Picto is a tool for generating and rendering views from EMF models in Graphviz, SVG and HTML, developed in the context of the Epsilon platform (eclipse.org/epsilon)

1. Picto: Model Visualisation
via M2T Transformation
Dimitris Kolovos
dimitris.kolovos@york.ac.uk

2. Textual vs. Graphical Syntax
• Choice that needs to
be made when
implementing a DSL
• Textual: Xtext, Spoofax,
MPS
• Graphical: Sirius,
GMF/Eugenia,
MetaEdit+
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction
25/11/2019 Enterprise Systems Seminars 2

3. Graphical Syntax
+Taps into the power of
the visual system
• Visual representations
processed in parallel
+Essential for
engagement with non-
CS stakeholders
- Only editable with a
dedicated editor
- Find, replace, copy,
paste, comment out,
version control not
always straightforward
25/11/2019 Enterprise Systems Seminars 3
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

4. 25/11/2019 Enterprise Systems Seminars 4

5. Textual Syntax
+Editable with any text
editor
+Find, replace, copy,
paste, comment out,
version control
practically solved
- Text processed serially
by the auditory system
- Inaccessible to many
non-CS stakeholders
25/11/2019 Enterprise Systems Seminars 5
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

6. Textual vs. Graphical Syntax
• Text better for editing
• Once you are familiar
with the DSL and in the
zone
• Even for languages
which are traditionally
graph-like (e.g. state
machines)
• Diagrams better for
understanding and
presenting models to a
wider audience
25/11/2019 Enterprise Systems Seminars 6
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

7. Multiple Syntaxes
• Implement a graphical
and a textual editor
• Edit on both sides and
keep in sync
• Challenging in practice
• Graphical/textual
frameworks developed
by different vendors
• Lots of plumbing
involved
• A few prototypes but
cutting many corners
25/11/2019 Enterprise Systems Seminars 7
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

8. Graphical Views
• Textual syntax for
editing models
• Generation of read-
only graphical views
• Challenges
• Diagram layout
• Fine-tuning (e.g. size,
colour of
elements/labels)
25/11/2019 Enterprise Systems Seminars 8
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

9. Layout
• Several decent options
for automated graph
layout e.g.
• Graphviz
• Eclipse Layout Kernel
• DagreJS
• Important that
diagrams are kept
reasonably small
• But this is desirable
anyway
25/11/2019 Enterprise Systems Seminars 9
User -> ATM: Inserts card
ATM --> User: Requests PIN
User -> ATM: Provides PIN
ATM -> Bank: Check PIN against card
Bank --> ATM: Accepts PIN
ATM --> User: Asks for type of transaction

10. Fine-Tuning
public static void main(String[] args){
System.out.println("Hello world");
}
25/11/2019 Enterprise Systems Seminars 10

11. Fine-Tuning
public static void main(String[] args){
System.out.println("Helloworld");
}
25/11/2019 Enterprise Systems Seminars 11

12. Flexmi and Picto
• Flexmi: XML-based syntax for EMF models
• Reflective and fuzzy parsing
• Instantiable model element templates
• Presented in a previous ES Seminar
• Picto: Framework for model view generation and
rendering
• EMF models (for now)
• Views in Graphviz, SVG, HTML
• Views generated using M2T transformations (in EGL)
• Both tools in the latest interim version of Epsilon
(eclipse.org/epsilon)
25/11/2019 Enterprise Systems Seminars 12

13. Live demo
25/11/2019 Enterprise Systems Seminars 13

14. Picto – Future Work
• Layers
• Declarative graphical syntax specification
• Similar to Sirius/GMF/Eugenia
• Navigation from view to model editor
• Generation of views from multiple models
• Integration with model validation
• Change visualization
• Web application
25/11/2019 Enterprise Systems Seminars 14