Portable Music Player FAIL
Submitted by: Unknown
Sep 14, 2011 3:18 PM
Chuck Norris And Jean Claude Van Damme Confirmed By Stallone Himself To Be In EXPENDABLES 2!
Tue, 13 Sep 2011 19:22:15 PM CDT
Sep 12, 2011 2:57 PM
In Study, Fatherhood Leads to Drop in Testosterone
The study suggests that men’s bodies evolved hormonal systems that helped them commit to their families.
Sep 11, 2011 7:20 AM
Crazy Monster says “Why are you still at work?”
Crazy Monster says “Why are you still at work?”
Sep 15, 2011 9:40 PM
Miguel de Icaza: WinRT demystified
Windows 8 as introduced at Build is an exciting release as it has important updates to how Microsoft envisions users will interact with their computers, to a fresh new user interface to a new programming model and a lot more.
If you build software for end-users, you should watch Jensen Harris discuss the Metro principles in Windows 8. I find myself wanting to spend time using Windows 8.
But the purpose of this post is to share what I learned at the conference specifically about WinRT and .NET.
To do this, they have created a third implementation of the XAML-based UI system. Unlike WPF which was exposed only to the .NET world and Silverlight which was only exposed to the browser, this new implementation is available to C++ developers, HTML/Javascript developers and also .NET developers.
.NET developers are very familiar with P/Invoke and COM Interop. Those are two technologies that allow a .NET developer to consume an external component, for example, this is how you would use the libc "system (const char *)" API from C#:
COM Interop allows using C or C++ APIs directly from C# by importing the COM type libraries and having the runtime provide the necessary glue. This is how Mono talked with OpenOffice (which is based on COM), or how Mono talks to VirtualBox (which has an XPCOM based API).
There are many ways of creating bindings for a native library, but doing it by hand is bound to be both tedious and error prone. So everyone has adopted some form of "contract" that states what the API is, and the binding author uses this contract to create their language binding.
If you author a component in C++ or a .NET language, its API will be stored in a WinMD file and you will be able to consume it from all three environments (Native, JavaScript and .NET). Even in C++ you are not exposed to COM. The use of COM is hidden behind the C++ projection tools. You use what looks and feels like a C++ object oriented API.
To support the various constructs of WinRT, the underlying platform defines a basic set of types and their mappings to various environment. In particular, collection objects in WinRT are mapped to constructs that are native to each environment.
With WinRT, Microsoft has followed a simple rule: if an API is expected to take more than 50 milliseconds to run, the API is asynchronous.
The idea of course is to ensure that every Metro application is designed to always respond to user input and to not hang, block or provide a poor user experience.
Async programming has historically been a cumbersome process as callbacks and state must be cascaded over dozens of places and error handling (usually poor error handling) is sprinkled across multiple layers of code.
To simplify this process, C# and VB have been extended to support the F#-inspired await/async pattern, turning async programming into a joy. C++ got a setup that is as good as you can get with C++ lambdas and Javascript uses promises and "then ()".
When you use C# and VB, you are using the full .NET framework. But they have chosen to expose a smaller subset of the API to developers to push the new vision for Windows 8.
And this new vision includes safety/sandboxed systems and asynchronous programming. This is why you do not get direct file system access or socket access and why synchronous APIs that you were used to consuming are not exposed.
Now, you notice that I said "exposed" and not "gone".
What they did was that they only exposed to the compiler a set of APIs when you target the Metro profile. So your application will not accidentally call File.Create for example. At runtime though, the CLR will load the full class library, the very one that contains File.Create, so internally, the CLR could call something like File.Create, it is just you that will have no access to it.
This split is similar to what has been done in the past with Silverlight, where not every API was exposed, and where mscorlib was given rights that your application did not have to ensure the system safety.
You might be thinking that you can use some trick (referencing the GAC library instead of the compiler reference or using reflection to get to private APIs, or P/Invoking into Win32). But all of those uses will be caught by AppStore review application and you wont be able to publish your app through Microsoft's store.
