• Our demo:

• Real-time collaborative city planner

• Changes are distributed using XMPP

• XMPP bot updates traffic patterns

• Runs in Javascript on the server

Welcome!Welcome!

What is OWhat is O33??

• Collection of C++ components, made

available through Javascript API

• Runs on all major browsers, and all major

operating systems

• Library to create scriptable

C++ components

What is OWhat is O33??

• Comes in two flavors:

• O3 client-side:

• Runs as plug-in in the browser

• Extends DOM API with O3 components

• Useful if you’re developing in the browser

• O3 server-side:

• Runs as standalone application

• Uses Google’s V8 engine to run scripts

• Provides the same components

What is OWhat is O33??

• All O3 components are available on

both the client and the server!

• To use O3 at the client, you need a

plugin however…

What is O3?What is O3?

• O3 Library consists of three parts:–Component model–Reflection layer–Containers, algorithms, etc.

Component modelComponent model• Subset of Microsoft’s COM specification (as opposed to XPCOM, CORBA, etc.)

• Looks like this:

o3_iid(iFoo, 0x3F2504E0, 0x4F89, 0x11D3,

0x9A, 0x0C, 0x03, 0x05, 0xE8, 0x2C, 0x33, 0x01);

struct iFoo : iUnk {

virtual void bar(int x) = 0;

};

o3_cls(cFoo)

struct cFoo : cUnk, iFoo {

o3_begin_class(cUnk)

o3_add_iface(iFoo)

o3_end()

};

Reflection layerReflection layer• Special interface:

struct iScr : iUnk {

int resolve(const char*);

void invoke(iCtx* ctx, Access access,

int id, int argc, Var* argv,

Var* rval, Ex* ex);

…

};

• Allows you to query C++ objects for their methods and properties!

• Indexed based because some script engines require this

(i.e. IDispatch)

Containers, algorithms, etc.Containers, algorithms, etc.

• We don’t use STL (although you could!)

• Our containers have lots of useful features and

optimizations:

• Stack allocation for small strings

• Copy-on write semantics

• Automatic UTF-8/UTF-16 conversion (not possible with STL)

• Vectors are scriptable as well!

(using Array interface)

Writing componentsWriting components

• Writing O3 components is easy!

• All you need to do is add some tags:

o3_get int value(); // getter

o3_set int setValue(int value); // setter

o3_fun int function(int x); // function

• Code generator will do the rest!

(also written in Javascript)

Writing componentsWriting components

• We want our components to be as fast as possible!

• Immediate properties:

o3_imm_get int foo; // read-only

o3_imm_set int bar; // write-only

o3_imm int value; // read/write

• No getters/setters are generated, properties are

accessed directly.

Writing componentsWriting components

• We want to be able to load components on the fly!

• Extension properties:

• In C++:

o3_ext(“cO3”) o3_fun static int test(int x);

• In Javascript:

o3.loadModule(“test”);

o3.test(3);

Dealing with asyncDealing with async

• Use threads to implement asynchronous Javascript calls.

• Use message passing to implement callbacks

• This requires an explicit message loop on the server:

while (true)

o3.wait();

• Not needed at the client! (We can hook into

the browser message loop there…)

HTTP ComponentHTTP Component

• Based on XMLHttpRequest API

• Example:

var http = o3.http();

http.onprogress = function(http) {

if (http.bytesReceived > 10000)

…

}

http.onreadystatechange = function(http) {

if (http.readystate == http.COMPLETED)

…

}

http.open(“GET”, “www.ajax.org”);

http.send();

XML ComponentXML Component

• Based on XML DOM API

• Example:

var xml = o3.xml();

var doc = xml.parseFromString(string);

var element = doc.documentElement;

for (var child = element.firstChild;

child != element.lastChild;

child = child.nextSibling)

…

FS ComponentFS Component

• Example:

var cwd = o3.cwd;

var file = cwd.get(“test.txt”);

file.onchange = function(file) {

file.copy(cwd.get(“test.bak”));

}

• We’re working on other components as well!

• IMAGE

• SOCKET

• JS

Putting it togetherPutting it together

• Wait for update from XMPP server (using HTTP)

• Parse XMPP data (using XML)

• Calculate traffic patterns (using trip generation)

• Notify server of changes (using HTTP)

Thank you!Thank you!