Contributions in Distributed Systems Engineering

by “Jari Koistinen”

Presenter : S. J. Paheerathan

Thesis Presentation

Agenda

• Thesis Introduced• Research Argument

– Claims– Evidence– Warrants– Qualification

• Research Questions• Research Results• Author’s Contribution• Thesis Structure

Thesis Introduced

• Title: Contributions in Distributed Systems Engineering

• Author: Jari Koistinen• Type: Lit. & PhD • Year: 1998• Pages: 412• Parts: V• Chapters: 17

Elements of Research Argument

• Claim• Evidence• Warrant• Qualifications Claim

Warrant

Evidence

Qualifications

Claims, Warrants, Evidences and Qualifications

Two elements that must be stated explicitly

• Claim– What you want readers to

believe. (You should be checked by your

doctor)

• Evidence– Reasons they should believe

it. (Your blood sugar reading is 200)

Claim

Warrant

Evidence

Qualifications

Claims, Warrants, Evidences and Qualifications

• Warrants– General principle, an

assumption or premise that bridges the claim and its supporting evidence connecting them into a logically related pair.

– Answers questions not about whether the evidence is accurate, but about whether it is relevant to the claim or it can be inferred from the evidence

(Whenever someone has a blood sugar reading of more than 120 that’s a good sign that she may have diabetes)

Claim

Warrant

Evidence

Qualifications

Claims, Warrants, Evidences and Qualifications

• Qualification– Limits the certainty of

conclusions– Stipulate the conditions in

which the claim holds– Address the readers

potential objections– Make the author to

appear a judicious, cautious, thoughtful writer

Claim

Warrant

Evidence

Qualifications

Your reading is 200evidence, so you should be checked,claim because that much glucose in the blood is a goodqualification sign that you mayqualification have diabetics,

warrant unless, of course, you just ate something sugary.qualification

Claims, Warrants, Evidences and Qualifications

One of the two elements that must be stated explicitly

• Claim– What you want readers

to believe. (You should be checked by

your doctor)

Claim

Warrant

Evidence

Qualifications

Properties of Claims

• They become the heart of the research/report and fully reflects the personal contribution of the author.– Are they capable of attracting the readers and meet their

expectations? (Are they substantive?)– Will these lead the readers to think?, (Are they contestable?)

• Is this something they have long thought? OR

• Is it something they never thought about at all?

– Are they specific/explicit?• Is it stated in language that is specific?

• Do the readers know what concepts to expect?

Claim of the Thesis

• Main Claim Improvements are required to the state-of-the-art of

distributed object systems engineering to better meet increasing business and product development requirements.

Subordinate Claims

The technologies and computing platforms used to support enterprise systems development must have at least the following characteristics1. Architecture and implementation techniques must enable rapid

evolution.

2. Systems must satisfy Quality of Service requirements such as reliability, security and performance requirements.

4. Architecture and implementation must enable extension and improvement at low cost by providing means for reuse.

5. Systems must have means for ensuring architectural and design integrity as systems evolve for many years.

Claims, Warrants, Evidences and Qualifications

One of the two elements that must be stated explicitly

• Evidence– Reasons they should

believe it. (Your blood sugar reading is

200)

Claim

Warrant

Evidence

Qualifications

Properties of Evidence

• Though the claim is the heart of a thesis, most of the thesis will be devoted to supporting the evidence– Do the evidences certain or reliable? (Are they accurate?)– Do the qualifiers set within appropriate limit? (Are they precise?)– Are they sufficient?– Are they representative?– Are they authoritative?

• Applicable to the time/current

– Are they perspicuous?• Can readers see the evidence as evidence?

Evidence

• Even recent proposals on high level structuring of object oriented systems lack characteristics that make them suitable for distributed object systems engineering. Classes are too fine-grained for cost effective development and reuse of large distributed systems.

• The development of large scale distributed object systems is more difficult than in necessary as common object oriented software engineering methodologies do not support separately defined and managed interfaces.

• Methodologies today do not support the formal description of design invariants, and it is difficult to maintain them during long time of system evolution, they too do not support automatic enforcement of architectural and design constraints.

Evidence (Cont..)

• QoS aspects such as reliability, security and performance are hard to capture and take under consideration with commonly used software engineering techniques and methodologies.– Explicit techniques are commonly used only for critical

systems such as flight control, patient monitoring and often limited in dimensions and inadequate.

Claims, Warrants, Evidences and Qualifications

• Warrants– General principle, an

assumption or premise that bridges the claim and its supporting evidence connecting them into a logically related pair.

