Click here to close now.

Welcome!

.NET Authors: Carmen Gonzalez, Elizabeth White, Liz McMillan, Greg O'Connor, Jason Bloomberg

Related Topics: .NET, Silverlight, Web 2.0, Cloud Expo, Security

.NET: Article

Wildcard Subdomains in Windows Azure

Want to support my.fancy.app.can.serve.up.anything.mybrand.com in your Windows Azure application?

I was meeting with a small company today that has developed a SaaS solution around task and project management. It's a very cool application, and as is the fashion these days, uses subdomains to determine the end user's company as requests come to the browser. So, if I were to sign up for the application, my home url would be http://adamhoffman.getdonedone.com, whereas if you signed up (and had the unlikely name of Bill Ion), your home page would be http://billion.getdonedone.com. This is handled in ASP.NET application code on their Win2K8 servers hosted at Rackspace. The question quickly became "hey, we can do something similar in Azure, right?"

The answer is yes, and no, and yes. Let me explain.

My instant assumption was "yes", and ultimately, it is true that you can accomplish this behavior. It does, however, require that wherever you host your DNS that points to your application supports the concept of "wildcard DNS records", and more specifically, supports "wildcard CNAMEs". As it turns out, Go Daddy's DNS services don't support this, so we'll have to look elsewhere to get this functionality.

The next question you might be asking yourself now is why do we care about wildcard CNAME versus just wildcard DNS? Specifically, the answer lies in the way that Azure provides you high reliability. As a very quick DNS primer, you need to understand the difference between A records and CNAME records. Go read the link if you want the details, but the short answer is "A records point to IP addresses, CNAME records are aliases of other domain name records. OK, but why does this matter?

Well, as it turns out, when you want to put your fancy brand on your Azure based website, you can only do that by way of a CNAME record. The reason that you can't use an A record to point to your site is that your site doesn't have an IP address. Well, it does, but it's not something that you can get access to, and even if you could, it's not persistent, and will likely change. In order to avoid this problem, what you get is really a domain name that is a part of "cloudapp.net". For example, the website that I'm about to demo for you that supports wildcard subdomains is addressable by way of "wildcardsubdomain.cloudapp.net", but not by IP address. Well, OK, yes, smarty pants. It is addressable by IP as well. For example, at this moment I can also get to the same site at http://65.52.208.222, but I shouldn't rely on it. Who knows - by the time you read this, it might not work at all. If you want to know how I figured that out, check out nslookup.

The reason that's all true is that Azure relies on CNAME so that it can switch your IP around, but keep your site addressable. Why does it do it? It's mad network stuff related to load balancers, and the Azure Fabric controller, and it's done to ensure that your site has the maximum stability and uptime.

Okay, back to the problem at hand - getting our dynamic subdomains passed through to our application code to allow for multitenant applications split by the third level domain. How will we handle it? Here we go.

  1. First, we'll find a DNS service that supports wildcard CNAMEs.
  2. Next we'll configure that DNS service to point to our application.
  3. Finally, we'll write the application code that understands the incoming requests so that we can fork our clients appropriately.
  4. After finally, we'll take a look at the URL Routing features of ASP.NET and see if we can extend our example to integrate nicely with it.

On the first count, it's not actually as straightforward as you might think. For example, I've used GoDaddy to procure several of my domains (yes, I am aware of the SOPA thing, and won't get political here). As the link here reveals, wildcard CNAMEs aren't an option in GoDaddy's DNS servers, so we'll need to look elsewhere. I won't attempt to put together an exhaustive list here, but one DNS service that does support this concept is Amazon's Route 53 DNS service. Another nice feature of this is that it has an API, which actually opens up another possibility if we so chose. Our solution here to route all subdomains to a single hosted web site. An alternative to our multi-tenant single application approach would be to actually specifically provision subdomains and point them to different hosted web sites. So, instead of

*.adamhoffman.net CNAME wildcardsubdomain.cloudapp.net (which has application code that sorts it out)

we could, instead go with

customer1.adamhoffman.net CNAME customer1.cloudapp.net (which is for the customer1 domain), and
customer2.adamhoffman.net CNAME customer2.cloudapp.net (which is for the customer2 domain), and
so on...

Yes, we could do that, and with the Route 53 API, we could even provision those new CNAME records as necessary. But that's not the route we're going to use. We'd like to use the former option, and have a single wildcard CNAME record that just routes everything to our super smart application.

OK, so next, we'll get ourselves an Amazon account to set up our DNS services on Route 53. Once you've signed up, create, in Amazon's terminology, a hosted zone for the domain that we'll support wildcards on. Of course, you need to own this domain.

