CLDC 8: New Features and Opportunities for the Small Java Core Libraries

Copyright © 2013, Oracle and/or its affiliates. All rights reserved.1

CLDC 8: New Features and Opportunities for the Small Java Core Libraries

Michael Lagally Principal Member of Technical StaffRoger Riggs, Consulting Member of Technical Staff


The following is intended to outline our general product direction. It is

intended for information purposes only, and may not be incorporated into

any contract. It is not a commitment to deliver any material, code, or

functionality, and should not be relied upon in making purchasing

decisions. The development, release, and timing of any features or

functionality described for Oracle’s products remains at the sole

discretion of Oracle.


CLDC 8

Abstract: CLDC has been the Java platform for connected devices such as feature phones

since 2000. It is a platform for devices with very limited memory and CPU power. Oracle is leading an effort to update the CLDC platform with support for Java 8

language features and new library APIs. The platform defines a state-of-the-art runtime environment for small embedded devices and provides a set of carefully defined libraries that are most useful on resource-constrained devices.

CLDC 8 targets embedded devices such as wireless modules, smart meters, and healthcare monitoring and other M2M devices. The CLDC 8 configuration is standardized in the Java community process as JSR 360, with experts from the embedded and mobile industry in the expert group.

New Features and Opportunities for the Small Java Core


Program Agenda

Java ME Evolution Connected Limited Device Configuration (CLDC) Generic Connection Framework (GCF)


The Next Generation: Java ME 8 Platform

• First step in Java ME Java SE alignment• Dedicated embedded application platform• Address increased range of use cases and markets

Themes

Key Features

•Java ME CLDC 8: Updated VM + alignment with Java SE 8•Java ME Embedded Profile 8: Embedded application platform•Value-add new and enhanced APIs and features for embedded•Improved configurability and optimized footprint for deployment

• Target requirements starting at 128 KB RAM, 1 MB Flash/ROM

Target Markets

• Small to mid-embedded covering wide range of use cases/markets• Intelligent edge devices, communication nodes, healthcare

devices, smart sensors, smart meters, general IoT and M2M


Java ME 8 Focus

Platform Footprint

Device CPU/GPU/I-O ARM 7 Cortex M ARM9/11 MIPS32 - ARM Cortex A – PPC - Intel Atom

50KB-1MB

1MB-10MB

10MB-100MB Java MEJava SE

Java Card


Towards a Common Java

• CLDC is a strict subset of Java SE• CLDC code works on Java SE• Java ME vs. Java SE is a footprint/functionality tradeoff• Java ME & Java SE release cycles are in sync

Key Principles

• Modern and flexible platform for delivering embedded software• Unified development experience & community across Java• Aligned Java language, core APIs, development, and tools• Enable 9+ Million Java developers to develop for Java Embedded

Benefits

Ensure close alignment between ME/SE


Java ME 8 Platform Overview

Java VM

AdditionalAPIs(Examples)

Application Platform

Java ME CLDC 8 (JSR 360, aligned with Java SE 8)

Java ME Embedded Profile (MEEP 8, JSR 361)

AdditionalOptional APIs

On-Device I/O Access

Device I/O API

Vertical Specific APIsLocation

Messaging WirelessCommunication

Web Services

Protocols and Data Conversion

Sensors

SATSA

Security and Trust Services

AdditionalOptional JSRs

Security andManagement

Generic Connection Framework

GCF


Constraints of small embedded devices


Sample prototyping board

STM32F4 Discovery Board (Very Low Cost, ca. 15 USD) STM32F407VGT6 microcontroller

– 32-bit ARM Cortex-M4F core– 1 MB Flash– 192 KB RAM

3-axis accelerometer Omni-directional digital microphone Audio DAC with integrated class D speaker driver Eight LEDs, two push buttons (user and reset) USB OTG FS with micro-AB connector

Small Embedded

Source: http://www.st.com/st-web-ui/static/active/en/resource/technical/document/data_brief/DM00037955.pdf


Sample prototyping board

Raspberry Pi (Low Cost, ca. 25 USD) Broadcom BCM2835

– 700 MHz ARM1176JZF-S core– 512 MB RAM

2 USB ports SD card slot Onboard Network Audio / Video output

Small Embedded


Program Agenda



Java SE 8

CLDC 8: an Evolutionary update for CLDC

• Key Features• Synchronize with Java SE 8 Language Features into Java ME• Add developer friendly APIs to Java ME from Java SE• Virtual Machine Update to align with developer tools• Remain small and enable footprint optimizations

• Specification Characteristics• CLDC 8 is an extended strict subset of Java SE 8• Consolidated Generic Connection Framework• Backward binary compatibility

