Practices to write your own BOOTIFUL libraries.

1. Spring Booted, But…
黃培棠 (中華電信企業客戶分公司)
Pei-Tang Huang @ Chunghwa Telecom Co., Ltd.

2. Spring Boot Recap
Spring Boot is a framework for Spring Framework
• Spring Framework gluing things together, wrapped them
up, and left a lot of options for you.
• Spring Boot make your life easier by making a
opinionated choice for you.

3. Spring Framework as Ingredients
http://blog.mimacom.com/introduction-to-spring-boot/

4. Spring Boot as Cake
http://blog.mimacom.com/introduction-to-spring-boot/

5. What If You Are Working In A Cake Factory…
By Marcel Ekkel from Hong Kong, Hong Kong (Cheese cAke paradise?)
[CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

6. Or Something Like That…

7. Create Your Own Layer
All problems in computer science can be
solved by another level of indirection.
- David Wheeler

8. Making a Bootiful Library
Be even more opinionated!
• Provides default for most cases important to you.
• Automatically configure whenever possible.
Be polite!
• Default is only used to de-fault.
• Exposes properties for configuration.
• Conditional bypass auto configuration.

9. Here Comes The Compost
* {#} powered by
^/ /^ /^/ /y/ /^) /^/ /^/
=/= +
| /_ /_/ / / /-' /_/ `_> /
____,&.__~_ (c) Chunghwa Telecom Co., Ltd.
-------
Compost v0.2.0-SNAPSHOT // Spring Boot v1.4.1.RELEASE
2016-10-15 04:13:12.462 INFO 76431 --- [ restartedMain] com.cht.sample.Application : Starting Appli
2016-10-15 04:13:12.465 INFO 76431 --- [ restartedMain] com.cht.sample.Application : The following
2016-10-15 04:13:12.887 INFO 76431 --- [ restartedMain] ationConfigEmbeddedWebApplicationContext : Refreshing org
2016-10-15 04:13:13.662 INFO 76431 --- [ restartedMain] mpostSecurityConfigurationImportSelector : "cht.security.
2016-10-15 04:13:14.895 INFO 76431 --- [ restartedMain] o.s.b.f.xml.XmlBeanDefinitionReader : Loading XML be
2016-10-15 04:13:15.171 INFO 76431 --- [ restartedMain] o.s.b.f.s.DefaultListableBeanFactory : Overriding bea
2016-10-15 04:13:15.966 INFO 76431 --- [ restartedMain] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax
2016-10-15 04:13:16.099 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'managerT
2016-10-15 04:13:16.142 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'com.cht.
2016-10-15 04:13:16.245 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'org.spri
2016-10-15 04:13:16.437 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'objectPo
2016-10-15 04:13:16.443 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'org.spri
2016-10-15 04:13:16.639 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'cht.func
2016-10-15 04:13:16.643 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'com.cht.
2016-10-15 04:13:16.672 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'environm
2016-10-15 04:13:16.678 INFO 76431 --- [ restartedMain] .c.c.c.f.CompositeFunctionMappingService : Found followin
2016-10-15 04:13:16.678 WARN 76431 --- [ restartedMain] .c.c.c.f.CompositeFunctionMappingService : PropertiesFunc
2016-10-15 04:13:16.678 INFO 76431 --- [ restartedMain] .c.c.c.f.CompositeFunctionMappingService : Registered fun
2016-10-15 04:13:16.678 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'function
2016-10-15 04:13:16.682 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'com.cht.
2016-10-15 04:13:16.702 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'methodSe
2016-10-15 04:13:16.719 INFO 76431 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'org.spri

10. Choose A Right Tool
Content assist will you a lot of time!
Spring Tool Suite™ v.s. IntelliJ® IDEA Ultimate

11. Weave Your Own Safety Net
You have less excuse to skip test!
https://spring.io/blog/2016/04/15/testing-improvements-in-spring-boot-1-4
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class MyWebIntegrationTests {
@Autowired
private TestRestTemplate restTemplate;
@Test
public void exampleTest() {
String body = restTemplate.getForObject("/", String.class);
assertThat(body).isEqualTo("Hello World");
}
}
You have an application serverYou have the IoC container