Take a look now at the "delegation set" that Route 53 has assigned you. There are 4 DNS servers listed here, and these are the DNS servers that you need to tell your domain registrar about so that it makes sure that requests for your domain are handed off to these Route 53 DNS servers. In my case, my registrar for adamhoffman.net is Go Daddy, so I'll use the Go Daddy tools to point to these DNS servers.

With all of this done, there's only one final step. We need to tell the DNS servers that handle adamhoffman.net that the canonical name (CNAME) for *.adamhoffman.net is really wildcardsubdomain.cloudapp.net. Look at the CNAME record for *.adamhoffman.net in the following picture. That's the secret sauce.

More Stories By Adam Hoffman

Adam is an technical evangelist working for Microsoft. By day, you can likely find him somewhere in the Midwest, driving to somewhere, ready to figure out how the cloud can save your family from certain doom, and make you rich and successful in the process. Before he started evangelizing, Adam was a Senior Developer Lead for Microsoft in Redmond, working on Office 365, BPOS, and Office Live. He misses Redmond, and the excitement of the mother ship, but the call of bitter cold and lots of snow in Chicago was too much for him, and he had to return.

Prior that that he developed software and ran teams for Thomson Reuters, Method Engine (which he co-founded), VSA Partners, Navigant Consulting, Andersen Consulting, and a couple of CASE tool companies way back in the day. His favorite possession is a clone of the original Altair computer, running BillG's 8K BASIC, which he's still intending to hook up to the cloud, someday, somehow.

You can read his Windows Azure Blog at http://stratospher.es, and tweeter-er him at http://twitter.com/stratospher_es.

Additionally, if you'd like to keep track of his cloud connected car, you can follow it on Twitter at http://twitter.com/cloudcar1.

