Component-Based Software Development: Technologies, Quality Assurance Schemes, and Risk Analysis Tools Cai Xia Supervisor: Prof. Michael R. Lyu Markers: Prof. Kam-Fai Wong Prof. Ada Fu December 18, 2000

Presentation Outline  Introduction  Current component technologies  Quality assurance issues and a QA model for Component-Based Software Development (CBSD)  A risk analysis tool: ARMOR  Expected new features of our risk analysis tool  Demonstration of ARMOR  Conclusion and future work

Introduction  Software systems become more and more large-scale, complex and uneasily controlled  One of the most promising solution now is component-based software development approach  The process of CBSD is totally different from traditional systems  Quality Assurance is very important for component-based software systems

What is Component-Based Software Development? Component repository Software systems s elect assemble Component 1 Component 2 Component n... Commercial Off-the-shelf (COTS) components Software systems can be developed by selecting appropriate off-the-shelf components and then assembling them with a well-defined software architecture.

Advantages of CBSD Reduce Development cost Time-to-market Improve Maintainability Reliability Overall quality of software systems

What is A Component?  A component is an independent and replaceable part of a system that fulfills a clear function  A component works in the context of a well- defined architecture  It communicates with other components by the interfaces

System Architecture  Layered  Modular Special business components Common components Basic components App2 App1 App3 Application Layer Components Layer

Current Component Technologies  Common Object Request Broker Architecture (CORBA) from Object Management Group (OMG)  Component Object Model (COM) and Distributed COM (DCOM) from Microsoft  JavaBeans and Enterprise JavaBeans (EJB) from Sun Microsystems

CORBA  CORBA is an open standard for application interoperability  Allows applications/components to communicate with one another despite of different locations and designers.  The interface is the only way that applications/ components communicate with each other.  Object Request Broker (ORB) is the middleware that establishes the client-server relationships between components.  CORBA is widely used in OO distributed systems including component-based software systems

COM/DCOM  COM is a general architecture for component software vDefines how components and their clients interact directly and dynamically  DCOM is a protocol that enables software components to communicate directly over a network  Designed for use across multiple network transports, including Internet protocols such as HTTP

 JavaBeans for client-side component development, while Enterprise JavaBeans for server-side component development  Offers an efficient solution to the portability, security and reliability of component-based development.  The features are well suited for developing robust server objects independent of OS, Web servers and database management server. JavaBeans/EJB

Comparison of Current Component Technologies CORBAEJBCOM/DCOM Development environment Underdeveloped Emerging Supported by a wide range of strong development environments Binary interfacing standard Not binary standardsBased on COM; Java specific A binary standard for component interaction is the heart of COM Compatibility & portability Strong in standardizing language bindings; but not so portable Portable by Java language spec; but not very compatible. Not having any concept of source-level standard of standard language binding. Modification & maintenance CORBA IDL for defining component interfaces Not involving IDL filesMicrosoft IDL for defining component interfaces Services providedA full set of standardized services; lack of implementations Neither standardized nor implemented Recently supplemented by a number of key services Platform dependency Platform independent Platform dependent Language dependency Language independentLanguage dependentLanguage independent Implementation Strongest for traditional enterprise computing Strongest on general Web clients. Strongest on the traditional desktop applications

 Requirements analysis  Software architecture selection, creation, analysis and evaluation  Component evaluation, selection and customization  Integration  Component-based system testing  Software maintenance Life Cycle of CBSD

QA for Component-Based Software Two inseparable parts:  How to certify quality of a component?  How to certify quality of a component-based software system? Metrics for components:  Size  Complexity  Reuse frequency  Reliability

A Quality Assurance Model for CBSD  Component  System

Hong Kong SQA Model  Proposed by Hong Kong Productivity Council  Provides the standard for local software organizations  Meet basic software quality requirements;  Improve on software quality practices;  Use as a bridge to achieve other international standards;  Assess and certify them to a specific level of software quality conformance

Main Practices Requirement Analysis Component Architecture Design System Component Development Component Certification Component Customization System Integration System Testing System Maintenance

Process Overview  Component Requirement Analysis

Process Overview  Component Development

Process Overview  Component Certification

Process Overview  Component Customization

Process Overview  System Architecture Design

Process Overview  System Integration

Process Overview  System Testing

Process Overview  System Maintenance

The Feature of Our QA Model Compared with other existing models:  Simple, easy to apply  Design for local component vendors (small to medium size)  Focused on development process, according to the life cycle of CBSD  Not focused on the measure/predict the quality of components/systems

ARMOR: Analyzer for Reducing Module Operation Risk  The prototype was developed at Bell Lab in  A software risk analysis tool which automatically identifies the operational risks of software program modules.  Take data directly from project database, failure database and program development database.  Collect software metrics, select risk models, and validate the established models.

ARMOR Objectives  To access and compute software data deemed pertinent to software characteristics.  To compute product metrics automatically whenever possible  To evaluate software metrics systematically  To perform risk modeling in a user-friendly and user-flexible fashion  To display risks of software modules  To validate risk models against actual failure data and compare model performance  To identify risky modules and to indicate ways for reducing software risks

High Level Architecture for ARMOR

Component Evaluation and Risk Analysis Tool  Based on ARMOR  Add some Java feasure on it: o Java Classes o Program Coupling o Java Methods o Hierarchical Structure o Clone Detection

Existing Metrics on Java  Metamata  Jprobe  Both base on Java language  Adopted in current component market

Examples of Metamata Metrics MetricMeasuresDescription Cyclomatic Complexity ComplexityThe amount of decision logic in the code Lines of CodeUnderstandability, maintainability The length of the code; related metrics measure lines of comments, effective lines of code, etc. Weighted Methods per Class Complexity, understandability, reusability The number of methods in a class Response for a Class Design, usability, testabilityThe number of methods that can be invoked from a class through messages Coupling Between Objects Design, reusability, maintainability The number of other classes to which a class is coupled Depth of Inheritance Tree Reusability, testabilityThe depth of a class within the inheritance hierarchy Number of Attributes Complexity, maintainabilityThe amount of state a class maintains as represented by the number of fields declared in the class

Conclusion and Future Work  We look at the current technologies, quality assurance schemes for component-based software development.  Our work is to implement a component evaluation and risk analysis tool  The tool will make use of the well-adopted metrics  It is Java language oriented.

Q & A