One of the biggest changes we made to the recent SkyDrive release was how we deal with permissions on files and folders. Making these underlying changes to our service without impacting customers is a bit like replacing the engines on an airplane while it’s flying. The technical challenges were tremendous, but the end result is a system that allows far more flexibility in how you share your files and photos. This post was authored by David Nichols, Software Development Lead for our Storage system, and discusses the technical challenges in making app-centric sharing possible.

-Omar Shahine, Group Program Manager, SkyDrive.com

Our latest releases of SkyDrive include a major revision to our sharing system that lets you give other people permission to see—or even edit—your documents and photos. These releases involved a lot of work in both our front-end web system, which implements the user interface to SkyDrive.com, and our back-end file system, designed to provide persistent storage for your documents and photos. You can also see this capability in SkyDrive for Windows Phone and iPhone in the form of “view-only” and “view and edit” link sharing. Along the way we had several design challenges, and in this post  we’ll look at three of them: Sharing your data with people who don’t use Windows Live, sharing your data from anywhere in your file tree, and finding the files that people have shared with you.

Share your data with anyone

Social networks were still new when we first designed SkyDrive. Facebook wasn’t available outside of universities; MySpace was in its heyday; the idea of integration between networks was a long way off. We expected the sharing patterns to be either sharing with a specific list of contacts in Windows Live or with Messenger buddies. In particular, it was awkward to share with someone who doesn’t have a Windows Live account. The solution to this problem lies in the way we represent sharing permission for files and folders.

Every file or folder in SkyDrive has an optional “access control list” that shows who’s allowed to read or edit the file or folder. You can apply permissions at the folder level (which means that everything inside the folder has the same set of permissions), or you can apply different permissions to individual items inside the folder. This is similar to how enterprise systems (such as Microsoft Windows) track permission information, but our system has a twist.

In addition to being able to hold entries such as “user x” or “buddies of user y,” our system can also hold “token-based” access items. A token is just a string of random (and thus unguessable) bits. If you know the bits, you can gain whatever access the token gives you. We embed these tokens in URLs and send them out in the invitation email when you share a file. When the recipient clicks the link in the invitation, they either get direct access to the file, or get the option to add their Windows Live ID to the access list for the file.

Here’s an example of how this works

Let’s say that Alice wants to share her famous fried okra recipe with Bob, Carol, and David. She knows their email addresses but only has a Windows Live ID for Carol, who is one of her Messenger buddies. Alice uses the Share dialog on the file “Fried Okra.docx” and enters the email addresses for Bob, Carol, and David. After sending the invitation, the access list for “Fried Okra.docx” looks something like this:

Bob gets an email with the token URL, and simply uses it to read the document. As long as he saves the email, he can continue to use that URL (unless Alice changes her mind, see below). Carol uses the URL and logs in with her Windows Live ID. By doing so, not only can she see the document, but it shows up on her “Shared With Me” list whenever she uses SkyDrive. David has a Windows Live ID that Alice didn’t know about, so when he uses the URL, he’s able to substitute his actual Windows Live ID for the token and also see the okra recipe in his “Shared With Me” list. At this point, the access looks like this:

Why the comments? Their purpose is to help with revocation. Say Alice has a change of heart about sharing and wants to remove access from Bob and Carol. When she goes to edit access for the document, she needs to see something more informative than “Token 23.” Because the system remembered the original recipients the tokens were intended for, Alice can chose the correct items to remove from the access list. Once the token has been revoked, the URL in Bob’s saved email will stop working.

Share your files without moving them

The old sharing system for SkyDrive was optimized for the way we expected people to use the system at the time. SkyDrive was used mostly for sharing photos, so we wanted to make it as simple as possible to share an album at a time. We understood that tracking what was shared and what wasn’t could get complex, so we limited the possible “sharable things” to top-level albums in someone’s SkyDrive.

As we added support for storing, editing and finding Office documents, we realized that this simple sharing model wouldn’t capture the sharing patterns our users needed. As Tony East mentioned in his post Designing app-centric sharing for SkyDrive, part 1 of 2: Complexity of “simple,” the ability to share shouldn’t depend on file organization. You should be able to point to any file, anywhere, and share it without moving it.

