(c) Michael Stal, Keynote for OOP 2003 6/3/2015 slide 1 Power of Powerpoint:

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(c) Michael Stal, Keynote for OOP 2003

Power of Powerpoint:

Living in an Agile World- Überleben auf der ÜberholspurKeynote, OOP 2003

Michael Stal

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Agenda

Goal of this talk: To illustrate agility from different perspectives:

Definition of Agility Motivation behind Agility Agile Architecture Agile Technology Agile Organization Summary

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What the Hell is Agility?

According to my search engine agility is about Dog Training or Older People

According to many software engineers it is about eXtreme Programming and competing software

engineering methodologies So, what is the right answer, anyway?

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One View of Agility

"Agility is a core competency - it is the capability to respond in a satisfactory manner to change, uncertainty and unpredictability in the wider business environment.“

"Agility is a next generation manufacturing concept. It belongs in the 21st century and does not fully exist in any company today. The challenge for the future is to create agile companies using technologies, organisational forms and people to develop a new form of manufacturing that transcends existing mind sets that are becoming increasingly dominated by the dogma of lean production."

"If agility does not scare you, then you have not fully understood what it is about.“

All quotations taken from Paul T. Kidd, next generation manufacturing expert

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Agility and Software Development

If we follow this definition, agility is an important issue in our business: Software developers are definitely facing

change, uncertainty, and unpredictability! We all work in companies that are driven by

competition, increasing market requirements and higher speed of technology and product innovation.

Thus, we are driven by agility. As an example, let us take a look at software

development in the industry.

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Industry and Business -A Look into the Crystal Ball

Smart Traffic: Smart cooperation of vehicles, goods, infrastructures to enable fast and seamless transportation.

E-Government: Administration on the Web. Ubiquitous Services: Smart services that

can be consumed from anywhere using any device.

Intelligent Home.

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Forces

Web- and Net-based Integration of Applications, Services, and Systems

Quality of Service issues such as availability, resource and time constraints, ...

Deployment of Automated and Autonomous Systems

Smart, ubiquitious Services that share and distribute context

Heterogeneous Data Software as Service

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... And Consequences

Developers should not make too many assumptions about usage contexts and environments a priori.

Developers don‘t live on an island and must integrate legacy code and other peer systems.

Programmers need to develop and deploy their software on different heterogeneous machines and devices.

Running applications are reconfigured instead of recompiled. Software Engineering must cope with change requests in

Internet time.

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Multiple Aspects increase complexity of Software Engineering

Today‘s Forces: Global markets lead to strong competition Time-to-market and costs must be reduced Quality is a conditio-sine-qua-non Cyle times are extremely fast Software as Service and Software as (Web-based)

Integration Platform To meet these requirements multiple aspects have to be

considered that are strongly interdependent: Efficient organizations to steer software development

effectively Appropriate, stable but extensible software architecture

to meet today‘s and tomorrow‘s requirements Right technologies to implement the software

architecture

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Agile Architecture

"I conclude that there are two ways of constructing a software design: One way is to make it so simple there are obviously no deficiencies and the other way is to make it so complicated that there are no obvious deficiencies."

--- Tony Hoare, Turing Award Lecture, 1980

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Architecture Does Matter

„Software entropy“ should be maximized, i.e., loosely coupling between peers, decentralized information access, reflective approaches („Just-in-Time Integration“).

Software should be partitioned into composable services that can be spontaneously connected and orchestrated by business/technical processes (component-based software).

Software means to connect people and devices.

Legacy code must be integrated in order to protect investments.

It is important to leverage architectural concepts.

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Flavors of Architecture

Today‘s and even more tomorrow‘s Software Architecture is Multi-Tier, to logically and physically allow to distribute functionality,

and to separate concerns; Component-based, to enable integration, easy usage of vertical

services (persistence, transactions, security), scalability, and re-use; service-oriented, to support arbitrary devices (pervasive computing), to

enable the deployment of value-addes services; aspect-oriented, to ease separation of cross-cutting concerns from

business logic and to increase manageability and flexibility; (at least partially) decentral, to assure fault tolerance and allow to

integrate autonomous devices and services; open (and web-based), because heterogeneity is predominant

everywhere so that integration aspects will become one of the most important issues.

