Femto Java
Developing Java applications
for tiny footprint platforms
Eduard de Jong
QC Technology B.V.
BOF 2187
http://java.net/projects/femto-java
This BoF session
• Learn about a different way to develop Java
code for tiny platforms e.g. smart cards
– With unit testing of on-platform code
– In multiple packages in the same project
• See it used for Java Cardtm platform code
Tiny Java platform:
• A Java programmable platform with a
restricted and/or modified run time
• Deployment of Java code by optional pre-load
processing of class files
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Eduard de Jong
•
Invented & patented core technology used in Java Card
– 1994
•
Designed Java Card 2.0
– 1996
•
With the Java Card team at Sun Mircosystems Inc.
– Architect for DMDC deployment of smart cards (CAC)
– Till 2006
•
Active in ISO smart card standardization
– Since 1994
•
Designed electronic cash system for smart cards and mobile phones
– Implemented in UK with Java for Android and the Java Card Platform
– Deployments soon
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The Plan for this session
•
•
•
•
Background
Femto Java basics
Femto Java Card
Conclusion
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Progress
• Background
– Java Card vision
– Java Card practices
– Small Java
• Femto Java basics
• Femto Java Card
• Conclusion
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Java Card vision
• Run java applications in a very restricted device
– Initial constraints:
•
•
•
•
8 bit CPU
<64K Program
<16K Non-volatile memory
<1K RAM
• Specify a framework for smart card application generic operations
– IO
– Crypto
– Memory transactions
• Develop code for both sides at the same time
– Communication code generated from same source
• Card Applet
• Card terminal application
• Bypass explicit use of APDUs
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JC Development practice
• IDE project for Java Card platform one
package at a time
– All tools aimed at single-package development
• Design choice in Java Card to equate Java Card’s “fire
wall” with a Java package
• No support for unit testing
– No test driven development
– Marginal support for refactoring
• No compile on save
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History of small Java efforts
– Java Card (1996)
•
JC 2.0 (1997)
– Femto Java I (1997)
– Pico Java (1999)
– Spotless (1999)
•
•
–
–
–
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KVM
Java ME
Femto Java II (2000)
Squawk (2003)
Embedded Java (2011)
Femto Java III (2014)
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Progress of this session
Background
• Femto Java basics
– Femto Java platform
– Femto Java Code development process
– Net Beans integration
• Femto Java Card
• Conclusion
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Femto Java
Femto Java:
Principles & tools for developing Java code,
programs and libraries, on restricted
computing platforms:
–
–
–
–
Not the full Java runtime environment
Modified runtime functions
Java API with framework dedicated to platform purpose
Written in Java
•
•
Executed using a Java-like interpreter
Executable code created with post-compilation
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Femto Java Development
Code,
Compile
& test
• Target code, unit test code, functional test code,
support code
• Java SE runtime
• Processes annotations
• Restricted Platform runtime as library
• (Unit) tests
• Functional tests
• Restricted Platform runtime
• +java.lang.annotation
Compile
• Reveals Restricted Platform Java subset
errors
• Includes generated code
Test on target
platform
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• Post compile (convert)
• Load
• Function tests
• Reuse test and support code
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Femto in NetBeans
• NB Code development project for Java SE project
• Code for restricted platform is in one or more earmarked packages
• Creates a sub project type within the NB project
Femto core
modules
• Mark packages for sub project type
processing
• Perform Restricted Platform runtime
compilation
Restricted Platform I
Restricted Platform II
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• e.g. Java card
• e.g. Embedded Java for smart card
terminal
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Progress of this session
Background
Femto Java basics
• Femto Java Card
– Java Card tools
– Java Card emulator
• Runtime reference
• Unit test support
– Demo
• Conclusion
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Femto Java Card tools
• Tools need to support multiple packages
• Rethink CAP file
• Java Card Converter
– Wrapper around current tool
– Calling order constraints enforced.
• CAP tools
– Load APDU scripts generated in proper package calling order
• Dependency importer
– Recognizes multi-package CAP files
• On-card platform enhancements
– AbstractApplet
• Overridable initialization code
• TestApplet
– On-card debugging support
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Femto Java Card emulator
• Java Card platform API reference library
• Java Card platform implementation
– In Java
• Implements almost all Java Card features
– For (unit) testing
• Platform runtime environment instantiated per test
• External access to runtime static data
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Unit testing
The Java card runtime is instantiated at the start of each test.
class ShowFemtoUnitTest {
@Before void initJavaCardRuntime() {
//Create the runtime for the current test (Thread)
JavaCardTestContext.getInstance();
}
@Test void aMethodTest(){
//e.g. call a runtime static method
byte[] bArr =
JCSystem.makeTransientByteArray(10, 1);
//Dispatched to the current runtime instance
//test code …
}
}
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APDU Unit testing
Explicit reference to Java card runtime to access APDU buffer
class ShowFemtoUnitTest {
JavaCardTestContext context;
@Before void initJavaCardRuntime() {
//Keep reference to runtime context
context = JavaCardTestContext.getInstance();
}
@Test void aMethodTest(){
//Set the current APDU.
APDU apdu =
context.makeApdu(10, 0x80, 4, 0, 0, …);
//test code …
assertEquals(apdu, APDU.getCurrentAPDU());
}
}
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APDU level testing
The emulated Java Card runtime supports
–
–
–
–
Loading Java Card Applet instance
Specifying AID for the applet under test.
Specifying Shareable interface implementations
Initiating a session with an Applet
•
With answer to SELECT command
– Manufacturing APDUs for Applet session
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Demo Time
• Opening a Java SE Project
– Project prepared with Femto plugin modules
– Marking packages for Java Card processing
• Run unit tests for Java Card library
– Existing Java Card development with deployed
code
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Progress of this session
Background
Femto Java basics
Femto Java Card
• Conclusion
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Conclusion
With the “Femto” principle development
of code for the Java Card platform can
benefit from all the powerful present day
development tools in an IDE such as unit
testing and refactoring.
Principle applicable to a range of constrained Java
platforms
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Questions?
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Thank you for your attention
Eduard de Jong
eduard@dejongfrz.nl
http://java.net/projects/femto-java
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