@ThingsExpo Stories
SYS-CON Events announced today that On the Avenue Marketing Group, a sales and marketing firm that utilizes events to market and sell products to consumers, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. On the Avenue Marketing Group (OTA) is a sales and marketing firm that utilizes events to market and sell products to consumers. On behalf of our clients, we attend thousands of fairs, festivals, expos, concerts, conferences, and sporting events annually, helping them reach millions of individuals ...
Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming 16th Cloud Expo at the Javits Center in New York June 9-11 will find fresh new content in a new track called PaaS | Containers & Microservices Containers are not being considered for the first time by the cloud community, but a current era of re-consideration has pushed them to the top of the cloud agenda. With the launch of Docker's initial release in March of 2013, interest was revved up several notches. Then late last...
“In the past year we've seen a lot of stabilization of WebRTC. You can now use it in production with a far greater degree of certainty. A lot of the real developments in the past year have been in things like the data channel, which will enable a whole new type of application," explained Peter Dunkley, Technical Director at Acision, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Ciqada will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Ciqada™ makes it easy to connect your products to the Internet. By integrating key components - hardware, servers, dashboards, and mobile apps - into an easy-to-use, configurable system, your products can quickly and securely join the internet of things. With remote monitoring, control, and alert messaging capability, you will meet your customers' needs of tomorrow - today! Ciqada. Let your products take flight. For more inform...
Health care systems across the globe are under enormous strain, as facilities reach capacity and costs continue to rise. M2M and the Internet of Things have the potential to transform the industry through connected health solutions that can make care more efficient while reducing costs. In fact, Vodafone's annual M2M Barometer Report forecasts M2M applications rising to 57 percent in health care and life sciences by 2016. Lively is one of Vodafone's health care partners, whose solutions enable older adults to live independent lives while staying connected to loved ones. M2M will continue to gr...
SYS-CON Media announced today that @WebRTCSummit Blog, the largest WebRTC resource in the world, has been launched. @WebRTCSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @WebRTCSummit Blog can be bookmarked ▸ Here @WebRTCSummit conference site can be bookmarked ▸ Here
SYS-CON Events announced today that GENBAND, a leading developer of real time communications software solutions, has been named “Silver Sponsor” of SYS-CON's WebRTC Summit, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. The GENBAND team will be on hand to demonstrate their newest product, Kandy. Kandy is a communications Platform-as-a-Service (PaaS) that enables companies to seamlessly integrate more human communications into their Web and mobile applications - creating more engaging experiences for their customers and boosting collaboration and productiv...
Dave will share his insights on how Internet of Things for Enterprises are transforming and making more productive and efficient operations and maintenance (O&M) procedures in the cleantech industry and beyond. Speaker Bio: Dave Landa is chief operating officer of Cybozu Corp (kintone US). Based in the San Francisco Bay Area, Dave has been on the forefront of the Cloud revolution driving strategic business development on the executive teams of multiple leading Software as a Services (SaaS) application providers dating back to 2004. Cybozu's kintone.com is a leading global BYOA (Build Your O...
The best mobile applications are augmented by dedicated servers, the Internet and Cloud services. Mobile developers should focus on one thing: writing the next socially disruptive viral app. Thanks to the cloud, they can focus on the overall solution, not the underlying plumbing. From iOS to Android and Windows, developers can leverage cloud services to create a common cross-platform backend to persist user settings, app data, broadcast notifications, run jobs, etc. This session provides a high level technical overview of many cloud services available to mobile app developers, includi...
SYS-CON Events announced today that BroadSoft, the leading global provider of Unified Communications and Collaboration (UCC) services to operators worldwide, has been named “Gold Sponsor” of SYS-CON's WebRTC Summit, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. BroadSoft is the leading provider of software and services that enable mobile, fixed-line and cable service providers to offer Unified Communications over their Internet Protocol networks. The Company’s core communications platform enables the delivery of a range of enterprise and consumer calling...
While not quite mainstream yet, WebRTC is starting to gain ground with Carriers, Enterprises and Independent Software Vendors (ISV’s) alike. WebRTC makes it easy for developers to add audio and video communications into their applications by using Web browsers as their platform. But like any market, every customer engagement has unique requirements, as well as constraints. And of course, one size does not fit all. In her session at WebRTC Summit, Dr. Natasha Tamaskar, Vice President, Head of Cloud and Mobile Strategy at GENBAND, will explore what is needed to take a real time communications ...
What exactly is a cognitive application? In her session at 16th Cloud Expo, Ashley Hathaway, Product Manager at IBM Watson, will look at the services being offered by the IBM Watson Developer Cloud and what that means for developers and Big Data. She'll explore how IBM Watson and its partnerships will continue to grow and help define what it means to be a cognitive service, as well as take a look at the offerings on Bluemix. She will also check out how Watson and the Alchemy API team up to offer disruptive APIs to developers.
The IoT Bootcamp is coming to Cloud Expo | @ThingsExpo on June 9-10 at the Javits Center in New York. Instructor. Registration is now available at http://iotbootcamp.sys-con.com/ Instructor Janakiram MSV previously taught the famously successful Multi-Cloud Bootcamp at Cloud Expo | @ThingsExpo in November in Santa Clara. Now he is expanding the focus to Janakiram is the founder and CTO of Get Cloud Ready Consulting, a niche Cloud Migration and Cloud Operations firm that recently got acquired by Aditi Technologies. He is a Microsoft Regional Director for Hyderabad, India, and one of the f...
The 17th International Cloud Expo has announced that its Call for Papers is open. 17th International Cloud Expo, to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, APM, APIs, Microservices, Security, Big Data, Internet of Things, DevOps and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal today!
WebRTC is an up-and-coming standard that enables real-time voice and video to be directly embedded into browsers making the browser a primary user interface for communications and collaboration. WebRTC runs in a number of browsers today and is currently supported in over a billion installed browsers globally, across a range of platform OS and devices. Today, organizations that choose to deploy WebRTC applications and use a host machine that supports audio through USB or Bluetooth can use Plantronics products to connect and transit or receive the audio associated with the WebRTC session.
As enterprises move to all-IP networks and cloud-based applications, communications service providers (CSPs) – facing increased competition from over-the-top providers delivering content via the Internet and independently of CSPs – must be able to offer seamless cloud-based communication and collaboration solutions that can scale for small, midsize, and large enterprises, as well as public sector organizations, in order to keep and grow market share. The latest version of Oracle Communications Unified Communications Suite gives CSPs the capability to do just that. In addition, its integration ...
SYS-CON Media announced today that @ThingsExpo Blog launched with 7,788 original stories. @ThingsExpo Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @ThingsExpo Blog can be bookmarked. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago.
The world's leading Cloud event, Cloud Expo has launched Microservices Journal on the SYS-CON.com portal, featuring over 19,000 original articles, news stories, features, and blog entries. DevOps Journal is focused on this critical enterprise IT topic in the world of cloud computing. Microservices Journal offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. Follow new article posts on Twitter at @MicroservicesE
SYS-CON Events announced today that robomq.io will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. robomq.io is an interoperable and composable platform that connects any device to any application. It helps systems integrators and the solution providers build new and innovative products and service for industries requiring monitoring or intelligence from devices and sensors.
Wearable technology was dominant at this year’s International Consumer Electronics Show (CES) , and MWC was no exception to this trend. New versions of favorites, such as the Samsung Gear (three new products were released: the Gear 2, the Gear 2 Neo and the Gear Fit), shared the limelight with new wearables like Pebble Time Steel (the new premium version of the company’s previously released smartwatch) and the LG Watch Urbane. The most dramatic difference at MWC was an emphasis on presenting wearables as fashion accessories and moving away from the original clunky technology associated with t...