A Journey to Azure

Editor's Notes

• #8: Microsoft Azure is Microsoft's application platform for the public cloud. The goal of this topic is to give you a foundation for understanding the fundamentals of Azure, even if you don't know anything about cloud computing. Azure is growing all the time so it's easy to get overloaded. Start with the basic services, then go through the additional services. That doesn't mean you can't use just the additional services by themselves, but the basic services make up the core of an application running in Azure.
• #11: The ability to create a virtual machine on demand, whether from a standard image or from one you supply, can be very useful. This approach, commonly known as Infrastructure as a Service (IaaS), is what Azure Virtual Machines provides. Figure 2 shows a combination of how an Virtual Machine (VM) runs and how to create one from a VHD. To create a VM, you specify which VHD to use and the VM's size. You then pay for the time that the VM is running. You pay by the minute and only while it's running, though there is a minimal storage charge for keeping the VHD available. Azure offers a gallery of stock VHDs (called "images") that contain a bootable operating system to start from. These include Microsoft and partner options, such as Windows Server and Linux, SQL Server, Oracle and many more. You're free to create VHDs and images, and then upload them yourself. You can even upload VHDs that contain only data and then access them from your running VMs. Wherever the VHD comes from, you can persistently store any changes made while a VM is running. The next time you create a VM from that VHD, things pick up where you left off. The VHDs that back the Virtual Machines are stored in Azure Storage blobs, which we talk about later. That means you get redundancy to ensure your VMs won’t disappear due to hardware and disk failures. It's also possible to copy the changed VHD out of Azure, then run it locally. Your application runs within one or more Virtual Machines, depending on how you created it before or decide to create it from scratch now. This quite general approach to cloud computing can be used to address many different problems. Virtual Machine Scenarios Dev/Test - You might use them to create an inexpensive development and test platform that you can shut down when you've finished using it. You might also create and run applications that use whatever languages and libraries you like. Those applications can use any of the data management options that Azure provides, and you can also choose to use SQL Server or another DBMS running in one or more virtual machines. Move Applications to Azure (Lift-and-shift) - "Lift-and-shift" refers to moving you application much like you'd use a forklift to move a large object. You "lift" the VHD from your local datacenter, and "shift" it to Azure and run it there. You will typically have to do some work to remove dependencies on other systems. If there are too many, you may choose option 3 instead. Extend your Datacenter - Use Azure VMs as an extension of your on-premises datacenter, running SharePoint or other applications. To support this, it's possible to create Windows domains in the cloud by running Active Directory in Azure VMs. You can use Azure Virtual Network (mentioned later) to tie your local network and your network in Azure together.
• #12: One of the most common things that people do in the cloud is run websites and web applications. Azure Virtual Machines allows this, but it still leaves you with the responsibility of administering one or more VMs and the underlying operating systems. Cloud services web roles can do this, but deploying and maintaining them still takes administrative work. What if you just want a website where somebody else takes care of the administrative work for you? This is exactly what Web Apps provides. This compute model offers a managed web environment using the Azure Management portal as well as APIs. You can move an existing website application into Web Apps unchanged, or you can create a new one directly in the cloud. Once a website is running, you can add or remove instances dynamically, relying on Azure Web Apps to load balance requests across them. Azure Apps offers both a shared option, where your website runs in a virtual machine with other sites, and a standard option that allows a site to run in its own VM. The standard option also lets you increase the size (computing power) of your instances if needed. For development, Web Apps supports .NET, PHP, Node.js, Java and Python along with SQL Database and MySQL (from ClearDB, a Microsoft partner) for relational storage. It also provides built-in support for several popular applications, including WordPress, Joomla, and Drupal. The goal is to provide a low-cost, scalable, and broadly useful platform for creating websites and web applications in the public cloud. Web Apps Scenarios Web Apps is intended to be useful for corporations, developers, and web design agencies. For corporations, it's an easy-to-manage, scalable, highly secure, and highly available solution for running presence websites. When you need to set up a Website, it’s best to start with Azure Web Apps and proceed to Cloud Services once you need a feature that’s not available. See the end of the "Compute" section for more links that can help you to choose between the options.
