Current enterprise systems are widely implemented using statically typed languages such as Java. One of the reasons are strong type checks at compile time that help prevent runtime errors. The static type checks are also well integrated into current development tools. One of the less explored area are, however, static type checks of binary software components. Since current software usually contains a large amount of third-party components, the compilers can no longer cover the static type checks of the final product, especially the inter-dependencies of the components are out of their reach. In this work, we propose an approach that analyses the byte-code of Java classes to reconstruct the mutual dependencies of respective components first. Then, the dependencies are examined to find any type inconsistencies. As a result, this approach detects dependency problems early in the development phase and prevents undesirable run time product failures caused by them.

1. 1
Software Components Compatibility
Verification Based on Static Byte-Code
Analysis
Kamil Jezek, Lukas Holy, Premek Brada
University of West Bohemia
kjezek@ntis.zcu.cz

2. 2
Agenda
● Compatibility problems
● Dependencies reconstruction
● Classification of incompatibilities
● Implementation
● Limitations

3. 3
Problem
Source
code
Early compile
time checks
Late runtime
checks
LinkageError in Java
● NoSuchMethodError
● ClassNotFoundException
● ...

4. 4
Proposed Solution
● Dependencies reconstruction from binaries
● “as if compiled by compiler” but working with
binaries

5. 5
Proposed Solution
● Dependencies reconstruction from binaries
● “as if compiled by compiler” but working with
binaries

6. 6
Incompatibilities Classification
● Missing dependencies (1)
● Inconsistent dependencies (2)
● Redundant dependencies (3)
● Duplicated dependencies (4)
Source
code
(1)
(2)
(4)
(3)

7. 7
Dependency reconstruction
Component API (e.g. CGlib)
public class Enhancer {
public static void
registerCallbacks(
Class generatedClass,
Callback[] callbacks) { … }
public static void
registerStaticCallbacks(
Class generatedClass,
Callback[] callbacks) { … }
}
class ConfigurationClassEnhancer {
private Class<?> createClass(
Enhancer enhancer) {
Class<?> subclass =
enhancer.createClass();
Enhancer.registerStaticCallbacks(
subclass, this.callbackInstances);
return subclass;
}
}
API invocation (e.g. Spring)
Added in v2.2

8. 8
Dependency Evaluation
Component API API invocation
>
≥
<
≤
=
≠
Added in v2.2

9. 9
Limitations
● Limited to permanent byte-code
– Analyses also death code
– Byte-code generated at runtime, Java Reflection
ignored

10. 10
Conclusion
● Static incompatibilities not detected by
compilers in current software
● Proposed byte-code analyser to fill this gap
● Implemented as Maven plugin