Title: JavaScript for VW Applications Speaker: Holger Kleinsorgen & Jan Schümmer Wed, August 20, 11:45am – 12:30pm Video Part1: https://www.youtube.com/watch?v=ZGAMCz62OM0 Video Part2: https://www.youtube.com/watch?v=cUk4C3c5gG4 Video Part3: https://www.youtube.com/watch?v=Mt1kVFSEQG8 Description Complex applications benefit from a built-in scripting language that is easy to use and commonly understood. Smalltalk is a cool language for us, but in some cases and for the broad public, JavaScript is more suitable. Up to now there was no JavaScript implementation available for Smalltalk that covers the full JavaScript ECMA 5 standard and shows production quality. In our talk we will present features and implementation details of our JavaScript engine and show how we integrated it into the latest version of our product “k-infinity”. As the engine is available under MIT license in the Cincom public repository, we invite everyone to use it in their own applications. Bio: Holger Kleinsorgen and Jan Schümmer are looking back at more than twenty years of Smalltalk development. They are part of the COAST team (c.f. ESUG 2000), and together with their colleagues at intelligent views they are developing the semantic database k-infinity (c.f. ESUG 2001 and 2002).

1. JavaScript for VW Applica1ons
JavaScript
for
VW
Applica1ons
Holger
Kleinsorgen
&
Jan
Schümmer
intelligent
views,
Darmstadt,
Germany
ESUG
2014
–
Cambridge,
UK

2. JavaScript for VW Applica1ons
K-­‐Infinity
-­‐
our
core
product
2
• semanJc
database
• modelling
• querying
• data
integraJon
• web
frontend
(Java)
• REST
services
• highly
configurable
à
need
for
scrip1ng
throughout
the
system

3. JavaScript for VW Applica1ons
3
Smalltalk
sandbox
J
J
K
J
J
JavaScript
JJ
J
JJ
J
J
First
try:
KScript
easy
to
communicate
L
easy
to
learn
L
universal
/
wide
spread
LL
suitable
K
flexible
L

4. JavaScript for VW Applica1ons
Anything
reusable
out
there?
4
only
one
dead
ST
implementaJon
3rd
party
C
libraries
• Jed
to
web
environments
• uncertain
future
Mozilla
Rhino
• Java
implementaJon
would
need
JNI
• lack
of
flexibility
for
host
object
integraJon
We
wanted
real
Smalltalk
Objects
without
addiJonal
runJmes

5. JavaScript for VW Applica1ons
5
What
is
important?
• conform
to
the
specs
• easy
to
integrate
host
objects
• maintainable
What
is
not
that
important
• performance
à
simply
follow
the
250
pages
of
the
ECMA
5
spec

6. JavaScript for VW Applica1ons
Parser
6
• PeJtParser
• PEG
+
Memoizing
+
Stuff,
Smalltalk
notaJon
• Tweaked
for
more
precise
error
locaJons
• separated
into
lexical
and
syntacJcal
part
• follows
structure
of
ECMA
spec
• adapted
for
PEG
(no
lec
recursions,
alternaJves
parse
first
match)
• quirks
due
to
spec
• strict
mode
• disJnguish
regex
literals
from
expressions
• automaJc
semicolon
inserJon

7. JavaScript for VW Applica1ons
Parser
7

8. JavaScript for VW Applica1ons
RunJme
8
• Everything
represented
by
dedicated
objects
• JSEAbstractObject
(Javascript
objects
and
primiJves)
• JSEExecuJonEnvironment
+
JSEExecuJonContext
• JSEBinding,
JSEReference,
JSEProperty
• Implement
algorithms
of
the
spec
• VW
VM
garbage
collecJon
• Language
core
implemented
by
JSERunJmeImplementaJon
• Syntax
tree
transformed
to
code
blocks
• Code
blocks
are
evaluated
in
an
execuJon
context
• Interpreted
and
thus
quite
slow

9. JavaScript for VW Applica1ons
9
ECMAScript
Language
Specifica1on
5.1,
page
76

10. JavaScript for VW Applica1ons
ECMA
conformance
test
suite
10
• about
11500
unit
tests
• current
result:
313
failures,
95
errors
(4
%)
• browsers:
between
8
and
52
failures
/
errors
(0.06
%
–
0.45
%)
• test
cases
helped
to
find
the
nicy
/
exoJc
parts
• decided
to
accept
some
failures
for
the
Jme
being

11. JavaScript for VW Applica1ons
11
Demo
1me

12. JavaScript for VW Applica1ons
K-­‐Infinity
IntegraJon
12
Usage
Example
• definiJon
of
a
REST
service
SemanJc
Net
API
Debugger

13. JavaScript for VW Applica1ons
Ups
and
Downs
13
The
good
parts
• (mostly)
works
as
expected
• implementaJon
was
straight
forward
• use
cool
JS
libraries
• fast
enough
for
our
use
cases
The
cheesy
parts
• parser
hacks
• the
"usual"
browser
objects
are
not
available
• took
some
Jme

14. JavaScript for VW Applica1ons
Wish
list
14
• switch
to
single
grammar
• switch
to
VW
PEG
Parser
• nicer
to
read
due
to
DSL,
easier
to
maintain
• already
includes
JS
grammar,
needs
some
tweaks
though
• byte
code
compiler
• only
as
a
pet
project,
not
required
currently
• all
test
cases
pass
• ECMA
6
(especially
collecJons)

15. JavaScript for VW Applica1ons
15
JavascriptEngine-­‐Bundle
MIT
License
Public
Repository
{h.kleinsorgen|j.schuemmer}@i-­‐views.de
Thank
you
for
your
aRen1on