Xtext project and PhDs in Gemany

T.Baar: NSU TechTalk, The framework Xtext. 2015-11-24 1
Xtext: Eclipse-based framework for defining
Domain-Specific Languages (DSLs)
Thomas Baar
thomas.baar@ccfit.nsu.ru (temporary *)
NSU Tech Talk; Akademgorodok, 2015-11-24
Guest Lecturer at:
Home University:
* My stay at Novosibirsk State University is supported by DAAD (German Academic Exchange Service).

Domain-Specific Language (DSL)
A DSL is a notation for expressing observations, facts, algorithms
in an elegant way. The notation can be
- textual
- graphical
- table-oriented
or a mixture of the above.

Compared to general-purpose modeling languages (e.g. UML) or
programming languages (e.g. Java), DSLs have usually a (much)
less complex syntax while being expressive enough for the
domains they target!

Compared to general-purpose modeling languages (e.g. UML) or
programming languages (e.g. Java), DSLs have usually a (much)
less complex syntax while being expressive enough for the
domains they target!
Domain-specific models/programs are typically less complex
than models/programs written in a general purpose language.
Thus, they are easier to understand and to maintain.

DSL Examples
Domain
Typesetting
Language
Latex
Source: Britannica kids. kid.eb.com

DSL Examples
Domain
Automatic Software Build
Language
make

DSL Examples
Domain
Chemistry
Language
Mendeleev's periodic
system of chemical
elements

DSL Examples
Domain
Process Description
Language
Harel's statecharts

- Что такое?
• Eclipse-framework for defining textual DSLs
- actually, Xtext is the heart of Eclipse bundle "Eclipse for Java
and DSL developers"

and DSL developers"
• Open source, but professionally developed and maintained by
start-up company Itemis (Kiel, Germany)
- matured code, release 2.9 expected early Dec 2015
- nice documentation/tutorials
- active forum, fast bug-fixes

and DSL developers"
• Open source, but professionally developed and maintained by
start-up company Itemis (Kiel, Germany)
- matured code, release 2.9 expected early Dec 2015
- nice documentation/tutorials
- active forum, fast bug-fixes
• Very informative website www.eclipse.org/xtext
- short video tutorials explaining each editor feature
- links to what community has implemented using Xtext

Xtext: Mission & Workflow
Mission: Make the Definition and Usage of textual DSLs as easy as possible.

Overview on DSL Definition
DSL-Part Defined in Purpose
Grammar EBNF-inspired Grammar
language
specify lexer, parser
Validator Xtend * filter out non-intended input
models; trigger error-
markers in editor
Scope definitions Xtend resolve cross-references
Editor configurations
(Overview pane, content
assist/auto-completion,
font-selection, tooltips, etc.)
Xtend adjust editor features
Code generator Xtend specify code generator
Tests Xtend execute test cases for lexer,
parser, validator, scope
provider, editor, eclipse
integration, etc.
* Xtend - An extension of Java invented from Xtext-team in order to make typical
programming tasks (e.g. AST traversion, code templates) much easier.

More detailed DSL-Definition Workflow

Example Project
Beans

A Simple Example: Beans
-- Create an Xtext Project --

-- Define the Grammar --

Header
Start Rule
Feature in generated
EMF class
Cross-reference
Keyword
Optional Occurence

Xtext is build on top of the parser generator ANTLR. For the above grammar,
much longer input files for ANTLR have been generated (299 LOC, 24 LOC).
Header
Start Rule
Feature in generated
EMF class
Cross-reference
Keyword
Optional Occurence
The formalism for defining a grammar is a DSL!
This DSL has been implemented by Xtext itself ;-)

-- Testing the Parser using JUnit --
Pre-defined
helper classes
String templates
(enclosed by ''' )
Extension method
(actually defined
in ParserHelper and
not in String)

-- Adding a Validator: Making the syntax more precise --
class BeansDslValidator extends AbstractBeansDslValidator {
public static val INVALID_NAME = 'invalidName'
@Check
def checkBeannameStartsWithCapital(Bean bean) {
if (!Character.isUpperCase(bean.name.charAt(0))) {
error('Name must start with a capital',
BeansDslPackage.Literals.BEAN__NAME, INVALID_NAME
)
}
}
}
Mark input text as erroneous
under certain circumstances

-- Testing the Validator using JUnit --

-- Enjoy the Editor :-) --
Content assist
(aka auto-completion)
Grammar error
(missing ';')
Validation error
(no capital letter)

