Millicomputing - Open Hardware by the milliWatt

Mobile Skype Video Calls via Fring on Nokia

2009-11-24T10:24:00.000-08:00

It was just a matter of time, now it will spread to other platforms...

http://www.engadget.com/2009/11/24/fring-adds-skype-video-support-on-s60-threatens-to-make-front-c/

ARM CPUs for power efficient Web Servers - James agrees...

2009-09-07T01:46:00.000-07:00

James Hamilton highlights the power efficiency of ARM for general purpose web servers. It's almost two years since I gave the first talk on Millicomputing at the HPTS Workshop (which is where I met James for the first time) so its great to see him talking up the principles. He also makes the important point that ARM uses error correcting (ECC) memory, while the Intel Atom doesn't, and thus the Atom is actually less suitable for configuring large numbers in low power enterprise server applications.

The systems at http://www.linux-arm.org/Main/LinuxArmOrg are relatively inefficient blades, they have archaic spinning rust storage attached which must dominate the power consumption. A flash based storage subsystem would make much more sense to me. Web content delivery workloads are very well suited to low cost read-mostly flash storage. They do have a 1.2GHz ARM CPU and 1.5GB of RAM per blade, which is the biggest and fastest ARM configuration I've seen so far.

Wireless HD Video at 60GHz

2009-09-03T22:54:00.000-07:00

GiGaOM has an update on wireless HD video It seems that the UWB standard stalled, but alternatives are on the way.

Windows Mobile fades to irrelevance...

2009-08-19T10:00:00.000-07:00

see this comment on GigaOM like I said almost two years ago....

Augmented reality for the iPhone

2009-08-06T07:19:00.000-07:00

from Metaio just a demo, but heading in an interesting direction...

TI Sees multi-core phones in 2011

2009-06-23T20:21:00.000-07:00

Like I said at Ignite #velocityconf yesterday - see ARM Cortex A9 - which is 4x the iPhone 3GS http://gigaom.com/2009/06/23/ti-sees-multicore-phones-coming-in-2011/

iPhone 3GS Graphics

2009-06-19T16:16:00.000-07:00

The new hardware is a huge leap forward, the 3GS is in Xbox territory according to Noel - details: http://www.mobileorchard.com/a-huge-leap-forward-graphics-on-the-iphone-3gs/ and RoughlyDrafted http://www.roughlydrafted.com/2009/06/10/a-closer-look-at-iphone-3g-s-cortex-a8-arm-and-powervr-chips/
My order is in :-)

Ignite talk at Velocity Conference

2009-06-17T16:37:00.000-07:00

I'm at the Velocity Conference next week in San Jose, Mon-Wed. On Monday evening there is an Ignite session where we get 5 minutes to talk about something using 20 slides that auto-advance every 15sec. I've been accepted to do an update on Millicomputing, so I have to figure out how to get a slide deck together. I'm going to look back at what I predicted in 2007 and 2008, see how accurate I was, and look forward a couple of years for what low power devices we should expect to have in our pockets and our datacenters in 2010 and 2011.

Qualcomm Snapdragon - 1.3GHz Arm Cortex A8

2009-06-01T07:14:00.000-07:00

The performance of ARM architecture chips continues to increase, this announcement bumps the clock rate up to 1.3GHz and has a long list of integrated features.

The new chipset supports multi-mode UMTS and CDMA 3G connectivity in the same 15 x 15-mm package as well as featuring enhanced 2D acceleration and 3D graphics core, integrated GPS, high-def video recording and playback, Bluetooth 2.1, WiFi, and support for WXGA (1280x800 pixels) displays pumping out your choice of MediaFLO, DVBH, or ISDB-T digital mobile television.

Wireless broadband speeds in practice

2009-05-26T11:35:00.000-07:00

Useful table of standards and speeds via GigaOM

Spacial audio

2009-05-11T07:05:00.000-07:00

Another example of an idea I mentioned in my Millicomputing talk turning up at NTT. This is something that could be programmed on an iPhone using OpenAL I think. It's really the idea of using stereo sound to carry conversations, which depends upon people using stereo headsets. I think there needs to be additional value in the headset such as video capture of what I'm looking at, and into-eye video display like the MyVue, then spacial audio is an add-on not the main feature.