• #13: Suppose you want to build a cloud application that can support lots of simultaneous users, doesn't require much administration, and never goes down. You might be an established software vendor, for example, that's decided to embrace Software as a Service (SaaS) by building a version of one of your applications in the cloud. Or you might be a start-up creating a consumer application that you expect will grow fast. If you're building on Azure, which execution model should you use? Azure Web Apps allows creating this kind of web application, but there are some constraints. You don't have administrative access, for example, which means that you can't install arbitrary software. Azure Virtual Machines gives you lots of flexibility, including administrative access, and you certainly can use it to build a very scalable application, but you'll have to handle many aspects of reliability and administration yourself. What you'd like is an option that gives you the control you need but also handles most of the work required for reliability and administration. This is exactly what's provided by Azure Cloud Services. This technology is designed expressly to support scalable, reliable, and low-admin applications, and it's an example of what's commonly called Platform as a Service (PaaS). To use it, you create an application using the technology you choose, such as C#, Java, PHP, Python, Node.js, or something else. Your code then executes in virtual machines (referred to as instances) running a version of Windows Server. But these VMs are distinct from the ones you create with Azure Virtual Machines. For one thing, Azure itself manages them, doing things like installing operating system patches and automatically rolling out new patched images. This implies that your application shouldn't maintain state in web or worker role instances; it should instead be kept in one of the Azure data management options described in the next section. Azure also monitors these VMs, restarting any that fail. You can set cloud services to automatically create more or fewer instances in response to demand. This allows you to handle increased usage, and then scale back so you aren’t paying as much when there is less usage. You have two roles to choose from when you create an instance, both based on Windows Server. The main difference between the two is that an instance of a web role runs IIS, while an instance of a worker role does not. Both are managed in the same way, however, and it's common for an application to use both. For example, a web role instance might accept requests from users, then pass them to a worker role instance for processing. To scale your application up or down, you can request that Azure create more instances of either role or shut down existing instances. And similar to Azure Virtual Machines, you're charged only for the time that each web or worker role instance is running. Cloud Services Scenarios Cloud Services are ideal to support massive scale out when you need more control over the platform than provided by Azure Web Apps but don’t need control over the underlying operating system.
• #14: Applications need data, and different kinds of applications need different kinds of data. Because of this, Azure provides several different ways to store and manage data. Azure provides many storage options, but all are designed for very durable storage. With any of these options, there are always 3 copies of your data kept in sync across an Azure datacenter -- 6 if you allow Azure to use geo-redundancy to back up to another datacenter at least 300 miles away. For relational storage, Azure provides the feature SQL Database. Don't let the naming fool you. This is different than a typical SQL Database provided by SQL Server running on top of Windows Server. Formerly called SQL Azure, Azure SQL Database provides all of the key features of a relational database management system, including atomic transactions, concurrent data access by multiple users with data integrity, ANSI SQL queries, and a familiar programming model. Like SQL Server, SQL Database can be accessed using Entity Framework, ADO.NET, JDBC, and other familiar data access technologies. It also supports most of the T-SQL language, along with SQL Server tools such as SQL Server Management Studio. For anybody familiar with SQL Server (or another relational database), using SQL Database is straightforward. But SQL Database isn't just a DBMS in the cloud-it's a PaaS service. You still control your data and who can access it, but SQL Database takes care of the administrative grunt work, such as managing the hardware infrastructure and automatically keeping the database and operating system software up to date. SQL Database also provides high availability, automatic backups, point-in-time restore capabilities, and can replicate copies across geographical regions. Scenarios for SQL Database If you're creating an Azure application (using any of the compute models) that needs relational storage, SQL Database can be a good option. Applications running outside the cloud can also use this service, though, so there are plenty of other scenarios. For instance, data stored in SQL Database can be accessed from different client systems, including desktops, laptops, tablets, and phones. And because it provides built-in high availability through replication, using SQL Database can help minimize downtime. This feature is sometimes called different terms as it's part of a larger feature called "Azure Storage". If you see "tables", "Azure tables" or "storage tables", it's all the same thing. And don't be confused by the name: