Message Passing Coupling ($MPC$ )

Works with all instances of a common meta-model, regardless of whether they were produced with the Java or the UML front-end. The respective extends (Java) or generalization (UML) relations expressing the inheritance between two classes are mapped onto relations of type inheritance in the common meta-model (and the $MPC$specific view).

Handle

$MPC$

Description

The MPC measures the number of method calls defined in methods of a class to methods in other classes, and therefore the dependency of local methods to methods implemented by other classes. It allows for conclusions on the message passing (method calls) between objects of the involved classes. This allows for conclusions on re-useability, maintenance and testing effort.

Scope

Class

View

${V}^{MPC} = ({G}^{MPC}, {R}^{MPC})$

• Grammar ${G}^{MPC} = (\{\textrm{class}^{MPC}\}, \emptyset, \textrm{class}^{MPC})$
• Relations ${R}^{MPC}: \{\textrm{call}^{MPC} : \textrm{class}^{MPC} \times \textrm{class}^{MPC}\}$
• Mapping $\alpha^{MPC}$:
  

  $$\alpha^{MPC}(\textrm{Class}) \mapsto \textrm{class}^{MPC}$$

  $$\alpha^{MPC}(\textrm{Invokes}) \mapsto \textrm{call}^{MPC}$$

  
  

Definition

The $MPC$value of a class $c \in class^{MPC}$is defined as:

$$MPC(c) = outdegree^*(c, \textrm{call}^{MPC})$$

Scale

Absolute.

Domain

Integers $\in 0..\infty$.

Highly Related Software Quality Properties

 

Re-Usability 2.4

is negatively influenced by coupling.

Understandability for Reuse 2.4.1:

A part of a system that has a high (outgoing) efferent coupling may be highly inversely related to understandability, since it uses other parts of the system which need to be understood as well.

Understandability decreases with increasing MPC.

Attractiveness 2.4.4:

Parts that have a high (outgoing) efferent coupling may be highly inversely related to attractiveness, since they are using other parts of the system which need to be understood as well, and represent dependencies.

Attractiveness decreases with increasing MPC.

Maintainability 2.6

decreases with increasing MPC.

Analyzability 2.6.1:

Parts that have a high (outgoing) efferent coupling may be highly inversely related to analyzability, since they are using other parts of the system which need to be analyzed as well.

Analyzability decreases with increasing MPC.

Changeability 2.6.2:

Parts that have a high (outgoing) efferent coupling may be inversely related to changeability, since they are using other parts of the system which might need to be changed as well.

Changeability decreases with increasing MPC.

Stability 2.6.3:

Parts showing a high (outgoing) efferent coupling may be inversely related to stability, since they are using other parts of the system, which are can affect them.

Stability decreases with increasing MPC.

Testability 2.6.4:

Parts that have a high (outgoing) efferent coupling may be highly inversely related to testability, since they are using other parts of the system which increase the number of possible test paths.

Testability decreases with increasing MPC.

Portability 2.7

decreases with increasing MPC.

Adaptability 2.7.1:

Parts that have a high (outgoing) efferent coupling may be inversely related to adaptability, since they are using other parts of the system which might need to be adapted as well.

Adaptability decreases with increasing MPC.

Related Software Quality Properties

 

Functionality 2.1

is both negatively and positively influenced by coupling.

Interoperability 2.1.3:

Parts that have a high (outgoing) efferent coupling may be directly related to interoperability, since they are using/interacting with other parts of the system.

Interoperability might increase with increasing MPC.

Security 2.1.4:

Parts that have a high (outgoing) efferent coupling may be inversely related to security, since they can be affected by security problems in other parts of the system.

Security might decrease with increasing MPC.

Reliability 2.2

might decrease with increasing MPC.

Fault-tolerance 2.2.2:

Parts that have a high (outgoing) efferent coupling may be inversely related to fault-tolerance, since they can be affected by faults in other parts of the system.

Fault-Tolerance might decrease with increasing MPC.

Recoverability 2.2.3:

Parts that have a high (outgoing) efferent coupling may be inversely related to recoverability, since their data is distributed in other parts of the system making their recovery difficult.

Recoverability might decrease with increasing MPC.

Re-Usability 2.4

might decrease with increasing MPC.

Learnability for Reuse 2.4.2:

Parts that have a high (outgoing) efferent coupling may be inversely related to learnability, since they are using other parts of the system which need to be understood as well.

Learnability might decrease with increasing MPC.

Operability for Reuse - Programmability 2.4.3:

Parts that have a high (outgoing) efferent coupling may be inversely related to learnability, since they are using other parts of the system, which represent dependencies.

Programmability might decrease with increasing MPC.

Efficiency 2.5

might decrease with increasing MPC.

Time Behavior 2.5.1:

Parts that have a high (outgoing) efferent coupling may be inversely related to time behavior, since they are using other parts of the system, thus execution during test or operation does not stay local, but might involve huge parts of the system.

Time behavior might get worse with increasing MPC.

Resource Utilization 2.5.2:

Parts that have a high (outgoing) efferent coupling may be inversely related to resource utilization, since they are using other parts of the system, thus execution during test or operation does not stay local, but might involve huge parts of the system.

Resource utilization might get worse with increasing MPC.

References

 

• MPC is extensively discussed and validated in [14,2,4,11,19],
• it is implemented in the VizzAnalyzer Metrics Suite.

Since

1.0

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