CLDC 8


CLDC 8 architecture


ConfigurationsCLDC is scalable to small and very small devices


CLDC 8 Footprint Considerations

Stripping On Deployment– For fixed-function, minimal footprint deployments– Allows bundling application with the runtime and then stripping away

unnecessary components– Result: Minimal, non-modifiable binary containing application and

runtime

Optimizing Footprint Even Further


New Java Language Features






Library Updates

CLDC Library– Platform extensibility via Service Providers (ServiceLoader)– EventObject and EventListener– Subset of NIO Buffers– NIO Files and NIO Channels– Logging– StringBuilder and String Formatter– Comparable interface– Try with resources – Closeable and AutoCloseable


Library Updates

New Collections– List – ArrayList, LinkedList– Map – HashMap, LinkedHashMap, WeakHashMap– Set – HashSet, LinkedHashSet– Queue – Deque, ArrayDeque– Iterable and Iterator, ListIterator


Focus on: Service Providers

A service is a well-known set of interfaces and abstract classes that is implemented by a (service) provider.

Providers can be installed to extend the Java platform. Providers are located and instantiated on demand. Providers are identified via a provider-configuration file in the

META-INF/services resource directory.

An extension mechanism for the Java platform


Service Providers - Example

import com.XYZ.ServiceA;ServiceLoader<ServiceA> sl1=ServiceLoader.load(ServiceA.class);

An extension mechanism for the Java platform

ServiceB

ServiceBProvider1

ServiceBProvider2

com.XYZ.ServiceA

ServiceAProvider1

ServiceAProvider3

ServiceAProvider3

Resources:META-INF/services/com.XYZ.ServiceA:

META-INF/services/ServiceB:

ServiceAProvider1ServiceAProvider2ServiceAProvider3

ServiceBProvider1ServiceBProvider2


Updates to CLDC Virtual Machine


Unsupported Java SE 8 Features

No reflection No serialization No InvokeDynamic/Lambda expressions No JNI and application native code No User-defined class loaders No runtime annotations No thread groups and daemon threads No concurrency utilities Limited Math APIs (No BigDecimals) Limited security APIs Limited collection APIs (No sorted collection classes)


CLDC Summary


Program Agenda



Generic Connection Framework (GCF)


Generic Connection Framework (GCF)


New GCF Features


New GCF Features


New GCF Features


New GCF Features


New GCF Features


New GCF Features


New GCF Features Additional protocol parameters


New GCF Features: Access Point

The AccessPoint API enables:– Obtaining a list of available network access points– Querying the access technology (e.g. 3GPP, CDMA, Wi-Fi, Wired)– Getting Access-point technology-specific properties (e.g. 3GPP country

code, network code)– Selection of an access point for a connection– Detection of connect/disconnect situations

Selecting a Network Access Point


New GCF Features: Access Point

AccessPoint aps[] = AccessPoint.getAccessPoints(true);AccessPoint ap = aps[0];// attach an event listener to the first access pointap.addListener(new AccessPointListener() {public void notifyEvent(AccessPoint accessPoint, int eventType) { if ((eventType == AccessPointListener.EVENT_TYPE_AVAILABLE)) System.out.println(“signalstrength = ”+ ap.getProperty(“signalstrength")); }

});

// select the first access point for communicationConnectionOption<String> id = new ConnectionOption<>("AccessPoint”, ap.getId());Connection c = Connector.open("http://www.oracle.com/index.html", id);

Example


Development Tools for CLDC 8

Standard JDK 7 or 8 tools can be used for application development Embedded-specific hints & warning messages

– Provides developer with additional information to optimize code Debug structures are optional

– Debug features can be ignored/filtered out to save footprint Future tools under consideration may include

– Optimizing converter/compiler plugin for optimizing CLDC 8 applicationsIntegrated with Java ME SDK and IDEs


Java ME 8 - JCP

JSR 360: CLDC 8– EG Kick-off: February 2013– Early Draft: May 2013– Public Review: September 2013– Final Draft: December 2013

JSR 361: Java ME Embedded Profile– On Parallel Schedule

Activities and Schedule


Summary

Long anticipated updates to CLDC to align with SE 8 features Created for resource constrained devices Library updates

– Collection API updates– NIO Buffers, NIO Files, NIO Channels, Logging– Service Loader

Consolidated GCF Connections– Plus Multicast connection, Connection options, IPV6 – Secure Server Socket and Secure Datagrams

Tools and support for embedded platforms

CLDC 8 New and Improved


References and Related Sessions

CLDC8 – www.jcp.org/en/jsr/detail?id=360

Java.net project – java.net/projects/jsr360

Related sessions:– MEEP: A New Java Profile for the Embedded World [CON5330]

– Oracle Java ME Embedded: Small Embedded with Big Opportunities [CON2796]

– Java ME 8 Overview: A New Platform for Embedded Development for Small Devices [CON2267]

http://www.jcp.org/en/jsr/detail?id=360

https://java.net/projects/jsr360


Safe Harbor Statement

The preceding is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions.The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.


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CLDC 8: New Features and Opportunities for the Small Java Core Libraries