You can still do whatever ugly hack you please on your system. It just wont be possible to publish that through the AppStore.
Finally, the .NET team has taken this opportunity to do some spring cleaning. mscorlib.dll and System.dll have been split in various libraries and they have moved some types around.
In the .NET case, creating a WinRT component has been drastically simplified. The following is the full source code for a component that adds 2:
There are also some limitations, you can not have private fields on structures, and there is not Task<T> for asynchronous APIs, instead you use the IAsyncOperation interface. Update to clarify: the no private fields rule is only limited to structs exposed to WinRT, and it does not apply to classes.
To make it easy for HTML apps to adhere to the Metro UI style and interaction model, Microsoft distributes Javascript and CSS files that you can consume from your project. Notice that this wont work on the public web. As soon as you use any WinRT APIs, your application is a Windows app, and wont run in a standalone web browser.
.NET and C++ developers get to use XAML instead.
There is clearly a gap to be filled in the story. It should be possible to use Microsoft's Razor formatting engine to style applications using HTML/CSS while using C#. Specially since they have shown the CLR running on their HTML/JS Metro engine.
Right now HTML and CSS is limited to the Javascript use.
If you build software for end-users, you should watch Jensen Harris discuss the Metro principles in Windows 8. I find myself wanting to spend time using Windows 8.
But the purpose of this post is to share what I learned at the conference specifically about WinRT and .NET.
The Basics
Microsoft is using the launch of Windows 8 as an opportunity to fix long-standing problems with Windows, bring a new user interface, and enable a safe AppStore model for Windows.To do this, they have created a third implementation of the XAML-based UI system. Unlike WPF which was exposed only to the .NET world and Silverlight which was only exposed to the browser, this new implementation is available to C++ developers, HTML/Javascript developers and also .NET developers.
.NET developers are very familiar with P/Invoke and COM Interop. Those are two technologies that allow a .NET developer to consume an external component, for example, this is how you would use the libc "system (const char *)" API from C#:
[DllImport ("libc")]
void system (string command);
[...]
system ("ls -l /");
We have used P/Invoke extensively in the Mono world to create bindings to native libraries. Gtk# binds the Gtk+ API, MonoMac binds the Cocoa API, Qyoto binds the Qt API and hundred other bindings wrap other libraries that are exposed to C# as object-oriented libraries. COM Interop allows using C or C++ APIs directly from C# by importing the COM type libraries and having the runtime provide the necessary glue. This is how Mono talked with OpenOffice (which is based on COM), or how Mono talks to VirtualBox (which has an XPCOM based API).
There are many ways of creating bindings for a native library, but doing it by hand is bound to be both tedious and error prone. So everyone has adopted some form of "contract" that states what the API is, and the binding author uses this contract to create their language binding.
WinRT
WinRT is a new set of APIs that have the following properties:- It implements the new Metro look.
- Has a simple UI programming model for Windows developers (You do not need to learn Win32, what an HDC, WndProc or LPARAM is).
- It exposes the WPF/Silverlight XAML UI model to developers.
- The APIs are all designed to be asynchronous.
- It is a sandboxed API, designed for creating self-contained, AppStore-ready applications. You wont get everything you want to create for example Backup Software or Hard Disk Partitioning software.
- The API definitions is exposed in the ECMA 335 metadata format (the same one that .NET uses, you can find those as ".winmd" files).
WinRT Projections
What we call "bindings" Microsoft now calls "projections". Projections are the process of exposing APIs to three environments: Native (C and C++), HTML/Javascript and .NET.To support the various constructs of WinRT, the underlying platform defines a basic set of types and their mappings to various environment. In particular, collection objects in WinRT are mapped to constructs that are native to each environment.
