Jakarta Activation

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Within computing, Jakarta Activation (JAF; formerly JavaBeans Activation Framework) is a Jakarta EE API that enables developers to:

• determine the type of an arbitrary piece of data,
• encapsulate access to it,
• discover the operations available on it and
• to instantiate the appropriate bean to perform the operation(s).

It also enables developers to dynamically register types of arbitrary data and actions associated with particular kinds of data. Additionally, it enables a program to dynamically provide or retrieve JavaBeans that implement actions associated with some kind of data. Originally an extension API, it was available as a standard API in Java SE (from Java SE 6 on) and Java EE, but was removed in Java SE 11.

DataSource Interface

• Provides access to an arbitrary collection of data
• Get name of the data, data-type name (content type), and the data itself as Input Stream or Output Stream
• Two implementation classes provided
  • URLDataSource simplifies the handling of data described by URLs
  • FileDataSource simple DataSource object that encapsulates a file provides data typing services -> delegated to a FileTypeMap object.
• Other implementations
  • javax.mail.internet.MimePartDataSource
  • javax.mail.util.ByteArrayDataSource

DataContentHandler interface

• Convert the object to a byte stream and write it to the output stream
• Convert streams in to objects
• Used to get object/data which can be transferred
• Uses java.awt.datatransfer.DataFlavor to indicate the data that can be accessed. DataFlavor is a data format as would appear on a clipboard, during drag and drop, or in a file system.

CommandMap class

• An abstract class provides an interface to a registry of command objects available in the system
• Developer develop their own implementation or use
  • MailcapCommandMap class that implements a CommandMap whose configuration is based on mailcap files (1524)
• Command list available from a MIME Type is stored in CommandInfo object.

CommandObject interface

• Interface to be implemented by JavaBeans components that are ActivationFramework aware
• Simple interface with one method:
  • setCommandContext(String verb, DataHandler dh)

Example: Compose an e-mail with attachment

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.internet.*;
import javax.mail.*;

...

// Create a message.
MimeMessage message = new MimeMessage(session);

...

// Create the Multipart to be added the parts to
Multipart multipart= new MimeMultipart();

// Create and fill the first text message part
MimeBodyPart mbp = new MimeBodyPart();
mbp.setText("Body");
multipart.addBodyPart(mbp);

// Create a file attachment and fill as second message part
mbp = new MimeBodyPart();
FileDataSource fds = new FileDataSource("C:\\attachment.zip");
mbp.setDataHandler(new DataHandler(fds));
mbp.setFileName(fds.getName());
multipart.addBodyPart(mbp);

// Add the multipart to the message
message.setContent(multipart);

...

External links

• JSR 925: JavaBeans Activation Framework 1.2 Specification
• Introduction to JavaBeans Activation Framework
• Introductory presentation
• Hanson, Jeff (2007-10-30). "REST easy with the JavaBeans Activation Framework". JavaWorld. https://www.infoworld.com/article/2077786/rest-easy-with-the-javabeans-activation-framework.html. 
• Example also available in Java 6 New Features: A Tutorial book, chapter-13 ISBN:0-9752128-8-5