Thursday, December 27, 2012

ADF Mobile : Device Interaction API - Pictures, GPS and Email With Attachments

During the AMIS ADF Masterclass I showed how to take a picture from within an ADF Mobile application, attach it to an Email and send that email out to several recipients. To top it of, I even added the GPS coordinates to the subject, so you know where the picture was taken. And all of that with the push of one single button. Sounds complicated ? Well actually it is very simple.

There are two ways to interact with device services. One is by using the page Definition, the second is by using the API.I decided not to use the pageDef, but to invoke the device datacontrol from java by using the API. Then it is also possible to invoke multiple actions in one java method. In this case I take a picture, get the coordinates and send an email.

How to take a picture ?
Taking a picture is easy. Just call the getPicture() method, and make sure (for this use case) to set Destination Type to File.
 public String getPicture(){  
   //destinationType = 1 so that the image is returned as a filename      
   String theImage = DeviceManagerFactory.getDeviceManager().getPicture(  
           , false  
   return theImage;  

That takes care of taking the picture.

How to get the current coordinates ?
By invoking getCurrentPosition it is very easy to get the GPS coordinates. Simply call the getCurrentPosition() method, and you will get the current coordinates. The coordinates are refreshed every 60 seconds.
 public Location getPosition(){  
   Location currentPosition = DeviceManagerFactory.getDeviceManager().getCurrentPosition(  
                                   , true);  
   return currentPosition;  

How to send an email ?
First take a look at the signature of the sendEmail() method. This immediately makes clear how to proceed from here...
         java.lang.String to  
         ,java.lang.String cc  
         ,java.lang.String subject  
         ,java.lang.String body  
         ,java.lang.String bcc  
         ,java.lang.String attachments  
         ,java.lang.String mimeTypes)  

The signature explains how it works. All that is needed are Strings. If you want to use multiple recipients, you need to separate them by comma's. The final question is: "how to attach the image that was just created ?".

Attaching the image.
You can do two things. Either use the String that is returned by calling getPicture(), or directly attach the file from the Temporary Directory which I do in this case.
 public void sendEmail(String attachment, Location here){  
   String directoryPathRoot = AdfmfJavaUtilities.getDirectoryPathRoot(0); //TemporaryDirectory  
   String content = "Amis wishes you all the best for 2013. This email contains an image as attachment. ";  
       content = content + "The picture was taken at: latitude=" + here.getLatitude() +  
            ", longitude=" + here.getLongitude();  
   attachment = directoryPathRoot+"/Pic.png";  
                            , null  
                            , "Merry Xmas and a Happy new year"  
                            , content  
                            , bcc  
                            , attachment  
                            , "image/jpg");  

The content and bcc in the above code sample are Strings that can be set in the method.

Putting it all together
The only thing you need is a button to invoke a method in the bean.
 amx:commandButton text="Take Picture" id="cb3"  

The method executeLogic() does the magic by invoking all three methods described above.
 public void executeLogic(ActionEvent actionEvent) {  
   String att = getPicture();    
   Location whereAmI = getPosition();  
   sendEmail(att, whereAmI);  

Push the button, the camera is invoked, and after that, the email client is invoked, showing an email with the attachment, the content (including GPS coordinates) and the recipients.

Sunday, December 16, 2012

Book Review : Oracle ADF Real World Developer's Guide

In October 2012 yet another ADF Book was published. This book "Oracle ADF Real World Developer's Guide" is authored by Jobinesh Purushothaman. Jobinsh works with Oracle as a Principal Solutions Architect for the Oracle Application Development Framework. The book is full of essential tips and tricks for building ADF applications. In this post I will share my book review with you and I give you the chance to win a free copy.

This book is suitable for ADF developers who are looking forward to build healthy and better performing applications using Oracle ADF. A book filled with step-by-step instructions and real-time examples with illustrations, diagrams, and tips that help developers learn the visual and declarative programming model offered by ADF. Using this book, readers will learn to get started with building business services using ADF business components, validate business data in different layers of an application and understand the use of EJB and web services in an ADF application.

The book contains 12 Chapters containing anything from getting started to Advcance topics.

Before I go into each chapter, I must say that this book has a couple of outstanding ways of explaining the ADF Framework. First of all there are many simple diagrams (and images) explaining the framework and parts of the framework. These diagrams are easy to understand, because thay only contain relevant information. You are not being distracted by colors or misleading images. It is just simple images, but very clear.

Next there are the sequence diagrams. These diagrams explain what exactly happens (at class level) when for instance you issue execute query from an ADF Application. As far as I know this is the first book that uses these sequence diagrams to explain ADF in a very clear way.

Finally I need to point out the valuable code samples that are in the book. Get yourself a digital copy so you can easy copy and past these code snippets into your ADF application.

Now lets take a look at the chapters.

