Building a Native (kind of) Android App using Grails, HTML 5, CSS, Javescript hosted on CloudFoundry

Been very busy with personal life lately and haven’t had time to do much of interesting stuff specifically on CloudFoundry, Grails and Android.
Here is my attempt to build an android application entirely based on HTML 5, CSS and JS. Ever since I found out that LinkedIn built their Mobile app based on those technologies instead of pure native application. I have been very interested in trying it out myself.
I truly am a believer in CloudFoundry! I think it is going to change how “Cloud” service is provided (PaaS). (Wanted to blog about CloudFoundry Micro but my machine doesn’t Support VT 😦 so may be will get to blog about it sometime later…)

Let’s Jump on to our today’s topic.
Here is my vision:
1. Build a Grails application that is hosted on cloudfoundry. This will serve as a mobile website. I will be using jQuery Mobile.

2. Build a Native looking app using PhoneGap that will interface to the grails web application hosted on cloudfoundry.

About the application:

We will build an android application that will give events that are going on around you given your location. We will be using YQL to get the data. You can learn more about YQL at http://developer.yahoo.com/yql/

Since I want it to be a good size blog entry and not to long, This will be part I of the application.
By the end of this blog I should have.
1. Grails App optimized for mobile hosted on Cloudfoundry
2. Android App based on PhoneGap that will serve as an interface to the Grails App built above.

Let’s Start with the first part:

Building Grails App and hosting it on CFoundry:

I am going to build it from the ground up. I may skip few things, but, if you just want to know how this is done, you can read my old blog post about building a grails app on Cfoundry here.

Creating Grails app and installing the CFoundry plugin:

  $ grails create-app FindEventsGA
  $ grails install-plugin cloud-foundry

(Note: Refer to the link above to set up your Cloudfoundry account in Config.groovy)

Setting up jQuery Mobile Test page:
If you followed me till here you should have a standard grails app all ready to go.
Now, Lets wire up the jQuery Mobile. At the time of this writing, jQuery Mobile Beta 3 was the latest.
Now Navigate to your “index.gsp” in your “views” folder and replace the current content with the following content.

 

<!DOCTYPE html> 
<html> 
<head> 
<title>Grails Mobile App on CloudFoundry</title> 
<meta name="viewport" content="width=device-width, initial-scale=1"> 
<link rel="stylesheet" href="http://code.jquery.com/mobile/1.0b3/jquery.mobile-1.0b3.min.css" />
<script type="text/javascript" src="http://code.jquery.com/jquery-1.6.3.min.js"></script>
<script type="text/javascript" src="http://code.jquery.com/mobile/1.0b3/jquery.mobile-1.0b3.min.js"></script>
</head> 
<body> 
<div data-role="page" id="dashboard">
	<div data-role="header">
		<h1>GrailsApp</h1>
	</div><!-- /header -->

	<div data-role="content">	
		<p>Hello From Grails Mobile App!</p>	
	</div><!-- /content -->
</div><!-- /page -->
</body>
</html>

Above HTML 5, will replace the standard Grails homepage.
In the Page above, it simply imports jQuery Mobile JS and CSS.
You can read more about them at jQuery Mobile page http://jquerymobile.com/applicatio

Now we are ready to publish the app.

Lets run the following command from the grails project directory and verify that it renders the page correctly.
(Note: If you are using Eclipse with Grails plugin or STS, you can simply press “Ctrl+Alt+Shit+G” –> This will give you grails command prompt where you can simply type “prod cf-push”)

$ grails prod cf-push

I set up my application to be hosted under “http://findevents.cloudfoundry.com/&#8221;
After the app has been published, We can get to it through a browser.
See an screen Shot below.

Since I have pushed the app up in the cloudfoundry “cloud”, I can navigate to it from my mobile browser.
Here is how it looks on the device.

We are half way done! – Building a native application
Now the web app is ready, Let’s set up the android application.

Create a new android project on Eclipse or any other IDE of your choice. (http://developer.android.com has tutorials if you are new to Android development.)

After you have a Android Project ready. We will go to PhoneGap and download their Jars.

Go to PhoneGap website and download their android tools.
http://www.phonegap.com/download-thankyou

Unzip the file and place following artifacts.