Asynchronous APIs
Microsoft feels that when a developer is given the choice of a synchronous and an asynchronous API, developers will choose the simplicity of a synchronous API. The result usually works fine on the developer system, but is terrible when used in the wild.With WinRT, Microsoft has followed a simple rule: if an API is expected to take more than 50 milliseconds to run, the API is asynchronous.
The idea of course is to ensure that every Metro application is designed to always respond to user input and to not hang, block or provide a poor user experience.
Async programming has historically been a cumbersome process as callbacks and state must be cascaded over dozens of places and error handling (usually poor error handling) is sprinkled across multiple layers of code.
To simplify this process, C# and VB have been extended to support the F#-inspired await/async pattern, turning async programming into a joy. C++ got a setup that is as good as you can get with C++ lambdas and Javascript uses promises and "then ()".
Is it .NET or Not?
Some developers are confused as to whether .NET is there or not in the first place, as not all of the .NET APIs are present (File I/O, Sockets), many were moved and others were introduced to integrate with WinRT.When you use C# and VB, you are using the full .NET framework. But they have chosen to expose a smaller subset of the API to developers to push the new vision for Windows 8.
And this new vision includes safety/sandboxed systems and asynchronous programming. This is why you do not get direct file system access or socket access and why synchronous APIs that you were used to consuming are not exposed.
Now, you notice that I said "exposed" and not "gone".
What they did was that they only exposed to the compiler a set of APIs when you target the Metro profile. So your application will not accidentally call File.Create for example. At runtime though, the CLR will load the full class library, the very one that contains File.Create, so internally, the CLR could call something like File.Create, it is just you that will have no access to it.
This split is similar to what has been done in the past with Silverlight, where not every API was exposed, and where mscorlib was given rights that your application did not have to ensure the system safety.
You might be thinking that you can use some trick (referencing the GAC library instead of the compiler reference or using reflection to get to private APIs, or P/Invoking into Win32). But all of those uses will be caught by AppStore review application and you wont be able to publish your app through Microsoft's store.
You can still do whatever ugly hack you please on your system. It just wont be possible to publish that through the AppStore.
Finally, the .NET team has taken this opportunity to do some spring cleaning. mscorlib.dll and System.dll have been split in various libraries and they have moved some types around.
Creating WinRT Components
Microsoft demoed creating new WinRT components on both C++ and .NET.In the .NET case, creating a WinRT component has been drastically simplified. The following is the full source code for a component that adds 2:
public sealed class AddTwo {
public int Add (int a, int b)
{
return a + b;
}
public async IAsyncOperation SubAsync (int a, int b)
{
return a - await (CountEveryBitByHand (b));
}
}
You will notice that there are no COM declarations of any kind. The only restriction is that your class must be sealed (unless you are creating a XAML UI component, in that case the restriction is lifted). There are also some limitations, you can not have private fields on structures, and there is not Task<T> for asynchronous APIs, instead you use the IAsyncOperation interface. Update to clarify: the no private fields rule is only limited to structs exposed to WinRT, and it does not apply to classes.
UI Programming
When it comes to your UI selection, you can either use HTML with CSS to style your app or you can use XAML UI.To make it easy for HTML apps to adhere to the Metro UI style and interaction model, Microsoft distributes Javascript and CSS files that you can consume from your project. Notice that this wont work on the public web. As soon as you use any WinRT APIs, your application is a Windows app, and wont run in a standalone web browser.
.NET and C++ developers get to use XAML instead.
There is clearly a gap to be filled in the story. It should be possible to use Microsoft's Razor formatting engine to style applications using HTML/CSS while using C#. Specially since they have shown the CLR running on their HTML/JS Metro engine.
Right now HTML and CSS is limited to the Javascript use.
