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QMaxUSE

0. Latest Release

check out here for the latest changes and features of QMaxUSE.

1. Overview

QMaxUSE is an automated verification tool that is able to verify consistencies of a UML class diagram annotated with OCL invariants. QMaxUSE has two distinct features: (1) A query langauge that allows users to select parts of class diagram to be verified. (2) A powerful algorithm that is capable of performing concurrent verification on large number of complex OCL invariants. This is achieved by decomposing a large model into multiple queries.

2. Download and Run

Once you have JDK installed, you can just download QMaxUSE and run it without installing any additional libraries. QMaxUSE is a command-line based tool and currently supports Windows 10(x64), Ubuntu 20.04(x64) and macOS Big Sur(x64). If you would like to build your own version of QMaxUSE, please see here for details.

3. Running QMaxUSE on Windows 10 (x86/x64), Ubuntu 20.04(x64), macOS Big Sur (x64)

  • Make sure you have JDK installed.
  • Download QMaxUSE from here, and go to the lib directory type: 
     java -jar qmaxuse.jar
    to lanuch QMaxUSE.

3.1 Solver Support

Currently, the latest version of QMaxUSE supports two solvers: z3 and cvc5 (for ubuntu and macOS). To switch between z3 and cvc5 for verification tasks, one can use the following command at QMaxUSE prompt:

	set-solver:<solver name>

Here, <solver name> can be either z3 or cvc5. If switch is successful, QMaxUSE will display a corresponding sovler's version information.

3.2 Mode Switch

You can now specify two modes for verification. 1by1 mode allows QMaxUSE to verify one query at a time, other query verification will wait unitl the current thread finishes. async model allows QMaxUSE to use a pool of threads to verify multiple queries at a time, this yield much faster verification results. To switch between these two modes, you can use the following command at QMaxUSE prompt:

	set-mode:<name>

Here, <name> can be either 1by1 or async. By default, QMaxUSE uses 1by1 mode.

3.3 MaxUSE Support

QMaxUSE is fully compatible with MaxUSE. Everything is supported by MaxUSE is available in QMaxUSE including finding as many satisfiable features as possible and pinpointing all OCL conflicting constraints. However, you may need to setup Z3 for MaxUSE. See the instructions here. Technical details about how MaxUSE works are described here.

4. USEAGE

4.1 Issuing a query

Our query langauge allows users to issue a query to select parts of a class diagram to be verified. QMaxUSE accepts queries from command line. Here are some query examples:

  • Example 1: selecting classes, attributes and associations.

     $select Person, Student.year, Student:study:Module.

    Classes Person, Student and Module are selected. An attribute year (Student) is selected. An association study is selected. Note class Module is implicitly selected here because of study association.

  • Example 2: using a wild character

     $select Student.*, Student:*:Module

    All attributes of Student class and any associations with association-ends Student and Module are selected.

  • Example 3: selecting OCL invariants.

     $select Person, Student with Student::*

    Classes Person, Student and all ocl invariants defined under Student class are selected. Further, all relevant clases, attributes and associations used in an ocl expression are also selected.

  • Example 4: exclusion

     $select Student.* with Student::* but Student::inv4

    All ocl invariants defined under Student class are selected except for inv4. Further, all relevant clases, attributes and associations used in an ocl expression are also selected.

  • Example 5: aliasing and joint queries

     $select Department, Asssignment, Student:finish:Assignment as query1
 $select Student, Module with Student::* as query2
 $query1 & query2

    The first query has an alias query1. The second query has an alias query2. The last query is a joint query: query1 intersects query2. The intersection of two sets of feature are selected.

  • Example 6: saving your queries for later usage

     module QuerySet
 	select Person.*, Student.*, Module.*, Assignment:*:* with Student::*, Module::* but Person as class_query
 end

    The above query is saved in a query module called QuerySet. This query module is a part of (university) specification and it is automatically loaded when QMaxUSE reads this specification. A user can type

     $QuerySet.class_query

    to issue class_query. A query module can contain multiple aliased queries. Note that to reuse a query at a later stage, you must give a query an alias.

  • Example 7: query with OCL injection (coming soon)

     select Person.*, Student.* with Student::* inject {Student.allInstances()->forAll(s|s.modules->notEmpty())}

    The above query is injected with an OCL invariant. The verification procedure will verify the query along with injected OCL. The verification will tell the consequences if the injected OCL invariant could break the consistencies or not. This is particularly useful for those who are not sure about adding an OCL invariant to a class whether will break the consistencies.

4.2 Concurrent verification

QMaxUSE uses a specialised algorithm to decompose OCL invariants into multiple queries that can be verified concurrently. To use this feaure in QMaxUSE,

  • Load your specification into QMaxUSE, at the command prompt type qverify.
  • The verification results are shown in the command prompt.
  • A screenshot can be found here

5. SMT2 ASSERTIONS

QMaxUSE's verification procedures use Z3 SMT solver as its solving engine. To interact with Z3, it uses uran as its intermediate interfaces. Uran is responsible for generating well-formed SMT2 assertions and interpretation.

6. Benchmark

Overall, QMaxUSE improves up to 30x efficiency in verification. In particular, QMaxUSE performs very well on models with extreme size of OCL invariants. Try out some models from our benchmark.

7. Remarks

  • The implementation of QMaxUSE spans over the past 2 years.
  • We are extending our query langauge to include OCL and SMT assertion injection.
  • We are working on integrating a string solver into QMaxUSE.
  • QMaxUSE will be included as a solution to one of our industrial partners.
  • QMaxUSE supports OCL constructs used in the benchmark, and not all OCL constructs are supported (we are currently adding more).

8. Papers:

  • QMaxUSE: A New Tool for Verifying UML Class Diagrams and OCL Invariants (SCP 2023)
  • A Query-based Approach for Verifying UML Class Diagrams with OCL Invariants (ECMFA 2022)
  • QMaxUSE: A Query-based Verification Tool for UML Class Diagrams with OCL Invariants (FASE 2022)
  • A Formal Approach to Finding Inconsistencies in a Metamodel (Software and Systems Modeling 2021)
  • MaxUSE: A Tool for Finding Achievable Constraints and Conflicts for Inconsistent UML Class Diagrams (iFM 2017)
  • Finding Achievable Features and Constraint Conflicts for Inconsistent Metamodels (ECMFA 2017)

9. Acknowledgement

We woud like to thank our industrial partner LingCui Yu, HuangXin Xin and their teams from SYSUCC for helpful comments on this research.

Last updated: 31-May-2022