Lecture 1 - Introduction to architecture by Michel Chaudron - Part 1

Summary

This lecture introduces software architecture, discussing its importance, fundamental concepts, and role in system design. It covers the challenges faced by software engineers, the evolution of software complexity, and the strategic planning needed for effective architecture. The lecture emphasizes the interplay between business, user requirements, and technology, highlighting architecture's role in aligning these forces and its impact on project costs and risks.

Takeaways

• 🏗️ Software architecture is the structure of a computing system that comprises software components, their externally visible properties, and the relationships among them. It is crucial for determining system qualities like performance, modifiability, and security.
• 🤔 The importance of software architecture lies in its role in reducing product costs, decreasing time to market, and managing the complexity of increasingly interconnected and globally competitive software systems.
• 📈 As software grows in size and complexity, architects must plan for evolution to keep the system manageable. This involves understanding the impact of design decisions on system components and their interactions.
• 👥 Software architecture serves multiple purposes, including answering why the system is needed, documenting important design decisions, and guiding the system's implementation.
• 🔍 Architecture documentation is essential for describing and communicating the system's important aspects to all stakeholders, facilitating feedback and steering the design in a value-adding direction.
• 🛠️ The architecture guides the implementation by providing guidelines for design and addressing common design problems, such as security, which can vary in perspective depending on the stakeholder's role.
• 🔄 An architecture should be designed to accommodate foreseeable changes and new features, aiding in reducing maintenance costs and enhancing the system's adaptability.
• 🌐 The global workflow of architecture design involves a backlog of issues to be tackled, driven by context requirements and evaluation results, emphasizing the iterative nature of the architecture development process.
• 🔍 Different perspectives on architecture exist, such as enterprise-level architecture focusing on business processes and systems coordination, and product family architecture emphasizing commonalities and variability management.
• 💡 A proper software architecture process involves negotiating and balancing functional and quality requirements with possible solutions, highlighting the intertwined nature of requirements engineering and software architecture.

Q & A

What is the primary focus of the advanced software architecture course?

The primary focus of the advanced software architecture course is to help learners understand the fundamentals of architecture and design, starting by describing what software architecture is, why it is important, and discussing the general issues that must be considered such as requirements, constraints, and the intersection between the user, business, and technology.

Why is software architecture important in the context of increasing software complexity and global competition?

Software architecture is important because it helps manage the complexity of software, which is rapidly increasing and becoming more interconnected. It also plays a crucial role in reducing the cost of products, decreasing time to market, and ensuring that software can evolve and adapt to changing requirements and technologies in a competitive global market.

What are the three main purposes of software architecture?

The three main purposes of software architecture are: 1) to answer questions related to why the system is needed, 2) to document the important design decisions, and 3) to guide how the system shall be built, providing guidelines for design and implementation.

How does software architecture support business objectives?

Software architecture supports business objectives by allowing stakeholders to see what the system will be like and how it will meet their expectations, showing which modules and technologies need to be implemented and integrated for a working system, and helping in achieving targeted quality of the system by defining common solutions to be used across the system.

What is the role of architecture in managing the complexity of a system?

Architecture helps in managing the complexity of a system by providing a common definition of the system to be built, guiding the implementation, and maintaining an overview of complex systems. It also aids in systematic analysis of 'what if' questions and identifying the consequences of changes or alternative design decisions.

What is the relationship between software architecture and the development of a product family?

In the context of product families, software architecture is crucial for exploiting commonalities between different products while managing variability. It helps in designing an architecture that supports the evolution and extension of different features across various product variants within the family.

How does the architecture process involve negotiation and balancing of requirements and solutions?

The architecture process involves an iterative cycle where initial functional and quality requirements lead to the development of an initial architecture. This architecture is then discussed with stakeholders, leading to further refinement of requirements and architecture until an agreement is reached, ensuring that the final design meets both functional and quality needs.

What are the different perspectives on what constitutes software architecture?

Different perspectives on software architecture include viewing it as the structure of a system comprising software components and their relationships, as the fundamental concepts and properties embodied in its elements and design principles, and as the set of design decisions that determine the quality properties of a system.

How does the architecture process handle the evolution of software over time?

The architecture process acknowledges that software is always changing and incorporates principles for evolving the architecture. It is not just a static picture but also defines how the architecture can evolve over time, ensuring that the system remains manageable and adaptable.

What is the significance of architecture in the early stages of a project's lifecycle?

