apis for the internet of things
TRANSCRIPT
APIs for the Internet of Things
Peter Hoddie @phoddie@kinoma
@APICraftSF February 25, 2016
@kinoma
Overview1. IoT is the modernization of embedded computing, defined by
connectivity
2. How IoT devices are programmed needs to change
3. The unique challenges, demands, and priorities of IoT
4. Why Kinoma uses JavaScript together with C
5. Three areas of API functionality that are central to IoT
6. How Kinoma is building a set of APIs for IoT
@kinoma
@kinoma
Why JavaScript for IoT• JavaScript is the closest thing we have to a
universal programming language
Web (Desktop)
Mobile (Apps and Web)
Server
Embedded
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High level programming languages on embedded systems
Relatedly, writing software to control drones, vending machines, and dishwashers has become as easy as spinning up a website. Fast, efficient processors … are turning JavaScript into a popular embedded programming language—unthinkable less than a decade ago.
JavaScript for IoT
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• JSON built in – de facto data format of the web • Exceptionally portable – OS independent • Helps eliminate memory leaks so devices can run
for a very long time – garbage collector
Secure foundation
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• Sandbox • Core language provides no access to network, files, hardware, screen,
audio, etc. • Scripts can only see and do what the system designer chooses to
provide • Secure – many classes of security flaws in native code are nonexistent
• Uninitialized memory • Stack overflow • Buffer overruns • Mal-formed data injection
First truly major enhancements to the language. ES6 contains more than 400 individual changes including:
• Classes – familiar tool for inheritance
• Promises – clean, consistent asynchronous operation
• Modules – reusable code libraries
• ArrayBuffer – work with binary data
JavaScript 6th Edition – Features for IoT
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@kinoma
How small a system can run JavaScript?• 512 KB RAM • 200 MHz ARM Cortex M4 • Wi-Fi b/g • Most complete ES6 implementation anywhere • Open source
What does JavaScript forIoT devices look like?
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HTTP Client
let HTTPClient = require("HTTPClient");let http = new HTTPClient(url);
http.onTransferComplete = function(status) {trace(`Transfer complete : ${status}\n`);
};http.onDataReady = function(buffer) {
trace(String.fromArrayBuffer(buffer));};
http.start();
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HTTP Server
let HTTPServer = require("HTTPServer");let server = new HTTPServer({port: 80});
server.onRequest = function(request) {trace(`new request: url = ${request.url}\n`);request.addHeader("Connection", "close");request.response();
};
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I2C Accelerometerlet accel = new I2C(1, 0x53);let id = accel.readChar(0x00);if (0xE5 != id)
throw new Error(`unrecognized id: ${id}`);
accel.write(0x2d, [0x08]);accel.write(0x38, [(0x01 << 6) | 0x1f]);
let status = accel.readByte(0x39);let tmp = accel.readByte(0x32);let x = (tmp << 8) | accel.readByte(0x33);tmp = accel.readByte(0x34);let y = (tmp << 8) | accel.readByte(0x35);tmp = accel.readByte(0x36);let z = (tmp << 8) | accel.readByte(0x37);
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Adding ES6 to your product• Just a few steps to get the basics working • Get XS6 from GitHub • Build it with your product
• Entirely ANSI C – likely builds as-is • All host OS dependencies in three files xs6Host.c,
xs6Platform.h, and xs6Platform.6 • Update as needed for your host OS / RTOS
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Hello World
/* test.js */trace("Hello, world!\n");
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Hosting scripts in your code#include <xs.h>int main(int argc, char* argv[]) {
xsCreation creation = {128 * 1024 * 1024,/* initial chunk size */16 * 1024 * 1024, /* incremental chunk size */8 * 1024 * 1024, /* initial heap slot count */1 * 1024 * 1024, /* incremental heap slot count */4 * 1024, /* stack slot count */12 * 1024, /* key slot count */1993, /* name modulo */127 /* symbol modulo */
};xsMachine* machine = xsCreateMachine(&creation, NULL,"my virtual machine", NULL);xsBeginHost(machine);xsRunProgram(argv(1));xsEndHost(machine);xsDeleteMachine(machine);return 0;
}
Reading environment variablesTo allow a script to do this trace(getenv("XS6") + "\n");
trace(getenv("XSBUG_HOST") + "\n");
xsResult = xsNewHostFunction(xs_getenv, 1);xsSet(xsGlobal, xsID("getenv"), xsResult);
void xs_getenv(xsMachine* the){ xsStringValue result = getenv(xsToString(xsArg(0))); if (result) xsResult = xsString(result);}
Implement xs_getenv in C
Add getenv function to the virtual machine
Avoid the “100% pure” trap• It doesn’t make sense to code
everything in script • Native code is great
• Fast • Access to native functionality • Access to hardware functions • Re-use of proven, reliable code • Secure
JavaScript has proven to be accessible to designers, students, and engineers
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Scriptable is scalable• Your organization can’t implement everything itself
• Interactions with other devices • Mobile experience • Interactions with cloud service
• Building partnerships directly is slow, expensive, and limited • Opening your product to Apps let’s individuals and companies
integrate your product with theirs • Brings new abilities, new customers, access to new markets
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Scriptable IoT will lead us to theright standards
• New “standard objects” for IoT to augment JavaScript built-ins • Common programming models • Modules / libraries that are common across devices • Perhaps enhancements to JavaScript for needs of IoT
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Scriptable will realize potential of IoT• We can’t organize to connect all these
devices and services together • This is not a central design / control
problem • Organic exploration and growth • Consumers will get the magic they
expect, just as the mobile app ecosystem snapped into place
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[In Closing]• [Review your main ideas in summary form; repetition is important for
comprehension and recall, so repeat your important points. This also indicates to the audience that your talk is coming to an end and they can start to formulate their questions.]
• Calls to action:
• [Additional resources to point them to]
• [Recommended reading]
• [Where to dig into Kinoma APIs]
• Final statement before opening up to questions; what you want your audience to remember after it has forgotten everything else from your talk.
