Renaissance in Software Architecture

1
Renaissance in Software Architecture

• Slides for a talk at the
• Colloquium in memory of Gilles Kahn
• Paris, January 12, 2007
• Erik Sandewall
• Linköping University, Sweden

2
Computing Environment

• A software system that is an integrated tool
  for the development and the use of software.

3
Each software environment isan individual in a
software species

Each contains a spectrum from program to
data each of them can evolve over
time.
4
Consolidation of the software system Eliminate
design redundancies between

• Operating system (esp. its shell)
• Programming language and system
• Database system
• Various servers their corresponding clients
• Various branches of an office system
• Dialog engine other engines
• Simulation framework other frameworks
• . . .

5
Where to start the design?

• A programming language
• Conventions for procedure calls
• An interpretive programming system
• An architecture for processes on the OS level
• A system for datatype declarations
• A programming language and its debugging system

6
Where to start the design?

• A programming language
• Conventions for procedure calls
• An interpretive programming system
• An architecture for processes on the OS level
• A system for datatype declarations
• A programming language and its debugging system
• A textual representation for structured
  information (and for markup of text)

7
A textual representation for structured
information (and for markup of text)

• First example S-expressions
• Also textual representation in Python, etc.
• Also XML, RML, OWL
• Alternatives YAML

8
A textual representation for structured
informationModes of usage

• Persistent storage between runs
• Presentation to the user, for editing
• Message-passing between processes
• Parametric information for software modules
• High-level knowledge representation
• Archival representation of information
• Integrate in markup language for text

9
A textual representation for structured
informationKey issues for the design

• Should the representation be human readable, or
  not?
• Expressiveness
• Performance requirements
• Assumptions about the computation system where
  used

10
A textual representation for structured
informationChoices for the design

• Should the representation be human readable, or
  not? It should, this is important
• Expressiveness High requirements
• Performance requirements Moderate
• Assumptions about the computation system where
  used As described above

11
An example

• --------------------------------------------------
  --------
• -- plan7
• type method
• plan intend t1 t2 (remex uav-01 (check
  bridge4))
• intend t1 t3 (remex uav-03 (check
  bridge8))
• intend t4 t5 (send group4
  position3)
• time-constraints afterall t2 t3 t4
• --------------------------------------------------
  --------

12
Leonardo Data Expression Language

• Entities, strings, numbers
• a1, a2, an
• lta1, a2, angt
• recordtype a1, an, f1 v1,
• tag value a maplet
• (symbfun a1, a2, an)
  this is a new entity
• predicate a1 an extend to logic
  

13
The Leonardo computation system
Activation of individual
Repository
Real World
User/Operator
14
System consolidationleads to realignment of
facilitiesKernel facilities in Leonardo

• Conversion of information structures between
  computational and textual form
• Command executive
• Management of time on several granularity levels
• Management of modules and configurations
• General purpose version management
• Spawning and migration of software individuals

15
Project structure

• Hypothesis A consolidated computation system
  along these lines can avoid duplication of
  conventions and facilities
• Validation Design LDX, system platform, and
  several generic applications. Assess whether
  duplication was effectively avoided.
• Intended result Concise description of the
  design, and grounded account of reasons for
  distict design decisions.

16
Project status

• Representation and platform exist (but subject to
  additional, gradual modifications)
• A few applications exist and are in actual use,
  but by a single user (myself)
• Additional applications are intended to be ported
  from previously developed platform
• Documented on
• http//www.ida.liu.se/ext/leonardo/

17
Earlier work

• No full match (as far as I know)
• Earlier work on programming environments, in
  particular in the context of dynamic
  programming languages
• Systematic design of document editing and
  formatting systems
• Very much in the tradition(s) that were pioneered
  by Gilles Kahn.

18
This is not the End.