Architecture is significant in the early stages of a project's lifecycle because the decisions made in these initial stages determine 90% of the cost and risk of the entire project. A solid architecture can reduce development costs in the long run and ensure that the system is robust and adaptable to future requirements.

Outlines

00:00

🏗️ Introduction to Software Architecture

This paragraph introduces the concept of software architecture, emphasizing its importance and fundamental role in the design process. Michelle Shodon, the lecturer, outlines the lecture's topics, which include understanding software architecture's definition, its purposes, and objectives. The paragraph also discusses the challenges faced by software engineers, such as reducing product costs and decreasing time to market. The complexity of software is highlighted, with an example of how video game software has evolved over time. The architecture serves multiple purposes: it answers why the system is needed, documents important design decisions, and guides the system's implementation. The importance of aligning the implementation with the architecture is also stressed.

05:00

📈 Business Objectives and Architecture

In this paragraph, the focus shifts to how software architecture supports various business objectives. The architecture serves as a tool for stakeholder discussions, allowing them to visualize and provide feedback on the system's design. It also aids in identifying necessary modules and technologies for system development, facilitating discussions on development schedules and potential reuse of components. The architecture is crucial for achieving targeted system quality by defining common solutions and enabling early analysis of various quality properties like performance, security, and maintainability. The paragraph also touches on the iterative process of architecture design, involving requirements engineering and constant negotiation and balancing of functional and quality requirements.

10:00

🌐 Software Architecture Definition and Perspectives

This paragraph delves into the definition of software architecture, describing it as the structure of a computing system that includes software components, their externally visible properties, and their relationships. The architecture is crucial for carrying system qualities like performance and security. Different perspectives on architecture are discussed, highlighting its role in focusing on important decisions and managing the complexity of systems. The paragraph also explores the concept of architecture in the context of enterprise-level coordination and communication, distinguishing between business processes, functional layers, application layers, and technical layers. Additionally, the distinction between designing architecture for a single product and a product family is discussed, emphasizing the need to manage variability while exploiting commonalities.

15:02

🔍 Importance of Architecture and Alignment

The final paragraph concludes the lecture by emphasizing the importance of architecture in the early stages of a project's lifecycle. It notes that architecture decisions made in the first 10% of the project determine 90% of the project's cost and risk, underscoring the need for a solid architecture. The paragraph also discusses the role of architecture in aligning business, user requirements, and the technological landscape, highlighting its ability to enable analysis and planning of how changes in one domain affect others. The lecture concludes by reiterating the value of architecture in reducing development costs and ensuring the system's robustness as new requirements are added.

Keywords

💡Software Architecture

Software architecture refers to the structure of a computing system, which includes the software components, their externally visible properties, and the relationships among them. It is the primary carrier of system qualities such as performance, modifiability, and security. In the video, it is emphasized that architecture is crucial for early analysis to ensure that the design approach will yield an acceptable system, and it is the foundation for making informed design decisions that affect the system's evolution and quality.

💡Design Decisions

Design decisions in the context of software architecture are the choices made that determine the quality properties of a system. These decisions are not just about the components and their relationships but also the rationale behind them. The script mentions that architecture consists of a set of design decisions, highlighting the importance of these decisions in shaping the system's functionality and evolution.

💡Requirements and Constraints

Requirements and constraints are essential considerations in software architecture. They define what the system must do and the limitations it must operate within. The script discusses how these factors intersect with user needs, business objectives, and technological capabilities, shaping the overall design and functionality of the software.

💡Components, Interfaces, and Connectors

Components, interfaces, and connectors are key concepts in software architecture. Components are the building blocks of the system, interfaces define how components interact, and connectors facilitate communication between them. The script uses these terms to illustrate how the architecture of a system is composed and how its parts interact, which is crucial for understanding the system's behavior and managing its complexity.

💡Evolution

Evolution in software architecture refers to the process of changing and improving the system over time. The script mentions that software starts simple but becomes more complex, necessitating a plan for evolution to keep the system manageable. This concept is critical in architecture design as it ensures that the system can adapt to new requirements and technologies.

💡Stakeholders

Stakeholders in the context of software architecture are individuals or groups who have an interest in the system. The script discusses how architecture allows stakeholders to see what the system will be like and how it will meet their expectations. Engaging stakeholders is crucial for gathering feedback and aligning the design with their needs and expectations.

💡Quality Properties

Quality properties in software architecture are attributes such as performance, security, and maintainability that the system must exhibit. The script highlights that an architecture should define common solutions to be used across the system, linking to the concept of conceptual integrity, and be the basis for analyzing various quality properties, ensuring that the system meets its intended goals.

