The document discusses the implementation and trade-offs between textual and graphical syntax in the context of domain-specific languages (DSLs), highlighting their respective advantages for editing and understanding models. It mentions tools like Flexmi and Picto for model visualization and transformation, along with future developments for better integration and user experience. The challenges of maintaining synchronization between graphical and textual frameworks are also noted.

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