staff-management-api

An opensource api which provides various options to manage office/household help/staff.

Pre-requisites

• Build Tool- Maven
• Git
• Jdk 8

Steps to setup project

1. Clone the git project

   git clone https://github.com/PoonamSharma93/staff-management-api.git
   cd staff-management-api
   

2. Build the project using maven build tool

   mvn clean install
   

3. Run the jar

   java -jar target/staff_management-x.x.x.jar --spring.profiles.active=prod
   

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Api

• /
  The get api shows the active profile
• /schedule
  The post api process the request asynchronously in another thread and initiates a scheduler to perform task for certain number of times.
• /headers
  The post api return the request of header back in response

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CRUD Operation with Hibernate

Steps:

1. Add Data-Jpa dependency to enable hibernate in spring boot project. ModelMapper is used to map VO/DTO to DAO object.

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
   </dependency>
   <dependency>
      <groupId>org.modelmapper</groupId>
      <artifactId>modelmapper</artifactId>
      <version>2.3.5</version>
   </dependency>
   

2. Use h2 Database into the project

   <dependency>
      <groupId>com.h2database</groupId>
      <artifactId>h2</artifactId>
      <scope>runtime</scope>
   </dependency>
   

   add parameters in application.properties

   spring.h2.console.enabled=true
   spring.h2.console.path=/console
   

3. User Repository :

   We create a User named dao (data access object) bean and UserDTO named its dto (data transfer object). DTO/VO is the one which transfer the data between the processes or the classes. DAO/Entity is the object with interacts with the db to enable CRUD operaion.

   To perform CRUD operation we are going to make use of Http Methods:

   • POST : Create
   • GET : Read
   • PUT : Update
   • DELETE : Delete

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Jackson Json View

• @JsonView: To limit or control fields display for different views of a model object
• @JsonInclude: To ignore the null fields, put @JsonInclude(JsonInclude.Include.NON_NULL) on class level or field level.
• @JsonIgnore: To ignore few fields for all the Views.
• @JsonPropertyOrder: To specify the order of fields of the model. We can also specify the alphabetic order of a collection type field by @JsonPropertyOrder(alphabetic = true)

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Hibernate Association Mapping

Always use a Set to denote a collection instead of a List. Hibernate removes all the associative entity and reinsert the remaining ones in case of List.

• @OneToMany (Society to Customer) : The best way to use OneToMany mapping is to rely on ManyToOne to make it Bidirectional
• @ManyToOne (Customer to Society) : It is default initialized by EAGER type. To improve performance we are using (fetch = FetchType.LAZY)
• @ManyToMany (User to Customer) : We should use @JoinTable to prevent creation of separate table for maintaining the foreign keys between the entites
• @OneToOne

The @OneToMany and @ManyToMany associations are defaulted to LAZY loading and @OneToOne and @ManyToOne are defaulted to EAGER loading. We can change this by @OneToMany(fetch = FetchType.LAZY )

Component Mapping

@Emdedded and @Embeddable (User to Addesss) : The address fields are shown in the User table only. Separate table is not created for Address.

CascadeType

Cascading : When we perform some action on the target entity, the same action will be applied to the associated entity. For LAZY initialization mapping use CascadeType.All so that the child object is inserted on insertion of parent object.

orphanRemoval=true: Delete orphan(no longer connected to parent entity) child entity.

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Liquibase

Description

Liquibase is an open source version control tool for database schema migration. Using Change Log file, liquibase will use it as configiration guidelines to make changes to the underlying database schema. The changesets files can be in various formats including XML, JSON, YAML, and SQL. It creates its own 2 table for maintaining version and lock i.e DATABASECHANGELOG and DATABASECHANGELOGLOCK.

Steps:

1. Add liquibase dependency

   <dependency>
      <groupId>org.liquibase</groupId>
      <artifactId>liquibase-core</artifactId>
   </dependency>
   

2. Add parameters in application.properties. Default path is db/changelog/db.changelogmaster.yml

   spring.liquibase.change-log=classpath:/db/changelog/changelog-master.xml
   

3. Create master databasechangelog xml file and other specific changeset file. Include these changeset files in the master file

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Github Action

Description

This feature of Github can be used for CI/CD integration while commiting or pushing our code.