-- Specify a Code Generator using Xtend --
class BeansDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
resource.allContents.toIterable.filter(typeof(Bean)).forEach[
fsa.generateFile('''beans/«name».java''', compile)
]
}
def compile(Bean bean) {
'''
public class «bean.name» «IF bean.superType != null»extends «bean.superType.name» «EN
«FOR att : bean.attributes»
private «att.type.typeToString» «att.name»;
«ENDFOR»
«FOR att : bean.attributes»
public «att.type.typeToString» get«att.name.toFirstUpper»() {
return «att.name»;
}
public void set«att.name.toFirstUpper»(«att.type.typeToString» _arg) {
this.«att.name» = _arg;
}
«ENDFOR»
}
'''}
def typeToString(BasicType type) {
if (type.literal.equals("string")) "String" else type}
}
Output written in .java file
Each bean becomes a Java class
Each bean attribute is mapped to
Java attribute, getter- and setter-
method

-- Enjoy the Code Generator :-) --
One input file
(written in our
DSL)
Location of generated
artifacts
Three output files
(written in target
language)

-- Testing Code Generator using JUnit --
class BeansGeneratorTests {
@Rule
@Inject public TemporaryFolder temporaryFolder
@Inject extension CompilationTestHelper
@Inject extension ReflectExtensions
@Test
def void testTwoCompiledClasses() {
'''
bean Person{string name;}
bean Student extends Person{
boolean isMaster;
studentID; // implicitely typed as int
}
}
'''.compile [
getCompiledClass("Person").assertNotNull
getCompiledClass("Student").assertNotNull
]
}
}
both classes
has been compiled
successfully

-- Testing Code Generator using JUnit --
@Test
def void playWithGeneratedJavaCode() {
'''
bean Person{string name;}
bean Student extends Person{
boolean isMaster;
studentID; // implicitely typed as int
}
}
'''.compile [
getCompiledClass("Student").newInstance => [
assertNull(it.invoke("getName"))
val aName = "Johnson"
it.invoke("setName", aName) // invoking inherit method
assertEquals(aName, it.invoke("getName"))
val anInt = 1234
it.invoke("setStudentID", anInt)
assertEquals(anInt, it.invoke("getStudentID"))
]
]
}
create instance
of Student and
invoke setter/getter
by reflection

Summary
• Differences of domain-specific and general-purpose
languages
• Short overview on purpose and architecture of
Xtext
• Gone through small example (hopefully) showing the
efficiency gain

Summary
• Differences of domain-specific and general-purpose
languages
• Short overview on purpose and architecture of
Xtext
• Gone through small example (hopefully) showing the
efficiency gain
Try it out by yourself! Xtext is very versatile and stable.

Thank you!

T.Baar: NSU TechTalk, Writing a PhD Thesis in Germany. 2015-11-24 1
How to write a PhD thesis in Germany
Thomas Baar
thomas.baar@ccfit.nsu.ru (temporary *)
NSU Tech Talk; Akademgorodok, 2015-11-24
Guest Lecturer at:
Home University:
* My stay at Novosibirsk State University is supported by DAAD (German Academic Exchange Service).

What do you like Germany for?
Source of map: "Deutschland topo" by Botaurus-stellaris - Own work. Licensed under CC BY-SA 3.0 via Commons -
https://commons.wikimedia.org/wiki/File:Deutschland_topo.jpg#/media/File:Deutschland_topo.jpg

What do you like Germany for?
Source of map: "Deutschland topo" by Botaurus-stellaris - Own work. Licensed under CC BY-SA 3.0 via Commons -
https://commons.wikimedia.org/wiki/File:Deutschland_topo.jpg#/media/File:Deutschland_topo.jpg
Cultural heritage
(literature, music,
architecture)
Social welfare
Innovative companies
High-quality products
(„Made in (West-)Germany“)
Efficiency
German beer :-)

Up-/Downsides of Efficiency

Ups
- high wages
- cheap products/food
- as a country: strong
economic position
(much more export
than import)

Ups
- high wages
- cheap products/food
- as a country: strong
economic position
(much more export
than import)
Downs
- high unemployment
rate
- expensive workplaces
 do not call a
craftsman ...
- high pressure on
employees
 Diesel Gate at VW

Efficiency also in Academia
• Comparing Student/Employee ratio of
- Hochschule für Technik und Wirtschaft (HTW) Berlin
 University of Applied Sciences
- Humboldt-University (HU) Berlin
- Novosibirsk State University (NSU)
0
5000
10000
15000
20000
25000
30000
35000
HTW Berlin HU Berlin NSU
Size of Universities
Employees Students

0
5
10
15
20
25
30
Students per Employee
0
5000
10000
15000
20000
25000
30000
35000
Employees Students

0
5
10
15
20
25
30
Students per Employee
0
5000
10000
15000
20000
25000
30000
35000
Employees Students
This is the paradise !!!