this technology doesn't provide relational storage. In fact, it's an example of a NoSQL approach called a key/value store. Azure Tables let an application store properties of various types, such as strings, integers, and dates. An application can then retrieve a group of properties by providing a unique key for that group. While complex operations like joins aren't supported, tables offer fast access to typed data. They're also very scalable, with a single table able to hold as much as a terabyte of data. And matching their simplicity, tables are usually less expensive to use than SQL Database's relational storage. Scenarios for Tables Suppose you want to create an Azure application that needs fast access to typed data, maybe lots of it, but doesn't need to perform complex SQL queries on this data. For example, imagine you're creating a consumer application that needs to store customer profile information for each user. Your app is going to be very popular, so you need to allow for lots of data, but you won't do much with this data beyond storing it, then retrieving it in simple ways. This is exactly the kind of scenario where Azure Tables makes sense. Azure Blobs (again "Blob Storage" and just "Storage Blobs" are the same thing) is designed to store unstructured binary data. Like Tables, Blobs provides inexpensive storage, and a single blob can be as large as 1TB (one terabyte). Azure applications can also use Azure drives, which let blobs provide persistent storage for a Windows file system mounted in an Azure instance. The application sees ordinary Windows files, but the contents are actually stored in a blob. Blob storage is used by many other Azure features (including Virtual Machines), so it can certainly handle your workloads too. Scenarios for Blobs An application that stores video, massive files, or other binary information can use blobs for simple, cheap storage. Blobs are also commonly used in conjunction with other services like Content Delivery Network, which we will talk about later.
• #15: When you have published your app - whether it runs on mobile devices, desktops, or web browsers - Application Insights tells you how it is performing and what users are doing with it. It will keep a count of crashes and slow response, alert you if the figures cross unacceptable thresholds, and help you diagnose any problems. When you develop a new feature, plan to measure its success with users. By analysing usage patterns, you understand what works best for your customers and enhance your app in every development cycle. Although it's hosted in Azure, Application Insights works for a wide and growing range of apps, both on an off Azure. Both J2EE and ASP.NET web apps are covered, as well as iOS, Android, OSX and Windows applications. Telemetry is sent from an SDK built with the app, to be analyzed and displayed in the Application Insights service in Azure. If you want more specialized analytics, export the telemetry stream to a database, or to Power BI, or any other tools. Application Insights scenarios You are developing an app. It might be a web app or a device app, or a device app with a web back end. Tune the performance of your app after it is published, or while it is in load testing. Application Insights aggregates telemetry from all the installed instances, and presents you with charts of response times, request and exception counts, dependency response times, and other performance indicators. These help you tune your app's performance. You can insert code to report more specific data if you need it. Detect and diagnose problems in your live app. You can get alerts by email if performance indicators cross acceptable thresholds. You can investigate specific user sessions, for example to see the request that caused an exception. Track usage to assess the success of each new feature. When you design a new user story, plan to measure how much it is used, and whether users achieve their expected goals. Application Insights gives you basic usage data such as web page views, and you can insert code to track the user experience in more detail.
• #16: Azure Mobile Apps provides many useful functions that can save you time when building a backend for a Mobile application. It allows you to do simple provisioning and management of data stored in a SQL Database. With server-side code you can easily use additional data storage options like blob storage or MongoDB. Mobile Apps provides support for notifications, though in certain cases you can instead use Notification Hubs as described next. The service also has a REST API that your mobile application can call to get work done. Mobile Apps also provides the ability to authenticate users through Microsoft and Active Directory as well as other well-known identity providers like Facebook, Twitter, and Google. You can use other Azure Services like Service Bus and worker roles, and connect to on-premises systems. You can even consume 3rd party Add-Ons from the Azure Store (like SendGrid for email) to provide additional functionality. Native client libraries for Android, iOS, HTML/JavaScript, Windows Phone, and Windows Store make it easier to develop for apps on all major mobile platforms. A REST API enables you to use Mobile Services data and authentication functionality with apps on different platforms. A single mobile service can back multiple client apps so you can provide a consistent user experience across devices. Because Azure supports massive scale already, you can handle the traffic as your app becomes more popular. Monitoring and logging are supported to help troubleshoot issues and manage performance.