1. Get the Android “phonegap-1.0.0.jar” (or whatever version you get) from and “Android” directory in the zip and place it in your Project under “libs” folder. (Create the “libs” directory under your android project)

2. In your android project, create “www” folder under “assets” folder (assets folder should already be in your android project). Copy the “phonegap-1.0.0.js” found in the Android folder in the zip file into this www directory.

3. Copy the “xml” folder found in the Android folder inside the zip file into “res” folder in your android application.

Your Project should look similar to one below:

As we added the jar, let’s add it to the build path.
To do this, simply right click on the project and click on “Properties”.
Navigate to “Java Build Path”>”Libraries”. Click on “Add JARs…” and point to the phonegap jar.

Now, navigate to your Main Activity on your android Project and make following changes.

1. Extend the activity to “DroidGap” instead of “Activity”

2. add URL to your grails application.

 super.loadUrl("http://findevents.cloudfoundry.com");

Your class may look similar to the following:

import android.os.Bundle;

import com.phonegap.DroidGap;

public class FindEventsGADroidActivity extends DroidGap {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.loadUrl("http://findevents.cloudfoundry.com");
    }
}

Now let’s change the AndroidManifest.xml and we are ready for the show time.

Add following xml before the <application tag

<supports-screens 
	    android:largeScreens="true"
		android:normalScreens="true" 
		android:smallScreens="true"
		android:resizeable="true" 
		android:anyDensity="true" />

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 

Add android:configChanges="orientation|keyboardHidden" to the activity tag in AndroidManifest. (view image below)

Add a second activity below under you application tag in AndroidManifest. (view image below)

<activity android:name="com.phonegap.DroidGap" android:label="@string/app_name" android:configChanges="orientation|keyboardHidden"> 
     <intent-filter> </intent-filter>
 </activity> 

Your Manifest should look something like below:

Learn more about PhoneGap at http://www.phonegap.com/start

We are done!

Show Time
Run your application and you should see the Grails app that will apear like a native application on your device.

See below for a screen shot of my application.

We have accomplished our goal for this post and are at a good stopping point.
We now have a grails app thats running on cloudfoundry appear as a native app on Android!

In the next post I will be working on gestures etc on grails app and will use YQL.
Most interestingly use device gps etc to find location. We will have to make some significant changes to the project. Hope you enjoyed this post.

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Setting up MySQL on Cloudfoundry

In my previous post, I showed how to create a quick Grails app on Cloudfoundry.
It was a very simple ‘Hello World’ type example app. In this post we are going to dig little deeper into cloudfoundry.

At the time of this writing, Cloudfoundry supports 3 different type of data store.
1. MongoDb – No SQL Database
2. redis – A persistent key value database
3. MySQL – Most popular free database

CloudFoundry calls these “Services”. You can create/instantiate these services for your application.
Let’s continue on with our previous example. We will create a MySQL database service and we will call it ‘hcfmysql-db’ (abbreviation to HelloCloudFoundryMySQL)

1. Creating CloudFoundry Service
You can create an instance by invoking the ‘cf-create-service’ command, Lets create ‘hcfmysql-db’

grails cf-create-service mysql hcfmysql-db

You should see an output like upon successful creation.

....

Service 'hcfmysql-db' provisioned.

You can verify that instance was created by running the following Grails command

grails cf-services

You should see output like follows:

============== System Services ==============

+---------+---------+-------------------------------+
| Service | Version | Description                   |
+---------+---------+-------------------------------+
| mysql   | 5.1     | MySQL database service        |
| redis   | 2.2     | Redis key-value store service |
| mongodb | 1.8     | MongoDB NoSQL store           |
+---------+---------+-------------------------------+

=========== Provisioned Services ============

+---------------+---------+
| Name          | Service |
+---------------+---------+
| hcfmysql-db   | mysql   |
+---------------+---------+

2. Binding the Database to the application
In Cloudfoundry, you will have to “bind” the services you created to the application you are working with.
In our example above, we will have to bind the hcfmysql-db with our HelloCloudFoundry app .
to do so, you can run “cf-bind-service” command.
For instance, in our example we can do:

grails cf-bind-service hcfmysql-db --appname=hellocloudfoundry

You should see the following output

Creating new service binding to 'hcfmysql-db' for 'hellocloudfoundry'.

