Spring PetClinic Sample Application

Undo usage

See below for the usual PetClinic overview but this section describes the Undo usage. It assumes that an env var UNDO_HOME has been set which points to a directory containing the contents of the lr4j-record zip file.

Forcing the maven junit tests to fail

We have modified the code to allow us to force an error to occur when adding a pet. This is done by specifying a system property on the command line containing the name of the pet to be rejected. Because one of the junit tests adds a pet named "Betty" we can make that test fails by running the build as follows:

./mvnw -Dundo.bad.pet.name=Betty -Dundo.basedir=$UNDO_HOME package

This will also output recordings of the tests which fail because we have an UndoTestExecutionListener which detects test failures and uses the LR4J API to save the recording. Note that recording is always on regardless of success or failure of the test.

Forcing a failure in the web app

Similarly we can force a rejection of a particular pet name to occur (together with recording) by running the web app as follows:

java -Dundo.bad.pet.name=Rover -DargLine="-XX:-Inline -XX:TieredStopAtLevel=1 -XX:UseAVX=2 -Dsun.zip.disableMemoryMapping=true -agentpath:$UNDO_HOME/lr4j-record-1.0.so=save_on=always,output=rover.undo,max_event_log_size=1G" -jar target/spring-petclinic-2.4.2.jar

Then to produce a failure, after navigating to http://localhost:8080/ do:

• click on FIND OWNERS
• click on Find Owners (you can leave search box blank to show all)
• click on any of the names
• click Add New Pet
• enter the name Rover (or whatever you chose as undo.bad.pet.name) and the other fields and then click Add Pet

You should see the message rejected to force test failure

Debugging the failure with IntelliJ

After launching lr4j_replay in the usual way and attaching with IntelliJ, set a breakpoint at line 46 of src/main/java/org/springframework/samples/petclinic/owner/PetValidator.java:

 37     public void validate(Object obj, Errors errors) {
 38         Pet pet = (Pet) obj;
 39         String name = pet.getName();
 40         // name validation
 41         if (!StringUtils.hasLength(name)) {
 42             errors.rejectValue("name", REQUIRED, REQUIRED);
 43         }
 44
 45         if (name.equals(System.getProperty("undo.bad.pet.name"))) {
 46             errors.rejectValue("name", "invalid", "rejected to force test failure");
 47         }

Understanding the Spring Petclinic application with a few diagrams

See the presentation here

Running petclinic locally

Petclinic is a Spring Boot application built using Maven. You can build a jar file and run it from the command line:

git clone https://github.com/spring-projects/spring-petclinic.git
cd spring-petclinic
./mvnw package
java -jar target/*.jar

You can then access petclinic here: http://localhost:8080/

Or you can run it from Maven directly using the Spring Boot Maven plugin. If you do this it will pick up changes that you make in the project immediately (changes to Java source files require a compile as well - most people use an IDE for this):

./mvnw spring-boot:run

In case you find a bug/suggested improvement for Spring Petclinic

Our issue tracker is available here: https://github.com/spring-projects/spring-petclinic/issues

Database configuration

In its default configuration, Petclinic uses an in-memory database (H2) which gets populated at startup with data. The h2 console is automatically exposed at http://localhost:8080/h2-console and it is possible to inspect the content of the database using the jdbc:h2:mem:testdb url.

A similar setup is provided for MySql in case a persistent database configuration is needed. Note that whenever the database type is changed, the app needs to be run with a different profile: spring.profiles.active=mysql for MySql.

You could start MySql locally with whatever installer works for your OS, or with docker:

docker run -e MYSQL_USER=petclinic -e MYSQL_PASSWORD=petclinic -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=petclinic -p 3306:3306 mysql:5.7.8

Further documentation is provided here.

Working with Petclinic in your IDE

Prerequisites

The following items should be installed in your system:

• Java 8 or newer.
• git command line tool (https://help.github.com/articles/set-up-git)
• Your preferred IDE
  • Eclipse with the m2e plugin. Note: when m2e is available, there is an m2 icon in Help -> About dialog. If m2e is not there, just follow the install process here: https://www.eclipse.org/m2e/
  • Spring Tools Suite (STS)
  • IntelliJ IDEA
  • VS Code

Steps:

1. On the command line

   git clone https://github.com/spring-projects/spring-petclinic.git
   

2. Inside Eclipse or STS

   File -> Import -> Maven -> Existing Maven project
   

   Then either build on the command line ./mvnw generate-resources or using the Eclipse launcher (right click on project and Run As -> Maven install) to generate the css. Run the application main method by right clicking on it and choosing Run As -> Java Application.

3. Inside IntelliJ IDEA In the main menu, choose File -> Open and select the Petclinic pom.xml. Click on the Open button.

   CSS files are generated from the Maven build. You can either build them on the command line ./mvnw generate-resources or right click on the spring-petclinic project then Maven -> Generates sources and Update Folders.

   A run configuration named PetClinicApplication should have been created for you if you're using a recent Ultimate version. Otherwise, run the application by right clicking on the PetClinicApplication main class and choosing Run 'PetClinicApplication'.

4. Navigate to Petclinic

   Visit http://localhost:8080 in your browser.

Looking for something in particular?

Spring Boot Configuration	Class or Java property files
The Main Class	PetClinicApplication
Properties Files	application.properties
Caching	CacheConfiguration

Interesting Spring Petclinic branches and forks

The Spring Petclinic "main" branch in the spring-projects GitHub org is the "canonical" implementation, currently based on Spring Boot and Thymeleaf. There are quite a few forks in a special GitHub org spring-petclinic. If you have a special interest in a different technology stack that could be used to implement the Pet Clinic then please join the community there.

Interaction with other open source projects

One of the best parts about working on the Spring Petclinic application is that we have the opportunity to work in direct contact with many Open Source projects. We found some bugs/suggested improvements on various topics such as Spring, Spring Data, Bean Validation and even Eclipse! In many cases, they've been fixed/implemented in just a few days. Here is a list of them:

Name	Issue
Spring JDBC: simplify usage of NamedParameterJdbcTemplate	SPR-10256 and SPR-10257
Bean Validation / Hibernate Validator: simplify Maven dependencies and backward compatibility	HV-790 and HV-792
Spring Data: provide more flexibility when working with JPQL queries	DATAJPA-292

Contributing

The issue tracker is the preferred channel for bug reports, features requests and submitting pull requests.

For pull requests, editor preferences are available in the editor config for easy use in common text editors. Read more and download plugins at https://editorconfig.org. If you have not previously done so, please fill out and submit the Contributor License Agreement.

License

The Spring PetClinic sample application is released under version 2.0 of the Apache License.