Renesas Low power HD Video processor

2009-05-06T06:51:00.000-07:00

Sighted at engadget mobile, where they think it could turn up in mobile devices that do both input and output of HD video at 1080p, 30fps

Andy Bechtolsheim on the Solid State Storage Revolution

2009-05-05T22:35:00.000-07:00

At the MySQL conference Andy gives a talk that is up on YouTube.

He gives a good overview of the hardware changes, but doesn't talk about the software challenges, where many of the assumptions and algorithms that are built into all the common operating systems, filesystems and databases are simply wrong. There is a lot of work to be done here. My own work at Sun involved several attempts to point this problem out over the years, and if I had done a better job of getting traction for my ideas, there would be a lot more preparation and research in this area by now. The specific examples include trying to explain the benefits of embedding NVRAM products into servers during the 1990's, and doing extensive testing with solid state disks around 2002. The current size and cost benefits that we see were very predictable, and so are the problems. The SSD's at the time were very expensive, but they were perfectly capable of supporting research and development of new algorithms, and an opportunity was missed.

The next thing that is coming is non-volatile RAM (all the RAM in the system), in case anyone is listening. There need to be fundamental changes in operating systems (user level memory protection models etc.) and we then have the ability to build truly diskless database servers, with safely persistent in-memory databases, in user space, no device drivers.

Wireless Video standards war

2009-04-29T07:56:00.000-07:00

A bunch of references from GigaOM - it looks as if UltraWideBand 480Mbit USB is in trouble, and the alternatives are a dedicated Wireless HD video standard and Wifi based video streaming. UWB has some nice characteristics, but perhaps the ubiquity of WiFi wins again.... (There have been many cases over the years of technologies losing to Ethernet and IP based networks in the end).

http://gigaom.com/2008/10/31/ultra-wideband-near-death-as-wiquest-shuts-down/

http://gigaom.com/2008/04/09/wireless-hd-is-the-new-front-in-a-standards-war/

http://gigaom.com/2008/08/15/vcs-hope-to-see-wi-fi-everywhere/

I just want to be able to stream video from my iPhone to my TV set without any wires, don't care what the technology is, and I'm thinking of getting a WiFi enabled TV with Netflix embedded in it around the end of this year.

MIT Medialab's Sixth Sense

2009-04-20T22:54:00.000-07:00

This is exactly the kind of user interface development that I've been looking forward to as part of my Millicomputing meme. I hope it inspires some products soon...

iPhone 3.0 hardware interface implications

2009-03-26T22:41:00.000-07:00

An insightful posting by Daniel Eran on the iPhone 3.0 hardware interface controller, and its significance.

All I would like to add is that I really hope wideband/wireless USB is a feature of the next iPhone hardware. 480Mbits/s without any wires, and with wireless video output, so your pocket can drive your projector sunglasses, TV, meeting room projector or computer screen without even leaving your pocket.

Intel licenses Atom to TSMC

2009-03-02T21:20:00.000-08:00

Intel licenses low power Atom CPU design to TSMC. This is another step along the road of bringing the Intel x64 architecture down into low power embedded devices to compete with ARM.

TI OMAP4 is based on ARM Cortex A9

2009-02-16T10:19:00.000-08:00

Nice summary on GigaOM about the new chip just launched by TI.

This continues along the direction I outlined two years ago, high def video and graphics processing, very long battery life, high speed networking and lots of CPU capacity in a multicore chip, sampling soon, and in products in 2010.

Extended iPhone cookbook XML parser

2009-01-04T23:59:00.000-08:00

Erica Sadun published a tree based XML parser for the iPhone that works quite well. I needed to extend it to parse attributes and I posted my code back to Erica's google code forum. This works quite efficiently, my app parses complex XML for 100 movies in less than a second as it picks out the instant format ones.

Parsing API Results - XML vs. JSON

2008-10-29T08:56:00.000-07:00

There is an option to get JSON format or XML format back from the API. I'm investigating ways to parse JSON to see if its easier than XML (simply add output=json to the URL call).

My open source google code efforts are on hold for now since I have much more demand for new features in my app than people asking for source code. Let me know if you want code and I will assist on a case by case basis. Later on I will post cleaned up code to the google code project.

Netflix API - Parsing the results of an API call - Part 5

2008-10-10T22:52:00.000-07:00

One of the first API calls I needed to call gets the user's name and other information. In my case all I need is the first and last names, and the flag that says whether the user can use instant watching. This flag is set true for main accounts, and false for account profiles that don't have an instant queue.

