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Repo for short Serverless Java workshop, targetting IBM Cloud Functions platform

## Prerequisites: 
1. Do the setup here: [Setup for workshop](https://github.com/prpatel/Serverless-Workshop-Setup-All-Platforms)
2. Make sure to have Java 8 installed
3. You'll need maven to package the jar file

### 0. Test IBM Cloud Functions From The CLI

1. Run the following command to invoke a test function from the command-line.

```
   $ ibmcloud wsk action invoke whisk.system/utils/echo -p message hello --result
   {
       "message": "hello"
   }
   ```

*If you're using the local OpenWhisk instance, simply drop the 'ibmcloud' at the beginning of the command, and run the rest*

*If this command executes successfully, you have verified that the IBM Cloud CLI and Cloud Functions plugin have been installed and configured correctly. If this does not work, please contact the workshop organiser to provide assistance!*

### 1. Get to know the Web Console
Open up the webconsole/ folder for a step-by-step guide working with cloud functions right from a browser!

### 2. Build and deploy your first Serverless Java App!

From where you cloned this git repo:
0. cd java-code
1. mvn package  
2. ibmcloud fn action create helloJava target/hello-world-java.jar --main com.example.FunctionApp
3. ibmcloud fn action invoke --result helloJava --param name World

You should see:
{
    "greetings": "Hello! Welcome to OpenWhisk"
}

"--result" means just show the results. Omit that, and see what you get back :)
This also adds the "--blocking" flag, discussed below.

### 3. Get to know some OpenWhisk commands

* ibmcloud wsk list
    * note that "wsk" is used here instead of fn! The ibmcloud" command wraps the OpenWhisk "wsk" command with either "fn" or "wsk"!
* ibmcloud wsk action invoke --blocking helloJava
    * this invokes the action in an sync fashion, you'll get a alot of text back, but you're interested in this:
    ***
        "activationId": "13a3f62589214b7da3f62589214b7d1e",
    ***
    * this is what you'll use to get the result back later!
* ibmcloud wsk action invoke helloJava
    * this invokes the action in an sync fashion, with something called an activationId
        ***
            ok: invoked /_/helloJava with id 5923d0321aa04fffa3d0321aa0cfffc2
        ***
        * this is what you'll use to get the result back later!
        * ibmcloud wsk activation result 5923d0321aa04fffa3d0321aa0cfffc2
        ***
                        
            {
                "greetings": "Hello! Welcome to OpenWhisk"
            }
        ***        
    * To  get the last invocation result: ibmcloud wsk activation result --last
    * To get everything (not just result): ibmcloud wsk activation get 5923d0321aa04fffa3d0321aa0cfffc2

* ibmcloud fn action update helloJava target/hello-world-java.jar --main com.example.FunctionApp
    * This will update the Cloud Function!

### 4. What about logs?

* Each activation has logs!
* ibmcloud wsk activation get --last
    * look for  "logs"
* I miss my "tail -f" ... how do I do that?
    * ibmcloud wsk activation poll

### 5. To the Web! Let's create Web actions
* To find the URL from which you can invoke an action use this command:
```
ibmcloud wsk action get helloJava --url
```

* But hang on, we haven't told OpenWhisk we want it to be a Web Function! Runt this first:
```
ibmcloud fn action update helloJava --web true
```

(run the command with --url again to get the URL now)

* Check that it's enabled by going to the [IBM Cloud Functions Console](https://console.bluemix.net/openwhisk/actions)
![IBM Cloud Functions Actions Console](https://raw.githubusercontent.com/prpatel/serverless-java-mini-workshop/master/images/ibmcloudConsoleActions.png)

* Since this Cloud Function just returns JSON, we need to append ".json" to the URL. You can test this by using curl
```
curl -i https://us-south.functions.cloud.ibm.com/api/v1/web/SAMPLE_URL/default/helloJava.json
```
Use the first command in this section to get the URL... don't forget to append .json !

* You can also just paste this URL into the browser!
![Cloud Function in browser](https://raw.githubusercontent.com/prpatel/serverless-java-mini-workshop/master/images/webactioninbrowser.png)

### 6. Create a HTML Web Cloud Function
So far we've just been creating JSON return values. What if we want to return some HTML?

* Create a new class, called WebHello.java (it's OK to copy FunctionApp.java)
* Change the code so that the response has a body with some HTML, like so:

``` response.addProperty("body", "<html><body><h3>" + result + "</h3></body></html>");  ```

* Create a web-enabled Cloud Function using this command (from the java-code directory):

``` ibmcloud fn action create webHello target/hello-world-java.jar --main com.example.WebHello --web true ```

* Use the command from the previous section to get its URL

``` 
ibmcloud fn action get webHello --url
```
* Invoke it by pasting the URL into the browser. If you appended .json to it, you'll get the it in json format. Do not append .json to it - and you'll see an a message wrapped in an H3 tag!
* What about the name parameter this Cloud Function takes? Append this to the URL:
``` 
webHello?name=Pratik
```
Of course, put your name instead of mine :)

### 7. Sequences

Go into the sequences/ folder and follow instructions there!

### 8. Triggers

Go into the triggers/ folder and follow the instructions there!

### Continue your journey for serverless
1. Calling our Serverless fns from a Web application!
2. Using cloud db's for saving data
3. Using redis for in-memory storage of sessions
4. Using an API Gateway for organizing endpoints
5. Layering Authentication on top
6. Advanced debugging
7. Much Much more!