💡Product Families

Product families are sets of systems that share many commonalities, such as mobile telephones or software in cars. The script discusses the challenges in designing architecture for product families, which arise from the need to support and maintain a large number of variants. The goal is to exploit commonalities while managing variability, which is crucial for efficient development and maintenance.

💡Backlog

In the context of software architecture, a backlog is a list of issues to be tackled, such as open problems or ideas that still need to be investigated. The script uses the term, borrowed from Agile development methods like Scrum, to describe how the architecting process is driven by a backlog, which contains items that are refined and evaluated iteratively.

💡Conceptual Integrity

Conceptual integrity in software architecture is the idea that a system should be designed as a coherent whole, with a consistent set of design principles. The script mentions that defining common solutions across the system is linked to this concept, emphasizing the importance of a unified vision in architecture design to ensure that the system's parts work together harmoniously.

💡Risk Analysis

Risk analysis in software architecture involves identifying and assessing potential problems that may arise during the development or operation of the system. The script discusses how an architecture can be used to show whether the implementation of a new feature will be simple or complicated, aiding in feasibility and risk analysis. This is crucial for making informed decisions and mitigating potential issues early in the development process.

Highlights

Software architecture is crucial for understanding the fundamentals of design.

Architecture involves considering requirements, constraints, and the intersection of user, business, and technology needs.

Software architecture defines the role, purposes, and objectives, emphasizing components, interfaces, and connectors.

The size and complexity of software are rapidly increasing, posing challenges for software engineers.

Software architecture helps in reducing product costs and decreasing time to market for new products or features.

An empirical law in software engineering states that software complexity increases over time, necessitating a plan for evolution.

Software architecture serves as a common definition of the system to be built, aiding in communication among stakeholders.

Architecture documentation is essential for guiding the implementation of the system by providing design and implementation guidelines.

Monitoring the correspondence between implementation and architecture is key to successful architecture implementation.

Software architecture supports business objectives by facilitating stakeholder discussions, planning development schedules, and enhancing common understanding.

Architecture impacts the targeted quality of the system by defining common solutions and enabling early analysis of various quality properties.

Architecture design should be adaptable to integrate foreseeable changes and new features, reducing maintenance costs.

Software architecture helps in managing the complexity of systems, allowing for systematic analysis of potential changes.

The software architecture process involves negotiating and balancing functional and quality requirements with possible solutions.

Requirements engineering and software architecture are intertwined, not strictly separated phases.

A proper software architecture can reduce development costs in the long run and ensure the system's robustness.

Architecture is about thinking in advance and planning for the lifecycle of the project to develop the right architecture.

The importance of architecture is emphasized as decisions made in the initial 10% of a project's lifecycle determine 90% of the cost and risk.