12. KnowingYourDependencies
com.example:demo:jar:0.0.1-SNAPSHOT
+- org.springframework.boot:spring-boot-starter:jar:1.4.1.RELEASE:compile
| +- org.springframework.boot:spring-boot:jar:1.4.1.RELEASE:compile
| | - org.springframework:spring-context:jar:4.3.3.RELEASE:compile
| | +- org.springframework:spring-aop:jar:4.3.3.RELEASE:compile
| | +- org.springframework:spring-beans:jar:4.3.3.RELEASE:compile
| | - org.springframework:spring-expression:jar:4.3.3.RELEASE:compile
| +- org.springframework.boot:spring-boot-autoconfigure:jar:1.4.1.RELEASE:compile
| +- org.springframework.boot:spring-boot-starter-logging:jar:1.4.1.RELEASE:compile
| | +- ch.qos.logback:logback-classic:jar:1.1.7:compile
| | | - ch.qos.logback:logback-core:jar:1.1.7:compile
| | +- org.slf4j:jcl-over-slf4j:jar:1.7.21:compile
| | +- org.slf4j:jul-to-slf4j:jar:1.7.21:compile
| | - org.slf4j:log4j-over-slf4j:jar:1.7.21:compile
| +- org.springframework:spring-core:jar:4.3.3.RELEASE:compile
| - org.yaml:snakeyaml:jar:1.17:runtime
- org.springframework.boot:spring-boot-starter-test:jar:1.4.1.RELEASE:test
+- org.springframework.boot:spring-boot-test:jar:1.4.1.RELEASE:test
+- org.springframework.boot:spring-boot-test-autoconfigure:jar:1.4.1.RELEASE:test
+- com.jayway.jsonpath:json-path:jar:2.2.0:test
| +- net.minidev:json-smart:jar:2.2.1:test
| | - net.minidev:accessors-smart:jar:1.1:test
| | - org.ow2.asm:asm:jar:5.0.3:test
| - org.slf4j:slf4j-api:jar:1.7.21:compile
+- junit:junit:jar:4.12:test
+- org.assertj:assertj-core:jar:2.5.0:test
+- org.mockito:mockito-core:jar:1.10.19:test
| - org.objenesis:objenesis:jar:2.1:test
+- org.hamcrest:hamcrest-core:jar:1.3:test
+- org.hamcrest:hamcrest-library:jar:1.3:test
+- org.skyscreamer:jsonassert:jar:1.3.0:test
| - org.json:json:jar:20140107:test
- org.springframework:spring-test:jar:4.3.3.RELEASE:test

13. Bill Of Materials
Keep library versions in ONE place
• spring-boot-dependencies
• io.spring.platform:platform-bom
Declare dependencies without <version>:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>

14. Versioning Matters
Spring Project Versioning
{number}.{release_type}
{number} => {major}.{minor}.{micro}
Semantic Versioning
MAJOR.MINOR.PATCH
https://github.com/spring-projects/spring-build-gradle/wiki/Spring-project-versioning
No breaking changes at this level??

15. Release Train
Grouping individual projects into one entity.
spring-data-releasetrain
• Arora, Baggage, Codd, Dijkstra, Evans, Fowler,
Gosling, Ingalls
spring-cloud-dependencies
• Angel, Britxon, Camden
spring-cloud-stream-dependencies
• 1.0, Brooklyn

16. Define Your Own BOM
Except referring to the BOM, no dependencies
version should be used in projects.
Define properties for version, unless:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.8.RELEASE</version>
</parent>
<properties>
<spring-boot.version>1.4.1.RELEASE</spring-boot.version>
</properties>

17. Maven, Maven?!
Mystic version number 2.1.1?
--- maven-dependency-plugin:2.8:tree (default-cli) @ compost-case-web ---
com.cht.compost:compost-case-web:jar:0.2.0-SNAPSHOT
+- com.cht.commons:cht-commons-web:jar:0.3.0-SNAPSHOT:compile
| +- ...
| +- org.webjars:jquery:jar:2.1.1:compile (version managed from 1.11.0-1)
| +- org.webjars:angular-ui-utils:jar:0.1.0-1:compile
| | +- ...
| | - (org.webjars:jquery:jar:2.1.1:compile –
| | version managed from 1.6.2; omitted for duplicate)
| +- org.webjars:ng-grid:jar:2.0.11:compile
| | +- ...
| | - (org.webjars:jquery:jar:2.1.1:compile –
| | version managed from 1.8.3; omitted for duplicate)
| +- org.webjars:bootstrap:jar:3.2.0:compile
| | - (org.webjars:jquery:jar:2.1.1:compile –
| | version managed from 1.11.1; omitted for duplicate)
- ...