The return data from the API call is in XML format, so this code shows how to use the XML parser to pick information out of the data returned from an API call. I provide a convenience method that combines the first and last names, and I didn't need the other link information, so it is ignored, but the code could easily be extended to pick it out as needed.

Some of the code below doesn't display properly. I'm going to set it up in google code soon to make it easier to manage.


//
//  NetflixUser.h
//  Instant Flix
//
//  Created by Adrian Cockcroft on 10/8/08.
//  Copyright 2008 millicomputing.com
// Licenced using Creative Commons Attribution Share-Alike
//  http://creativecommons.org/licenses/by-sa/3.0/

#import 


@interface NetflixUser : NSObject {
NSData  *rawData;
NSString *first_name;
NSString *last_name;
bool  can_instant_watch;
NSXMLParser *userParser;
NSString *currentElement;
}

@property(readonly) bool can_instant_watch;

- (NetflixUser *)initWithAPIResponse:(NSData *)response;
- (NSString *)name;

@end


//
//  NetflixUser.m
//  Instant Flix
//
//  Created by Adrian Cockcroft on 10/8/08.
//  Copyright 2008 millicomputing.com
// Licenced using Creative Commons Attribution Share-Alike
//  http://creativecommons.org/licenses/by-sa/3.0/

#import "NetflixUser.h"

/* Sample returned raw data

[userid]
Adrian
Cockcroft
true













*/

@implementation NetflixUser

@synthesize can_instant_watch;

- (NetflixUser *)initWithAPIResponse:(NSData *)response {
rawData = response;
[rawData retain];
first_name = nil;
last_name = nil;
can_instant_watch = NO;

//NSString *responseBody = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
//NSLog(@"NetflixUser: %@", responseBody);

userParser = [[NSXMLParser alloc] initWithData:rawData];

  // Set self as the delegate of the parser so that it will receive the parser delegate methods callbacks.
  [userParser setDelegate:self];
  [userParser setShouldProcessNamespaces:NO];
  [userParser setShouldReportNamespacePrefixes:NO];
  [userParser setShouldResolveExternalEntities:NO];
  [userParser parse];

return self;
}

- (NSString *)name {
return [first_name stringByAppendingFormat:@" %@", last_name];
}

- (void)parserDidStartDocument:(NSXMLParser *)parser{
//NSLog(@"started parsing");
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
NSString * errorString = [NSString stringWithFormat:@"Unable to parse XML (Error code %i)", [parseError code]];
NSLog(@"error: %@", errorString);
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{  
  //NSLog(@"found this element: %@", elementName);
currentElement = [elementName copy];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{   
//NSLog(@"ended element: %@", elementName);
currentElement = nil;
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
//NSLog(@"found characters: %@", string);
// save the characters for the current item...
if ([currentElement isEqualToString:@"first_name"]) {
 first_name = [string copy];
} else if ([currentElement isEqualToString:@"last_name"]) {
 last_name = [string copy];
} else if ([currentElement isEqualToString:@"can_instant_watch"]) {
 if ([string isEqualToString:@"true"]) {
  can_instant_watch = YES;
 } else {
  can_instant_watch = NO;
 }
}
}

- (void)parserDidEndDocument:(NSXMLParser *)parser {
//NSLog(@"found %@ who %@ instant watch", self.name, (can_instant_watch? @"can": @"cannot"));
}

@end

Netflix API - Netflix Specific OAuth iPhone Code - Part 4

2008-10-01T00:09:00.000-07:00

I have already discussed how to get OAuth to build for an iPhone in Part 2. To use OAuth to call Netflix there are two small changes needed. The first one is that the way that characters are escaped in URLs needs to be tightened up a bit, otherwise the signature strings will work some of the time and fail when they happen to contain the wrong character sequence. This took a while to figure out...

The file NSString+URLEncoding.m needs to have a few characters (space, plus and asterisk) added as shown below:

Note, I'm having a hard time getting code to look good here, its hard to find a way to render code in a narrow column that doesn't mess up the formatting and works in more than one browser using blogger.com tools and templates.


- (NSString *)encodedURLString {
NSString *result = (NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                             (CFStringRef)self,
                                             NULL,
                                             CFSTR("?=& +*"),     // legal URL characters to be escaped
                                             kCFStringEncodingUTF8); // encoding
return result;
}

- (NSString *)encodedURLParameterString {
   NSString *result = (NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                             (CFStringRef)self,
                                             NULL,
                                             CFSTR(":/= +*"),
                                             kCFStringEncodingUTF8);
return result;
}

The second thing is that when the authentication is complete, Netflix returns a token that contains an encoded user identifier, as well as a secret and a key. The standard OAuth code only expects the secret and key, so a new NetflixToken class was created to hold the extra information, and to persist it in the iPhone's defaults store along with the secret and key. This means that once the user has signed into OAuth once, this information is saved and they never have to sign in again unless either Netflix or the User revokes the token. One more method was added to remove an entry from the defaults store, for use during logout.