Application 'hellocloudfoundry' updated
Service 'hcfmysql-db' added

Application 'hellocloudfoundry' stopped.

Trying to start Application: 'hellocloudfoundry'.
.........
Application 'hellocloudfoundry' started.

3. Setting up the app to use the database
When we do the binding to a cloud foundry application, CF will set up the connection settings to the services at runtime. This makes the settings very transparent and intuitive.
Lets configure our app for the data.
Edit the DataSource.groovy found under /grails-app/config

production {
        dataSource {
			dialect = org.hibernate.dialect.MySQLInnoDBDialect
			driverClassName = "com.mysql.jdbc.Driver"
			username = "n/a"
			password = "n/a"
            url = "n/a"
            dbCreate = "update"
        }
    }

Note that i have set up ‘n/a’, under username, password and url. You can put anything you want here as these will be overridden by cloudfoundry at runtime.

This is it! You are done.

4. Putting it all together
Let’s verify that our database is working. To do this we can create a “Domain” Class and we will do a scaffolding.

Lets create a Domain class called “Person” with id and name as two attributes.

grails create-domain-class Person

We will update the class as follows

package hellocloudfoundry

class Person {
    long id
    String name
    static constraints = {
    }
}

We will create a controller as follows

grails create-controller Person

Update the controller as follows


package hellocloudfoundry

class PersonController {

    def scaffold = Person
}

Lets the deploy the app on the cloudfoundry.
Since we had already deployed the app before you can do an update

grails prod cf-update

Now you can navigate to your app in my example I deployed my app as manijshrestha.cloudfoundry.com
so i can navigate to
http://manijshrestha.cloudfoundry.com/person/list

Setting up a Grails app on Cloud Foundry

I was lucky enough to get access to cloud foundry. I have heard a lot about how easy it is to deploy a grails app on cloudfoundry. I had to try it myself and here is my experience trying to do so….

Building An App
Lets just create a simple grails app called “HelloCloudFoundry”. to do so, we can create a grails app by running the “grails create-app” command like follows:

   /home/manijshrestha/workspace/$grails create-app HelloCloudFoundry

Once the app is created lets just dummy up a index.gsp, I usally delete the default one grails creates and replace it with my own with body text “HelloWorld”. For this example I replaced the content of the index.gsp with simple html as follows

<html>
    <head>
        <title>Hello Cloud Foundry</title>
    </head>
    <body>
        Hello From the Cloud!
    </body>
</html>

Installing cloud foundry plugin
I was pretty impressed that grails already had a cloupowershellpowershelld foundry plugin, to install lets just run our typical grails install as follows

/home/manijshrestha/workspace/HelloCloudFoundry$ grails install-plugin cloud-foundry 

Now, it should install the plugin for cloudfoundry

Configuring the App
To set up the app its fairly easy, edit the Config.grooy file found in grails-app/conf/Config.groovy
and set up with your credentials. If you don’t have an account get one via http://www.cloudfoundry.com
You should receive an email with user username and password

grails.plugin.cloudfoundry.username = 'your.email@server.com'
grails.plugin.cloudfoundry.password = 's3kr3t'
grails.plugin.cloudfoundry.appname = 'YOUR-APP-NAME'

thats it!!! we about 90 percent done!

Deploying
Now, lets deploy our app!!! Yes we are there now..

Now lets just run a grails command to push the app to the cloud foundry

from the command line run

NOTE: technically, we should configure our database like mysql or mongodb etc, but for our demo we will just push it, the command will asks us to create one and we will do so.

   $grails prod cf-push

You will see some input dialogs asking you for the app url? and also since, we didn’t configure a service it will ask you if you would like to bind a mysql service, See my responses below:

Application Deployed URL: 'manijshrestha.cloudfoundry.com'? 
manijshrestha.cloudfoundry.com

Would you like to bind the 'mysql-XXXX' service? ([y], n)
y

And BOOM we are done now you can navigate to your application URL
in my case its

http://manijshrestha.cloudfoundry.com/

Hopefully you enjoyed this, feel free to comment!

Helpful Links:
http://www.grails.org/plugin/cloud-foundry
http://grails-plugins.github.com/grails-cloud-foundry/docs/manual/index.html