The problem with this lay in an early decision to store file access information in a different service than the SkyDrive backend. Until this release, the access lists for folders were stored in our contacts and relationships system, ABCH. While this made sense in light of the scenarios at the time, the new sharing model was going to cause scaling issues, because every shared file in SkyDrive would require data in ABCH.

To get the access lists back in SkyDrive, we needed a data migration. Data migrations are quite complicated in large scale on-line systems, because the user data is partitioned across many servers in our data centers. Both SkyDrive and ABCH partition the users across servers, but we use different patterns to do so. So while Alice and Bob’s data might be on the same server in SkyDrive, their data is likely on different servers in ABCH.

We know how to do this: start up a set of migration tasks in our job system, have them examine each user individually, and then move that user’s data. Because we’re moving data from one system to another, this can take as long as few months to complete. To speed up the effective migration speed, we used a local-to-SkyDrive pass that tweaked our internal data format to support on-demand migration. As soon as this was done, we were ready to support the new features. If a user edits sharing on an existing folder, we bring the data for that folder over right away. In the meantime, our migration job is moving all the data, whether it’s changed or not.

Find what’s shared with you

Another feature of our sharing system that’s different from conventional file systems is the “Shared With Me” list. While you can save all the invitation emails you get that are letting you know about files your friends have shared, we’ve found that it’s great if the system can manage this list for you. Because we partition our file data on servers by the user who owns the data, this isn’t trivial to do. If ten people share files with Alice, the access lists for those files are on ten different servers out of hundreds in our system, so there’s no one good place to go to for the list. To solve this problem, our implementation builds on our full-text indexing system, so let’s take a look at that.

Full-text systems work by taking documents in the system and finding all the words in each. From this, they create “inverted indices,” which have words and the corresponding list of documents that contain those words. For example, there might be an entry like “okra: 1,7,107,243,512,514,…” and another, “recipe: 3,56,107,201,512,703,…” which means that the word “okra” appears in the first, seventh, 107st, 243^rd, etc. documents, and that “recipe” appears in the third, 56^th, 107^th, 201^st, etc. documents. To find all documents with “okra” and “recipe”, we take the intersection of the two lists (which is easy, since they’re in order), and discover that the 107^th and 512^th documents contain both words. 

For SkyDrive, we have a full-text index of all documents in the system. However, we can’t let people see all the documents in a search result, only the ones they are allowed to view. To do this, we index the Windows Live IDs of the allowed viewers onto the documents as well. In addition to the word entries above, we add special strings to the documents that get indexed much like the words do, but which encode the permission data. For example, the string “VIEWER=carol@hotmail-example.com” would mean that Carol has view permission for a specific document. Then the inverted index gets an entry like “VIEWER=carol@hotmail-example.com: 39, 107, 762, ...” When Carol searches for “okra recipe,” we change the query to “okra recipe VIEWER=carol@hotmail-example.com.” So Carol gets document 107 back, but not document 512, which she isn’t allowed to read.

With this index, an obvious way to implement “Shared With Me” is to search for the documents Carol is allowed to read. This isn’t exactly right, but it’s close. First, we want to exclude documents that she owns, because we’re showing them elsewhere. Second, we need to include photos, which normally aren’t in the full- text index. Finally, we don’t really want all the files Carol has access to, but only the files or folders where someone explicitly added Carol. If Alice shares a folder with 100 documents, we want only the folder to show up in Shared With Me, not all 100 of the contained documents. If she shares a single spreadsheet, we want to show it too.

The answer to these problems is to index all the shared files or folders with a second index field which tracks exactly the documents and folders that got explicitly shared. This field is only on the shared items, not on files contained within folders, and doesn’t include the document owner. Our search is then for “SHARED-WITH=carol@hotmail-example.com,” which gives us exactly what we want.

Moving forward

Our changes in the system are a big step forward in our ability to support our sharing scenarios, but we know we aren’t done yet. As we collect feedback from you, we’ll continue to evolve how the sharing system works. With this work, we think we’re in a good spot to move forward rapidly.

David Nichols

Software Development Lead, SkyDrive.com

A few weeks ago, we released an upgrade to SkyDrive.com that fundamentally changed the way you can share files and collaborate using SkyDrive. Omar Shahine gave a great overview in his blog post a couple of weeks ago, but I wanted to dive into deeper detail about how our new, simple app-centric sharing for Office documents and photos came about. Tomorrow, David Nichols will publish part 2, which will go into the technical challenges behind these changes.

