Model-Driven Software Development - Web Abstractions 1

transcript

Web Abstractions 1data models, user interface templates, access control

Course IN4308Master Computer Science

Delft University of Technology

Eelco Visserhttp://eelcovisser.org

Lecture 3

Wednesday, March 10, 2010

Application Model = Domain Model + Interaction Design

System

Domain Model = State?Interaction Design = Behaviour?

From high-level declarative model

System

automatically generate

efficient & complete implementation

How to model applications?

Wat makes a blog?

Wat makes a webshop?

Wat makes a chair?

Purpose=>

Features

Application Model = Collection of UML Diagrams

generate implementation from model

- Consider

★ interaction styles

★ layout

★ color schemes

★ fonts

★ personalization

★ ...

- Parameters of the modeling language?

★ generic, orthogonal definition?

Details make the difference

UI programming is like assembly programming

concerned with screen components

not with interaction styles & concepts

want: declaration of user interaction

Problem: ‘UI tweaking’

- code generation produces standardized/limited UI

Alternative: extra ‘hand coding’ e.g. UI templates not part of model

Conclusion: - modeling not adequate for interaction design

- user interface programming is low-level

instead of a general purpose solution (UML)

address specific class of software systems

Intermediate Goal for MDSD

develop better programming abstractions

for horizontal domains

before tackling vertical domains

‘let’s first make it easier to build web apps’

horizontal (technical) domains

vertical (‘business’) domains

accounting

Properties of Domain-Specific Languages

DSL design requires tradeoff between

- Expressivity

- Coverage

- Portability

- Interoperability

- Completeness

- Maintainability

Extensive discussion in Quarter 4

The Web Domain

browser server database

app.war

a web application lives on the server

Concerns in Web Programming

- Persistent data

★ data integrity

★ search

- User interface

★ data validation

★ styling, layout

★ navigation

★ actions

- Workflow

- Access control and more ...

Problems in Web Programming

- Separate language for separate concerns

★ (that’s good)

- Lack of integration

★ no consistency checking

★ different language styles

- Low-level configuration

★ boilerplate code

WebDSL

a domain-specific language for web applications

separation of concerns & linguistic integration

Web Abstractions

from a declarative point of view(we’ll investigate underlying mechanisms later)

Eelco Visser. WebDSL: A Case Study in Domain-Specific Language Engineering. GTTSE 2008: 291-373

Data Model Definition

entity declarationproperty

object identifier

domain-specific type

Data Model for Wiki

page definition

page navigation (page call)

Page Definition & Navigation

Displaying Data

markup

rendering values

parameter

template definition

template call

Templates (Page Fragments)

wiki.css

data binding

pageflow

Modifying Data

submit

Core Wiki

navigate

actionWednesday, March 10, 2010

Core Wiki

navigate

actionWednesday, March 10, 2010

Creating Objects

find/create object by id

pass string

Modifying Data

Core Wiki

action

navigate creates page

Page Index

Output Object = Navigation

default definitioncustom definition

Access Control

Danny M. Groenewegen, Eelco Visser. Declarative Access Control for WebDSL: Combining Language Integration and Separation of Concerns. ICWE 2008: 175-188

Principal

turn on access control

representation of principal

Principal

turn on access control

representation of principal

Authentication

Registration

Access Control Rules

‘may access page f with argument x if boolean expression e is true’

Wiki Access Control Rules

‘only logged in users may edit pages’

‘anyone can view existing pages, only logged in users can

create pages’

More Web Abstractions

- Access control policies

★ constraints over objects

★ role-based AC, discretionary AC

- Data validation

★ form validation

★ data integrity

- Loading/accessing templates (partial pages)

★ (AJAX)

- Search

- Workflow

The Future of Quarter 3

- Lecture 4

★ More web abstractions

- Lecture 5

★ What does WebDSL abstract from?

★ Or: from DSL to Code

- Lecture 6

★ Language workbenches

★ Grammars

- Lecture 7

★ Language modeling

Schedule

Lab this week

★ Finish & submit proposal Design 1

★ Entity declarations

★ Basic setup for user interface

★ Case 1: domain analysis in digital library domain

★ Case 2: web abstractions

★ Week 4 is ‘spring’ break; Week 5: lecture no, lab yes

★ Week 6: access control policies, validation, search, ...

Model-Driven Software Development - Web Abstractions 1

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