Cloned Product Variants: From Ad-Hoc to Well-Managed Software Reuse

Cloned Product Variants:From Ad-Hoc to Well-Managed

Software Reuse

Julia RubinIBM Research - Haifa, Israel

University of Toronto, Canada

December 9, 2013

Joint work with Prof. Marsha Chechik

Software Product Line Engineering emerged as a discipline that promotes Planned and Predictive Software Reuse

K. Pohl et al., Software Product Line Engineering: Foundations, Principles, and Techniques, 2005

P. C. Clements and L. Northrop, Software Product Lines: Practices and Patterns, 2001

In reality, software products are often created ad-hoc,

by cloning and modifying existing variants (the “clone-and-own” approach)

Example – GPS Products

GPS-Pro

Life Traffic InfoPOI

Layered MapTrip Computer

* Managing forked product variants, Julia Rubin, Andrei Kirshin, Goetz Botterweck, Marsha Chechik, SPLC 2012.


GPS-Pro GPS-EZ



POILayered Map

A cheaper version …



GPS-Pro GPS-EZ



POI (extended)Layered Map

Product implementations start growing apart …

3D Buildings

Shortest TimeRouting

Night Mode



GPS-Pro GPS-EZ






Night Mode

3D Buildings

Night Mode ?

Does Night Mode work with

3D Buildings?

Does Night Mode work with

3D Buildings?


GPS-Pro GPS-EZ






Night Mode

3D Buildings

Night Mode

Can Shortest Time Routing be

copied?

req ?


GPS-Pro GPS-EZ






Night Mode

3D Buildings

Night Mode

Are the implementations of POI consistent

between the products?



?





req

As the number of cloned variants grows and they further grow apart,

ad-hoc reuse becomes challenging

What can we do?

Unify clones into a Single Copy Representation (Merge-refactoring)

Unify clones into a Single Copy Representation (Merge-refactoring)

Time-, cost- and labor-

intensive

Rapidly available

Independence of developers

Reuse of verified code

No upfront investment

Despite disadvantages, some are happy with cloning

* An Exploratory Study of Cloning in Industrial Software Product Lines, Yael Dubinsky, Julia Rubin, Thorsten Berger, Slawomir Duszynski, Martin Becker, and Krzysztof Czarnecki,

CSMR 2013

Exploratory Study: 6 industrial product lines realized via cloning*

Strategy 1: Unify clones into a Single Copy Representation (Merge-refactoring)– cost- and effort-intensive, benefits are not always immediate

Strategy 2: Provide support for efficient reuse with cloning (Clone-based Software Product Line Engineering)


Both Strategies Coexist

Which is often delayed

When performed, it is done incrementally

(for a subset of products), while the remaining ones are still

maintained as clones

Merge-refactoring is a long journey

Companies need assistance with both merge-refactoring and supporting existing clones

Exploratory Study: Companies in Different Stages of Reuse Management

Company 3

Company 2

Company 1

Goal: study development activities, gather and classify needs and requirements

* Managing Cloned Product Variants: A Framework and Experience. Julia Rubin, Krzysztof Czarnecki, and Marsha Chechik, SPLC 2013

Result: a framework for managingcloned product variants

A Framework for Managing Cloned Product Variants

development activities

6. Merge7. Reorganize

1. FindFD2. FindFI

3. Same?4. Interact?

5. Depends-on?

Merge-Refactoring: put variants together

Supporting Clones: establish new variants,

share features, etc.

conceptual operators







Identify artifacts implementing a feature

(known as feature location)


1. FindFD2. FindFI


5. Depends-on?







Are two features from distinct products indeed identical?


1. FindFD2. FindFI


5. Depends-on?








1. FindFD2. FindFI


5. Depends-on?

Can two sets of features from distinct products work together? (known as feature interaction)








1. FindFD2. FindFI


5. Depends-on?

Does one feature require another from the same

product?







Unification of either multiple sets of features from distinct products or of

complete products


1. FindFD2. FindFI


5. Depends-on?








1. FindFD2. FindFI


5. Depends-on?

Product-preserving refactoring of a product line architecture


common development activities





Some operators received a lot of attention in the literature

(under specific conditions)while other are poorly studied


1. FindFD2. FindFI


5. Depends-on?


common development activities





Our framework helps organizing knowledge around possible

implementation of the operators


1. FindFD2. FindFI


5. Depends-on?

Main Benefits of the Framework


Merge-Refactoring Supporting Clones


Identify required support

Categorize existing work

and identify gaps

Build solutions for

purpose

…Scope

company’s investment

What’s Next?• Improve the framework by considering additional

scenarios – We do not claim that the current framework is complete

(or will ever be), but it is reasonable for the real-life scenarios that we analyzed

• Invest in the implementation of the individual operators– For realistic use cases

• Investigate the economic effectiveness of merge-refactorings

• Develop novel approaches for managed reuse that rely on cloning– Mitigating its disadvantages while leveraging advantages

Summary

Thank You!

Documents

Cloned Product Variants: From Ad-Hoc to Well-Managed Software Reuse