In Short
Microsoft has created a cool new UI library called WinRT and they have made it easy to consume from .NET, Javascript and C++ and if you adhere by their guidelines, they will publish the app on their appstore.Xamarin at BUILD
If you are at build, come join us tonight at 6:30 at the Sheraton Park hotel, just after Meet the Experts. Come talk about Mono, Xamarin, MonoTouch, MonoDroid and MonoMac and discuss the finer points of this blog over an open bar.Comments
There is a long list of comments in the moderation queue that are not directly related to WinRT, or bigger questions that are not directly related to WinRT, .NET and this post's topic, so I wont be approving those comments to keep things on focus. There are better forums to have discussions on Metro.Sep 9, 2011 1:31 PM
*that* guy
Call me crazy, but I kind of want to track down this David Thorne guy and force him to be my friend. More amazing complaints found here.
Sep 9, 2011 11:00 PM
Monthly Measure Calendar and Ruler by Sebastian Bergne
Sebastian Bergne has created a monthly universal calendar that's also a ruler.
Sep 13, 2011 3:49 AM
SolarCity to Launch Largest Residential Rooftop Project
SolarCityThe company reports it has received funding from two major investment banks – U.S. Renewables Group and Bank of America – plus a loan guarantee from the Department of Energy. SolarCity recently received $280 million investment from Google. With this infusion of capital, the company plans to install 160,000 solar photovoltaic systems on houses and other buildings on military bases around the country in the next five years.
“This is the largest domestic residential rooftop solar project in history,” Energy Secretary Steven Chu said in a statement announcing the deal. “It can also be a model for other large-scale rooftop solar projects that help America regain its lead in the solar industry.”
Since it was founded in 2006, the company has installed 16,000 rooftop units. “This is a massive kick of momentum for the company,” said Lyndon Rive, SolarCity’s founder and CEO in a company press announcement.
In the wake of recent DOE loan failures to large solar companies like Solyndra, which filed for bankruptcy last week, Rive stresses that this deal is nearly risk-free for the lenders and government, with SolarCity putting up its own money for the panels and only getting reimbursed by its lenders after each project is complete.
Renewable Energy World reports that SolarCity owns, operates and maintains the systems, and sells the electricity to the end-user. In working with investment banks to pool together often-complicated state and federal incentives, the company streamlines the process and simply offers the customer solar electricity — often at prices lower than current electric rates.
SolarCity says it will try to employ American veterans and family members for the 750 people needed to complete the project, showing that green jobs do indeed exist. The company has seen extraordinary growth in recent years. After starting in 2006 with just two people, SolarCity has added over 600 employees since 2006.
PHOTO: SolarCity
Sep 14, 2011 1:47 PM
New instrument alert: Björk's gameleste
Popout
On the occasion of Biophilia, her new album and multimedia performance project, Björk has commissioned several new instruments, including one known as the gameleste. Incorporating gamelan-like bronze bars in a celeste housing, the gameleste is the work of the British percussionist Matt Nolan and the Icelandic organ craftsman Björgvin Tómasson. Nolan has a video about the making of the instrument; "Crystalline," one of two gameleste songs on the album, can be heard here, in a video by Michel Gondry. I've only just begun to explore the complex universe of Biophilia, which Björk first described to me a couple of years ago, at a Shun Lee dinner before Des Canyons aux étoiles at Alice Tully Hall. The concept is all but impossible to sum up briefly: it embraces not only live shows and an album (due from Nonesuch on Oct. 11) but also a documentary, iPad apps, instrument construction, and educational workshops, all exploring "relationships between musical structures and natural phenomena." Björk discusses the project in a long interview with Brandon Stosuy for Stereogum. The music I've heard so far is mesmerizing, and the ageless melody of "Virus" strikes me as one of the most gorgeous inventions of Björk's career.
