软件工厂

软件工厂
软件工厂(Software Factories)观念介绍 Model Driven Architecture (MDA) 微软DSL与GAT

软件总线和软件工厂
直到目前为止,软件开发仍然属于手工作坊阶段,如果要 和制造业的水平相对应的话,基本上是处于蒸气机发明之 前的水平. 随着软件开发技术的发展,软件开发也将象制造业一样, 步入"工业"时代.不过对于软件开发来说,机器仍然是代 码,只不过这些代码是用来代替开发人员的编码活动的, 他具有比手工编码更高的生产力. 我们把这些高产量的"机器"描述成现代化的软件工厂.那 么,软件工厂到底是什么?
软件工厂
软件工厂在组件和软件总线的基础上发展,并根据组件和软件总线的 技术特点,定义了一系列的管理活动,以提高开发效率. 软件工厂是我们定义的软件质量框架的一种实现方式.对于不同的软 件组织来说,根据自身的研发特点来定义软件工厂的构成是非常重要 的.具体的内容包括管理实践的选择,组件的积累,软件总线的技术 实现. 前两项实践都属于管理实践范畴的内容,而第三项实践则偏重于建立 软件工厂的底层支撑框架. 软件工厂的概念代表了一种新的软件开发模式.他的优势在于能够把 技术和管理结合起来,提高生产力.

MDA Model driven architecture
Contents
What is MDA? Challenges for MDA Program generation from models MDA terminology Basic modeling technology Modeling language extensibility Building a MDA application Model transformations (information, activities) About tools

What is MDA?
using modeling languages as declarative progamming languages
– rising of abstraction level for programmers – improved productivity, quality, longevity outlook
has been used to generate real-time and embedded systems although term MDA coined later
– strategic direction of OMG as announced in 2002) – Java community process, ebxml, rosettanet using similar concepts
Challenges for MDA
B2B and B2C integration needs of enterprises
Reguirement: Preserve investment
EJB 1.1 --> EJB 2.0 XML --> XML Schema MTS --> COM+ CORBA 2.0 --> CORBA 3.0
– As enterprise borders shift requiring platform shift – As platforms themselves change
Solution: Isolate information and processing logic from technology specifics
– Build platform independent models
UML is independent of CORBA, COM, EJB, XML, etc thus is well-suited as a language for dexcribingn Map these models to specific platforms Maintain the separation at the implementation level

Enterprise and its boundaries
Frankel:2001
No Universal Component Middleware
Major Challenge!
CORBA EJB .NET ...

Integration communication
Frankel:2001
Enterprise system integration trend
"middleware" addresses integration within the enterprise with a distributed computer today aim for similar integration between enterprises
– Avoid typing in from computer-printouts
ebXML, .NET, RosettaNet and other Web Services initiatives aim to be "the" middleware to link enterprises
– How to cope with them all?

Rising the level of abstraction
Part of general trend Already well-established front and back ends
– WYSIWYG GUI modeling and data modelign – Hand coding no longer predominatees
Early web-applications wired web front end directly to back end
– Some companies avoided building intermediate tiers – Web services and B2B require intermediate tiers to expose coarse grained business services – Abstraction to allow reuse of the coarse grain business services via various technologics.
Program generation from models
MDA is about using modeling languages as programming languages rather than merely as design languages can improve productivity, quality, and longetivity outlook new term, old invention
– CASE-tools in 1980's, integrated object-oriented development environments in 1990's, UML tools, etc.

Model Driven Architecture
New orientation for OMG activities
– New step beyond the Object Management Architecture (OMA)
Models are centric!
– Target middleware is not important!
Focus on Platform Independent Models (PIM)
– Without middleware details
Abstract Platform Specific Models (PSM)
– Including all middleware details
Define PIM to PSM transformations Preserving PIM when new middleware appears!
Some Key Terms
Model – A formal specification of the function, structure and/or behavior of a system. (Model .ne. UML) Platform – Technological and engineering details that are irrelevant to the fundamental functionality of a software component. Platform Independent Model (PIM) – A formal specification of the structure and function of a system that abstracts away technical details (e.g., funds transfer) Platform Specific Model (PSM) – The technical details (CORBA, SOAP, EJB)

Basic modeling technology
UML – unified modeling language MOF – meta object facility XMI – XML metadata interchange
UML
IDL as abstraction very limited
– generates same level constructs, stubs and skeletons
modeling languages – declarative?
– separation of abstract syntax from concrete syntax – invariants, pre- and postconditions – precise action semantics and standard mappings on various platforms – mappings represent a standard engineering solution for a collaboration concept
UML has defined profiles for introducing separate sets of transformation rules
– to model particular domain, eg. business information, busienss services, collaborations, realtime systems, telecom – to parametrize mapping to sepcific technologies
class vs. behavioural models

MOF
M3 UML class, UML association UML attribute, UML state, M2:met M1: models MOF class, MOF attribute, MOF association
amodel s
class "customer", … table "employee", …
M0: objects and data
XMI - XML metadata interchange

Building an MDA Application
Platfor mIndepe ndent Model
A Detailed Model, stating Pre- and PostConditions in OCL, and Semantics in Action Language
Start with a PlatformIndependent Model (PIM) representing business functionality and behavior, undistorted by technology details.
Generating Platform-Specific Model
Platfor mIndepe ndent Model
Map a PIM to Specific Middleware Technologies via OMG Standard Mappings
CORBA Model
MDA tool applies a standard mapping to generate PlatformSpecific Model (PSM) from the PIM. Code is partially automatic, partially hand-written.