Part I : getting started

1 : Getting Started with Oracle ADF
The most interesting part for me is the section on "Comparing the Fusion web application technology stack to the Java EE web application". This is explaining ADF in the context of a Java EE application. Currently I am involved in a project where we need to "rebuild" a Java EE application in ADF. There is a lot of discussion in this project about responsiblity of eaach layer. This chapter can help Java EE developers understand the ADF framework. The image on page 13 of the book ADF and Java EE by putting both in one diagram next to eachother.

Also the part about the generated Metadata files is valuable. Ussualy these files (like adf-settings, weblogic-application) are taken for granted, but Jobinesh explains what all the metadata files are about.

Part II : ADF Business Components

2 : Introduction to ADF Business Components
3 : Introducing Entity Object
4 : Introducing View Object
5 : Advanced Concepts on Entity Objects and View Objects
6 : Introducing the Application Module
This part provides a detailed look at how entities, view objects and application modules are defined and how they work at runtime. I was impressed by the level of detail in chapter 2. It is great that I have a couple of more chapters that go even into more detail.  This chapter really made me wanna continue reading. Chapters 3 and 4 are introducing the basic concepts of View Objects and Entity Objects. Both chapters contain very helpful sequence diagrams explaining what happens internally within entity objects and view objects.

At the start of chapter 5 Jobinesh tells the reader to "Take a deep breath and prepare yourself".  The part that follows takes a deep dive into entity objects. This chapter is full of in depth Entity Object knowledge. Allthough I have been working with ADF for many many years there were some interesting featured in this chapter that I did not know about. (mainly because I never had to use these). For instance, did you know that you can call getAttribute(attrIndex,EntityImpl.ORIGINAL_VERSION) on an entity object to read the originally retrieved value for an attribute ? I allways use(d) getPostedAttribute(int attribIndex).

At the end of the Entity Object section there is an interesting part on "Building programmatically managed entity objects" including code samples.

The most interesting part of the View Object section is about working with ViewCriteria Programmatically. Also the section about working with XML data is a noce one. I never got to use this functionallity in real life. Jobinesh explains very well how to do this, and I hope to get a use case soon. The chapter ends with a section about "Building business components dynamically".

After reading chapter 5 I can only say one thing: "I am impressed !".

Chapter 6 covers important topics like properties, passivation, activation, application module pooling.

7 : Binding Business Services with the User Interface
Chapter 7 really contained nothing new to me. However, if you are new to ADF, this chapter contains very good explanation of the binding layer. There is an interesting part about "Invoking an application module from a Java servlet". I did use this approach in several occassions. It is good to have a section on this in the book. Again in this chapter there are several simple diagrams that help you understand what happens in the binding layer.

8 : Building Data Bound Web User Interfaces

This is about building data bound web user interfaces. It has a small section on layout components. It also talks about working with tree and treetables programmatically. One of the things I learned form this chapter is how to use the "RowCountThreshold" attribute in an iterator binding. Never did that before.... On page 327 there is a "best practice" that you should know about: "If the scope of the managed bean is higher than the request, then you should not bind the UI components' elements in the JSF page with the UI component instances defined in a managed bean using the binding attribute in the component tag"

9 : Controlling the Page Navigation
For me there really wasn't anything new but, if you are new to ADF, it is again a very nice chapter.

10: Taking a Closer Look at the Bounded Task Flow
This chapter takes a deep dive into the bounded taskflow. There are sections on "dynamic taskflow calls, Lazy Loading and there is even a section on Contextual events.

11: More on Validations and Error Handling
Yet another chapter containing very valuable tips. Very interesting is the part where you learn how to vreate a custom validator containing client side java scriupt validation.
Also you learn how to define model layer validation which is in fact rarely used. And there is an interesting diagram that helps you understand how the framework engages
DCErrorHandlerImpl during the page life cycle for handling exceptions thrown by business components when accessing them in the binding context

12: Oracle ADF Best Practices
This chapter summarizes the best practices and coding tips that developers will find useful when building ADF applications. Learning the best practices will help you to avoid common pitfalls that others might have faced.  The content for this chapter is based on input from various teams who have successfully used ADF.

My advise is that you should really buy this book ! It is full of valuable tips and tricks ! When you buy this book, all code samples in this book are available online so you can download these and play with them.
The book is available here.

Get yourself a free Christmas present !

For the contest I have two copies of Oracle ADF Real World Developer’s Guide to be given away to two lucky winners.

How you can win:
To win your copy of this book, all you need to do is come up with a comment below highlighting the reason "why you would like to win this book”.

Please note: Winners residing only in the USA and Europe would get a chance to win print copies. Others would be provided with eBook copies.
Duration of the contest & selection of winners:The contest is valid for 7 days (contest ends 23-12-2012 23:59 GMT) , and is open to everyone. Winners will be selected on the basis of their comment posted.