On the occasion of Biophilia, her new album and multimedia performance project, Björk has commissioned several new instruments, including one known as the gameleste. Incorporating gamelan-like bronze bars in a celeste housing, the gameleste is the work of the British percussionist Matt Nolan and the Icelandic organ craftsman Björgvin Tómasson. Nolan has a video about the making of the instrument; "Crystalline," one of two gameleste songs on the album, can be heard here, in a video by Michel Gondry. I've only just begun to explore the complex universe of Biophilia, which Björk first described to me a couple of years ago, at a Shun Lee dinner before Des Canyons aux étoiles at Alice Tully Hall. The concept is all but impossible to sum up briefly: it embraces not only live shows and an album (due from Nonesuch on Oct. 11) but also a documentary, iPad apps, instrument construction, and educational workshops, all exploring "relationships between musical structures and natural phenomena." Björk discusses the project in a long interview with Brandon Stosuy for Stereogum. The music I've heard so far is mesmerizing, and the ageless melody of "Virus" strikes me as one of the most gorgeous inventions of Björk's career.
Sep 13, 2011 7:23 AM
Point Break Remake Announced
Alcon Entertainment has announced plans to remake the 1991 Kathryn Bigelow action thriller Point Break . Full details of the project (which is said to be fast-tracked for release through Warner Bros.) are detailed in the below press release: Alcon principals Andrew Kosove and Broderick Johnson secured rights to the project the week of the original film’s 20th anniversary from RGM Media, John McMurrick and Chris Taylor. Kosove and Johnson will produce along with Michael DeLuca, John Baldecchi, Chris Taylor and Kurt Wimmer (“Salt,” “Law Abiding Citizen,” upcoming “Total Recall”), who also wrote the screenplay. RGM Media principal Devesh Chetty and investor John McMurrick, Chairman of Marloss Entertainment, will serve as Executive Producers. The film is being fast tracked, with...
Sep 9, 2011 4:07 PM
Quote of the Day
In reaction to last night’s debate between the Republican Presidential hopefuls:
Listening to GOP Presidential candidates talk about science is like listening to children talk about sex: They know it exists, they have strong opinions about what it might mean, but they don’t have a clue what it’s actually about.(via The Daily Dish)
Sep 9, 2011 6:17 PM
Pointy-haired bosses & SQL
Not my usual type of blog post but I couldn't resist sharing this! Thanks to Scott Barrett.
(Hopefully that doesn't instantly remind you of your boss!!)
(Hopefully that doesn't instantly remind you of your boss!!)
Sep 14, 2011 9:22 AM
Miami Heat By Heart: Reflections on Family, Faith, and F**king Glen Rice
I don’t like quoting The National Enquirer as a reputable source, but when a story like this breaks you have to share it with everyone you know — according to the Enquirer, Joe McGinniss’ upcoming book Rogue: Searching for the Real Sarah Palin features claims and confirmation that the former governer and Vice Presidential nominee hooked up with three-time NBA All-Star Glen Rice circa 1987, when he was still in college and she was an Alaskan sports reporter. Glen Rice had sex with Sarah Palin. That is today’s actual sports news.
From the story:
In the book, which will be published on September 20th, McGinniss claims Sarah had a steamy interracial hookup with basketball stud Glen Rice less than a year before she eloped with her husband Todd.I don’t even know what that means.
Sarah hooked up with the NBA great, then a 6-foot-8 junior at the University of Michigan when he was playing in a college basketball tournament in Alaska in 1987, the book says. At the time, Sarah, just out of college, was working as a sports reporter for the Anchorage TV station KTUU.
A publishing source told The ENQUIRER that McGinniss claims Sarah had a “fetish” for black men at the time and he quotes a friend as saying Sarah had “hauled (Rice’s) ass down.”
I guess the premarital sex is sacred unless you’ve got a chance to hook up with a basketball player. And despite a “fetish for black men at the time” (good job seeing black people as people and not things, Presidential Hopeful), Palin ended up marrying the whitest guy on the planet, and none of her brain damaged kids — and I’m talking about Bristol here, don’t get me wrong — get to paternally claim the stars of NBA Jam. Does Rony Seikaly know about any of this?
In case you’re ready to believe Sarah Palin when she goes on TV later and claims the story is an “out and out fabrication” perpetrated by some portmanteau word combining “media”, “liberal” and “spend-o-crat”, don’t … at least one of the people snuggling in that sleeping bag on a cold, mooseless night in 1980s Alaska is confirming the rumor.
