SCRUM Design Pattern

8/3/2019 SCRUM Design Pattern

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SCRUM - Design Pattern 1

SCRUM A Pattern Language for

Hyperproductive SoftwareDevelopment

Design Patterns

Summer 2002

Syracuse University

Srinivasa NeeruduVivekananthan Murugesan


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Software Development

Do we have a fixed set of rules for

Software Development?

Linear Sequential Model Waterfall Model

Prototyping Model Spiral Model

Iterative Model

CMM [Capability Maturity Model]


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Waterfall Model


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Spiral Model


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SCRUM


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Comparison


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Incorrect Assumptions

Repeatable/Defined Problem:

There is a step or steps to capturerequirements.

BUT

Systems have different applications,different environment, different end users,etc.


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Incorrect Assumptions(2)

Repeatable/Defined Solution:

System Architecture can be fully specified.

BUT

In reality, it is evolved partly because of

missing or changing requirements andpartly because of creative processinvolved.


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Repeatable/Defined Developers:

All developers have same capability.

BUT

In reality, it varies widely so that a process

that works for one developer may not work

for another one.


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Repeatable/Defined OrganizationalEnvironment:

Schedule, Client Behavior, Priority (QualityVs Price Vs Manpower) remain constant.

BUT

In reality, they are highly subjective andvery hard to define.


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Solution

SCRUM

It offers a collection of empirical techniques

that assume existence of uncertainties butprovide practical and specific techniques to

tame them.

Iterative, Incremental and Adaptive

Software Development Model


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How does SCRUM work?

SCRUM

MasterSprint

DemoAfter

Sprint

BacklogSCRUMMeetings


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How does SCRUM work? (2)

Sprint:

A period of approximately 30 days in which an

agreed amount of work will be performed to create

a deliverable.

SCRUMs goal is to deliver as much quality

software as possible within a series (three to

eight) of Sprints


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Each stage in the Development Cycle

(Requirements, Analysis, Design,

Evolution, Delivery) is mapped to aSprint or Series of Sprints.

Unlike conventional way, there is nopredefined process within a Sprint


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SCRUM Meetings drive the completion ofthe allocated activities

Each sprint operates on a number of workitems called Backlog

No more items are externally added into theBacklog within a Sprint, where as derivedwork items can be added.


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SCRUM Meetings are held daily to

determine the following

Items completed since the last SCRUMMeeting

Issues or Blocks that need to be resolved

[SCRUM Masteris responsible]

Tasks to be done before the next Meeting


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Demonstration after Sprint is for:

Show the customer whats going on

Give the developer a sense ofaccomplishment

Integrate and test a reasonable portion of

the software being developed

Ensure real progress in development


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SCRUM Patterns

Sprint

Backlog

SCRUM Meeting


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Sprint - Context

You are a software developer or a coach

managing a software development team

where there is a high percentage of

discovery, creativity, or testing involved

You are building or expanding systems,

which allow partitioning of work, with cleaninterfacing, components, or objects


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Sprint - Problem

You want to balance the needs of

developers to work undisturbed

management and the customers to see the real

progress

AS WELL AS

control the direction of software development

progress.


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Sprint - Forces

Developers need to work undisturbed andneed support of logistics. Management andusers need to be convinced about real

progress.

Often, by the time systems are delivered theyare obsolete and may require major changes.

The problem is the inputs are collected in thestart of the project but they undergo changesas the working model is used.


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Sprint Forces (2)

Because development process involves many

uncertainties, it is impossible to make a

complete, detailed specification, plan or

schedule

Some problems are even difficult to describe

without a notion of the solution.Experimentation, feedback and creativity are

required towards the same.


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Solution

Divide the project in Sprints

A Sprint is a period of approximately 30 Days.

Each Sprint takes a pre-allocated amount ofwork from the Backlog

The work assigned is by priority and byapproximation of what can be accomplishedduring the Sprints length


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Solution (2)

During the sprint no items are added to theallocated spring Backlog.

External additions are only added to theglobal Backlog, but blocks resulting from thesprint can be added to the allocated SpringBacklog

A Sprint ends with a demonstration of addednew functionality


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Solution (3)

Sprint results in a visible and usabledeliverable that is shown to the users at thedemonstration.

An increment can be either intermediate orshippable

The Goal of a Sprint is to complete as muchquality software as possible and to ensurereal progress.


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Rationale [Fundamental reasons; the basis]

Development Process is fast and steady asno items are added to the backlog externally

The ability to choose a process per Sprint isempowering and enables adaptation tochanging circumstances

Sprints are short; therefore the problem ofcompleting a Sprint is much simpler than thatof completing a project


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Rationale (2)

Developers get feedback frequently

[after every Sprint] and therefore feel

their success [and failure] withoutcompromising the whole project

Project Status is visible since the sprintproduces working code


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Resulting Context

High degree ofinvolvement by the participantsthrough Demos and the prioritizing of the Backlog

With SCRUM we get a large amount ofpost-planningflexibility (for both customer and developer).

Difficulties in grouping backlog for a Sprint mayindicate that priorities are not clear to management or

to the customer.


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Backlog

Context(from: sprint).

You are connected to a software project orany other project that is chaotic in nature

that need information on what to do next.


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Backlog contd.

