DOT’98 Heidelberg 1 A. Hoffmann & M. Born Requirements for Advanced Distribution and Configuration Support GMD FOKUS Andreas Hoffmann & Marc Born Email:

DOT’98 Heidelberg 1A. Hoffmann & M. Born

Requirements for Advanced Distribution and

Configuration Support

GMD FOKUS

Andreas Hoffmann & Marc Born

Email: { a.hoffmann , born } @fokus.gmd.de


• Problems concerning deployment of distributed applications

• Requirement for engineering language

• Requirement for platform extensions

• Conclusion

Overview


Need for distribution and configuration information

ODL SDL

SystemDesign

Validation

MSCUML

Requ.Captering

Design ImplementationAnalysis

Java

C++

Coding

Coding

Execution

Information for distribution and configuration

needed


• Partitioning of specification and implementation into parts ready for distribution

• What is the unit for partitioning and distribution?– Depends from used language!– SDL: system, block, process– C++: CORBA objects?– ODL: objects, groups

The partitioning problem


• Assignment of the entities resulting from the partitioning (server, clients) to entities of the target environment (nodes, capsules ...)

• Configuration (setting of properties)

The installation or initial configuration problem


• Re-assignment of the entities resulting from the partitioning to entities of the target environment

• Caused by several reasons:– QoS (or other constraints) violation– Version control– Changes of the environment

The re-configuration problem


Partitioning of specification/implementation

Target environment description

Assignment of engineering spec. parts to target environment

Configuration of target environment and spec. parts

Dynamic update of Deployed System

The process of configuration and distribution


What is needed to support deployment of distributed applications?

Engineering Language

• Partioning• Assignment• Configuration

Platform Extensions

• Dynamic re-configuration


ODP - background for engineering Language

• ODP => Framework for open distributed systems

• Viewpoint Model => Managing the complexity of concurrent systems

• Only concepts; no methodology or concrete language

• Several appropriate languages for Computational Viewpoint• ODL => System structure (on Type Level Only)• SDL => System structure and behaviour• ...

• Need for an Engineering Viewpoint language


Advantages of separation of computational and engineering model

• Computational model remains stable

• Computational model serves for several purposes

=> Validation & simulation, test case gen., performance

analysis

• Several engineering-mappings for the same computational

model possible


Concepts of Engineering Language

• Defines engineering issues of the system– Partitioning of the system– Properties like binding mechanisms for interfaces (binder, stub, protocoll)– Communication mechanisms

• Defines the target environment

– Nodes, capsules, cluster– Ressources and properties

• Allows assignment of constraints– QoS– Performance

• Textual and graphical representation?


Mapping from Computational to Engineering Viewpoint (2)

O1O1

O3O3 O4O4

O2O2

Nod

e1N

ode2

En

gine

erin

g1

Nod

e2

Nod

e1

Nod

e4

En

gine

erin

g3

O1O1

O3O3 O4O4

O2O2N

ode3

O2O2

O1O1 O3O3

O4O4

Nod

e1N

ode2

En

gine

erin

g2

O1O1

O3O3 O4O4

O2O2C

ompu

tati

onal

En

viro

nm

ent1

En

viro

nm

ent2


Support for Constraints• Static and dynamic constraints

– Static: Evaluation before CO instantiation• Compiling constraints• Instantiation constraints

– Dynamic:Evaluation after CO instantiation• Runtime constraints

• Types of constraints– Ressource constraints (e.g. band width, memory)– Execution constraints (e.g. shutdown coordination)– QoS constraints (e.g. response time)

• Constraints for – Types of COs and Groups of COs– Instances of those types– Both combined

=> Instance constraints must be compliant to type constraints

QoS

Objective Subjective

Performance Time Cost Usability


Support for Constraints(2)Computational Model

O1O1

O3O3 O4O4

O2O2

Instance Level

Engineering Model

Configuration

Assignment

Constraints

Node1

Node2

Environment Model

ConstraintsConstraints

T1T1

T3T3 T4T4

T2T2

Type Level

Constraints


Environment description• Model for soft-/hardware

– Equipment, devices, OS, DPE (Distr.Proc. Env.) functions

• Concepts– ODP concepts: node, capsule, cluster, ...– Ressources and ressource types (for execution, communication)– Representations of DPE functions– Technology aspects (for practical reasons)

• Purpose– Description of an existing target environment– Abstract deployment requirements for a service

• Kinds of environment model– Abstract (DPE transparency)– Concrete (To support a concrete DPE)


Environment Model (2)

Computational Model

Abstract Environment

Model

Assignment(Abstract configuration)

Assignment(Concrete configuation)

Concrete Environment

Model

Concrete Environment

Model

Mapping Compliance

Concrete DPE


Required platform extensions

• Monitoring of properties and analysis• Evaluation of constraints (QoS, Performance ...)• Advanced management functions

• Cloning• Replication• Migration• Version control


Conclusions

• Problems are:– Partitioning

– Initial configuration (installation)

– Dynamic re-configuration

• Possible solutions are:– Development of engineering language

– Enhancement of execution platforms

• Starting points for development are:– ODP as theoretical background

– UML and other notations for language development

– Existing distributed processing environments (P715, GMD ...)

Documents

DOT’98 Heidelberg 1 A. Hoffmann & M. Born Requirements for Advanced Distribution and Configuration Support GMD FOKUS Andreas Hoffmann & Marc Born Email: