4.2 architecture introduction

Department Computer Science

University of Basel

Process Models

Software Life-Cycle Management

Architecture Introduction

What do we deal with by the way?

We …• Plan & Define

• Architect & establish

• Maintain & operate

… our Company’s Information System …

Department of Computer Sciences – University of Basel 2

What is a Company Information System?• Flight Booking System @ Lufthansa, Germany, mid 60ies

A Company Information System is comprised of ...• Processes

A Company Information System is comprised of ...• Function points and applications

A Company Information System is comprised of ...• Data, Data Structures and Data Containers (Folders, Binders et al)

A Company Information System is comprised of ...• Some sorts of technological infrastructure and underpinnings

What has changed is that ...• „Things“ have taken off the ground

• ... and become ...- Virtual

- Clonable

- Shippable

- Configurable

- Investigable

- Deletable

.. far beyond what was possible in the „things“ world of the mid 60ies Department of Computer Sciences – University of Basel 8

Architecture is not new

The Solution Architect in the 60ies had to arrange processes, data, applications, tools, spaces and other means, fundamental to the given business models …

Architecture is not new

… similar to what the Solution Architects have to in 2008

... just the means changed a bit in the meantime

Architectural disorientationWhy bother?

Architectural disorientation

What is architecture?

What are you expected to do as an architect?

How is architecture manifested?

A tube

A brush

How do you distinguish good from bad architecture?

Where and when does architecture occur?

Why is architecture to be developed – why is it useful?

Whereby is architecture developed?

Who is responsible for architecture?

How do you approach architecture?

What do you need to know as an architect?

Architecture evolves in its context – Barcelona …

All too often reality

We start with a „wish list“.

What follows is „a concept“.

A „first pilot“ is implemented.

The pilot goes life.

Changes are required.

To implement the changes we need to deviate from the original „concept“.

Software architectecture was created:

„Big Ball of Mud“-Pattern

In computer programming, Big Ball of Mud is a term for a system or computer program that has no real distinguishable architecture. It usually includes more than one of the other anti-patterns.

Maintaining a shantytown is labor-intensive and requires a broad range of skills.

One must be able to improvise repairs with the materials on-hand, and master tasks from roof repair to ad hoc sanitation.

However, there is little of the sort of skilled specialization that one sees in a mature economy.

All too many of our systems are, architecturally, little more than shantytowns.

Investment in tools and infrastructure is too often inadequate.

Tools are usually primitive, and infrastructure such as libraries and frameworks, is undercapitalized.

Individual portions of the system grow unchecked, and the lack of infrastructure and architecture allows problems in one part of the system to erode and pollute adjacent portions.

Question 4 you

What are symptoms of bad architecture?

Symptoms of immature architectures

Results of analysis phase are not adequately considered.

Holistic view of IT-System is missing.

Complexity increases and becomes unmanageble.

Planning and risk-management becomes difficult.

Reuse of expertise as well as system building blocks is difficult.

Flexibility, maintainability, interoperability become a problem.

Architecture documentation is missing or not up-to-date.

Steep learning curve for new staff entering the project.

Redundancy of code and functionality.

System‘s building blocks are heavily interdependent.

Very long development and change cycles.

System complexity

Have you ever seen or touched Architecture?

.. even here ..

We believe “No” ..

Design-time PerspectiveSystemPerspective(Physics)

Architecture is an inherent aspect of any system

But you can’t see nor can you touch it on the system level

Architecture is tangible only on the level of models and plans

Architecture is mainly about quality .. not functionality

Architecture has a mid- to long-term ROI .. you cannot avoid it

ArchitecturePerspective(Models & Plans)

Architecture of a computer or IT-system is not immediately tangible. Nevertheless does every IT-system have an architecture

There are many architecture definitions out there, which are typically comprised of the following aspects:• Structure

• Behaviour and collaboration of architectural building blocks

• Discipline and methodology

Architecture covers everything .. from a system‘s problem domain analysis phase up to this system‘s retirement

Architecture makes complexity manageable by focussing onto only the substantial aspects of an IT-system

System

People

An Architecture defines behavior

An Architecture Balances Stakeholder Needs• The needs of the end user are associated with intuitive and correct behavior,

performance, reliability, usability, availability, and security.