Here is a quick video Omar made that covers some of the highlights in this post:

What was wrong with the old way?

SkyDrive has been an amazing service from the beginning. To give you some historical perspective: SkyDrive was originally designed for people to share files with other people on the Windows Live network. The first “app” on SkyDrive was a photo sharing experience that shipped in December 2008. Office Client and Web App integration followed in the summer of 2010. The way people share and collaborate has really changed over the past few years. Let’s take a look at some of the user scenarios that grew challenging with our old model:

• If you want to share files, you need to organize things in a particular way. SkyDrive is about your stuff. And since everyone organizes their stuff their own way, we wanted to create a system that lets you share files no matter where they are on your SkyDrive. With our old model you had to create folders or documents in the root of your SkyDrive and give people permission to view or edit them.
• Getting started collaborating on a document is challenging. Because the permission granularity was at the folder level, you needed to put your document in a folder, share that folder, and then your friends or colleagues needed to go to the folder and find and open the document. It was just too many steps.
• You need to know your friend’s Windows Live ID. Our success rates for sharing were low because people have multiple email addresses or will come across a link in Facebook or LinkedIn. For example, I know Joe as joe@contoso.com, but his Windows Live ID is joe@hotmail.com. So in the past, I would share a link with Joe, and he would click on the link and be asked to sign in. He would sign in with his Windows Live ID and not have access to the item!

The challenge of simple vs. powerful

As we worked to design the new model, we really wanted to keep it simple while still providing great features for our power users. Some specific challenges were:

• Sharing files shouldn’t depend on how they’re organized. While the model worked well enough for photos, it was way too hard to get started collaborating and taking advantage of our amazing Microsoft Office integration. We knew it was critical to separate organization from sharing.
• Sharing folders works well for collections like photos, but for collaborating on documents you really need single file sharing. The bar here was email attachments. People have been sharing single files forever this way, and we wanted to create a system that was better.
• Most people don’t understand “ACL math,” so keep it simple. Windows has an incredibly rich Access Control List (ACL) model. It allows you to have conditions that include inheritance of permissions and conditions that break the inheritance of permissions. These rich capabilities can result in complex sharing scenarios that may be desirable in enterprise scenarios, but often add an unhelpful amount of complexity for most people.
• Optimize for sharing more broadly than just with people in the Windows Live network. People want to share files with another person. More and more, people have several different addresses which added friction to our old sharing model. When you shared a folder with another person using a specific email address, the recipient had to sign in to Windows Live using the matching email address or they couldn’t access the document.
• We needed a more resilient and transparent sharing notification system, preferably email. Email is the way people have been sharing and collaborating with each other for a long time. That’s the way it should feel like. Power users should have a way to share directly with their social networks or get a link they can use the way they want.

The new SkyDrive sharing experience

SkyDrive lets you store and share your files—but it does more than that. We also provide rich experiences for important file types, specifically Office documents and photos. So when we talk about “app-centric sharing,” we mean that you don’t have to leave the context of what you’re doing or looking at to share.

Sharing single documents

With the new SkyDrive sharing model, you can easily share single documents to start collaborating. If I select any document in my SkyDrive, I can click “Share” and bring up the sharing dialog that Omar talked about in his blog post. But here’s the best part. Let’s say you’re using the Word Web App to write a blog post (!) and you want to send it out to the folks who need to review it. Instead of having to leave the context of Word, you can just click the File menu and choose “Share.” This brings up the—by now familiar—SkyDrive sharing dialog. Just choose the people you want to share with and get back to writing that blog post. Now that’s simple, app-centric sharing!

Sharing single photos and documents

This also works for photos and albums. If I’m browsing my albums and see one I want to share, in this case some shots I took with my new camera, I can use the new right-click menu on the album cover and share the entire album (folder) from there:

Maybe I want to see who I’ve already shared the album with, so I’ll open the album. Here’s what I see in the info pane:

I’ve already shared this album with my friends on Facebook, but I want to share it with Omar, so I just start typing his name. All of my Hotmail contact email addresses are available in the “To” line:

Note that when Omar clicks on the link, he can immediately view what I shared with him, even if he doesn’t have a Windows Live ID yet.