First the NetflixToken.h header file:


//
//  NetflixToken.h
//  Instant Test
//
//  Created by Adrian Cockcroft on 9/11/08.
//

#import 
#import "OAToken.h"

@interface NetflixToken : NSObject {
@protected
 NSString *key;
 NSString *secret;
 NSString *user;
}
@property(copy, readwrite) NSString *key;
@property(copy, readwrite) NSString *secret;
@property(copy, readwrite) NSString *user;

- (id)initWithKey:(NSString *)aKey secret:(NSString *)aSecret user:(NSString *)aUser;
- (id)initWithUserDefaultsUsingServiceProviderName:(NSString *)provider prefix:(NSString *)prefix;
- (id)initWithHTTPResponseBody:(NSString *)body;
- (int)storeInUserDefaultsWithServiceProviderName:(NSString *)provider prefix:(NSString *)prefix;
- (int)removeFromUserDefaultsWithServiceProviderName:(NSString *)provider prefix:(NSString *)prefix;
- (OAToken *)oaToken;

@end

Then the code itself, this is all based on a simple extension of OAToken, which is part of the OAuth code base mentioned in part 2.


//
//  NetflixToken.m
//  Instant Test
//
//  Created by Adrian Cockcroft on 9/11/08.
//

#import "NetflixToken.h"

@implementation NetflixToken

@synthesize key, secret, user;

#pragma mark init

- (id)init {
    [super init];
    self.key = @"";
    self.secret = @"";
 self.user = @"";
    return self;
}

- (id)initWithKey:(NSString *)aKey secret:(NSString *)aSecret user:(NSString *)aUser {
 [super init];
 self.key = aKey;
 self.secret = aSecret;
 self.user = aUser;
 return self;
}

- (OAToken *)oaToken {
 return [[OAToken alloc] initWithKey:self.key secret:self.secret];
}

- (id)initWithHTTPResponseBody:(NSString *)body {
    [super init];
    NSArray *pairs = [body componentsSeparatedByString:@"&"];
    
    for (NSString *pair in pairs) {
        NSArray *elements = [pair componentsSeparatedByString:@"="];
        if ([[elements objectAtIndex:0] isEqualToString:@"oauth_token"]) {
            self.key = [elements objectAtIndex:1];
        } else if ([[elements objectAtIndex:0] isEqualToString:@"oauth_token_secret"]) {
            self.secret = [elements objectAtIndex:1];
        } else if ([[elements objectAtIndex:0] isEqualToString:@"user_id"]) {
   self.user = [elements objectAtIndex:1];
  }
 }
    
    return self;
}


- (id)initWithUserDefaultsUsingServiceProviderName:(NSString *)provider prefix:(NSString *)prefix
{
 [super init];
 NSString *theKey = [[NSUserDefaults standardUserDefaults] stringForKey:[NSString stringWithFormat:@"OAUTH_%@_%@_KEY", prefix, provider]];
 NSString *theSecret = [[NSUserDefaults standardUserDefaults] stringForKey:[NSString stringWithFormat:@"OAUTH_%@_%@_SECRET", prefix, provider]];
 NSString *theUser = [[NSUserDefaults standardUserDefaults] stringForKey:[NSString stringWithFormat:@"NETFLIX_%@_%@_USER", prefix, provider]];
 if (theKey == NULL || theSecret == NULL)
  return(nil);
 self.key = theKey;
 self.secret = theSecret;
 self.user = theUser;
 return(self);
}


- (int)storeInUserDefaultsWithServiceProviderName:(NSString *)provider prefix:(NSString *)prefix
{
 [[NSUserDefaults standardUserDefaults] setObject:self.key forKey:[NSString stringWithFormat:@"OAUTH_%@_%@_KEY", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] setObject:self.secret forKey:[NSString stringWithFormat:@"OAUTH_%@_%@_SECRET", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] setObject:self.user forKey:[NSString stringWithFormat:@"NETFLIX_%@_%@_USER", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] synchronize];
 return(0);
}

