Transcript Graduation Project

Masters Project
Extraction of State Machine Diagrams of
Legacy C code with Cpp2XMI
Vanderlande Industries B.V. (Veghel)
Dennie van Zeeland
[email protected]
Slide 1, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Outline
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Introduction
Project goal
Related work
Tools
State Machine patterns
Switch-Case / Switch-Case pattern
Overview of design of Cpp2XMI
CPPML
Case Study - FSC
Problems encoutered
Conclusions / Future work
Slide 2, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Introduction
• Vanderlande Industries (VI)
- Automated material handling systems:
• distribution centres
• baggage handling at airports
• express parcel sortation facilities
• Flow System Controller (FSC)
- Controls the product flows in conveyor systems for transport and
sortation
- Controls all motors, photocells and other active components
- Send and receive control and status information
- Realtime control of equipment
- Separated GUI
- Standard interfaces with equipment
- Fully configurable for all VI sorting equipment
Slide 3, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Project goal
• Reverse Engineering documentation from C/C++ source code
- Why:
• Limited documentation available for V5/V6
- State machine diagrams
• Identifying possible flaws in current versions
• V7 is being developed from scratch
• Extracting dynamic behavior from source code for V7
• Identifying requirements
- Building a tool for extracting state machine diagrams from code
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Preprocessing source code
Parsing source code
Finding patterns in source code of state machines
Creating diagrams
Slide 4, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Related work
• ESPaRT [KNOR98]
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Finding state machine patterns and replacing them by better constructs
• Bandera [CORB00]
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Extract state machines and produce input for model checkers
• Symbolic Execution [WALK08]
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Program conditioning
• Brastra [YUAN06]
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Extracting state machines using unit tests
• Log based state machine extraction [GANN06]
Slide 5, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Tools
• Cpp2XMI
- Developed by Elena Korshunova for LaQuSo
- C++ to UML-diagrams
• Class diagram
• Sequence diagram
• Activity diagram
• Columbus/CAN toolset
- Pre-processor + Parser + Linker
- Static analyser (Class diagram extraction)
- CPPML (C++ Markup Language)
• Use Cpp2XMI as basis and extend it with
- State machine diagram
Slide 6, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
State Machine Patterns
• Global type of patterns for implementing state machines
- Nested Choice Patterns
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Switch/Case – Switch/Case pattern (mainly used in FSC)
Switch/Case – If/Else
If/Else – Switch/Case
If/Else – If/Else
- Jump Tables
• Pointer to a function pointer array represents state variable
• Function pointer array is the jumb table
• Table contains the event handler functions
- Object oriented approach
• States as classes
- Goto statements
• Use goto statements to jump through program
• Each goto statement corresponds to a state transition
Slide 7, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (1)
• States
Source Code
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/* State of the object */
enum OBJ_STATE
{
STATE_A,
STATE_B,
STATE_C
};
...
switch (...) {
case STATE_A:
...
case STATE_B:
...
case STATE_C:
...
default:
...
}
...
Diagram
All possible states
Determine current
state
Slide 8, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (2)
• Transitions
Source Code
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/* events to react on */
enum OBJ_EVENT{
EVENT1,
EVENT2,
EVENT3
};
...
switch (...) {
case STATE_A:
switch (event) {
case EVENT1:
...
case EVENT2:
...
} break;
case STATE_B:
switch (event) {
case EVENT1:
...
case EVENT2:
...
} break;
...
}
Diagram
All possible events
Determine arrived
event
Slide 9, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (3)
• Object with current state variable
Source Code
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typedef struct {
bool initialised;
OBJ_STATE state;
} OBJ;
...
switch (obj->state) {
case STATE_A:
switch (event) {
case EVENT1:
obj->state = STATE_B;
break;
case EVENT2:
obj->state = STATE_C;
break;
} break;
case STATE_B:
switch (event) {
case EVENT1:
obj->state = STATE_B;
break;
case EVENT2:
obj->state = STATE_C;
break;
} break;
...
}
Diagram
Object with variable
for current state
Assign new state to
state variable
Slide 10, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (4)
• Control Function
Source Code
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Diagram
static void OBJ_control(OBJ *obj, OBJ_EVENT event)
{
switch (obj->state) {
case STATE_A:
switch (event) {
case EVENT1:
obj->state = STATE_B; Control
break;
Event that needs
Function
case EVENT2:
obj->state = STATE_C;
to be handled
break;
}
break;
case STATE_B:
switch (event) {
case EVENT1:
obj->state = STATE_B;
break;
case EVENT2:
obj->state = STATE_C;
break;
}
break;
...
}
}
Slide 11, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (5)
• Multiple events with the same event-handler
Source Code
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Diagram
static void OBJ_control(OBJ *obj,
OBJ_EVENT event) {
switch (obj->state) {
case STATE_A:
switch (event) {
case EVENT1:
Multiple events are
case EVENT2:
obj->state = STATE_C;
handled the same way
break;
}
break;
case STATE_B:
switch (event) {
case EVENT1:
obj->state = STATE_B;
break;
case EVENT2:
obj->state = STATE_C;
break;
}
break;
...
}
}
Slide 12, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (6)
• State assignment in called function
Source Code
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do_Function(OBJ *obj)
{
...
obj->state = STATE_C;
...
}
...
static void OBJ_control(OBJ *obj,
OBJ_EVENT event)
{
switch (obj->state) {
case STATE_A:
switch (event) {
case EVENT1:
do_Function(obj);
break;
case EVENT2:
obj->state = STATE_C;
break;
}
break;
...
}
}
...
