© ingo arnold advanced software engineering duale hochschule baden-württemberg view models...

© In

go

Arn

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Advanced Software Engineering

Duale Hochschule Baden-Württemberg

View ModelsIntroduction – Views and Perspectives

View ModelsOverview

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Levels are like different zooms. The observed object remains the same – it’s the level of detail which varies

View ModelsOverview

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Views are like filters, which ignore (on a given zoom-level) certain aspects while exclusively focussing others

View ModelsLevels

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Systems can be analyzed, described and understood on different levels of abstraction (Architecture Levels).

On Architecture Levels the according architectural decisions are taken as well as appropriate artefacts would be positioned.

An Architect should always be well aware of the Architec-ture Level that he acts upon.

View ModelsLevels

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View ModelsLevels

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View ModelsLevels

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Organisation Level Examples• Data-exchange protocol between IT-Systems is SQLNet

• Enterprise canonical data-format defines data exchange format

• Remoting protocol for functional invocations is IIOP

• All IT-Systems have to be documented according to guideline X

• Data-exchange communication style must be asynchronous based on corporate MOM infrastructure

• Corporate development process is mandated for life-cycle mana-gement of all IT-Systems

• Corporate roles must be mapped to IT-Systems’ actors

View ModelsLevels

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System Level Examples• Data-exchange protocol between Building-blocks is serialized

Java

• IT-System canonical data-format defines data exchange format that must be used between Building-blocks

• Remoting protocol for functional invocations across Building-blocks is Java-RMI

• All Building-blocks have to be documented according to JavaDoc standard

• Data-exchange communication style between Building-blocks can be either synchronous (for strongly coupled Building-blocks) or asynchronous (for loosely coupled Building-blocks)

• Building-blocks’ roles must be tracable to corporate roles

View ModelsLevels

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Building-block Level Examples• All inter-class communication is abstracted via Java-Interfaces

• Programming environment Java for business logic Building-blocks, ASP.NET for all web-facing Building-blocks

• Inter-thread communication via thread-safe data-objects

• Code-level documentation standard to follow is XDocLet

• JAAS-standards to follow for implementation of security model

View ModelsLevels

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Nota bene – places can sometimes be houses!

What is this?

View ModelsViews

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It‘s difficult to cover all aspects of a given IT-System with a singular view

Not all aspects are always relevant

Architecture views help the architect to reduce the number of aspects made visible at a given moment in time

Architecture Levels are an organisational tool – views make architecture tangible

Architecture models like Zachman or Togaf use the con-cept of Levels to orderly arrange and frame views.

View ModelsViews

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Such models also describe how views have to be used in conjunction in order to provide overviews tailored to ap-propriate stakeholders

The view concept is used to express actual content and show the aspect of current interest of a given whole

Complementary views are organized within Architecture Models (e.g. Zachmann, TOGAF)

Architecture views help to gain architectural completeness with regards to a given aspect

Typically Architecture views are incrementally developed

View ModelsViews

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Examples of aspects that can be observed within views• Logical building-blocks

• Physical building-blocks

• Deployment of building-blocks to operational nodes

• Security

• Physical infrastructure

• Locations and data-centres

• IT-System interdependencies

• Datapaths

• System-Management components

View ModelsViews

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A complete set of views should address the following aspects• Architectural context

• Architectural building blocks as well as the relationship amongst these

• Relationships between views

• Process of developing a specific view for a given IT-System

Ideally Architecture views are disjunct and loosly coupled

View ModelsViews

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An IT-System‘s architectural description is the sum of all architecture views – thus it is multi-dimensional

View ModelsViews

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Views in the context of Levels and Stakeholders

View ModelsViews

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How UML et al relates to views• Class diagrams model static structure of a system

• Class diagrams can be used to sketch business concepts as well as to express class-level designs

• You need to always understand view-point, first. The fact that a class-diagram was used doesn’t tell you on which abstraction level you are

Business concepts IT-System Design

View ModelsViews

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How UML et al relates to views

View ModelsView Models

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View Models are generally comprised of ...• Form

• Method & Process

• Tool

• Content

View ModelsView Models

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View Models are generally comprised of ...• Form determines what to describe and capture

views and element types

• Method & Process determine why and how to capture check-lists and cookbooks

• Tool determines whereby to capture repository management, notions and reporting

• Content is what was actually captured objects of element types

View ModelsView Models

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View Models

MOTIVATION DATA FUNCTION NETWORK

SCOPE

BUSINESS

APPLICATION

TECHNOLOGY

List of business goals / strategies

List of things important to the business

List of processes the business performs

List of locations in which the business operates

Business Plan E.g. Semantic Model

Ent.: Business EntityRel.: Business Relationship

E.g. Business Process Model

Proc.: Business ProcessIO: Business Resources

E.g. Business Logistics Model

Node: Business LocationLink: Business Relation

Business Rule Model E.g. Logical Data Model

Ent.: Data EntityRel.: Data Relationship

E.g. Application Architecture

Proc.: Application FunctionIO: User Views

E.g. Distributed Systems Architecture

Node: S-FunctionLink: Line characteristics

Rule Design E.g. Physical Data Model

Ent.: Database / TableRel.: Phys. Relationships

E.g. System Design

Proc.: Program FunctionIO: Data Elements, IFs.

E.g. HW-Technology Architecture

Node: HW systemLink: Line Specification

View - Filter

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View ModelsView Models

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View Models

MOTIVATION DATA FUNCTION NETWORK

SCOPE

BUSINESS

APPLICATION

TECHNOLOGY

List of business goals / strategies

List of things important to the business

List of processes the business performs

List of locations in which the business operates

Business Plan E.g. Semantic Model

Ent.: Business EntityRel.: Business Relationship

E.g. Business Process Model

Proc.: Business ProcessIO: Business Resources

E.g. Business Logistics Model

Node: Business LocationLink: Business Relation

Business Rule Model E.g. Logical Data Model

Ent.: Data EntityRel.: Data Relationship

E.g. Application Architecture

Proc.: Application FunctionIO: User Views

E.g. Distributed Systems Architecture

Node: S-FunctionLink: Line characteristics

Rule Design E.g. Physical Data Model

Ent.: Database / TableRel.: Phys. Relationships

E.g. System Design

Proc.: Program FunctionIO: Data Elements, IFs.

E.g. HW-Technology Architecture

Node: HW systemLink: Line Specification

View - Filter

Vie

w -

Lev

el

Questions?

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