Software architecture - what is it and why it's important. Lecture for full-stack students in Elevation Academy. What are the features and qualities we use to measure software architecture pattern performance. Some diagrams were taken from Oreilly's "Software architecture patterns" book.

1. uri@wibbitz.com
Software Architecture

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• What is software architecture & why we need it
• Characteristics of a software system
• Review 4 common software architecture patterns
and understand their characteristics
Content

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The description of a software system structure,
components and their relations.
A phase in software development:
Requirements —> Architecture —> Implementation
What is software architecture?

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• Understand how the system will behave - each structure
has different qualities. (Agility, Scalability etc.)
• Serves as a blue print for developing the software and for
the project itself
• Enables reuse of software structure
Why architecture?

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• No clear definition of roles, responsibilities and relationships for code
components
• Hard to decide where to add required functionality
• Usually tightly coupled and hard to change code
• Hard to characterize the code
No architecture means

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Architecture characteristics

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Overall agility
• The ability to respond quickly to a constantly changing environment
Architecture characteristics

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Ease of deployment
• How easy it is to deploy the application - small change requires
deploy of the whole application
Architecture characteristics

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Testability
• How easy it is to test the system
Architecture characteristics

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Performance
• Efficiency of the system, usually in term of performance speed
Architecture characteristics

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Scalability
• The ability of the system to handle growth
Architecture characteristics

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Ease of development
• How easy it is to develop the system, considering complexity and
level of coupling.
Architecture characteristics

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Architecture patterns

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• Code components are organized in layers each with specific role
• Number of layers is not defined
A common use is a 3 layered structure with
• Presentation - User interface and browser comm. logic
• Business logic - some times divided to additional persistence
layer
• Database
Pattern: Layered Architecture (n-tier)

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• Customer data request
• Customer data includes orders
data
• Delegate in the presentation
layer knows which module in
the business layer to use for
each request (and it’s contract)
Layered arch. example

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Pattern Analysis - Layered arch.
Overall agility low
Ease of deployment low
Testability high
Performance low
Scalability low
Ease of development high

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• Distributed asynchronous pattern - highly scalable
• Made out of decoupled, single purpose event processing components
that asynchronously receive, process and publish events.
Pattern: Event-Driven Architecture

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• Example: Insurance system
• Event: an insured person moves
• Event processing stream:
• Customer event-processor: Change customer address and publish event
(customer address changed)
• Quote event-processor: Recalculate insurance rates and publish event
(recalc quote event)
• Claims event-processor: Updates an outstanding insurance claim and
publish event
Continues until no more events are published for that particular initiating event.
Event-Driven arch. example

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Pattern Analysis - Event-Driven arch.
Overall agility high
Ease of deployment high
Testability low
Performance high
Scalability high
Ease of development low

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• AKA plug-in architecture
• Natural pattern for implementing product-based applications
(downloaded in versions)
• Pattern allows to add additional application features as plug-ins to
the core application.
Microkernel Architecture

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Pattern Analysis - Microkernel arch.
Overall agility high
Ease of deployment high
Testability high
Performance high
Scalability low
Ease of development low

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• This is a distributed architecture pattern consists of (small) services
• Microservices main characteristics:
• Small and focused - doing one business function
• Loosely coupled - operates independently of one another
• Language Neutral
Pattern: Microservices Architecture

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• This is a distributed architecture - all components are fully decoupled
and accessed by some sort of remote protocol like HTTP(REST)
• Consists of service components
• Independently deployable
• Usually handles specific business use case
• Granularity issue - Service component can consist of one module
or a portion of the application
Pattern: Microservices Architecture

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• Setting service component granularity level is a challenge
• Need to orchestrate calls - too fine
• Making inner calls - too fine
• Too coarse means missing pattern advantages
Microservices - granularity level

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Pattern Analysis - Microservices arch.
Overall agility high
Ease of deployment high
Testability high
Performance low
Scalability high
Ease of development high

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Pattern Analysis
Layered Event-D Microkernel Microservices
Overall agility low high high high
Ease of deployment low high high high
Testability high low high high
Performance low high high low
Scalability low high low high
Ease of development high low low high

33. Thank You!