go-gurus · grohmio · Mar 6, 2023 · Mar 7, 2023 · Mar 7, 2023 · Mar 8, 2023
diff --git a/slides/18-golang_vs_java_springboot/SLIDES.md b/slides/18-golang_vs_java_springboot/SLIDES.md
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+<!-- .slide: data-background="img/GOLANG_VS_JAVA_SPRINGBOOT/00.jpg" data-background-size="100%" data-background-position="50% 50%" -->
+----
+
+## golang vs. Java Spring Boot
+
+In this chapter we create 2 services with identical content.
+One is built in Golang the other using Spring Boot.
+After the services are fully running and close to production, we will contrast them using various metrics.
+
+----
+
+### Complete Source Code
+* [github.com/go-gurus/golang_vs_java_springboot](https://github.com/go-gurus/golang_vs_java_springboot)
+
+----
+
+### prerequisits
+* golang
+* Java 17
+
+----
+
+### Spring Boot Beer Fridge
+* use the special link to spring `initializr` [start.spring.io/...](https://start.spring.io/#!type=maven-project&language=java&platformVersion=3.0.4&packaging=jar&jvmVersion=17&groupId=io.grohm&artifactId=beerfridge&name=beerfridge&description=Demo%20project%20for%20the%20big%20comparison%20between%20Golang%20and%20Java%20Spring%20Boot%20in%20the%20GO-Tour%20workshop.&packageName=io.grohm.beerfridge&dependencies=web,devtools,lombok,data-jpa,liquibase,postgresql) to init the project
+* unpack the sources
+* install dependencies
+```shell
+cd beerfridge
+./mvnw clean install
+```
+
+----
+
+* we will get an error message like this
+```shell
+[ERROR] Errors: 
+[ERROR]   BeerfridgeApplicationTests.contextLoads » IllegalState Failed to load Applicat...
+[INFO] 
+[ERROR] Tests run: 1, Failures: 0, Errors: 1, Skipped: 0
+...
+[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.22.2:test (default-test) on project beerfridge: There are test failures.
+[ERROR] 
+[ERROR] Please refer to /Users/grohmio/repos/github/go-gurus/golang_vs_java_springboot/springboot/beerfridge/target/surefire-reports for the individual test results.
+...
+```
+----
+
+* the application context could not be loaded in the test, because the DB connection is missing
+* lets fix that
+```shell
+# docker-compose.yml
+version: '3.1'
+
+services:
+    beerfridge_db:
+        image: postgres
+        restart: unless-stopped
+        ports:
+            - "5432:5432"
+        environment:
+            POSTGRES_USER: beerfridge_backend
+            POSTGRES_PASSWORD: beerfridge_db_pw
+            POSTGRES_DB: beerfridge_backend_db
+        volumes:
+            - beerfridge_db_data:/var/lib/postgresql/data
+        networks:
+            - beerfridge_db_net
+
+volumes:
+    beerfridge_db_data:
+
+networks:
+    beerfridge_db_net:
+
+```
+----
+
+* configure the application context
+
+```yaml
+# springboot/beerfridge/src/main/resources/application.properties
+### datasource
+spring.datasource.url=jdbc:postgresql://${DATABASE_HOST:localhost}:${DATABASE_PORT:5432}/${DATABASE_NAME:beerfridge_backend_db}
+spring.datasource.username=${DATABASE_USER:beerfridge_backend}
+spring.datasource.password=${DATABASE_PASSWORD:beerfridge_db_pw}
+```
+----
+
+* next build an initial changeset for liquibase
+
+```yaml
+# springboot/beerfridge/src/main/resources/application.properties
+databaseChangeLog:
+  - changeSet:
+      id: 2023-03-07-init-database
+      author: Andreas Grohmann
+      changes:
+        sqlFile:
+          dbms: postgresql
+          encoding: utf-8
+          path: postgres/2023-03-07-init-database.sql
+          relativeToChangelogFile: true
+```
+
+* generate an empty file for now
+```yaml
+# springboot/beerfridge/src/main/resources/db/postgres/2023-03-07-init-database.sql
+
+```
+
+----
+
+* lets setup the db in a new terminal and try again with no errors expected
+
+```shell
+docker-compose up beerfridge_db
+```
+```shell
+./mvnw clean install
+```
+
+----
+
+* now lets speed up things a little bit by using code generation, add the swagger code gen maven plugin
+
+```xml
+<!-- springboot/beerfridge/pom.xml -->
+...
+	<build>
+		<plugins>
+    ...
+    <plugin>
+				<groupId>org.openapitools</groupId>
+				<artifactId>openapi-generator-maven-plugin</artifactId>
+				<version>6.4.0</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>generate</goal>
+						</goals>
+						<configuration>
+							<inputSpec>
+								${project.basedir}/src/main/resources/openapi.yml
+							</inputSpec>
+							<generatorName>spring</generatorName>
+							<apiPackage>io.grohm.beerfridge.gen.api</apiPackage>
+							<modelPackage>io.grohm.beerfridge.gen.model</modelPackage>
+								<supportingFilesToGenerate>
+									ApiUtil.java
+								</supportingFilesToGenerate>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
+</project>
+```
+
+----
+
+* also add some dependencies
+```xml
+<!-- springboot/beerfridge/pom.xml -->
+...
