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Java

Learning objectives

Generate a Spring microservice using the IBM Cloud Developer Tools CLI, provision and bind services to it, and then deploy to IBM Cloud. Understand the code that is generated and how that provides a great starting point for you to begin adding your own code.

Prerequisites

Install the IBM Cloud Developer Tools CLI.

Estimated time

It takes approximately one hour to read and follow the steps in this how-to.

Steps

Step 1. Generate the code

If you haven’t already done so, then you’ll need to follow the instructions to install the IBM Cloud Developer Tools CLI, if you want to try things out for yourself. You can generate a Spring microservice using the CLI as shown below with the generated code being put into a folder under the current directory.


spring $bx dev create
? Select a pattern:
1. Web App
2. Mobile App
3. Backend for Frontend
4. Microservice
5. MFP
Enter a number> 4

? Select a starter:
1. Basic
Enter a number> 1

? Select a language:
1. Java ‑ MicroProfile / Java EE
2. Node
3. Python
4. Java ‑ Spring Framework
Enter a number> 4

? Enter a name for your project> springmsdemo
? Enter a hostname for your project> springmsdemo
? Do you want to add services to your project? y/n
? Select a service:
1. Cloudant NoSQL Database
2. Object Storage
Enter a number> 1

? Select a service plan:
1. Lite
2. Standard
3. Dedicated Hardware
Enter a number> 1

Successfully added service to project.

? Do you want to add another service? y/n
The project, springmsdemo, has been successfully saved into the current directory.
OK

Before carrying on, let’s look at what we’ve just selected and what has been generated. The first couple of selections establish that we want a microservice and it’s going to use Spring. Things get interesting when we’re presented with the service options. If you pick a service, in this case Cloudant, then not only is code generated to bind to that service but it is also provisioned ready for use.

Other files that are generated will be used when running your application locally in a docker container. The README is a good place to start as it will provide an overview on what has been generated as well as more information about the services that were selected.

Step 2. Run the microservice

The CLI is then used to build and run the microservice locally. The build stage creates a docker container that provides the necessary tools to build the microservice, a second container is then used to run the built container.


springmsdemo $bx dev build
Deleting the container named 'bx‑dev‑springmsdemo‑tools' ...
Creating image bx‑dev‑java‑maven‑tools based on Dockerfile‑tools...
Image will have user added
OK
Creating a container named 'bx‑dev‑springmsdemo‑tools' from that image...
OK
Starting the 'bx‑dev‑springmsdemo‑tools' container...
OK
Building the project in the current directory started at Wed Aug 23 13:49:37 2017
OK
Stopping the 'springmsdemo' container...
The 'springmsdemo' container was not found
Stopping the 'bx‑dev‑springmsdemo‑tools' container...
OK
springmsdemo $bx dev run
Stopping the 'springmsdemo' container...
The 'springmsdemo' container was not found
Creating image springmsdemo based on Dockerfile...
OK
Creating a container named 'springmsdemo' from that image...
OK
Starting the 'springmsdemo' container...
OK
Executing run command started at Wed Aug 23 13:50:17 2017

  .   _                        
 /\ / '   ()     \ \ \ 
( ( )__ | ' | '| | ' \/ ` | \ \ \ 
 \/  )| |)| | | | | || (| |  ) ) ) )
  '  |_| .|| ||| |\, | / / / /
 =========||==============|__/=///_/
 :: Spring Boot ::        (v1.5.4.RELEASE)

2017‑08‑23 12:50:22.167  INFO 17 ‑‑‑ [           main] application.SBApplication                : Starting SBApplication v1.0‑SNAPSHOT on d6e23df14534 with PID 17 (/project/springmsdemo‑1.0‑SNAPSHOT.jar started by root in /project)
...
(output snipped)

You can now test your microservice locally by going to http://localhost:8080/v1/cloudant.

The really nice thing is that although the list of databases is empty, the list has been read from the Cloudant service instance that was provisioned earlier.


@RestController
public class Example {

  @Autowired @ServiceName(name="springmsdemo‑cloudantNoSQLDB‑4dce")
  private CloudantClient client;

  @RequestMapping("v1/")
  public @ResponseBody ResponseEntity<String> example() {
    List<String> list = new ArrayList<>();
    //return a simple list of strings
    list.add("Some data");
    return new ResponseEntity<String>(list.toString(), HttpStatus.OK);
  }

  @RequestMapping("v1/cloudant")
  public @ResponseBody ResponseEntity<String> cloudant(){
      List<String> list = new ArrayList<>();
      try {
          list = client.getAllDbs();
      } catch (NullPointerException e) {
          return new ResponseEntity<String>("Server Error", HttpStatus.INTERNAL_SERVER_ERROR);
      }
      return new ResponseEntity<String>("Available databases : " + list.toString(), HttpStatus.OK);
  }

}

Step 3. Deploy to IBM Cloud

The final step is to deploy the microservice to IBM Cloud. Simply type bx dev deploy on the command line, and that’s it. You can then view the microservice in the IBM Cloud console (along with the service that was created).

Summary

In this how-to, you learned how to use the IBM Cloud Developer Tools CLI plugin to create a Spring microservice bound to a Cloudant database, build and run it locally, and then deploy it IBM Cloud — all in under five minutes!