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Architect‘s Toolset to reach these Goals

Processes, such as the Unified Software Development Process or MDA.

Notations, such as UML. Technologies, such as frameworks and

distributed object computing. Enabling techniques like separation of

concerns; and programming paradigms, such as object technology.

Each approach addresses a specific aspect in the process of constructing high-quality software architectures.

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Is this sufficient?

However, all these concepts do not tell how to solve a very specific problem that arises during the construction of a particular software system.

For example, how to keep two cooperating components consistent to each other, or how to organize the event handling in a distributed system?

Solving such problems is still left to developer’s intuition and experience in software construction.

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Patterns

Experts mostly do not invent solutions. When experts work on a particular

problem it is unusual for them to tackle it by inventing a new solution that is completely distinct from existing ones.

Confronted with a ‘new’ problem they often remember a similar one they once solved successfully and adapt the ‘old’ solution to the new context.

Experts think in Problem/Solution pairs. Reusing ideas keeps development smart

and agile, wasting time does not!

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Let’s take a lookat a well-knownpattern

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Observer (1)

Observer (GoF)

ProblemChanging the internal state of a

component may cause inconsistencies to the state of

other components.

How can we restore consistency effectively in a way that:

the information provider must not depend on information consumers;

and the information consumers that depend on the information provider must not be known a

priori.

House1 Door_A; Window_1a Window_1b ...

is presented as

depends ondepends on

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Observer (2)

Solution-StructureImplement a change propagation

mechanism between the information provider, the subject, and the information consumers, the observers.

The Subject maintains a registry of observers and notifies all registered observers about changes to its state.

An Observer declares an update function to be called by the subject’s change propagation mechanism.

Concrete Observers implement the update function in a system-specific manner.

Subject

attachdetachnotifysetDatagetData

s->getData()

Observer

update

ConcreteObserver

updatedoSomething

state = X;

notify();

stateobserverList

for all observersin observerList do notify();

*

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Observer (3)

Solution-Dynamics

The Observers register with the subject’s change propagation mechanism.

A Client modifies the subject’s data.

The Subject starts its change propagation mechanism.

The Subject calls the update function of every registered observer.

The Observers retrieve the changed data from the subject and update themselves.

Subject Observer 1 Observer 2

attach(this)

attach(this)

setDatanotify

update

getData

update

getData

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Observer (4)

Benefits Defined handling of dependencies between

otherwise strongly coupled components Support for dynamic configuration of

a subject with observers Adding new observers does not affect the

subject or the change propagation mechanism

Liabilities Indirection Unnecessary updates Update cascades

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Properties of Patterns

A Pattern presents a concrete solution schema

for recurring design problems; documents proven design

experience; specifies concepts above the level of

individual classes and objects; describes structure and behavior of

cooperating objects; provides a common vocabulary and

concept understanding; and addresses specific quality properties

of the problem’s solution. Thus patterns are a perfect means

for agile software development.

ObserverProblem

Solution

House1 Door_A; Window_1a Window_1b ...

is presented asdepends ondepends on

Subject

attachdetachnotifysetDatagetData

s->getData()

Observer

update

ConcreteObserver

updatedoSomething

state = X;notify();

stateobserverList

for all observersin observerList do notify();

*Subject Observer 1 Observer 2

attach(this)

attach(this)

setDatanotify

update

getData

update

getData

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Best Practice Patterns

No patterns is an island. Using whole pattern systems that cover best practices in a

given domain such as Core J2EE Patterns helps to minimize integration and implementation efforts (thus increasing architectural agility):

Delegate

ServiceLocator

Session Facade

TransferObject

DataAccessObject

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Patterns for Architectural Analysis

It is often forgotten that patterns do not only help to build new software architectures, but

Patterns are also an appropriate means to understand exising software architectures.

Take a look at your favourite platform (Java, .NET) and reverse engineer it by mining its underlying principles.

In practice, software architects need to do both: They leverage patterns to design new functionality and they reverse engineer the patterns behind legacy code

for integration purposes

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Quality is a First Class Object

We cannot sacrifice quality for agility. For software projects it is surprisingly difficult to achieve quality. Quality is nothing others take care for after you finished your project! There are two important aspects:

Does the architecture meet the functional requirements? Does it also meet its non-functional requirements such as

performance, security, scalability? Quality Assurance starts before the project starts and it never ends.