In the book, McGinniss quotes Rice as confirming the one-night stand.What’s next, are we gonna find out that Manute Bol nailed Michele Bachmann?
[h/t Deadspin]
Sep 12, 2011 11:56 AM
Scientists take first step towards creating 'inorganic life'
(PhysOrg.com) -- Scientists at the University of Glasgow say they have taken their first tentative steps towards creating 'life' from inorganic chemicals potentially defining the new area of 'inorganic biology'.
Sep 13, 2011 9:05 AM
SpongeBob Found to Impair Preschoolers' Thinking — Should You Be Worried?
Results of a new study suggest small children suffer negative short-term cognitive effects after watching the popular show.
Sep 14, 2011 2:37 PM
NYC Chooses Alta to Operate Bike-Share System With 10,000 Bikes
New York City has selected Alta Bike Share to run its public bike-share system, under an arrangement that promises to make bicycling an integral new transit option for hundreds of thousands of New Yorkers. The Public Bike System Company, which supplies systems in London, Washington, Boston, and Montreal, will produce the bikes and kiosks.
The winning bid features the hallmarks of the world’s best bike-share systems — there will be many bikes and many stations, spaced closely together so that any kiosk is a short walk from the user’s destination.
Transportation Commissioner Janette Sadik-Khan, Deputy Mayor Howard Wolfson, and a group of elected officials are announcing the selection of the winner this afternoon, and we’ll have a report from the event later today. For now, here are the some key factoids:
Bike-share is going to change NYC’s streets. Stay tuned.
The winning bid features the hallmarks of the world’s best bike-share systems — there will be many bikes and many stations, spaced closely together so that any kiosk is a short walk from the user’s destination.
Transportation Commissioner Janette Sadik-Khan, Deputy Mayor Howard Wolfson, and a group of elected officials are announcing the selection of the winner this afternoon, and we’ll have a report from the event later today. For now, here are the some key factoids:
- Within the service area, which will stretch from the Upper West Side and Upper East Side to Bed Stuy and Greenpoint, New Yorkers will have access to 10,000 public bikes at about 600 stations.
- Annual memberships will cost under $100. Members will be able to make trips of up to 30 minutes at no charge.
- The stations will be sited with input from local communities, and the City Council will hold hearings on the program.
- The system must operate without public subsidy.
Bike-share is going to change NYC’s streets. Stay tuned.
Sep 18, 2011 6:42 PM
有朋友替共產黨的“GFW”另想了個中文名字：“共匪亡”。看來豬頭方搞的這項目真不是共匪的吉祥物。當初共匪自己替它選了個這樣的名字，真是天意。
有朋友替共產黨的“GFW”另想了個中文名字：“共匪亡”。看來豬頭方搞的這項目真不是共匪的吉祥物。當初共匪自己替它選了個這樣的名字，真是天意。
Sep 8, 2011 3:15 PM
My Little Pop Icons by Mari Kasurinen
My Little Princess Leia
I come from the generation of My Little Pony so when I saw these sculptures by Mari Kasurinen, I knew that those of you who were also 80s children would understand.
My Little Storm Trooper
My Little Lady Gaga (#2)
My Little Edward Scissorhands
My Little Batman
My Little Spock
My Little Ironman
See the entire collection here.
Share This: Twitter | Facebook | Discover more great design by following Design Milk on Twitter and Facebook.
© 2011 Design Milk | Posted by Jaime in Art | Permalink | No comments
Sep 14, 2011 10:47 PM
How We Connect Users
How We Connect Users
14 September 2011by Sarah Mei
Note: this is the first in a series of technical posts about Diaspora’s software architecture and code. If you have topics you’d like to see covered in future installments, please let us know.
