamic – REST is easier to implement and learn to use, SOAP requires more bandwidth and resources to work efficiently

Question 14

What is Microservices?

Answer 14

Microservices: evolution of SOA

Designed for Failure:
Designed for scale, if a service fails, the system should stay alive. Gave rise to chaos engineering

Deplopyment & Containerization:
Independent deployability over reuse. Microservices are often placed within a virtual container system such as Docker.

Automation:
Again, fast deployment depends on infrastructure
automation, DevOps, continuous integration