Programmer's Drinking Song (sung to the tune of ``100 Bottles of Beer'‘): 99 little bugs in the code, 99 bugs in the code, fix one bug, compile it again, 101 little bugs in the code. 101 little bugs in the code....(Repeat until BUGS = 0) -- Anonymous

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Aspect-Oriented Software Architecture

How can we keep our systems flexible and easily reconfigurable? We can reach this goal by taking separation of concerns to an even higher level

Non-functional properties are typical candidates for the emergence of cross-cutting concerns

Cross-cutting concerns define aspects of a software system that are not localizable and therefore spread across the system such as security aspects

While OO helps to decompose functionality (separation of concerns), it doesn‘t help to factor out cross-cutting concerns

Generative techniques and Aspect-oriented Programming are potential candidates that come to our rescue

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The Need for Integration

Software Users often use systems that consist of

heterogeneous islands. need fast RoI for IT investments.

Smart integration helps reducing the costs. Integration solutions require:

Architecture with strong separation of concerns (component-based, multiple Tiers).

Appropriate technologies that offer maturity, acceptance, support, and productivity.

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Levels of Integration

Unfortunately, there are different layers of integration.

We must cope with almost all of them.

Platform Integration

Interoperability of Data & Communication

Service Integration

Persistence Integration

Workflow Integration

Web Integration

Client Integration

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Integration Pyramid

Until now for each integration layer software engineers tried to follow the best-of-breed approach. However this approach might lead to heterogeneity and even increase complexity .

A uniform and cross-cutting techical solution leads to a much better integration solution because this approach spans all layers.

Today‘s platform such as Java and .NET are already targeting this multi-layer integrating problem. They hide heterogeneity by a homogeneous stack of APIs.

Integration between Java and .NET through Web technologies/XML.

Client

Business and Web Layer

System-Level Protocol Layer

Middle Layer

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Agile Technology

“The most likely way for the world to be destroyed, most experts agree, is by accident. That’s where we come in. We’re computer professionals. We cause accidents."

--- Nathaniel Borenstein, Programming as if People Mattered

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Technology does also matter

Necessary to choose the right software technologies: IDEs, CASE-Tools, CM-Tools, Test-Tools, Middleware.

The best architecture and the best process will not help if you choose the wrong technologies. Some technologies are more like shooting youself in the foot.

Take integration as an example. You‘ve got a choice of integration platforms:

Microsoft .NET J2EE Web + XML CORBA EAI

Think „Service-based“ not just „Web-based“!

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Case Study: Selecting the right Middleware

For integration and communication, middleware solutions are essential

There are different kinds of communication middleware: Object-oriented Middleware (e.g., CORBA, COM, RMI) Message-Oriented Middleware (e.g., JMS, MSMQ) Transaction Monitors (e.g., Tuxedo)

Middleware decisions depend on the concrete requirements of your application domain. If different approaches are appropriate, you may

Choose the best-of-breed approach, or use Hybrid solutions (e.g., EJB, .NET+MSMQ+COM+)

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The Web reveals Limitations

Lacking interoperability between middleware solutions. Insufficient Web integration. No programmatic access.

HTTP TUNNELFRONTEND BACKEND

Web Server

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Future Vision: Service-Oriented Approach

User E-Shop

login

displayItems

selectItem

CustomerObjcreate

checkPreferences

Inventory

checkAvailability

updatePage

paycheckCredit

Credit Cart Company

checkCreditdisplayOrderInfo

accept

handleOrder

Web XpressTransport Co

sendOrder

logoff

fini

www.e-shop.com www.credit.com www.transport.comBrowser @ Home

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The Web is an excellent integration platform since it relies on open standards.

Using the Web we can establish an architecture that supports web-based inter-application communication

paradigms, provides location transparency, allows to add, exchange, or remove services

dynamically, hides system details from the developer.

The Web is the Computer

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Solution Architecture: The Web as a global middleware

marshal

unmarshal

receive_result

service(proxy)

Client-side Proxy

marshal

unmarshal

dispatch

receive_request

Server-side Proxy

start_up

main_loop

service(impl.)