- (int)removeFromUserDefaultsWithServiceProviderName:(NSString *)provider prefix:(NSString *)prefix
{
 [[NSUserDefaults standardUserDefaults] removeObjectForKey:[NSString stringWithFormat:@"OAUTH_%@_%@_KEY", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] removeObjectForKey:[NSString stringWithFormat:@"OAUTH_%@_%@_SECRET", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] removeObjectForKey:[NSString stringWithFormat:@"NETFLIX_%@_%@_USER", prefix, provider]];
 [[NSUserDefaults standardUserDefaults] synchronize];
 return(0);
}
@end

Netflix API - Announcement - Part 3

2008-10-01T00:03:00.000-07:00

Here is the official announcement of the API and how to get access to it.

Starting Wednesday, Oct. 1 the Netflix API is open to all:

The Netflix API:

- Allows access to data for 100,000 movie and TV episode titles on DVD as well as Netflix account access on a user’s behalf
Netflix has more than 2 billion ratings in its database
Netflix members rate more than 2 million movies a day
Netflix ships more than 2 million DVDs on a typical day

- Is free

- Allows commercial use
E.g. if a developer creates an iPhone app and wants to sell it for $0.99, that’s ok

Technically, the Netflix API:

- Includes a REST API, a Javascript API, and ATOM feeds

- Uses OAuth standard security to allow the subscriber to control which applications can access the service on his or her behalf

Developers can get access:

- Starting 10/1

- By self sign up at http://developer.netflix.com

Netflix API - Getting OAuth to work on iPhone - part 2: Adding the OAuth Code

2008-09-17T23:23:00.000-07:00

To start with I found some examples by Nick Dalton that helped me build a simple application that included a Web View, a screen that acts like a web browser but with my custom Objective-C code embedded in it. This is important, because the OAuth sign-in process uses a web page, but on the iPhone, if you spawn a copy of Safari to visit a web page, your application quits first.

Next the Source Code Manager in Xcode was configured to load the OAuthconsumer Objective-C framework via subversion. This was easy and obvious, enter the URL http://oauth.googlecode.com/svn/code/obj-c/ and checkout the code.

When trying to import the framework I discovered that Apple does not allow user specified binary frameworks to be added to iPhone applications. To work around this the source code was copied from the Xcode project for the framework, to the Xcode project for my Instant Test application. I renamed the framework Classes folder as OAuth and copied to my project via drag and drop, choosing to copy the underlying files. The Cocoa Categories, Protocols and Other Sources>Crypto folder were also copied. The Tests folder did not compile for iPhone so don't bother to copy it over.

The standard system Security.Framework doesn't need to be added to the Frameworks folder. I initially thought it did, but its probably only needed for the KeyChain code.

The iPhone doesn't support the KeyChain functionality, so if you try to build for iPhone it will fail. It does however build for the iPhone Simulator, which is confusing. Open up the OAuth source code, and delete the last two files OAToken_KeychainExtensions.h and OAToken_KeychainExtensions.m.

Since the code is no longer a framework, the header file references need to be changed from #include to #include "file" for all the includes in OAuthConsumer.h apart from the first Foundation one.

At this point, before you try and call anything, try a build, it should compile with no errors. If it doesn't, look for missing files.

At this point, you should have all you need to connect to an OAuth service

Netflix API Getting OAuth to work on iPhone - Instant Queue Add part 1: why?

2008-09-16T22:23:00.000-07:00

Why develop an iPhone app? Its "the future", a useful skill, and I can carry whatever I develop in my pocket and make it do whatever I want.

I work at Netflix, and I have instant watching on my TV, I built an application "Instant Queue Add" that lets me add a title to my instant queue using my iPhone in a couple of touches. It takes the Top20 and New Choices RSS feeds to find content, and it spawns a copy of Safari to add to instant queue for each pick. The first time it starts, you have to login, then it remembers the Netflix cookie. However I really want to add more features and avoid spawning a copy of Safari with a screen scraped URL.

The Netflix API uses a new standard called OAuth for Open Authentication. There are lots of features, but its complex, and there is no standard off the shelf library for OAuth on the iPhone. However it is a useful building block for more advanced applications.

In this series of posts, I will document the steps I'm making to get OAuth to work on the iPhone using Objective-C and Xcode. My starting point is this code base and tutorial by Jon R. Crosby, which is based on desktop MacOS X, and doesn't directly support the iPhone.