Experimental work based on discussions at SpringOne2GX 2012. See also the 'bootstrap' branch of Spring.
## Elevator Pitch
Opinionated view of the Spring family so that new users can quickly get to the 'meat and potatoes'. Assumes no knowledge of the Java development ecosystem. Absolutely no code generation and no XML.
Spring Bootstrap is "Spring for Snowboarders". If you are kewl, or
just impatient, and you want to use Spring, then this is the place to
be. Spring Bootstrap is a toolkit and runtime platform that will get
you up and running with Spring-powered, production-grade applications
and services with absolute minimum fuss. It takes an opinionated view
of the Spring family so that new and existing users can quickly get to
the bits they need. Assumes no knowledge of the Java development
ecosystem. Absolutely no code generation and no XML (unless you really
want it).
The goals are:
* Radically faster and widely accessible getting started experience
for Spring development
* Be opinionated out of the box, but get out of the way quickly as
requirements start to diverge from the defaults
* Provide a range of non-functional features that are common to large
classes of projects (e.g. embedded servers, security, metrics,
health checks, externalized configuration)
* First class support for REST-ful services, modern web applications,
batch jobs, and enterprise integration
* Applications that adapt their behaviour or configuration to their
environment
* Optionally use Groovy features like DSLs and AST transformations to
accelerate the implementation of basic business requirements
## Installing
You need to build from source for now, but when it's done instructions will look like this:
1) Get Java
Download and install the Java SDK from www.java.com
1) Get Java. Download and install the Java SDK from www.java.com
2) Get Spring
`curl -s try.springsource.org | bash` or use the Windows installer
3) Get to Work!
spr run yoursourcefile.groovy
$ curl -s try.spring.io | bash
or use the Windows installer
## What? It's Groovy then? or like Grails? or another Roo?
There is a command line tool that uses Groovy underneath so that we can present simple snippets that can just run:
3) Get to Work!
$ cat > app.groovy
@Controller
class ThisWillActuallyRun {
@RequestMapping("/")
@ResponseBody
String home() {
return "Hello World!"
}
}
$ spring run app.groovy
$ curl localhost:8080
Hello World!
By inspecting the code for well known annotations we can `@Grab` appropriate dependencies and also dynamically add `import` statements. Groovy makes this really easy.
If you don't want to use the command line tool, and you would rather work using Java and an IDE you can. Just add a `main()` method that calls `SpringApplication` and add `@EnableAutoConfiguration`:
import org.springframework.bootstrap.*;
import org.springframework.context.annotation.*;
## What? It's Groovy then? or like Grails? or another Roo?
@Configuration
@EnableAutoConfiguration
@ComponentScan
public class MyApplication {
There is a command line tool that uses Groovy underneath so that we
can present simple snippets that can just run just like the slimline
`app.groovy` example above. Groovy makes this really easy.
public static void main(String[] args) throws Exception {
SpringApplication.run(MyApplication.class, args);
}
}
If you don't want to use the command line tool, or you would rather
work using Java and an IDE you can. Just add a `main()` method that
calls `SpringApplication` and add `@EnableAutoConfiguration`:
The 'spr' command line application compiles and runs Groovy source, adding `import` statements and `@Grab` annotations. The application can also watch files, automatically recompiling and restarting when they change.
}
### SpringApplication
The `SpringApplication` class provides the main entry point for a standalone Spring Application. Its sole job is to create and refresh an appropriate Spring `ApplicationContext`. Any contained beans that implements `CommandLineRunner` will be executed after the context has started. A `SpringApplication` can load beans from a number of different sources, including classes, packages (scanned) or XML files. By default a `AnnotationConfigApplicationContext` or `AnnotationConfigEmbeddedWebApplicationContext` depending on your classpath.
## Spring Bootstrap Themes
### EmbeddedWebApplicationContext
The `EmbeddedWebApplicationContext` will probably be part of Spring 4.0. It provides a Spring 'WebApplicationContext' that can bootstrap itself and start and embedded servlet container. Support is provided for Tomcat and Jetty.
There are a number of themes in Bootstrap. Here are the important
ones:
### @EnableAutoConfigure
The `@EnableAutoConfigure` can be used on a `@Configuration` class to trigger auto-configuration of the Spring context. Auto-configuration attempts to guess what beans a user might want based on their classpath. For example, If a 'HSQLDB' is on the classpath the user probably wants an in-memory database to be defined. Auto-configuration will back away as the user starts to define their own beans.
### The Spring CLI
### @Conditional
The `@Conditional` annotation will probably be part of Spring 4.0. It provides allows `@Configuration` classes to be skipped depending on conditions. Bootstrap provides `@ConditionalOnBean`, `@ConditionalOnMissingBean` and `@ConditionalOnClass` annotations are used when defining auto-configuration classes.
The 'spring' command line application compiles and runs Groovy source,
making it super easy to write the absolute minimum of code to get an
application running. Spring CLI can also watch files, automatically
recompiling and restarting when they change.
### Bootstrap Core
The main library providing features that support the other parts of
Spring Bootstrap. Features include:
* `SpringApplication` - a class with static convenience methods that
make it really easy to write a standalone Spring Application. Its
sole job is to create and refresh an appropriate Spring
`ApplicationContext`.
* Embedded web applications with a choice of container (Tomcat or
Jetty for now)
* `@EnableAutoConfigure` is an annotation that triggers
auto-configuration of the Spring context. Auto-configuration
attempts to guess what beans a user might want based on their
classpath. For example, If a 'HSQLDB' is on the classpath the user
probably wants an in-memory database to be
defined. Auto-configuration will back away as the user starts to
define their own beans.
* `@Conditional` is an annotation in Spring 4.0 that allows you to
control which parts of an application are used at runtime. Spring
Bootstrap provides some concrete implementations of conditional
configuration, e.g. `@ConditionalOnBean`,
`@ConditionalOnMissingBean` and `@ConditionalOnClass`.
### Spring Bootstrap Service
<!-- FIXME: change the name -->
Spring Bootstrap Service uses auto-configuration features to decorate
your application with features that make it instantly deployable and
supportable in production. For instance if you are writing a JSON web
service then it will provide a server, security, logging, externalized
configuration, management endpoints, an audit abstraction, and more.
If you want to switch off the built in features, or extend or replace
them, it makes that really easy as well.
### Spring Bootstrap Applications
<!-- FIXME: change the name -->
Spring Bootstrap Applications are a set of convenient dependency
descriptors that you can include in your application. You get a
one-stop-shop for all the Spring and related technology that you need
without having to hunt through sample code and copy paste loads of
dependency descriptors. For example, if you want to get started using
Spring and JPA for database access just include one dependency in your
project, and you are good to go.
## Building the code
Use maven to build the source code.
mvn clean install
$ mvn clean install
## Importing into eclipse
You can use m2e or `maven eclipse:eclipse`.
Project specific settings are configured for source formatting. If you are using m2e please follow these steps to install eclipse support:
Project specific settings are configured for source formatting. If you
are using m2e you can follow these steps to install eclipse support
for formatting:
* Select `Install new software` from the `help` menu
* Click `Add...` to add a new repository
* Click the `Archive...` button
* Select `org.eclipse.m2e.maveneclipse.site-0.0.1-SNAPSHOT-site.zip` from the `eclipse` folder in this checkout
Dave Syer
12 years ago