+  <dependencies>
+    ...  
+    <!-- Swagger Code Generation -->
+		<dependency>
+			<groupId>org.openapitools</groupId>
+			<artifactId>jackson-databind-nullable</artifactId>
+			<version>0.2.6</version>
+		</dependency>
+		<dependency>
+			<groupId>io.springfox</groupId>
+			<artifactId>springfox-boot-starter</artifactId>
+			<version>3.0.0</version>
+		</dependency>
+		<dependency>
+			<groupId>io.swagger.core.v3</groupId>
+			<artifactId>swagger-annotations</artifactId>
+			<version>2.2.8</version>
+		</dependency>
+		<dependency>
+			<groupId>javax.validation</groupId>
+			<artifactId>validation-api</artifactId>
+			<version>2.0.1.Final</version>
+		</dependency>
+		<dependency>
+			<groupId>javax.annotation</groupId>
+			<artifactId>javax.annotation-api</artifactId>
+			<version>1.3.2</version>
+		</dependency>
+		<dependency>
+			<groupId>javax.servlet</groupId>
+			<artifactId>javax.servlet-api</artifactId>
+			<version>4.0.1</version>
+		</dependency>
+```
+
+----
+
+* lets add the openapi interface file using [editor.swagger.io/](https://editor.swagger.io/) and the `swagger.yml` from our previous section
+
+```yaml
+# src/main/resources/openapi.yml
+openapi: 3.0.1
+info:
+  title: A beer fridge service
+  description: Beer fridge service build with openapi-generator
+  version: 1.0.0
+servers:
+- url: /
+paths:
+  /beers:
+    get:
+      tags:
+      - beers
+      operationId: getAllBeers
+      parameters:
+      - name: limit
+        in: query
+        schema:
+          type: integer
+          format: int32
+          default: 20
+      responses:
+        200:
+          description: list the beer operations
+          content:
+            application/io.grohm.go-workshop.beer-fridge.v1+json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/beer'
+    post:
+      tags:
+      - beers
+      operationId: addOne
+      requestBody:
+        content:
+          application/io.grohm.go-workshop.beer-fridge.v1+json:
+            schema:
+              $ref: '#/components/schemas/beer'
+        required: false
+      responses:
+        201:
+          description: Created
+          content:
+            application/io.grohm.go-workshop.beer-fridge.v1+json:
+              schema:
+                $ref: '#/components/schemas/beer'
+        default:
+          description: error
+          content:
+            application/io.grohm.go-workshop.beer-fridge.v1+json:
+              schema:
+                $ref: '#/components/schemas/error'
+      x-codegen-request-body-name: body
+  /beers/{id}:
+    delete:
+      tags:
+      - beers
+      operationId: destroyOne
+      parameters:
+      - name: id
+        in: path
+        required: true
+        schema:
+          type: integer
+          format: int64
+      responses:
+        204:
+          description: Deleted
+          content: {}
+        default:
+          description: error
+          content:
+            application/io.grohm.go-workshop.beer-fridge.v1+json:
+              schema:
+                $ref: '#/components/schemas/error'
+  /temperature:
+    get:
+      tags:
+      - fridge
+      operationId: getTemperature
+      responses:
+        200:
+          description: return the current fridge temperature
+          content:
+            application/io.grohm.go-workshop.beer-fridge.v1+json:
+              schema:
+                $ref: '#/components/schemas/temperature'
+components:
+  schemas:
+    beer:
+      required:
+      - origin
+      - title
+      - volume-percentage
+      type: object
+      properties:
+        id:
+          type: integer
+          format: int64
+          readOnly: true
+        title:
+          minLength: 1
+          type: string
+        origin:
+          minLength: 1
+          type: string
+        volume-percentage:
+          type: number
+          format: float
+    temperature:
+      type: integer
+      format: int64
+    error:
+      required:
+      - message
+      type: object
+      properties:
+        code:
+          type: integer
+          format: int64
+        message:
+          type: string
+
+```
+
+----
+
+* start the generation
+
+```shell
+mvn clean compile
+```
+
+* check the generated files under `springboot/beerfridge/target/generated-sources/openapi/src/main/java/io/grohm/beerfridge/gen`
+
+----
+
+### What we have learned
+* TBD
+* TBD
+
+----
+
+### Further readings
+
+* Swagger Editor
+  * [editor-next.swagger.io](https://editor-next.swagger.io/)
+  * [editor.swagger.io/](https://editor.swagger.io/)
+* openapi-generator
+  * [github.com/OpenAPITools/openapi-generator](https://github.com/OpenAPITools/openapi-generator)
+  * [github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/spring.md](https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/spring.md)
+* openapi-generator-maven-plugin
+  * [github.com/OpenAPITools/openapi-generator/tree/master/modules/openapi-generator-maven-plugin](https://github.com/OpenAPITools/openapi-generator/tree/master/modules/openapi-generator-maven-plugin)
+
+---