Quick side trip—Getting everyone’s addresses

SkyDrive sharing (and emailing from Hotmail) will be even more powerful if you connect your social networks to Windows Live. Thanks to some great work by our Connect team, you can connect your social networks to Windows Live by going here. This will ensure that you can share directly with your friends on your connected networks. If you’re connected to LinkedIn, you automatically get those email addresses. For Facebook, you need to do an import by clicking on the Facebook icon after you get connected. Below are the steps you need to follow to import your Facebook email addresses so you can share your files and folders with your friends. Note: You can only import the email addresses of friends that have shared their email address with you.

1. Connect Facebook to Windows Live by clicking here.
2. Go to http://profile.live.com/connect and click the Facebook logo.

• Click the Facebook logo on this dialog box and follow the instructions.

Email notifications with links that work

When I click on “Share” in this case, Omar receives an email from me in his inbox. This means that Omar will know that I’m the one who sent him the link. No more fishing through junk mail to find the link. You even get a copy in your “Sent items” folder in Hotmail so you see exactly what you shared and when you shared it.

Also, if for some reason your message doesn’t get through, you can look in your Hotmail “Sent items” folder and see the mail that was sent. You can even forward the mail to other people.

Changing permissions

Now I see that Omar can view the photos:

But I want to let Omar add some of his own photos to this folder, so I’m going to change his permission to “Can edit” using the dropdown.

If I want to remove either permission, I just use the ‘delete’ icon to the right of the permission. Overall, this lets you grant and revoke permissions in a granular way.

Straightforward sharing means no “ACL math”

The easiest way to think about SkyDrive permissions is to think about parents and children and the way children inherit certain traits from their parents. Each folder can have a set of permissions (though they are private by default). Each folder can also have “children” (subfolders and files) which inherit permissions from their parent. As you set permissions on things, the action is additive. So let’s say that I shared a folder with Omar, Mike and Dave, and then shared a document in that same folder with Sarah. At that point, Mike, Omar, Dave and Sarah can all see that file. But only Mike, Omar and Dave can see the other files in the folder. We make this clear in the UI by showing where the permission came from, along with a handy link to navigate to the folder where that permission is set so you can easily change the permission.

I’ll go back to my blog post example. I gave Omar permission to my “Blog Posts” folder so he could see all the drafts. I have a subfolder under “Blog Posts” where I keep screen shots for the blog post called, surprisingly, “Screen Shots.” My friend Piero has a fantastic eye, and I want him to take a look at the screen shots before I publish. Omar has permission to the parent folder, and by way of inheritance Omar can automatically also see and edit the contents in the subfolder “Screen Shots.” His permissions to the child folder derived from the parent, “Blog Posts” folder.

The UI shows who can do what for each folder or file that you select, so you always know who can view and edit your stuff.

Our magic links

Earlier I mentioned the email mismatch problem. It used to be hard to share with Omar if I only knew his Microsoft address but not his Windows Live ID. Now, our links sent in email and shared on social networks contain a token to let the recipient view the document, so that it works no matter which email address I send it to, even if the recipient doesn’t have a Windows Live ID. While I can restrict it to a specific email address for really sensitive stuff, the predominant case is that the intended recipient gets the link and clicks on it. David Nichols’ post tomorrow will dive more deeply into how the tokens work.

Other ways to share

Publish to your connected social networks

The sharing dialog also lets you quickly share folders and files with your friends on social networks. Want to share that photo album? Have a Word document with a great recipe you want to share? Need your friends to take a look at your resume on LinkedIn? Now you can.

Get a link (for power users)

The other great way to share is to use our “Get a link” feature. This allows you to create a reusable link that you can include for your own scenario. In addition to standard “view” and “edit” enabled links, you can also make a document public and discoverable. Simply click “Get a link” for any of these types and copy the link.

You can revoke these links just like any others you create by clicking the delete icon in the info pane.

We are really excited about the new sharing model and the powerful collaboration scenarios it unlocks. Be sure to read David Nichols’ post tomorrow for Part 2.

Tony East
Lead Program Manager, SkyDrive.com

Today, we’re pleased to announce that all of our customers have the latest release of Hotmail, with several new features, including those that we talked about in our earlier post about fighting the war on graymail. We’re excited about this release and hope you will be, too. So without further ado, here are ten new reasons to love Hotmail.