Github Action to build jar of code code while performing push operation

Steps:

1. Create a WorkFlow File of yml type .github/workflows/continuous-integration-workflow.yml
2. Following is the syntax of maven build workflow

   name: Java CI
   
   on: [push]
   
   jobs:
      build:
         runs-on: ubuntu-latest
         steps:
            - uses: actions/checkout@v2
            - name: Set up JDK 1.8
              uses: actions/setup-java@v1
              with:
                java-version: 1.8
            - name: Build with Maven
              run: mvn -B package --file pom.xml
   

3. Commit this file to the branch where you want your workflow to run.

Whenever you try to push your code to that branch a maven action will be performed. If the file syntax or anything goes wrong, the workflow will fail.

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Run docker image in google cloud instance

Created an compute engine instance in google cloud with linux operating system and build docker image over it. Used Commands:

cd staff-management-api
docker build -t app:1.0 .
docker run -itd -p 3333:9090 -v /home/poonamsnu/springboot_docker/:/app --name springboot_docker app:1.0
docker exec springboot_docker /bin/sh

Used mount point for docker container to save logs on the hostmachine usine VOLUME command in dockerfile

Command to pull docker image to local repository

docker pull poonam00/springboot_docker

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Swagger

Description

We are using OpenApi Specification 3.0(latest swagger) in this project for documentation purpose.

Steps

1. add dependency

<dependency>
    <groupId>org.springdoc</groupId>
    <artifactId>springdoc-openapi-ui</artifactId>
    <version>1.2.32</version>
</dependency>

2. add @ResponseStatus on Exception handler class to generate documentation for response code
3. add @Operation to give description to the api and @ApiResponses to generate documentation for possible response code of the api
4. add @OpenAPIDefinition to define title, version and description of the project

The documentation is available at endpoint /swagger-ui.html

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Spring Cloud Config

Description

Spring Cloud Config is Spring's client/server approach for storing and serving configuration files across multiple applications and environments. It generally have 3 modules:

1. Config Server : It is a spring boot application which fetch config client's configurations from git repo
2. Config Client : It loads its application.properties files from git repo through cinfig server
3. Git Config Repo : Here we store all the application.properties for different environments.

Config server is availabe at repo https://github.com/Poonam00/springcloudconfigserver

Git config repo is available at https://github.com/Poonam00/config-repo

For the config client to access the configurations from git repo following step are required to be taken:

1. Add dependency in pom.xml

<dependency>
   <groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter</artifactId>
	<version>2.2.2.RELEASE</version>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-config</artifactId>
	<version>2.2.2.RELEASE</version>
</dependency>

2. Give config server url in bootstrap.properties
3. Use @RefreshScope in the class where configuration properties are used
4. Enable actuator's /refresh end point to refresh the bean of configuration when some congifiguration changes are needed to be reflected

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Caching

Description

Cache is used to improve performance by storing the data temporarily and reduces the number of database hits as much as possible.

Steps:

1. Add cache dependency to enable simple cache in spring boot project.

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

2. Enable Caching by using annotation @EnableCaching. The auto-configuration enables caching and setup a CacheManager. Spring provides a ConcurrentHashMap as default cache, but we can override CacheManager to register external cache providers as well easily.

Caching Annotations involves:

• @Cacheable: defines a cache for a method's return value. It initializes a cache with the name provided in the attributes and uses key to store object with key-value pair. If no key is specified, by default hashcode is used as key.
• @CachePut: used to update the cache.
• @CacheEvict: it removes the entry being deleted. We can also clear the entire cache by using attribute allEntries=true.
• @CacheConfig: it is a class level annotation that provides a common cache-related setting.
• @Caching: used when we need both annotations @CachePut or @CacheEvict at the same time on the same method.

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