– Answers questions not about whether the evidence is accurate, but about whether it is relevant to the claim or it can be inferred from the evidence

(Whenever someone has a blood sugar reading of more than 120 that’s a good sign that she may have diabetes)

Claim

Warrant

Evidence

Qualifications

Properties of Warrants

• They are the basis of our belief and reasoning.– False warrants– Unclear warrants– Inappropriate warrants– Inapplicable warrants

Warrants• Distributed computing is the infrastructure on which present

and future enterprises will built their information systems.– enterprises are increasingly becoming global, considering the whole

world as their market place.– different parts of the business are widely distributed and they need to

share business critical information and functions– failures or inadequacies in infrastructure will be very costly.

• To flourish enterprise must have functionally complete, flexible and reliable information systems.

• Rapid deployment of new functions and incorporation of new sites are critical for businesses today.

• Need to accommodate rapid change, search for new ways of doing business, technologies.

Claims, Warrants, Evidences and Qualifications

• Qualification– Limits the certainty of

conclusions– Stipulate the conditions in

which the claim holds– Address the readers

potential objections– Make the author to

appear a judicious, cautious, thoughtful writer

Claim

Warrant

Evidence

Qualifications

Your reading is 200evidence, so you should be checked,claim because that much glucose in the blood is a goodqualification sign that you mayqualification have diabetics,

warrant unless, of course, you just ate something sugary.qualification

Qualifications

• Development of large scale distributed enterprise systems using object orientation.

Research Questions

• Is it possible to develop concepts and well-defined language for coarse-grained modularization of object oriented software such that we obtain multi-class components that have well defined interfaces and dependencies?

• Is it possible to introduce separately defined first class interfaces such that systems are more evolve-able and can be naturally mapped to distributed object infrastructures without imposing any conceptual burdens on developers?– Whether separating inheritance and non-inheritance

boundaries, annotating interfaces with architectural categories, and aggregating sets of tightly-knit interfaces improve the internal quality of a software system?

Research Questions (Contd..)

• Is it possible to formalise architectural and design constraints in a manner that is intuitive to use, expressive enough and enables the implementation of efficient checking procedures?

• Is it possible to introduce a specification technique that enable us to describe, for distributed objects, quality of service requirements and characteristics involving multiple QoS requirements and characteristics involving multiple QoS dimensions?– If so, will it possible to use this technique both during the

design of multi-class components and as a run-time representation for QoS information?

Research Results

• Concepts, language and tools for modularization and structuring of multi-class components and interfaces of large object oriented systems.– Concepts have been implemented in a prototype tool and a

variation of concepts have been integrated with an industrial design language and tool environment.

– Concepts have been applied to the design of a real telecommunication application and resulted in more well-defined architectures and high-level structures.

Research Results (Contd..)

• Concepts, language and tools for the description and enforcement of architectural styles for a variety of architectural building blocks such as mutli-class components, interfaces and individual classes.– Concepts and language have been given a formal semantics

based on tree logic. Integration of a tree logic inference engine within an industrial design environment has been prototyped.

– User evaluation proved that commonly used design constraints can be expressed in the language and that the formal basis enables efficient implementation of real-time checking.

Research Results (Contd..)

• Concepts, language and tools for the description and exchange of QoS information for object oriented components. – The language has been implemented and a corresponding

run-time representation and wire representation has been defined and implemented. It has been used to design a QoS negotiation mechanism indicating adequate expressiveness.

– Concepts and language have been used in case studies with good results.

Contributions of the thesis

• Efficient large-grained structuring of modules and interfaces.– Novel and improved concepts and a language for the

description and structuring of large grained modules and interfaces.

• A refined interface concept separating different types of interfaces and grouping of closely related interfaces

• case studies and practical experience indicate that systems can be built with these concepts to be more easily evolved, enabling iterative and parallel development, and mapped to distributed object technologies.

• The concept and language enables the treatment of interfaces as a first class concept in system architectures.

Contributions of the thesis (Contd..)

• Formal Architectural styles.– Novel concepts and a language for the formal description of

invariants for architectural designs and design constraints.• Allows general design languages to be used to develop systems

with specific architectural constraints and characteristics.

• Allows formal treatment and efficient checking while providing adequate expressive power.

Contributions of the thesis (Contd..)

• QoS specification language and run-time representations.– Novel concepts for QoS specification of object oriented

components which are separate from any syntactic and semantic descriptions of components.

• The language balances the expressibility with the need for conformance checking of independent specifications of a particular interface.

• A well defined language to enable independent implementation of infrastructure components that can interchange QoS specifications.

Structure of the thesis

• Collection of licentiate thesis, four conference papers and two research reports.– Part I - Summarises the research area, research questions

and results– Part II - Licentiate Thesis, proposes concepts for dealing with

programming in the large and a case study on a real large scale distributed system development

– Part III -Two papers, • one is on the industrial application of the concepts presented in

the Lit. thesis and

• other is on further development, formalisation and implementation of the architectural style concepts mentioned in the Lit. Thesis.

Structure of the thesis (Contd..)

– Part IV - Papers and research reports on declarative QoS specification on Object Oriented components.

– Part V - Epilogue, Concluding remarks.– Bibliography

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