1. Keep only the latest message from any sender with Schedule cleanup

Today’s inboxes can get cluttered with lots of emails from the same sender, like newsletters or event calendars. Hotmail can automatically manage these messages by keeping only the latest email from a given sender. It’s easy—just select the sender, then choose Schedule cleanup on the Sweep menu, and then select “Only keep the latest message from this sender.” Hotmail will immediately delete all but the latest email from that sender, and each time a new message arrives from this sender, the older message will be deleted.

2. Delete messages as they get old with Schedule cleanup

With other kinds of email, like daily deals and offers, you might want to keep several messages, but only for a few days. Hotmail can automatically clean these up, too, by deleting or moving these messages to a folder after a set amount of time. Just select a set of messages, then choose Schedule cleanup on the Sweep menu, and then select either Delete or Move all messages older than 3, 10, 30, or 60 days. Hotmail will take care of the rest automatically.

3. One-click Unsubscribe

Have you gotten yourself on a mailing list you no longer need? It happens to all of us – you sign up to some web site, and the next thing you know, you’re getting a bunch of newsletters that you don’t really want. With Hotmail, unsubscribing from unwanted newsletters has never been easier. We’ve combined Unsubscribe with the power of Sweep, so unwanted messages are removed from your inbox instantly and permanently with One-click Unsubscribe. Just select (or open) a newsletter, and then choose Unsubscribe on the Sweep menu. Hotmail takes care of all the details like telling the sender to take you off their list, setting up a rule to block messages from that sender, and even cleaning up your inbox if you want—all  in one easy step.

4. Flags done right

We all get important email that we need to get back to later. Now, Hotmail makes it easy, by letting you instantly flag important messages and pinning those messages to the top of your inbox. Those messages stay pinned even when new email arrives, so you never lose track of that email gift card, your flight itinerary, or other important messages. You can even set up rules to automatically flag messages from specific senders.

Here’s a video showing you how to use flags:

5. PhotoMail and DocMail—improved with preview and inline editing

Millions of people share photos through email. Now, Hotmail gives you a beautiful photo album every time you send photos, and with our new release, you get to see that album as you compose your mail. You can even edit the title of your album right inline and add and remove photos before sending.

6. Send files using SkyDrive

Let’s face it, attachments can be a hassle. If the files are too big, or if you attach too many, you might hit sending limits. Or, even worse, the people to whom you’re sending the files might hit limits with their email system, and never receive what you’re sending. That’s why we built SkyDrive right into Hotmail. Now, whenever you send a file, photo or document, you can choose to have that file stored on SkyDrive instead of sending it as an attachment. Using SkyDrive means that everyone will receive the files without any problems, and you no longer have to worry about attachment limits. It’s so easy to use SkyDrive that you can even make it the default for sending all attachments.

7. Forgotten attachment detector

Speaking of attachments, have you ever sent an email to someone meaning to include a file or photo, but forgot to attach it? Hotmail now includes a new Forgotten Attachment Detector that reminds you to attach a file when there are phrases like “see attachments” in an email with no attachments. We’re still tweaking how it works, but right now our detector will catch about 75% of forgotten attachments.

8. Instant Actions that you can customize

We’ve spent a lot of time studying how people use their inbox, and as part of that, we know that certain actions occur very frequently. We’ve taken several common actions—delete, flag, and mark as read/unread—and made them instantly accessible in just one click with our new Instant Actions. But we went one step further. The new Hotmail lets you customize your own Instant Actions so that your inbox works the way you want. You can set up Instant Actions to categorize messages, sweep messages, mark messages as junk or even move messages to a folder, making things like one-click archive a snap.

9. Folder management

We heard from our customers that they wanted more from our folders and subfolders. That’s why we made sure creating and managing folders is easier than ever before. Now, you can create new folders inline and drag one folder into another to create a nested hierarchy. You can also move messages to a folder using drag and drop. And the new right-click menu gives you fast, easy access to common folder operations:

10. Hotmail for Android phones

If you’re using an Android phone, you can now easily access your Hotmail account with the official Hotmail Android app. The app has full EAS support to sync all of your email, calendar, and contacts. It supports multiple Hotmail accounts on the same device and displays new mail notifications on the Home screen. The app has been downloaded by over two million Android users. It can be installed by visiting the Android Market and searching for Microsoft Hotmail, or just by clicking here. Best of all, it’s free!