Diagram
State assignment
in called function
Slide 13, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Switch/Case – Switch/Case pattern (7)
• Conditional transitions
Source Code
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bool y = true;
switch (obj->state) {
case STATE_A:
switch (event) {
case EVENT1:
if (y) {
obj->state = STATE_B;
}
else {
obj->state = STATE_C;
}
break;
case EVENT2:
obj->state = STATE_C;
break;
} break;
case STATE_B:
switch (event) {
case EVENT1:
obj->state = STATE_B;
break;
case EVENT2:
obj->state = STATE_C;
break;
} break;
...
}
Diagram
Conditional
transitions
Slide 14, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Overview of design of Cpp2XMI (1)
Abstract Syntax
Tree in XML-format
CPPML
C++ Source
Code
Preprocessor
Pre-processed
C++ Source
Code
Columbus
Parser &
Exporter
Library
Filter
XMI
Class Diagram in
XML (XMI)-format
Filtered
Columbus
CPPML
Diagram
Extractor
XMI (with
layout)
Filtered
Columbus XMI
Class, Sequence,
Activity Diagram in
XML (XMI)-format
Slide 15, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Overview of design of Cpp2XMI (2)
Parser for
CPPML
Abstract
Syntax Tree
(CPPML
filtered)
Store
(internal
datastructure
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Collaboration
Organizer
Activity
Organizer
X
Second
Parser for
CPPML for
Objective C
State
Machine
Organizer
Could be
improved
Add Layout
using ClassLayout
Store
(internal
datastructure
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Add Layout
using DotLayout
Add Layout
using
SeuenceLayout
Add Layout
using
StateDotLayout
Store
(internal
datastructure
) + Layout
Form XMItags / Write
to File
UML model
in XMI 1.1
(with layout)
Slide 16, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Case Study - FSC (1)
• Applied Cpp2XMI to FSC V6
Slide 17, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Case Study - FSC (2)
• Example: SPUR
Slide 18, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Case Study - FSC (3)
• Example: Triplesorter
Slide 19, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Case Study (4)
• Some results of the Cpp2XMI State Machine Diagram Extractor
- V6: 27 State Machine Diagrams, 2 false positives
- Extracted state machine is for 70% identical to original documented
state machine (Gappex)
- Correctness was checked and confirmed by domain experts
Slide 20, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Problems encountered
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Preprocessing issues
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Sax parser issues
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JDOM (Memory peak level: 1,8GB)
SAX (will not solve memory peaks)
Bug in XMI-part
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However it’s a DAG, which makes pattern recognition is tricky
Cpp2XMI doesn’t extract control-statements (do, while, if, switch
break, continue, etc.) correctly (for C)
Performance issues with CPPML parser
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Sax parser halts on the escape character (0x1B)
CPPML should have a tree-structure (1 on 1 with AST)
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Columbus Parser doesn’t understand anonymous structs/enums
Duplicate id’s, which raises errors when importing XMI into case-tools
(Enterprise Architect)
Position information not part of XMI
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Enterprise Architect doesn’t do anything with position information
Slide 21, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Conclusions / Future work
• Conclusions:
- UML state machines are useful for the developers and maintainers
- Can be derived automatically from source code (by finding patterns)
- Was very successful in the case study and is in general promising
• Future work:
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Expanding the state machine patterns
Combine with logging to get a general state machine
Export function for model checkers
On Entry / On Exit
Metrics / analysis over overlap of state machine diagrams
Filter / Zoom
Use original CPPML parser
XMI conversion
Improve performance issues (due to choice of parser)
Slide 22, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
Questions?
Slide 23, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
References (1)
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[KNOR98]
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[CORB00]
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Roland Knor, Georg Trausmuth and Johannes Weidl
Reengineering C/C++ Source Code by Transforming State Machines
Proceedings of the Second International ESPRIT ARES Workshop on Development and Evolution of
Software Architectures for Product Families
1998
ISBN: 3-540-64916-6, Page 97—105
Springer-Verlag
James C. Corbett, et al.
Bandera: extracting finite-state models from Java source code
Proceedings of the 22nd international conference on Software engineering,
2000
ISBN: 1-58113-206-9, Page 439—448
ACM
[WALK08]
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Neil Walkinshaw et al.
Automated discovery of state transitions and their functions in source code
Journal: Software Testing Verification Reliability (Vol 18, nr 2)
2008
ISBN 0960-0833, Page 99—121
John Wiley and Sons Ltd.
Slide 24, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland
References (2)
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[YUAN06]
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[GANN02]
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Gerald C. Gannod and Shilpa Murthy
Using Log Files to Reconstruct State-Based Software Architectures
Workshop on Software Architecture Reconstruction at WCRE 2002
2002
[FERE02]
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Tao Xie and Evan Martin and Hai Yuan
Automatic extraction of abstract-object-state machines from unit-test executions
Proceedings of the 28th international conference on Software engineering
2006
ISBN: 1-59593-375-1, Page 835—838
ACM
Rudolf Ferenc et al.
Columbus - Reverse Engineering Tool and Schema for C++
Proceedings of the International Conference on Software Maintenance
2002
ISBN: 0-7695-1819-2, Page 172
IEEE Computer Society
[KORS06]
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E. Korshunova and M. Petkovic and M. G. J. van den Brand and M. R. Mousavi
CPP2XMI: Reverse Engineering of UML Class, Sequence, and Activity Diagrams from C++ Source Code
WCRE '06: Proceedings of the 13th Working Conference on Reverse Engineering
2006
ISBN: 0-7695-2719-1, Page 297—298
IEEE Computer Society
Slide 25, Presentation: Extraction of State Machine Diagrams of Legacy C code with Cpp2XMI, 4-2-2009 | Dennie van Zeeland