18. Keep a CHANGELOG
Don’t let your friends dump git logs into changelog
http://keepachangelog.com/en/0.3.0/
# Change Log
All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](http://keepachangelog.com/)
and this project adheres to [Semantic Versioning](http://semver.org/).
## [Unreleased]
### Added
- zh-CN and zh-TW translations from @tianshuo.
- tr-TR translation from @karalamalar.
### Changed
- Start versioning based on the current English version at 0.3.0 to help
translation authors keep things up-to-date.
## [0.3.0] - 2015-12-03
...

19. Meta-Annotations and Composed Annotations
Annotations on annotation everywhere
https://github.com/spring-projects/spring-framework/wiki/Spring-Annotation-Programming-Model
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = @Filter(
type = FilterType.CUSTOM,
classes = TypeExcludeFilter.class))
public @interface SpringBootApplication {
@AutoConfigurationPackage
@Import(EnableAutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {

20. Define @ConfigurationProperties
Whenever Possible
It’s type-safe, IDE-friendly.
And more expressive than:
@lombok.Data
@Component
@ConfigurationProperties(prefix = "connection")
public class ConnectionProperties {
private String username = "anonymous";
@NotNull
private InetAddress remoteAddress;
}
@Value("${connection.username:anonymous}")

21. Name Your Property Seriously
There are only two hard things in
Computer Science: cache invalidation
and naming things.
- Phil Karlton

22. Renaming Your Property
Just like refactoring method names.
@Deprecated
@DeprecatedConfigurationProperty(
reason =
"Property deprecated in Jackson 2.7",
replacement =
"spring.jackson.default-property-inclusion")
public Include getSerializationInclusion() {
return getDefaultPropertyInclusion();
}

23. AutoConfiguration
META-INF/spring.factories
Nothing special but @Configuration.
Serves as fallback after normal @Configurations
been processed.
# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=
com.example.autoconfigure.MyAutoConfiguration

24. @ConditionalOn*
Eliminating all @Configurations will not work.
Use built-in annotations where possible:
@ConditionalOnBean
@ConditionalOnClass
@ConditionalOnMissingBean
@ConditionalOnMissingClass
@ConditionalOnProperty
…

25. @Profile
Define profiles for properties,
not for @Configurations or @Beans.
1. You can modify or override properties more easily.
2. You can always define property like my.feature-for-
the-profile.enabled to achieve the same goal.
3. ProfileCondition is not a SpringBootCondition.

26. @Orders Matter
Hints for Spring Boot.
• @AutoConfigureAfter
• @AutoConfigureBefore
Take built-in AutoConfiguration as Anchor
• Override built-in configuration by invalidate its Condition.
• Register beans and pass them into auto configuration.
• Refine Spring Boot auto configured beans.

27. Learning From Spring Boot
Spring Boot is an Expert at using libraries
But you still have to know them with <3
• Not every operation is idempotent or cumulative,
WebSecurityConfigurerAdapter for example.

28. Doing Well as A Monolithic
Package as WAR
POM.xml
<packaging>war</packaging>
@SpringBootApplication
public class Application
extends SpringBootServletInitializer
implements WebApplicationInitializer {
...
}

29. JBoss EAP
JBoss EAP v6.0 – 6.2
• Have to remove embedded server.
JBoss EAP v6.x
• spring.jmx.enabled=false
• server.servlet-path=/*
• http://stackoverflow.com/a/1939642
• Multipart request charset encoding value is wrong.
• Have to downgrade JPA and Hibernate.
JBoss EAP v7
• Trying…

30. Oracle WebLogic Server
WebLogic 11g and below
• Not supported.
WebLogic 12c
• Filter registration logic is WRONG!
• https://github.com/spring-projects/spring-boot/issues/2862#issuecomment-99461807
• Have to remove embedded server.
• Have to downgrade JPA and Hibernate.
• Have to specify <wls:prefer-application-packages/> in weblogic.xml.

31. IBM WebSphere Application Server
WebSphere AS v8.5.5
• Have to remove embedded server.
• Have to downgrade JPA and Hibernate.

32. From Spring Framework
To Spring Boot
1. Create intermediate project incorporating Spring
Boot.
2. Remove functions duplicated to Spring Boot.
3. Pull up @Configuration as AutoConfiguration.
4. Extract application properties.

33. 放飯!