Transcripts

welcome to the advanced software

architecture

course my name is Michelle shodon and

this is the lecture introduction to

architecture this lecture contains a

series of topics that will help you

understand the fundamentals of

architecture and

design it starts by describing what

software architecture is and why it is

important it discusses the general

issues you must consider such as

requirements and constraints and the

intersection between the user the

business and the

technology this is followed by a

description of the most important

concepts of the field of software

architecture firstly we define the role

of software architecture and present its

purposes and objectives

at the end the key concepts are

presented such as components interfaces

and

connectors the size and complexity of

software increases

rapidly moreover software is

increasingly connected to other pieces

of

software and all of this is in a global

competition where software being

produced in one country can be sold

easily in another

country all of these together lead to a

collection of challenges that software

Engineers are facing

today to start the cost of products must

be

reduced also the time to market for

delivering a new product or feature must

be decreased significantly

significantly single products are

becoming part of product

families and software is upgraded after

after

deployment there is an empirical law in

software engineering which states that

the complexity of software increases

over

time

always this is

inevitable software starts simple and

feasible but a plan is needed for

evolution to keep the system

manageable to illustrate the growth of

software over the years the following

example presents grow graphs of video

game

software each node in a graph represents

a module which represents a major piece

of

functionality and the arcs represent

couplings between these

modules two nodes with an arc between

them need to communicate

intensively so design decisions made in

one note will propagate an impact its

neighbors by looking at figures 1

through before you should get a general

idea of how the situation has changed

over time both size and complexity have

increased a

lot creating software is a collective

effort of many designers and Engineers

together the first thing an architect

needs to do is to analyze and understand

the purpose of the software being

designed architecting involves

considering many aspects that are

crucial to get working

products a second important purpose of

an architecture is that of being a

common definition of the system to be

built in this sense the architecture

documentation is a way of describing and

communicating the important aspects of

the system to all

stakeholders thirdly the architecture is

the main guide for the implementation of

the system the implementation work is

done by the designers and

developers guiding the implementation is

done by providing guidelines for the

design and

implementation for instance by stating

which mechanisms should be used for

addressing commonly occurring design

problems for example

security and these guidelines could

cover different view

points so the three main purposes of an

architecture are

to answer questions related to why the

system is

needed to document what are the

important design

decisions and how the system shall be

built and once the architecture is done

it is important to to constantly monitor

the correspondence of the implementation

to the

architecture this is a key to the

successful implement impementation of

the

architecture there are several business

objectives that can be supported through

a software

architecture firstly an architecture can

be discussed with

stakeholders the architecture allows

stakeholders to see what the system is

going to be like and how it will how it

will meet their

expectations stakeholders then have a

chance to give feedback and steer the

design of the system into the direction

that yields most value to

them secondly an architecture shows

which modules and Technologies need to

be Implement implemented and integrated

in order to get a working

system this enables the discussion on

the development schedule as well as

offering options for

reuse an explicit representation of the

architecture also triggers discussion

and enhances common understanding

amongst the developers of the system

thirdly creating an architecture has a

positive impact on achieving the

targeted quality of the

system to start an architecture should

Define the common solutions to be used

across the

system this links to the concept of

conceptual Integrity which we will

discuss later in the

course moreover an architecture can be

the basis for analyzing various qual

properties of the

system for example based on a software

architecture Architects can discuss what

will be its performance or performance

bottlenecks other quality properties

that can be analyzed based on an

architecture include amongst many others

security and

maintainability at an early stage of

development it is still easy and not yet

costly to improve an architectural

design

and thereby the systems quality based on

the insights of such architectural

analyses finally the architecture should

be designed such that foreseeable

changes and new features can be

integrated easily into the

system in this way the architecture AIDS

in reducing the maintenance costs of a

system systems are becoming very

complex often they are so complex that

no single person can oversee all the

relevant aspects of a

system an architecture can help in

maintaining an overview of complex

systems also when an architecture

diagram looks complicated it probably is

complicated and it needs to be

simplified as such an architecture helps

in managing the complexity of a

system in a similar ve

having an architecture representation

allows for systematic analysis of what

if

questions the explicit representation

helps in identifying all the

consequences that a change or an

alternative design decision may

have an architecture can be used to show

whether the implementation of a new

feature will be simple or

complicated as such the architecture

AIDS in a ing

feasibility and in discovering risks or

more generally in doing risk

analysis a proper software architecture

process involves negotiating and

balancing of functional and quality

requirements on one hand and possible

solutions on the other

hand this means requirements engineering

and software architecture are not

subsequent phases that are strictly

separated but instead they are heavily

intertwined an initial set of functional

and quality requirements is the starting

point for developing an initial

architecture this initial architecture

results in a number of issues that

require further discussion with

stakeholders for instance a solution may

be too costly integration with already

existing systems may be

complex maintenance may be an issue

because of a lack of Staff with certain

expertise or performance requirements

cannot be

met these insights leads to further

discussion with

stakeholders a revised set of

requirements and ultimately to a revised

architecture this iterative process

continues until an agreement is

reached only then will a detailed design

and implementation

proceed this slide shows the global

workflow that is common to architecture

design

Methods at the center a backlog is

depicted the backlog contains a list of

issues to be tackled these are open

problems or ideas that still have to be

investigated the name backlog deres from

scrum and Agile development

method there the backlog drives the

project in architecture design the