Keep the feedback coming – this week, we’re on Twitter

We hope you enjoy the latest release. Let us know what you think—we’d love to hear your feedback. We will be hosting a live Twitter Q&A on the new Hotmail features tomorrow, December 16th, on Twitter from 12:30PM until to 1:30PM, Pacific Time.  Use the hashtag #HotmailQnA in your question and follow us (@Hotmail) to participate in the conversation.

And, as always, thank you for using Hotmail.

Dick Craddock

Group Program Manager, Hotmail

We’ve previously talked about the principles that guide us as we strive to continue delivering the most convenient ways to chat with the people who matter the most to you. Today we’re taking another step, with the public availability of access to the Messenger network via XMPP, an open standard. This means that anyone can build innovative messaging clients—either stand-alone or built into their devices—that include access to Messenger’s 300 million active users.

This builds on our perspective that you should simply be able to:

• Choose the services you want, without re-spamming your friends with invites—More than 300 million people actively use Messenger every month. The vast majority of them also actively use other services like Facebook and Yahoo, where they have contact lists that they build and deepen every day. Because of this, we’ve steadily connected Messenger to other services, so that your Windows PC, Windows Phone, and Hotmail make it easy to sign in to your existing services and chat with who you want, without having to re-spam all your friends and force them to join yet another network.
• Choose the devices you want, without having to switch services—Similarly, Messenger has been available for many years on a wide range of devices, using apps built both by Microsoft and through our broad partner program. In addition to the classic Messenger desktop programs for the PC and Mac, Messenger clients are available for most mobile phones and mobile operators around the world, including Windows Phone 7, iPhone, Android, Blackberry OS, Nokia Symbian, Samsung Bada, and many more.

We continue with our commitment to these principles, especially around enabling people to access Messenger from all of their devices by exposing an XMPP interface to Windows Live Messenger. XMPP is the Extensible Messaging and Presence Protocol which is an open technology for real-time communication used by a number of popular IM networks from Google Talk to Facebook Chat and now Messenger.

With the release of the XMPP interface for Messenger, any XMPP based chat client that can also support OAuth 2.0 for authentication will be able to connect to Windows Live Messenger to enable people to see which of their friends are online and chat with them in real-time and.

Supported XMPP Specifications and Code Samples

We currently support the following XMPP specifications

• RFC6120: XMPP: Core
• RFC6121: XMPP: Instant Messaging and Presence. Roster management is not supported.
• XEP-0054: vcard-temp. The Messenger XMPP service supports fetching vCards, but doesn't support updating vCards.
• XEP-0085: Chat State Notifications
• XEP-0203: Delayed Delivery

Developers interested in learning more about our XMPP interface can check out our code samples on GitHub along with the overview documentation on the Live Connect developer center. These should give you enough information to get started building integration with the Messenger network into your mobile apps, devices and web sites.

As you look over our XMPP implementation, please share your comments and feedback with us in the comments or on our developer forums. We always look forward to hearing from our developer community and improving the product based on your feedback.

Your favorite services on your favorite devices

Given that it’s the end of the year, I thought it would be informative to take stock of how what we’ve done so far to enable you to choose the device you want while continuing to enjoy our services. With this announcement, we now have universally available protocols for accessing all our major services. There’s OAuth 2.0 for Live ID, a REST API for SkyDrive, Exchange Active Sync for Hotmail, and XMPP for Messenger.

Thanks to these protocols there is universal access to SkyDrive, Hotmail and Messenger either using Microsoft-authored applications on mobile platforms like Windows Phone and iOS or using applications written by other developers such as HandyScan on Windows Phone and Hotmail for Android by Seven.

As we go into the new year, rest assured that we have more ways we plan to delight developers and our customers as we further our vision of enabling users to choose the services and the devices they want without compromise.

Dare Obasanjo

Lead Program Manager, Live Connect Platform

SkyDrive is your personal cloud for your documents, notes, photos and videos. Move your files into SkyDrive and immediately they’re available from any web browser anywhere in the world. As we detailed a few days ago, there have been a number of recent updates to SkyDrive.com to improve how you share with others, manage your files and folders, and browse through your stuff blazingly fast utilizing the latest web technologies (like HTML5 and CSS3).