Service

call_service_p

start_task

Client

calls*

1

calls

*

1

Message exchange*

Message exchange *1

register_server

find_server

establish_communication

Broker1

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Step 1 – Providing a Transport Protocol

A protocol defines syntax, semantics and order of messages exchanged between peers. SOAP is the right protocol.

<soap:Envelope><soap:Header>

<transaction><soap:mustUnderstandstand=„true“

xmlns=„http://tx.com“><id> 12345678 </id>

</transaction><soap:Header><soap:Body>

<m:getPhoneNumber><theName> Bill Gates </theName>

<m:/getPhoneNumber></soap:Body>

</soap:Envelope>

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Step 2: Defining a Service Description Language

A description language must be available to define Web service interfaces and how to invoke them.

We can use XML to specify deployment information and structural information.

That is what the Web Service Description Language (WSDL) is all about.

WSDL addresses syntax, not semantics!

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Step 3: Defining a global Service Broker

Client

Web Service

Descriptionof Web Service

(WSDL)

UDDI

1. search for web service

2. return service URL

4. send request using SOAP over HTTP

5. forward request to service

6. return result7. send result using

SOAP over HTTP

Web Server

3. read service description

UDDI is a global registry

Registration possible at any node

Registrations replicated at daily basis

Common SOAP protocol used

Publisher API

Inquiry API

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Step 4: All you need are Generators

Introduce tools that generate glue for connecting you with the Web ORB, i.e.,

Client Proxies for connecting the client with services. Server Proxies for seamless service deployment.

WSDL

ClientProxy

ServerProxy

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Web-based Service Frameworks

Workflow Engine

Web-based and -related Protocols (HTTP, XML, SMTP, ...)

Service Description, Discovery, Integration (UDDI)

Service Description (WSDL)

Service Context (Who, Where, When, Why, ....)

Virtual Machine

Micro/Macro Services

IntegrationLayer

Legacy

Backend Server

MainframeFrontend

Layer(Web Server)

Web Service User/Provider

Core Services (Calendar, Preferences, Transactions, ...)

Core Elements of Web Frameworks

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The Problem with Web-based Service Frameworks

Andrew Tanenbaum: „The best thing about standards is that there are so many to choose from“

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Agile Technologies

Although there are many technologies to choose from, there are technologies that support agility and some that do not.

Examples for agile technologies: Java and .NET Web Services Web and XML Standards Peer to Peer Pervasive Computing Ad Hoc Technologies (Plug‘n Play) CORBA Extensible and scriptable IDEs

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Agile Organization

“In any great organization it is far, far safer to be wrong with the majority than to be right alone.”

John Kenneth Galbraith

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Organizational Aspects

Experience and research have shown that organizational issues have a fundamental impact on software architectures and development processes.

Thus, it is important to optimize your organization in order to optimize your products.

Organizations need to be agile, i.e., effective and efficient:

“Efficiency is doing things right, effectiveness is doing the right things.” Peter Drucker

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Agility and Engineering

To be agile your engineering process should embrace change (Kent Beck) support an incremental approach with each

increment being a small mini project that moves you closer to the final product.

strongly rely on testing involve the users and their requirements without

giving away control:

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Top 10 Problems in Software Projects

What would you do if you were an agent and had to sabotage your competitors‘s projects?

No clear responsibilities within teams Missing, contradicting, and dynamically changing requirements No communication or too much communication Inadequate processes Wrong technologies Unexperienced developers Underestimation of software architecture activities No or insufficient quality assurance Unrealistic time frames Wrong tool set

In an agile world these issues prove to be even more painful, because they are being turned to Agile Problems

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Summary

Today‘s businesses are agile. As a consequence, software projects must also be agile.

Hence, Use agile processes Leverage agile architectures Select appropriate technologies Consider Web protocols for integration Don‘t forget to make your organization agile Don‘t believe in Gurus and Jedis (telling us for years how to

ease software development pain) And don‘t always wait for TNT (The Next Technology) to save

your projects! Most of the constituents for agile software development are already invented.

This summary in only one sentence: Agility denotes a Holistic Approach

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Last but not least : The Art of User Manuals

"If you cannot read this, please ask the flight attendant for assistance."

United Airlines Flight Safety Brochure

(c) Michael Stal, Keynote for OOP 2003 6/3/2015 slide 1 Power of Powerpoint:

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