• The needs of the system administrator are associated with intuitive behavior, administration, and tools to aid monitoring.

• The needs of the marketer are associated with competitive features, time to market, positioning with other products, and cost.

• The needs of the customer are associated with cost, stability, and schedule.

• The needs of the developer are associated with clear requirements and a simple, consistent design approach.

• The needs of the project manager are associated with predictability in the tracking of the project, schedule, productive use of resources, and budget.

• The needs of the maintainer are associated with a comprehensible, consistent, and documented design approach, as well as the ease with which modifications can be made

An Architecture May Conform to an Architectural Style• Every well-structured software-intensive system is full of patterns. (Booch

• An architectural style defines a family of systems in terms of a pattern of structural organization. More specifically, an architectural style defines a vocabulary of components and connector types, and a set of constraints on how they can be combined. (Shaw 1996)

An Architecture is influenced by its environment

Architecture is not concerned with a system‘s fine grained structures and elements (i.e. classes, objects, algorithms) but instead with such system‘s coarse-grained components and building blocks

Architecture is concerned with all decisions which are difficult to be changed later on

Architecture is more than just the result of an architect‘s design-activities – architecture is a science in its own right

Architecture and Design are two sides of the same coin:• All respective activities, decision making, ways of thinking are no different at all

• Architectural Decisions just have a wide ranging impact (across the system)

• Design decisions have a rather local and isolated scope (e.g. sub-system)

Architecture aims at sustaining investments

United Nations – Sustainability“Sustainability means meeting the needs of the presence without compromising the needs of the future”

Architecture is concerned with Macro-Structures of a system. Well, here the question remains: „what are such macro-structures?“• For example, lock-strategies for persistence-stores …

• … or addressing schema length (e.g. 32-bit versus 64-bit) seem pretty low-level technical at a first glance

• However, if they have a significant impact on the system’s ability to evolve and scale over time they are architectural

Architecture contributes to the non-functional capabilities of our systems, where investments are vital & crucial but also have a diminishing ROI

What is architecture?Well – and there are a few more ;-)

First we make our Systems – then our Systems make us

We make Software like we make cathedrals – first we make them and then we pray

What is architecture?The spirit of architecture

What’s so cool about the SAPs of this world?

Company A Company B Company C

Frameworks are applied architecture• Hollywood principle ( „don‘t call us – we call you“)

• Architecture constraints – it controls potential developer-freedom based on a system‘s fundamental structures (e.g. backbone process logic).

Frameworks are applied architecture• Architecture guides.

• Architecture reduces complexity by offering dedicated extension points.

• Architecture frees up developers from architectural decision making (i.e. Backbone process logic).

Frameworks are applied architecture• The SAP system is an HR generic process expert.

• Novartis is an expert in their specific HR process requirements.

• The overall architecture balances these forces and allows for both, controlled evolution and governance, as well as flexibility.

Example

Architecture – Definition

“The software architecture of a program or computing system is the structure or structures of the system, which comprise software components, the externally visible properties of those components, and the relationships among them” [Bass et al]

Architecture is concerned with ...• the structure and structure(s) of a system ..

• its individual building blocks or components ..

• their externally visible properties ..

• as well as their relationships amongst these.

Architecture is concerned with the main pillars of a computer-system – not with this system‘s details ..

.. but what the main pillars are, depends on viewpoint and perspective!

Solution context A Solution context BDepartment of Computer Sciences – University of Basel 44

.. but what the main pillars are, depends on viewpoint and perspective!