Yet as devices proliferate, having a great experience on the web is only one piece of a pretty complex puzzle. As people start to rely more on their smartphones, the need to be able to access files on-the-go is important. As we mentioned two weeks ago, we view device access as “table stakes” for personal cloud storage. People are choosing where to put their files based on how portable and accessible they are across the various devices they use; therefore, it’s critical that we continue to extend the SkyDrive experience to the devices you use every day.

SkyDrive for Windows Phone

With the recent release of Windows Phone 7.5 (“Mango”), we focused on deeply integrating SkyDrive into the phone itself through the Pictures and Office hubs. For instance, you can share photos stored on SkyDrive by email, text, or IM, use Office apps like Word, Excel, and PowerPoint with SkyDrive files, and even keep your phone’s camera roll up-to-date on SkyDrive automatically. This integration isn’t surface-level—SkyDrive is integrated into the apps you use, along with core phone functions. This is a great example of using SkyDrive as an App cloud for Office and Pictures, where the cloud is an underlying feature of the app itself. For more info on the differences between a File cloud, a Device cloud, and an App cloud, check out our post SkyDrive—designing personal cloud storage for billions of people.

Even with all that we’ve done to integrate SkyDrive into Windows Phone, we still have more to do. In talking with SkyDrive power users, we found that many still want the full SkyDrive experience from Windows Phone, including tasks like browsing their entire SkyDrive, sharing links to folders or files, deleting files, and creating folders. Many people who have more than a few dozen files will start to organize them, and we want to make sure people have a direct representation of SkyDrive on their phone. Folders are a natural and time-tested way to organize groups of files, and browsing based on how files are already organized is important for SkyDrive power users.

“If SkyDrive is where I chose to put my stuff, don’t limit what I can do with it,” they told us. So while the Pictures hub is the best way to experience SkyDrive photos, and the Office apps are the best way to view and edit SkyDrive documents, some people still wanted to go further.

Starting today, you can now use the new SkyDrive app on Windows Phone 7.5 to do more with your SkyDrive. It’s available in every country/region where we offer Windows Phone.

Browse your entire SkyDrive—documents, photos, any and all of your files

Being able to see all your folders and files (of all types) is important for SkyDrive power users, as it helps facilitate sharing and file management.

Share any SkyDrive folder or file with one or more people

Pick a file of any type, or even a folder, and share it with as many people as you like. This uses the same “Get a link” mechanism as SkyDrive.com does—you can give the recipients view-only or view-and-edit permissions to your file.

Manage your SkyDrive

Organizing your folders and files just the way you like it is now possible with the SkyDrive app. Create a new folder for a new project or photo album, or delete old files or folders that you no longer need.

Here’s a video detailing the features of the new SkyDrive app for Windows Phone:

SkyDrive for iPhone

We realize that not everyone who relies on SkyDrive for sharing photos or accessing Office documents uses Windows Phone… yet. We have a long history of supporting iPhone customers with built-in support for Hotmail and with apps like Bing, Messenger, OneNote (with SkyDrive sync), and now Skype.

More generally, we believe you should have access to your personal content no matter which device you use. This is why we are excited to invest in HTML5—both on the web and on mobile—on http://skydrive.com.

On the iPhone, we’ve taken the next step by making the new SkyDrive app for iPhone available in 32 languages worldwide. In addition to their OneNote notebooks, iPhone customers can now access all of their files in SkyDrive, create folders, delete files, and share links to folders and files directly using the Mail app.

And here’s a video detailing the features of the new SkyDrive app for iPhone. You’ll notice that the basics are the same, but the experience is tailored for the iPhone:

We’re thrilled to be releasing our new Windows Phone and iPhone apps today. Just as SkyDrive.com has evolved over the years to be the fastest and best way to access & share your data in the cloud, the way you use SkyDrive across your devices will evolve as well. We want you to have the best of a File cloud, the best of a Device cloud, and the App cloud. We also look forward to making SkyDrive available in more places, both directly and through the Live Connect platform for apps, sites and device OEMs. So stay tuned—we have a lot of great stuff coming!

The links below will take you to the Windows Phone Marketplace and/or the iTunes App Store to download the apps. Note that the apps are rolling out now and may take a few hours to be available in all countries/regions. If they’re not available yet in your area, try again in a few hours.

Get SkyDrive for Windows Phone

Get SkyDrive for iPhone

Mike Torres

Group Program Manager, SkyDrive Devices and Roaming