Mapping to Multiple Deployment Technologies
Platfor mIndepe ndent Model
Map a PIM to Many Middleware Technologies via OMG Standard Mappings
CORBA Model
Java/EJB Model
XML/SOA P Model
Other Model
MDA tool applies an standard mapping to generate PlatformSpecific Model (PSM) from the PIM. Code is partially automatic, partially hand-written.
PSM can be viewed as presentation model (Web): data schemas, web comps, etc Business logic model (EJB): data schemas, key classes, etc Data models (DBMS): tables, columns, keys, etc
Generating Implementations
Platfor mIndepe ndent Model
Map PSM to application interfaces, code, GUI descriptors, SQL queries, etc.
CORBA Model
Java/EJB Model
XML/SOA P Model
MDA Tool generates all or most of the implementation code for deployment technology selected by the developer.
Other Model
CORBA
Java/EJB
XML/SOA P
Other

Integrating Legacy & COTS
Platfor mIndepe ndent Model
Reverse-engineer existing application into a model and redeploy.
MDA Tools for reverse engineering automate discovery of models for re-integration on new platforms.
Legacy App
COTS App
Other Model
Other
Automating Bridges
Platfor mIndepe ndent Model
CORBA Model
MDA Tools combine application and platform knowledge to generate bridges
XML/SOA P Model
Bridge generation is simplified by common application models, simplifying creation of integrated applications both within and across enterprises.
CORBA System Interop Bridge
XML/SOA P System

Concepts: Refinement
Service Provisioning
Component Independent Business Model
Billing
Component Independent Business Model
Computation independent
Platform independent
Platform Independent Component view
Platform Independent Component view
Platform Specific
Platform Specific
Concepts: Patterns
Service Provisioning
Business Model PIM to Corba
Billing
Business Model
Platform Independent
Platform Independent
Platform Specific CORBA
Platform Specific CORBA

Concepts: Packages
Package P4 Abstraction Package P5 Refinement Relation Package P3 Interrelationship between P1 and P2
Package P1 System from viewpoint 1
Package P2 System from viewpoint 2
(a)
(b)
Package P6 Realization
MDA Example
Credit:

PIM, PSM, and Transformations in MDA
Platform Independent Model (PIM) TRANSFORMATION RULES
Platform Specific Model (PSM)
Platform Specific Model (PSM)
PIM to PSM Transformation Examples with MOF/XMI
UML Model (PIM)
Auto Color : String Door : Integer Engine : Integer
XMI Document (PSM)
XMI Red 4 2
I M
M O F
IDL, Java… (PSM)
interface Auto { Class Auto }; {public String color; public int Door; public int Engine; }
X
XMI DTD, Schema (PSM)

Transformation Models in MDA
PIM Software Infrastructure
UM L
EJ L4 M B U
PSM J2EE
L UM
PIM HealthCare Business Application (CIAS)
.Ne t J2E EPIM to PSM Transformation Model
UM L et .N
PSM .Net
Why New Component Models?
Often application designers want to use concepts not present in PSM
– e.g. CCM has no active JavaBeans properties
1) Creating a new PSM but also requires to develop the associated middleware
– Very expensive and time consuming!!!
2) Creating a new PIM and defining PIM to PSM transformation rules

The Message Filtering Example
A filter has
– 1 input for receiving messages to filter – Configurable filtering properties – 1 filtering function – 1 output for accepted messages – 1 output for rejected messages
Filter
P1 = V1 P2 = V2 F = M.C1 == P1 or M.C2 > P2
O K N O
Application = Assembling Filters

Problems
All must be done manually!
– Defining OMG IDL for message eventtypes, filter component and home types – Implementing CCM eventtypes, components and homes – Writing CCM XML descriptors

Extremely verbose, time consuming and error prone!!! How improving productivity and quality? How dealing with thousand messages and filters? How dealing with other Message Oriented Middleware (MOM)?
– Like EJB 2.0 message beans
Next Step on the Message Filtering Meta-Model
Only allow definition of message and filter types Only generate OMG IDL types, implementations, and CCM XML packaging descriptors Complete the meta model to describe filter instances and connections between them Then allow generation of CCM XML assembling descriptors for automatic deployment

Drawback around MDA-oriented Tools
Few MOF compliant tools to experiment the creation of new component meta models! Developing UML profiles are time and money consuming No portability of developed UML profiles between UML Tools!!! Few formalisms to express MDA transformation Few PSM meta models for
– OMG RFP under work – Programming languages like Java, C++, … – Component standard middleware – UML Profile Builders are still expensive and proprietary
MDA vs. CASE
CASE limitations
– Mappings to implementation technologies were proprietary
Risk to CASE customers too great
– Very limited to extend specification language
MDA overcomes these limitations
– Standardized mappings, for each domain – UML profiles and MOF