notion of backlog is usually not used

explicitly yet it is always there

if only in the head of the

architect there are three inputs to the

backlog

context requirements and evaluation

results the context refers to such

things as upfront ideas the architect

may have available assets that can be

used constraint sets and the

like obviously the requirements

constitute another important input

in each step of the architecting process

one or a few items from the backlog are

taken and used to refine the

architecture developed so

far the result of this refinement is

evaluated usually rather

informally and this evaluation May in

turn change the contents of the backlog

new items may be added for instance new

problems that were discovered items may

disappear or become Obsolete and the

priorities of backlog items may

change what is software

architecture a common definition of

software architecture is the

following the software architecture of a

Computing system is the structure of the

system which comprises software

components the externally visible

properties of those components and the

relationships among

them the architecture is the primary

carrier of system qualities such as

performance modifiability and

security none of these can be achieved

without a unifying architectural

Vision architecture is an artifact that

allows early analysis to make sure that

the design approach will yield an

acceptable

system by building effective

architecture you can identify design

risks and mitigate them early in the

development

process there are more than one

definition about software architecture

and they provide complimentary

views here are two other

views software software architecture is

about the fundamental concepts and

properties of a system in its

environment embodied in its elements

relationship and the principles of its

design and evolution so this definition

emphasizes the relation between

architecture and its

environments moreover as we said before

software is always

changing therefore the way that an

architecture can evolve is an important

part of the architectural design so it

is not only AES static picture but uh

architecture defines the principles

about evolving an

architecture a complimentary view on

architecture is that architecture

consists of the set of design decisions

that determine the quality properties of

a system

this definition emphasizes that

architecture is not only the outcome in

terms of components and

relations but also the reasoning or

rationale that underlies this

outcome the reasoning connects the

architecture design to its

contexts this insight has led to

substantial Research into software

architecture Knowledge

Management overall it's good to realize

that architecture design choices May

address different levels of abstraction

in the system

system here are a few additional angles

from software

architecture architecture should focus

on the important stuff whatever that is

this refers to the fact that software

Architects should concern themselves

with those decisions that have high

impact on the system and its

stakeholders also architecture should

focus on things that are hard to change

since designing the architecture takes

place at the beginning of A System's

life cycle the architect should focus on

decisions that have to be right in the

early stages of a

project in it practice different people

use the term architecture in different

ways this is because they have different

perspectives on

architecture often depending on the role

that a person plays in an

organization the next set of slides

explains some of these different

perspectives when you talk with someone

about architecture it's good to ask

which perspective they have so as to

avoid

misunderstandings the Enterprise level

of Architecture is focused upon

coordination and communication of

business processes and it systems across

an entire

organization generally an Enterprise

architecture distinguishes four

layers the first layer is that of

business

processes that means the operational

steps of a workflow in some business

unit or possibly across different

division

boundaries the second layer is the

functional layer this layer defines what

type of functions should be available in

the

system nowadays this layer Maps closely

on

Services the previous two layers are

abstract in the sense that they are

intangible

the next layer is the application

layer this layer describes the software

applications that Implement certain

functionality these applications are

supposed to supply the functions that

are described in the functional

layer this layer is not abstract in the

sense that applications exist in the

real

world and finally there is the technical

layer this layer contains

infrastructural elements of the it

landscape such as the actual computers

on which the applications run as well as

Hardware operating systems network

software and

middleware types of

architecture rather than producing

individual Unique Systems some

Industries produce sets of systems that

have many

commonalities for example mobile

telephones or software and

cars such sets of systems that share

many commonalities are called Product

families a topic that software

Architects must consider is the

difference between the design of

architecture for a single product and

the design of an architecture for

product

family the challenge in product families

arise from the large number of variant

that must be supported and

maintained often the different features

have their own needs for evolution and

extension each individual product within

the product family is called a product

variant

while possessing specific features to

meet particular set of customer

requirements all product variants are

similar in the sense that they share

some common customer perceived value

they have common structures and or

common product technologies that form

the platform of the

family a product family targets a

certain Market segment segment whereas a

product variant is developed to address

a specific set of customer needs of a

market segment

in summary the aim of having a product

family architecture is to exploit the

commonalities between different products

and yet make the variability

manageable one reason why architecture

is important is because it is an enabler

for alignment between three

independently evolving forces that shape

a system the business user requirements

and the technological landscape an

architecture should make it possible to

analyze and plan how changes in one of

these domains affect the other

domains we're approaching the end of

this lecture and now we want to

emphasize the importance of

architecture the architecting is

typically done in the first 10% of the

life cycle of a

project and the decisions made in these

initial 10% determine 90% of the cost

and risk of the entire

project so make making a proper

architecture is very

important a solid architecture can

reduce the cost of development in the

long run ensuring that the system won't

crack at the seams when you add the next

portion of

requirements so in short architecture is

about thinking thinking in advance

thinking ahead and yes the development

of good architecture takes a bit of time

it can cost a bit but it pays off in the

long

run as long as you anticipate and map

out the life cycle of your project it is

possible to develop the right

architecture without costing much time

or impacting your

schedule at the end of this lecture you

should now know and be able to

explain first what is a software

architecture secondly why is software

architecture

important the lecture introduction to

architecture is now finished thanks for

watching