iotivity: support for android..."/compass1", resource_type, interface, entityhandler,...

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IoTivity: Support for Android

Tim KourtLinux Foundation Collaboration Summit

February 20, 2015

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Introduction to the IoTivity

Building blocks

Dive into the code

Android API Overview

Demo

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What is the IoTivity Project?

IoTivity is an open source software framework providing connectivity for the Internet of

Things (IoT)

IoTivity is a reference implementation of the Open Interconnect Consortium (OIC)

specification

IoT technologies here will span multiple industries including:

• smart home

• automotive

• industrial automation

• healthcare

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IoTivity Example

Smart Light BulbSmart Light Switch

Multicast request: Get light bulbs

Unicast response: I’m a light bulb

What is your status?

Set Status: On

Status (Off, Dim :75, …)

OK, Done

RESOURCE

LightStatus: On/Off

Dimming: 0 - 100

Hue: RGB

Color Temp: KLocal Network

Client Server

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Building Blocks for Android SupportBuilding on top of an existing C++ SDK

• The IoTivity project has a well established C++ SDK for the unconstrained environments

• The Java language binding for the IoTivity is build on top of the C++ SDK and mimics its

APIs. The key reasons:

• Reuse of an existing code

• Maintainability

• Early detection of the programming errors

IoTivity Base (C++ SDK)

Application (C++)

IoTivity Base (C++ SDK)

JAVA

IoTivity Base (C SDK) IoTivity Base (C SDK)

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Binding the IoTivity C++ APIs to Java

C++ API:

typedef std::function<void(std::shared_ptr<OCResource>)> FindCallback;

OCStackResult findResource(const std::string& host,

const std::string& resourceURI,

FindCallback resourceHandler);

public interface OnResourceFoundListener {

public void onResourceFound(OcResource resource);

}

public static native void findResource(

String host,

String resourceUri,

OnResourceFoundListener onResourceFoundListener) throws OcException;

Java API:

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The Mechanics of Binding• Java Native Interface(JNI) is a programming framework that enables Java code running

in a Java Virtual Machine to interact with native libraries

• JNI glue layer (wrapper written in C++ ) maintains Java and native objects and

interoperability between them

• One-to-one relationship between the native and Java objects

Java library JNI glue layer Native library

OcJavaObject OcJniObject OCNativeObject

JNI

• Uses Java reflection to manipulate

OcJavaObjects

• Keeps a copy or refference to

OCNativeObjects

• Maintains refs for the listener objects

in JVM

• Keeps ref. to OcJniObjects

as a long

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Memory ManagementThe differences between the C++ and Java programming languages

• Java has garbage collection mechanism

• C++ uses explicit memory management

• Java class’s finalize methods are used to delete C++ objects

public class OcResource {

. . .

@Override

protected void finalize() throws Throwable {

super.finalize();

dispose();

}

private native void dispose();

private long mNativeHandle;

}

Java:

JNIEXPORT void JNICALL

Java_org_iotivity_base_OcResource_dispose

(JNIEnv *env, jobject thiz)

{

JniOcResource *resource =

JniOcResource::getJniOcResourcePtr(env, thiz);

if (resource)

{

delete resource;

. . .

JNI:

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Managing Listener Objects

OcPlatform.OnResourceFoundListener resourceFoundListener =

new OcPlatform.OnResourceFoundListener() {

@Override

public void onResourceFound(OcResource resource) {

//Do something

}

};

OcPlatform.findResource("",

RESOURCE_URI_1,

resourceFoundListener);


RESOURCE_URI_2,



RESOURCE_URI_3,


@Override


//Do something

Java API use case:

public interface OnResourceFoundListener {

public void onResourceFound(OcResource resource);

Event handlers

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JNIEXPORT void JNICALL Java_org_iotivity_base_OcPlatform_findResource

(JNIEnv *env, jclass clazz, jstring jHost, jstring jResourceUri, jobject jListener)

{

. . .

JniOnResourceFoundListener *onResFoundListener = AddOnResourceFoundListener(env, jListener);

FindCallback findCallback = [onResFoundListener](std::shared_ptr<OCResource> resource)

{

onResFoundListener->foundResourceCallback(resource);

};

OCStackResult result = OCPlatform::findResource(host, resourceUri, findCallback);

. . .

Managing Listener ObjectsEvent handlers

AddOnResourceFoundListener(env, jListener)

• Checks if jListener has been seen before:

• No: creates a global ref. in JVM, creates new wrapper JniOnResourceFoundListener and returns it

• Yes: increments reference counter for an existing JniOnResourceFoundListener and returns it

RemoveOnResourceFoundListener(env, jListener)

• Reverses the logic above

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Exceptions

OCStackResult result = OCPlatform::findResource(host, resourceUri, findCallback);

if (OC_STACK_OK != result)

{

ThrowOcException(result, "Find resource has failed"); //Java exception gets thrown

...