A single installation of the Diaspora software is called a pod. The Diaspora distributed network is made up of hundreds of these pods, each with a set of users – sometimes just one on an individual pod, sometimes tens of thousands on a community pod. Each pod is run by a different person or organization. But no matter what pod you sign up on, you can connect with users on any other pod.
When you have friends on different pods, your stream seamlessly mixes updates from remote friends with updates from friends on your pod. In this way Diaspora is a distributed social network that resembles, from the user’s perspective, a centralized social network.
But how do these users find each other? In a centralized system, all servers access the same database, so when you search for a friend, there’s only one place to look. But in the Diaspora ecosystem, each pod has its own database, inaccessible to the other pods. So how does pod A figure out who’s on pod B, or for that matter, pod C that’s never been heard from before?
It all starts with searching. Let’s say you’re setting up your own pod. Once you’ve downloaded the Diaspora source and gotten it running on a server accessible to the internet, you open it up, log in…and are faced with the vast emptiness of splendid isolation.
Let’s get you some friends
There is no central server that keeps a list of existing pods or existing users. Instead, Diaspora depends on an emerging-standard protocol called webfinger to discover users on remote pods. This all kicks off when you search for someone’s Diaspora ID in your pod’s search box.Aside: A Diaspora ID is made up of a username, followed by an @ sign, followed by the pod url. It looks a lot like an email address. But just like with Jabber IDs which also look like email addresses, you can’t send email to it. It’s just a unique identifier within the Diaspora ecosystem.So you’ve talked to a friend who’s on a (fictional) pod called otherpod.com, and you’ve gotten her Diaspora ID – sarah@otherpod.com. You want to connect, so you put sarah@otherpod.com into the search box on your pod and hit go. A few seconds later, you see her information on the search page with a nice “Add to Aspect” button alongside.
Magic!
I’d love to claim that, but sadly ponycorns are in short supply around here. Here’s how it goes down behind the scenes. A detailed explanation follows the diagram.
When it gets a search request for a Diaspora ID, the first thing your pod does is look in its local database to see if it already knows about this person. This is the grey diamond in the diagram. If it can skip all this drama and just show you the information, it does so. But because you’re on a brand new pod, the only user it knows about is you. So it prepares to retrieve the information you requested from the remote pod.
From here the process is:
1. Figure out where to search
2. Search
3. Retrieve detailed information
4. Cache data locally
5. Profit!
I suppose the last one is optional.
1. Find out where to search
Your pod extracts the pod URL from the Diaspora ID (sarah@otherpod.com becomes otherpod.com) and appends a standard location called “the host-meta route” to get this URL:http://otherpod.com/.well-known/host-metaThis route is part of the webfinger standard. It’s the basic way you ask a server whether or not it supports webfinger.
Your pod then accesses this location and gets back a piece of XML in a format called XRD. Basically, accessing the host-meta route is the same as asking the pod, “How should I send you inquiries about users?” The XRD document that it returns tells your pod how to construct the query for the particular user you’re interested in. Here’s what it looks like:
1 <?xml version='1.0' encoding='UTF-8'?>
2 <XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0' xmlns:hm='http://host-meta.net/xrd/1.0'>
3 <hm:Host>otherpod.com</hm:Host>
4 <Link rel='lrdd' template='https://otherpod.com/webfinger?q={uri}'>
5 <Title>Resource Descriptor</Title>
6 </Link>
7 </XRD>
The “template” on line 4 is the key. It tells your pod to query for the user by substituting their Diaspora ID for {uri}. So to search for your friend, your pod needs to construct need a URL like this:https://otherpod.com/webfinger?q=sarah@otherpod.com
Aside: All Diaspora pods accept user queries at the same location, so this step might seem redundant. But Diaspora pods also inter-operate with other, non-Diaspora social systems, and those may have different locations for querying for a user. In other words, when we get a Diaspora ID, we don’t actually know whether the pod is a Diaspora pod or something else. So we ask for the search route each time.
