What Is The Vehicle Routing Problem?

Many organizations deal with a vehicle routing problem on a daily basis: identifying the best sequence to deliver a number of items to a number of places with a fleet of vehicles. This kind of optimization problem is known as the vehicle routing problem (VRP), and it has several variations.

OptaPlanner can solve many of these vehicle routing variations and gives solution examples.

Graphhopper Map Setup In Vehicle Routing Problem

We have added the graphhopper dependency to the configuration of the graphhopper map. I included the dependency of the most recent version of Graphhopper. I'm using the most recent versions of OptaPlanner 8.35.0.Final and Graphhopper 7.0.

Add the following dependency to graphhopper-core in your pom.xml

<!-- https://mvnrepository.com/artifact/com.graphhopper/graphhopper-core -->
<dependency>
<groupId>com.graphhopper</groupId>
<artifactId>graphhopper-core</artifactId>
<version>7.0</version>
</dependency>

In Main Class, create a hashmap to store graphhopper data based on the vehicle's value. I've created the Vehicles enum, in which I define the vehicle and the vehicle's value.

The map file name and path URL are defined in the application.properties file.

I have created a class, ApplicationPropertyValue, in which I define the objects and the object value I get from application.properties files.

I have now added the startUp method for downloading and importing the map file to a new class called AppEvents. I'm using the EventListener on this method, so it will be called automatically when I run the application. It will check whether our map file is already downloaded or not; if not, the downloadOsmFile method will be called and the map will be downloaded, or if yes, it will call the loadGraphhopperFile method and simply import and load the graphhopper map.

downloadOsmFile Method code

loadGraphhopperFile Method

When you are calculating the distance, you have to set the profile. Otherwise, it will throw an exception that the profile is not set.

Closing Thoughts

I hope this blog helps you set up the map in VRP so that you can quickly set up the map in our project. I provide all the necessary setup information for setting up a map file. If you're using an older version of Graphhoper, you'll have to change some configurations.

Learn more about our OptaPlanner development services. Contact us at [email protected] for project-related queries. 

How Can We Migrate An OptaPlanner Project From Old To New Versions? 

Several features of OptaPlanner are currently deprecated, hence an upgrade to the project is required. In order to update our project, I'm identifying what modifications are necessary and how we may implement them.

Let's start with the pom.xml file. What dependencies are necessary for Spring Boot's OptaPlanner?

<dependency>
   <groupId>org.optaplanner</groupId>
   <artifactId>optaplanner-bom</artifactId>
   <version>${version.org.optaplanner}</version>
   <type>pom</type>
   <scope>import</scope>
</dependency>

Include this dependency inside of <dependencyManagement>.

<dependency>
   <groupId>org.optaplanner</groupId>
   <artifactId>optaplanner-spring-boot-starter</artifactId>
</dependency>

Add this one inside <dependencies>. Only these two dependencies are required for OptaPlanner.

Solver configuration :

Most likely, Spring users won't need to worry about solver configuration. Simply remove the score DRL and implement a constraint provider. Moreover, you can define a constraint-provider class path in SolverConfig.xml rather than a drl path.

If you want to remove the SolverConfig.xml file, you can do that, and the updated OptaPlanner project will automatically read the entityClass, solutionClass, and constraint provider classes, so there is no need to do any configuration for this; if you added more than one constraint provider, you will need to add the SolverConfig.xml file.

Define the localSearch configuration in a Java class if solverConfig.xml is not being used.

LocalSearchPhaseConfig localSearchPhaseConfig = new LocalSearchPhaseConfig()
        .withAcceptorConfig(new LocalSearchAcceptorConfig().withEntityTabuSize(5));

localSearchPhaseConfig.setLocalSearchType(LocalSearchType.TABU_SEARCH);

There are numerous search options available in LocalSearchType, like  HILL_CLIMBING, GREAT_DELUGE, LATE_ACCEPTANCE etc.

You can refer to the following documentation for further details on the LocalSearchPhaseConfig method: https://docs.optaplanner.org/latest/optaplanner-javadoc/org/optaplanner/core/config/localsearch/LocalSearchPhaseConfig.html

Use SolverManager to solve the problem; it offers the solve or solve and listen methods. Autowire the SolverManager and initialize it inside the constructor.

@Autowired
private SolverManager<SolutionClass, Long> solverManager;

Score Configuration :

For updating the score, you can use SolutionManager and initialize it inside constructor.

@Autowired
SolutionManager<SolutionClass, HardMediumSoftLongScore> solutionManager;

Set the initial score using the update or explain methods. Inside both methods, call the "callScoreDirector" method.

solutionManager.update(solutionClassObject);

or 

solutionManager.explain(solutionClassObject).getSummary();

Conclusion :

You can update your OptaPlanner project by implementing these modifications. Additional improvements are detailed in the OptaPlanner documentation, which is available via the URL provided below.

https://www.optaplanner.org/download/upgradeRecipe/upgradeRecipe8.html

We are a seasoned ERP development company that provides end-to-end OptaPlanner development services to cater to the diverse industry-specific needs of our clients. To learn more about OptaPlanner development and implementation in your business project, write to us at [email protected].