REVERSE ENGINEERING Reverse engineering conjures an image of the "magic slot." We feed an unstructured,
30.3 REVERSE ENGINEERING Reverse engineering conjures an image of the "magic slot." We feed an unstructured,
undocumented source listing into the slot and out the other end comes full docu- mentation for the computer program. Unfortunately, the magic slot doesn't exist. Reverse engineering can extract design information from source code, but the abstrac- tion level, the completeness of the documentation, the degree to which tools and a human analyst work together, and the directionality of the process are highly vari- able [CAS88].
The abstraction level of a reverse engineering process and the tools used to effect it refers to the sophistication of the design information that can be extracted from
source code. Ideally, the abstraction level should be as high as possible. That is, the The notation discussed
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reverse engineering process should be capable of deriving procedural design repre- here is explained in detail in Chapter 12.
sentations (a low-level abstraction), program and data structure information (a some- what higher level of abstraction), data and control flow models (a relatively high level of abstraction), and entity relationship models (a high level of abstraction). As the abstraction level increases, the software engineer is provided with information that will allow easier understanding of the program.
The completeness of a reverse engineering process refers to the level of detail that is provided at an abstraction level. In most cases, the completeness decreases as the
Three reverse abstraction level increases. For example, given a source code listing, it is relatively engineering issues
easy to develop a complete procedural design representation. Simple data flow rep- must be addressed:
abstraction level, resentations may also be derived, but it is far more difficult to develop a complete set completeness, and
of data flow diagrams or entity-relationship models. directionality.
Completeness improves in direct proportion to the amount of analysis performed by the person doing reverse engineering. Interactivity refers to the degree to which the human is "integrated" with automated tools to create an effective reverse engi- neering process. In most cases, as the abstraction level increases, interactivity must increase or completeness will suffer.
If the directionality of the reverse engineering process is one way, all information extracted from the source code is provided to the software engineer who can then use it during any maintenance activity. If directionality is two way, the information is
F I G U R E 30.3
The reverse engineering
Dirty source code process
Restructure code
Processing
Clean source code
Extract abstractions
Interface
Initial specification
Database
Refine & simplify
Final specification
fed to a reengineering tool that attempts to restructure or regenerate the old program.
The reverse engineering process is represented in Figure 30.3. Before reverse engi- neering activities can commence, unstructured (“dirty”) source code is restructured
WebRef
(Section 30.4.1) so that it contains only the structured programming constructs. 2 This The Design Recovery and
makes the source code easier to read and provides the basis for all the subsequent Program Understanding
reverse engineering activities. page provides useful
resources for The core of reverse engineering is an activity called extract abstractions. The engi- reengineering work:
neer must evaluate the old program and from the (often undocumented) source code,
wwwsel.iit.nrc.ca/
extract a meaningful specification of the processing that is performed, the user inter-
projects/dr/dr.html
face that is applied, and the program data structures or database that is used.
Parts
» The Concurrent Development Model
» SUMMARY Software engineering is a discipline that integrates process, methods, and tools for
» PEOPLE In a study published by the IEEE [CUR88], the engineering vice presidents of three
» THE PROCESS The generic phases that characterize the software process—definition, development,
» THE PROJECT In order to manage a successful software project, we must understand what can go
» METRICS IN THE PROCESS AND PROJECT DOMAINS
» Extended Function Point Metrics
» METRICS FOR SOFTWARE QUALITY
» INTEGRATING METRICS WITHIN THE SOFTWARE PROCESS
» METRICS FOR SMALL ORGANIZATIONS
» ESTABLISHING A SOFTWARE METRICS PROGRAM
» Obtaining Information Necessary for Scope
» An Example of LOC-Based Estimation
» QUALITY CONCEPTS 1 It has been said that no two snowflakes are alike. Certainly when we watch snow
» SUMMARY Software quality assurance is an umbrella activity that is applied at each step in the
» R diagram 1.4 <part-of> data model; data model <part-of> design specification;
» SYSTEM MODELING Every computer-based system can be modeled as an information transform using an
» Facilitated Application Specification Techniques
» Data Objects, Attributes, and Relationships
» Entity/Relationship Diagrams
» Hatley and Pirbhai Extensions
» Creating an Entity/Relationship Diagram
» SUMMARY Design is the technical kernel of software engineering. During design, progressive
» Data Modeling, Data Structures, Databases, and the Data Warehouse
» Data Design at the Component Level
» A Brief Taxonomy of Styles and Patterns
» Quantitative Guidance for Architectural Design
» Isolate the transform center by specifying incoming and outgoing
» SUMMARY Software architecture provides a holistic view of the system to be built. It depicts the
» The User Interface Design Process
» Defining Interface Objects and Actions
» D E S I G N E VA L U AT I O N
» Testing for Real-Time Systems
» Organizing for Software Testing
» Criteria for Completion of Testing
» The Transition to a Quantitative View
» The Attributes of Effective Software Metrics
» Architectural Design Metrics
» Component-Level Design Metrics
» SUMMARY Software metrics provide a quantitative way to assess the quality of internal product
» Encapsulation, Inheritance, and Polymorphism
» Identifying Classes and Objects
» The Common Process Framework for OO
» OO Project Metrics and Estimation
» Event Identification with Use-Cases
» SUMMARY Object-oriented analysis methods enable a software engineer to model a problem by
» Partitioning the Analysis Model
» Designing Algorithms and Data Structures
» Program Components and Interfaces
» SUMMARY Object-oriented design translates the OOA model of the real world into an
» Testing Surface Structure and Deep Structure
» Deficiencies of Less Formal Approaches 1
» What Makes Cleanroom Different?
» Design Refinement and Verification
» SUMMARY Cleanroom software engineering is a formal approach to software development that
» Structural Modeling and Structure Points
» Describing Reusable Components
» SUMMARY Component-based software engineering offers inherent benefits in software quality,
» Guidelines for Distributing Application Subsystems
» Middleware and Object Request Broker Architectures
» An Overview of a Design Approach
» Consider expert Web developer will create a complete design, but time and cost can be appropriate
» A Software Reengineering Process Model
» Reverse Engineering to Understand Data
» Forward Engineering for Client/Server Architectures
» SUMMARY Reengineering occurs at two different levels of abstraction. At the business level,
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