2. Search
Having figured out the right way to ask, your pod now queries for the user it wants. It accesses the query URL:https://otherpod.com/webfinger?q=sarah@otherpod.comThis returns us another piece of XML – another XRD document – that gives us some basic information about the user, but mostly just tells us where to go to find more detailed info. Here’s what it looks like:
1 <?xml version="1.0" encoding="UTF-8"?> 2 <XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0"> 3 <Subject>acct:sarah@otherpod.com</Subject> 4 <Alias>"https://otherpod.com/"</Alias> 5 <Link rel="http://microformats.org/profile/hcard" type="text/html" href="https://otherpod.com/hcard/users/4cec1e372c174347b90000ad"/> 6 <Link rel="http://otherpod.com/seed_location" type = 'text/html' href="https://otherpod.com/"/> 7 <Link rel="http://otherpod.com/guid" type = 'text/html' href="4cec1e372c174347b90000ad"/> 8 <Link rel='http://webfinger.net/rel/profile-page' type='text/html' href='https://otherpod.com/u/sarah'/> 9 <Link rel="http://schemas.google.com/g/2010#updates-from" type="application/atom+xml" href="https://otherpod.com/public/sarah.atom"/> 10 <Link rel="diaspora-public-key" type = 'RSA' href="[public key omitted for length]"/> 11 </XRD>
Aside: The webfinger XRD document is supposed to be just links to information elsewhere. However, as you can see, Diaspora embeds some actual information, such as the person’s public key, in the document. We implemented this before we fully understood how XRD was supposed to work. We should at some point move that information to the hcard (see next section).
3. Retrieve profile
To fill out profile details, the pod extracts the “hcard location” from the webfinger XRD document. An hcard is a standard, structured way to represent profile data in HTML. The hcard location is on line 5 of the document above, with URL:https://otherpod.com/hcard/users/4cec1e372c174347b90000adYour pod accesses the hcard location, and gets back a piece of HTML with additional profile details for the remote user, such as name. Here’s an excerpt of that hcard – it’s quite long.
1 <div id='content'> 2 <h1>Sarah Mei</h1> 3 <div id='content_inner'> 4 <div class='entity_profile vcard author' id='i'> 5 <h2>User profile</h2> 6 <dl class='entity_nickname'> 7 <dt>Nickname</dt> 8 <dd> 9 <a class='nickname url uid' href='https://otherpod.com/' rel='me'>Sarah Mei</a> 10 </dd> 11 </dl>It goes on, but I think you get the idea.
4. Cache data locally
Finally, having searched for the user and then retrieved her hcard, your pod extracts the profile details and saves them in its local database. sarah@otherpod.com now shows up in searches you do on your pod.5. Profit!
Once you start following your friend, you’ll get her updates as though she were a user local to your pod. If she also follows you, she’ll get your updates in her stream too. From there…who knows what could happen.This walkthrough covered just searching and basic user discovery, which is a tiny part of how Diaspora pods interoperate. Once you get into federation of posts and other content between pods, it’s a whole different ballgame. Stay tuned for that in an upcoming installment.
Sep 13, 2011 3:49 PM
Whoa - Apple Wins a 3D Display & Imaging System Patent Stunner
The US Patent and Trademark Office officially published a series of 13 newly granted patents for Apple Inc. today and one was a real stunner. Today's report focuses on this advanced 3D display and imaging system that packs one hell of a wallop. Apple's patent covers a wild 3D system that could generate an invisible space in front of the user that could allow them to work with holographic images or project their hands onto a screen in front of them to manipulate switches or move pieces of virtual paper or parts of a presentation. One could only image how this could be applied to 3D gaming, business or medical applications in the future. This is Apple's second major revelation about such an advanced 3D system and many supporting patent applications would suggest that the system is progressing quite well in Apple's research labs. The good news, is that future iOS devices will be one of the drivers behind this new beast. This is definitely one of Apple's coolest ideas to date.
Sep 10, 2011 7:03 PM
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Offer ends Monday at 10AM Pacific Time.
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