My Career
1990-97 Study of Computer Science at HU Berlin
1997-99 Research Assistent at HU Berlin
1999 How to continue? Hard decision!
1999-03 Doctoral Student at University of Karlsruhe
(today: KIT)
2003-07 Post-Doc, École Polytechnique Fédérale de Lausanne
(EPFL), Lausanne, Switzerland
2007-11 Senior Engineer in small software company, Berlin
2011 -- Professor at HTW Berlin

My Period of Writing PhD Thesis
• 2 years preliminary research work at HU Berlin
• my group in Karlsruhe
- 2 professors
- 2 post-docs
- 4 phd students
 funding from DFG (Deutsche Forschungsgemeinschaft): salary,
equipement, travelling
 basically no teaching obligations
- appr. 5-10 student assistents

- 2 professors
- 2 post-docs
- 4 phd students
We have the worst PhD supervisor ever, because he does not supervise us!

- 2 professors
- 2 post-docs
- 4 phd students
We have the worst PhD supervisor ever, because he does not supervise us!
We have the best PhD supervisor ever, because he does not supervise us!

How to find open Research Position?
• Ask your professor/supervisor here in Nsk
- people meet at conferences/workshops and
disseminate open positions
• Go to www.academics.de
- offers alert service
- informative links

Types of PhD Positions
• assistent position at university (Landesstelle)
+ contract extension no problem
- sometimes time-consuming teaching obligations
• research position at university (e.g. DFG financed)
+ focus on research; no teaching
- sometimes hard to get project extension
• position at research institute (Fraunhofer, Leibniz)
+ working on industry problems
- overloaded with work to reach next milestone
• research position in industry (Daimler Benz, Siemens)
+ working on industry problems
- no strong supervision; danger to become 'ordinary' project member

Initiative for Academic Excellence
• Initiated by chancellor Gerhard Schröder
Idea: Universities and clusters can apply for
special status "Place of Excellence"
- selected universities get huge research money from
Federal budget
- highly competitive (only 5-10 universities got status)
- only already renowned universities have chance to
become successful
Rational: Germany wants to "become better" in world-
wide rankings

Consequences of Excellence Initiative
• currently a lot of money "in the system"
• many interesting projects
• a lot of open positions :-)
- also due to the current very good job market
 many talented graduates go to industry

Consequences of Excellence Initiative
• currently a lot of money "in the system"
• many interesting projects
• a lot of open positions :-)
- also due to the current very good job market
 many talented graduates go to industry
!!! However !!!
- still only non-permanent positions
- becoming a professor after PhD project became
even more difficult (due to many qualified colleages
that completed PhD as well)

Will I have enough money to survive?
• as a PhD student: no fees to be paid

• Salary usually according to Tv-L 13: currently 3500 € per month
- from this appr. 50% reduction for taxes, health insurance,
pension plan
- !Attention! some research projects offer only 50% jobs
 "officially" 50% workload, but for sure only 50% payment

• Salary usually according to Tv-L 13: currently 3500 € per month
- from this appr. 50% reduction for taxes, health insurance,
pension plan
- !Attention! some research projects offer only 50% jobs
 "officially" 50% workload, but for sure only 50% payment
• Some prices:
- lunch in cafeteria: appr. 4 €
- food from supermarket: appr. 150 € per month
- 1-room flat in Berlin: from 400 € per month

Final Recommendations
• Do not worry about German language skills
- helpful in private life, but not mandatory at university
• my favourite position: research at university with professor
having 3-4 PhD students
• getting an 1-year-contract initially is rather normal
• publications
- do not wait too long with your first one
- write only if you found out something worth to be told
- also read books/articles on "How to write a good paper?/How
to give a good talk?"

Final Recommendations
Prof. Tom Henzinger: „Strive always to be as good as you can!“
(when writing applications,writing papers, giving talks)

Thank you!

Xtext project and PhDs in Gemany

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