1. 1
Spreadsheets are models too
Richard Paige, Dimitris Kolovos, Nicholas Matragkas
Department of Computer Science
University of York
@richpaige, @kolovos, @nmatragkas

2. 2MDE
• Aims to improve the quality and efficiency
of the software development process
– Promotes models to first-class citizens
– Reduces the need for human compilers
– Models are purposeful descriptions that are
processable by automated tools.
• Not restricted to a particular modelling
technology / model representation format
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3. 3Models?
EMF
XML XSD
Spreadsheets
Visio RDBMS

4. 4The MDE Community
EMF
XML XSD
Spreadsheets
Visio
RDBMS

5. 5Everyone else
EMF
XML XSD
Spreadsheets
Visio RDBMS

6. 6EMF Consolidation?
• Benefit from modern modelling languages,
DSLs, language workbenches, tools.
• Benefit from use of generic tools for model
management (e.g., for transformation,
validation, migration).
• Benefit from consolidated technology
platforms.
– Possibly better tool interoperability.

7. 7Spreadsheets for SE
• Versatile and intuitive
• Fill gaps in software development process
– When no specialised tool exist for the job
– When specialised tools are too expensive/
complicated
– When information needs to be collected from non-
programmers
• Some problems are inherently tabular (e.g.,
certification/assurance arguments, control
law modelling, data modelling, traceability).
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8. 8Spreadsheet = Model
• Spreadsheets are models with interesting
(valuable) properties.
– Structure is largely read-only
– Fixed implicit metamodel vs variable explicit
metamodel (with EMF/Ecore)
• Model editing vs metamodel then model editing.
– Specialised rather than generic tools.
• Excel/Google Spreadsheets interface vs. Eclipse
interface…

9. 9
Treat Spreadsheets Like
(EMF) Models?
• What are the benefits?
– Use generic tools (transformation, validation,
merging, comparison) on spreadsheets.
– Support richer heterogeneity in the MDE
space (not just EMF!).
– Better support for early stages of SE: bridge
between early requirements and structured
modelling.
– Support for large legacy models, e.g., 200
sheet x 500 row sheets, never re-engineered.

10. 10
Treat Spreadsheets Like
(EMF) Models (2)
• What are the benefits?
– No need to build DS(M)Ls for tabular
problems.
– Synergy with existing skills.
– Exploit MDE tools for pattern detection, repair/
update, ….
• Sometimes a spreadsheet is all that’s
needed; EMF and DSLs are overkill.

11. 11How?
• Injectors:
– Generate models (in EMF) from
spreadsheets.
– May need to generate spreadsheets
from models, i.e., some form of
(partially) bidirectional transformations.
– Specification blow-up?

12. 12How?
• Model management operations for
spreadsheets.
– i.e., implement typical MDE operations on
spreadsheets, using spreadsheet APIs,
Google Spreadsheet Service etc.
– Transformation, code generation, validation,
etc.
• Badly reinvented wheels?
– Weigh against maintaining traditional
spreadsheet interface/interaction model.

13. 13How?
• Provide a spreadsheet driver for MDE
languages/tools for
– Model querying
– Model-to-model transformation
– Model validation
– Model-to-text transformation
– Model comparison
– Model merging
• ... so that spreadsheets can be used in any
step of an MDE process

14. 14Basic Idea?
• Spreadsheet -> Model
• Worksheet -> Type
• Column -> Property
• Row -> Model element
modules
MSD,HCI
F
MSD,RQE
E
mt506
supervisor
mt506
4
jd5023 SmithJane 22
jd501 232 ThompsonJoe
D
age
C
lastname
B
firstname
A
id1
Student Staff
ED
teaches
C
lastname
B
firstname
A
id1
Module Mark

15. 15eclipse.org/Epsilon

16. 16Example (Query)
modules
MSD,HCI
F
MSD,RQE
E
mt506
supervisor
mt506
4
jd5023 SmithJane 22
jd501 232 ThompsonJoe
D
age
C
lastname
B
firstname
A
id1
Student Staff
E
dj5123 JacksonDaniel HCI
mt506 MSD,RQE2 ThomasMatthew
D
teaches
C
lastname
B
firstname
A
id1
Student Staff
Module
Module
Student Staff Module
Human Computer Interaction Spring4 HCI
D
RQE3 SpringRequirements Engineering
MSD2 AutumnModelling and System Design
C
term
B
title
A
id1
Mark
Mark
Mark
Student.allInstances->
select(s | s.age >= 18).println();

17. 17Example (M2T)
modules
MSD,HCI
F
MSD,RQE
E
mt506
supervisor
mt506
4
jd5023 SmithJane 22
jd501 232 ThompsonJoe
D
age
C
lastname
B
firstname
A
id1
Student Staff
E
dj5123 JacksonDaniel HCI
mt506 MSD,RQE2 ThomasMatthew
D
teaches
C
lastname
B
firstname
A
id1
Student Staff
Module
Module
Student Staff Module
Human Computer Interaction Spring4 HCI
D
RQE3 SpringRequirements Engineering
MSD2 AutumnModelling and System Design
C
term
B
title
A
id1
Mark
Mark
Mark
<ul>
[%for (s in Student.allInstances){%]
<li> [%=s.firstname] [%=s.lastname]
[%}%]
</ul>

18. 18Example (Validation)
context Mark {
constraint WithinRange {
check: self.mark <= 100 and
self.mark >= 0
message: “Mark ” + self.mark +
“ must be between 0-100”
}
}
Student Staff Module
Human Computer Interaction Spring4 HCI
D
RQE3 SpringRequirements Engineering
MSD2 AutumnModelling and System Design
C
term
B
title
A
id1
Mark
E
jd5023 74ICAR
jd5012 62TPOP
DC
mark
B
module
A
student1
Student Staff Module Mark

19. 19How?
• Develop a native spreadsheets driver for
Epsilon’s pluggable type system (EMC)
• Pros
– No intermediate artefacts
– No stale data
– Direct updates to the spreadsheet
– Can leverage native querying capabilities

20. 20Query Translation
• The implementation of primitive query
operations can be overloaded.
• The Google Spreadsheets driver rewrites
(EOL) queries at runtime, e.g., to:
– https://spreadsheets.google.com/feeds/list/tb-
<mark-worksheet-guid>/od6/private/full?
sq=mark>70
• Search is performed on the server
– Composite queries are supported

21. 21Conclusions
• How do we interface MDE approaches with
spreadsheets?
– Cannot/will not be re-engineered!
– Need to use “real” models in combination with
spreadsheets (and other “inferior” tech).
• Currently working on extending Google
Spreadsheets work with annotations.
– Health care data project (York+TU/e+Lille).
• Driver available at:
https://code.google.com/p/epsilonlabs/