Bindings throw and handle Java exceptions

env->CallVoidMethod(jListener, midL, jResource);

if (env->ExceptionCheck())

{

env->ExceptionClear();

LOGE("Exception is thrown in Java onResourceFound handler");

...

JNI

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IoTivity Android Stack

Android Java Application (.apk)

IoTovity Base Java API library(.aar)

IoTivity Base C++ libraries (.so)

IoTovity JNI C++ glue layer (.so)

NativeJNI

JAVA

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FunctionalityThe current Android API for IoTivity includes functionality for

• Resource registration

• Resource discovery

• Device discovery

• Resource management (get, set, observe)

• Resource tree (resources with sub-resources)

• Presence notification service defined as a virtual resource

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Registering a ResourceRegistering a resource requires two basic items

• A handler to process requests from the stack

• A URI path to register the resource

OcPlatform.EntityHandler entityHandler = new OcPlatform.EntityHandler() {

@Override

public EntityHandlerResult handleEntity(OcResourceRequest ocResourceRequest) {

// handle request

return EntityHandlerResult.OK;

}

};

OcResourceHandle resourceHandle = OcPlatform.registerResource(

"/compass1",

RESOURCE_TYPE,

INTERFACE,

entityHandler,

EnumSet.of(ResourceProperty.DISCOVERABLE));

Server

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Finding a Resource

This operation returns all resources of given type on the network service.

OcPlatform.OnResourceFoundListener resourceFoundListener =


@Override


//do something

}

};

OcPlatform.findResource(

"",

"coap://224.0.1.187/oc/core?rt=" + RESOURCE_TYPE,


Client

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Device Discovery

OcDeviceInfo devInfo = new OcDeviceInfo();

devInfo.setDeviceUuid("38454000-8cf0-11bd-b23e-10b96e4ef00d ");

devInfo.setFirmwareVersion(“2.3.4");

OcPlatform.registerDeviceInfo(devInfo);

Server

OcPlatform.OnDeviceFoundListener deviceFoundListener =

new OcPlatform.OnDeviceFoundListener() {

@Override

public void onDeviceFound(OcRepresentation ocRepresentation) {

Log.i(TAG, "Device Name: " + ocRepresentation.getValueString("dn"));

}

};

OcPlatform.getDeviceInfo("", "coap://224.0.1.187/oc/core/d", deviceFoundListener);

Client

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Resource Management (get, set, observe)

@Override

public void onGetCompleted(List<OcHeaderOption> headerOptionList,

OcRepresentation ocRepresentation) {

}

@Override

public void onPutCompleted(List<OcHeaderOption> headerOptionList,

OcRepresentation ocRepresentation) {

}

@Override

public void onObserveCompleted(List<OcHeaderOption> headerOptionList,

OcRepresentation ocRepresentation,

int sequenceNumber) {

}

resource.get(queryParamsMap, this);

resource.put(queryParamsMap, this);

resource.observe(queryParamsMap, this);

Client

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Resource Management (get, set, observe)

@Override

public EntityHandlerResult handleEntity(OcResourceRequest ocResourceRequest) {

...

if (handlerFlagSet.contains(RequestHandlerFlag.INIT)) {

...

}

if (handlerFlagSet.contains(RequestHandlerFlag.REQUEST)) {

switch (requestType) {

case GET:

break;

case PUT:

break;

}

OcPlatform.sendResponse(ocResourceResponse);

}

if (handlerFlagSet.contains(RequestHandlerFlag.OBSERVER)) {

...

}

return EntityHandlerResult.OK;

}

Server

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Resource Tree

OcResourceHandle doorOpener = OcPlatform.registerResource(

"/doorOpener",

...

OcResourceHandle light1 = OcPlatform.registerResource(

"/Light1",

...

OcResourceHandle light2 = OcPlatform.registerResource(

"/Light2",

...

OcResourceHandle motor = OcPlatform.registerResource(

"/motor",

...

OcPlatform.bindResource(doorOpener, light1);

OcPlatform.bindResource(doorOpener, light2);

OcPlatform.bindResource(doorOpener, motor);

Server

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Presence Notification

OcPlatform.startPresence(1);

//after some time

OcPlatform.stopPresence();

Server

public void onPresence(OcPresenceStatus ocPresenceStatus, int nonce, String hostAddress) {

//do something

}

OcPlatform.subscribePresence("coap://224.0.1.187“, this);

Client

iotivity: support for android..."/compass1", resource_type, interface, entityhandler,...

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