Problem:

What is the best way to organize thework to be done next and at any stage

of the project?


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Backlog contd.

Forces:

Project plans captured in pert and Gantt charts

often try to capture the tasks to be done in

advance. They often fail in their implementations,as they lack flexibility.

Not having a repository of tasks in any shape or

form simply translates into project failure.


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Backlog contd.

Solution:

Use backlog to organize the work of a

SCRUM team.

The backlog is a prioritized list.

Backlog is the work to be performed and

evolves into product


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Solution (2)

Sources of Backlog list:

Product Marketing.

Sales.

Technology.

Development.

Customer support.


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Solution (3)

The product manager or product marketing

manager prioritizes work and is

responsible for meeting the product vision.

SCRUM teams focus on highest priority

Backlogs.

The team decomposes the selected

Backlog into tasks.


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Resulting Context

Project work is identified dynamically

and prioritized according to:

The customers needs What the team can do


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SCRUM Meetings

Context (From: Backlog).

You are a software developer or a coachmanaging a software development team

where there is high percentage ofdiscovery, creativity, or testing involved.

Activities such as scientific research,innovation, invention, architecture,

engineering and a myriad of other businesssituations may also exhibit this behavior.


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Context (2)

You may be a Knowledge worker, an

engineer, a writer,a research scientist, or

an artist, or a coach or manager who is

overseeing the activities of a team in theseenvironments.


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Problem

What is the best way to control an

empirical and unpredictable process

such as software development,scientific research, artist projects, or

innovative designs where its hard to

define the artifacts to be produced and

the processes to achieve them?


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Forces

Estimation:

Accurate estimation for activities involving

discovery, creativity or testing is difficult.

Estimation is important. One must be able

to determine what are the future tasks

within some time horizon and prepareresources in advance.


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Forces(2)

These uncertainties come in at least five

flavors:

Requirements are not well understood.

Architectural dependencies are not easy tounderstand and are constantly changing.

Unforeseen challenges with the technology

exist.

Ambiguity in the solutions and related efforts toovercome challenges.

Bugs in software that are hard to resolve.


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Planning

Planning and reprioritizing takes time.

Involving knowledge workers in the

time planning meeting also decreasesproductivity.

No amount of planning in chaotic

system may reduce uncertainties.


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Planning (2)

Detailed plans are huge and hard to

follow.

Cost of verifying the correctness of ahuge plan is also a costly exercise.

No planning can increase uncertainties

among the team members and lower

the morale.


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Tracking

Too much monitoring wastes time andsuffocates the developers.

Does not increase the certainty of theindicators because of the chaotic natureof the system.

Too much data is meaningless.

No monitoring leads to blocks andpossible idle time between assignments


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Solution

SCRUM Meetings(~15 mins) are held

and three questions are asked by each

participant:

Q1. What have you worked on since the

last SCRUM Meeting?

The SCRUM Master logs the tasks that have

been completed and those that are still undone


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Solution (2)

Q2. What blocks, if any have you found in

performing your tasks in the last 24hrs?

SCRUM Master logs all blocks and later finds a

way to resolve the blocks.

Q3. What will you be working on in the next

24 hours?

The SCRUM Master helps the team members

choose the appropriate tasks.


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SCRUM Meeting

Typically take place at same time and

same place. Serve to build a strong

culture.

Schedule task for developers and

everybody else involved in the task.

Allow knowledge workers to accomplish

mid-term goals.


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Rationale

Its easy to over-or-under-estimate,which leads to either idle developer timeor delays in the completion of an

assignment. Frequent sampling of the project status

is good.

Constant reprioritization of tasks offeran adaptive mechanism for sampling.


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Rationale (2)

SCRUM Meetings help in creation of an

anticipating culture:

They increase the overall sense of urgency They promote the sharing of knowledge

They encourage dense communications

They facilitate honesty among developers

since everyone has to give a daily status.


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Rationale (3) (Systems

Dynamics)

From the Systems Dynamics point of view,software developed has a schedulingproblem because the nature of programming

assignments is rather probabilistic.

Estimates are hard to come by because: Inexperienced developers, managers, and

architects are involved in making the estimates. There are typically interlocking architectural

dependencies that are hard to manage.


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Contd.

There are unknown or poorly documented

requirements.

There are unforeseen technical challenges.

In that sense SCRUM Meeting acts like

a thermometer that constantly samples

the teams temperature.


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Known Uses

At Nike Securities in Chicago to run all

their projects

At Elementrix Technologies And many similar examples are quoted

in the book.


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Resulting Context

The application of this pattern leads to

Highly visible projects status

Highly visible individual productivity Less time wasted because of blocks

Less time wasted because of waiting for

someone else.

Increased team socialization.


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Conclusion

SCRUM is a knowledge creating

process with a high level of information

sharing during the whole cycle and work

progress.

Its application also generates a strong

culture with well-defined roles and

relationships, with meaningful andtranscending rituals.


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Contd.

The key to SCRUM is:

Pinning the date of completion forproduction or release.

Prioritizing functionalities

Identifying available resources

Decision about the architecture


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References

PLOP4 Book

http://jeffsutherland.com/oopsla/schwap

ub.pdf Related to PERT and Gantt

http://studentweb.tulane.edu/~mtruill/dev-

pert.html


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Thank You

SCRUM Design Pattern

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