Architecture – DefinitionAreas of Engagement

Strategic alignment & planning perspective with a focus on smoothly underpinning the continuous evolution of the overal IT Service landscape

Quality of Application and Infrastructure Service landscapes

with a clear focus on providing holistic views and view models for

planning purposes

Quality of individual Application and Infrastructure Services with a focus on quality attributes:• Stability• Performance• Extensibility• Security• Maintainability

Application & Infrastructure Architecture

Domain & Enterprise

Architecture

IT Planning & Strategy

Architecture – DefinitionAreas of Engagement

Architecture related Activities

Govern vs Perform

Application vs Infrastructure

Services

CCMOR Services

Enterprise vs Domain vs

Service

Trends & Innovation

Consulting

Communication

Planning & Roadmaps

Requirements

Dependencies

Concept & Design

PoCs & Candidates

Review & Verification

Documentation

Trends & Innovation

Training & Education

Assessment

Establish rules & policies

Execute rules & policies

ApplicationProcesses, Application, Data, Interfaces, …

InfrastructureMiddleware, Server, Storage, Frameworks, Network, Data Centers, …

Create

Change

Migrate

Operate

Retire

Enterprise (All)

Domain (Many)

Service (Single)

X X X X

Architecture contributes to the non-functional capabilities ( qualities) of a system as well as to its longevity• Extensibility (Quickly add PDF as a new UI channel)

• Adaptability and changebility (Add the role Supervisor to our system)

• Reusability (Reuse the Shopping Cart we developed for our portal)

• Managability (Grant the aquired company’s employees access to S)

• Security (Encrypt all data that goes into this database)

• Availability (Make sure the service is always up and running)

• Scalability (A marketing campaign is going to increase load on Site S)

• Performance (S is only used if search-result response time is below x)

Architecture shows the holistic whole only if all appropriate views are combined.

Function / Process View

Stakeholder View

Component View

Operational View

Deployment View

Hostand

operate

Package and

deploy

ImplementFunction

Function1 Function2 Function3

Architecture shows the holistic whole only if all appropriate views are combined .. but this should be done in order ..

Architecture shows the holistic whole only if all appropriate views are combined .. as shown here (Aarau Photo)

Architecture shows the holistic whole only if all appropriate views are combined .. as shown here (Aarau Model)

Architecture shows the holistic whole only if all appropriate views are combined .. as shown here (Public Transport)

Architecture shows the holistic whole only if all appropriate views are combined .. as shown here (Denisity of Populat.)

Architecture shows the holistic whole only if all appropriate views are combined .. as shown here (Buffer Zones)

Architecture shows the holistic whole only if all appropriate views are combined .. Zoom-Level is similarily important ..

Architecture shows the holistic whole only if all appropriate views are combined .. as filters ..

Architecture needs to be managed• One System

• Many Systems

Architecture needs to be managed over time• Yesterday ..

• Tomorrow

IT-Systems become increasingly more complex, which naturally leads to more specialised architectural domains and disciplines:• Enterprise-Architecture.

• Software-Architecture.

• Data-Architecture.

• Integration-Architecture.

• Network-Architecture.

• Security-Architecture.

• System-Management-Architecture.

• Etc.

One singular IT-System requires its overall architecture to take into consideration most – if not all – of the above listed areas and disciplines.

Architect

The Architect • is a Technical Leader

• role may be fulfilled by a team

• understands the system development process

• has knowledge of his business or technology domain

• has technology knowledge

• has design skills

• has programming skills

• is a good communicator

• makes decisions by balancing tradoffs

• is aware of organisations’ politics

• is a negotiator

Architecting

Architecting • is an art

• spans multiple disciplines

• is an ongoing activity

• is driven by many stakeholders

• often involves making tradeoffs

• acknowledges experience

• is both top-down and bottom-up

ArchitectingThe benefits of Architecting

The benefits of Architecting • it addresses system qualities

• it drives consensus

• it supports the planning process

• it drives architectural integrity

• it helps manage complexity

• it provides a basis for reuse

• it reduces maintenance costs

• it supports impact analysis

Questions?

4.2 architecture introduction

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