• #17: While you can write code to do notifications in Azure Mobile Apps, Notification Hubs is optimized to broadcast millions of highly personalized push notifications within minutes. You don't have to worry about details like mobile carrier or device manufacturer. You can target individual or millions of users with a single API call. Notification Hubs is designed to work with any backend. You can use Azure Mobile Apps, a custom backend in the cloud running on any provider or an on-premises backend. Notification Hub Scenarios If you were writing a mobile game where players took turns, you may need to notify player 2 that player 1 finished her turn. If that's all you need to do, you could just use Mobile Apps. But if you had 100,000 users play your game and you want to send a time sensitive free offer to everyone, Notification Hubs is the better choice. You can send breaking news, sporting events, and product announcement notifications to millions of users with low latency. Enterprises can notify their employees about new time sensitive communications, such as sales leads, so employees don’t have to constantly check email or other applications to stay informed. You can also send one-time-passwords required for multi-factor authentication.
• #18: Queuing is a simple idea: One application places a message in a queue, and that message is eventually read by another application. If your application needs just this straightforward service, Azure Queues might be the best choice. Because of the way the Azure grew over time, Azure Storage Queues and Service Bus Queues provide similar queuing services. The reasons why you would want to use one over the other are covered in the fairly technical paper . In many scenarios, either will work. Queue Scenarios One common use of queues today is to let a web role instance communicate with a worker role instance within the same Cloud Services application. For example, suppose you create an Azure application for video sharing. The application consists of PHP code running in a web role that lets users upload and watch videos, together with a worker role implemented in C# that translates uploaded video into various formats. When a web role instance gets a new video from a user, it can store the video in a blob, then send a message to a worker role via a queue telling it where to find this new video. A worker role instance-it doesn't matter which one-will then read the message from the queue and carry out the required video translations in the background. Structuring an application in this way allows asynchronous processing, and it also makes the application easier to scale, since the number of web role instances and worker role instances can be varied independently. You can also use the queue size as a trigger to scale the number of worker roles up and down. Too high, and you add more roles. When it gets lower, you can reduce the number of running roles to save money. You can use this same pattern between many different parts of your application even if they don't use web and worker roles. It allows you to scale the parts on either side of the queue up and down as demand and processing time requires. Service Bus provides a Publish-and-subscribe mechanism called Topics and Subscriptions. With publish-subscribe, an application can send messages to a topic, while other applications can create subscriptions to this topic. This allows one-to-many communication among a set of applications, letting the same message be read by multiple recipients. Service Bus Topics and Subscriptions Scenarios Anytime your are setting up where there are many messages that are all important, but various downstream systems only need to listen to differing subsets of those communications, Service Bus Topic and Subscriptions are a good option.
• #22: With today’s release, Windows Azure is more flexible than ever. Windows Azure helped pioneer the concept of Platform as a Service – and provides a rich set of managed, scalable services. Today, we are making these services even richer. Windows Azure also now supports Infrastructure as a Service – including the ability to host both Windows and Linux Virtual Machines in the cloud. Some of you might be surprised to hear the word Linux at a Microsoft event. Our support of Linux is just one example of how we are embracing openness in a fundamental new way. With today’s release, we are supporting more operating systems, more languages, more open protocols, and releasing all of our SDKs on GitHub under an open source license. The end result is a truly unique offering. You can now use both Platform as a Service and Infrastructure as a Service together. You can now use the best of both the Microsoft ecosystem and open source ecosystem together. And you can now build better and more scalable solutions than ever before.