Disciplined agile reuse engineering

© Disciplined Agile Consortium 1

Disciplined Agile Reuse Engineering

Agenda

•  Fundamentals –  What is reuse engineering? –  Why reuse engineering? –  What can you reuse? –  How do you know something is reusable? –  The not invented here (NIH) syndrome –  Where do reusable assets come from?

•  How does reuse engineering fit into agile software delivery?

•  Reuse engineering in practice –  What do reuse engineers do? –  How can you support and evolve reusable

assets over time? –  How do you fund reuse? –  Why is reuse engineering difficult?


Fundamentals © Disciplined Agile Consortium 3


Reuse Engineering is the purposeful creation (or rescue), management, support, and governance of reusable assets.

Why Reuse Engineering?

•  There are many reasons to consider reuse engineering: –  Quicker time to market –  Improved ROI –  Improved consistency –  Easier updates to common functionality –  Improved quality

•  There are a few reasons to not consider reuse engineering: –  It requires discipline –  It requires long-term funding


What Can You Reuse?


When Do You Know Something is Reusable?

•  Some definitions: –  Asset: An artifact that is retained after its initial purpose is fulfilled –  Robust asset: An asset that is appropriately documented and

generalized beyond the needs of a single team –  Reusable asset: An asset that has been reused at least three times in

three different contexts –  Reuseless asset: An asset that has been declared reusable but after

consideration by other teams has not actually been reused in practice


An asset isn’t reusable because you say so,

it’s reusable because it’s being reused

The Not Invented Here (NIH) Syndrome


•  Myth –  Developers won’t reuse something that they

didn’t create themselves

•  Facts –  Developers reuse things all the time

–  Developers are eager to reuse high-quality assets that are consumable (the assets meet their needs and they’re easy to work with)

–  Many times the creators of reuseless artifacts blame the NIH syndrome when their artifacts aren’t considered consumable by others

How does Reuse Engineering Fit In?


Strategic Scaling: The Agile IT Department


Reuse Engineering in Practice


What do Reuse Engineers Do?


Where Do Reusable Assets Come From?

•  There are several sources for reusable assets: –  Harvested assets

•  Asset is already in use •  Asset will need to be generalized and then

reintegrated into source solution •  The reuse team needs to take over

ownership of the asset –  Purchased/downloaded assets

•  Lower cost of support and evolution •  Asset may evolve in a direction that you

don’t like •  Marketplace support for asset may

disappear –  Built for reuse

•  Hard to predict what others will want •  Much more expensive to build something to

be reusable © Disciplined Agile Consortium 14

How Can You Support and Evolve Reusable Assets Over Time? •  Reusable assets:

–  Live beyond the life of a project –  Are used by multiple teams in different contexts –  Are used by teams with evolving requirements –  Are implemented using evolving technologies –  Are deployed onto evolving platforms

•  To support and evolve reusable assets, they need: –  To be findable –  Funding that isn’t tied to projects –  To be documented –  To have examples of how to use them in practice –  To have feedback mechanisms in place –  To be versioned and deprecated appropriately


Why is Reuse Engineering Hard?

•  What other teams want, particularly in the future, isn’t always obvious

•  There is a greater impact when a reused asset breaks •  Teams must go beyond source-code reuse •  Reuse requires enterprise awareness •  Reuse requires investment •  Your approach to funding will make or break reuse


How do You Fund Reuse?


•  There are several ways to fund reuse engineering: –  Funded reuse engineering team: Explicit reuse team exists –  Asset-level funding: The creation, support, and evolution of an asset

is explicitly budgeted for –  Development team-based funding: Team budgets include funding for

reuse –  No explicit funding: Reuse is ad hoc –  Charge-back funding: Assets are funded by charging teams to reuse

them

What do Reuse Engineers Do?


Strategic Scaling: The Agile IT Department


Got Discipline? DisciplinedAgileConsortium.org

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Scott Ambler + Associates is the thought leader behind the Disciplined Agile Delivery (DAD) framework and its application. We are an IT

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Disciplined agile reuse engineering

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