Welcome!

Microsoft Cloud Authors: Kevin Benedict, Pat Romanski, Liz McMillan, Lori MacVittie, Elizabeth White

Related Topics: @CloudExpo, Microservices Expo, Microsoft Cloud

@CloudExpo: Article

Cloud Computing, SOA and Windows Azure - Part 2

SOA Principles and Patterns

For a complete list of the co-authors and contributors, see the end of the article.

Windows Azure Platform Overview
The Windows Azure platform is an Internet-scale cloud computing services platform hosted in Microsoft data centers. Windows tools provide functionality to build solutions that include a cloud services operating system and a set of developer services. The key parts of the Windows Azure platform are:

  • Windows Azure (application container)
  • Microsoft SQL Azure
  • Windows Azure platform AppFabric

The infrastructure and service architectures that underlie many of these native services (as well as cloud-based services in general) are based on direct combined application of Stateful Services [786] and Redundant Implementation [766]. This is made possible by leveraging several of the built-in extensions and mechanisms provided by the Windows Azure platform (as explained in this chapter and Chapter 16).

The Windows Azure platform is part of the Microsoft cloud, which consists of multiple categories of services:

  • Cloud-based applications: These are services that are always available and highly scalable. They run in the Microsoft cloud that consumers can directly utilize. Examples include Bing, Windows Live Hotmail, Office Live, etc.
  • Software services: These services are hosted instances of Microsoft's enterprise server products that consumers can use directly. Examples include Exchange Online, SharePoint Online, Office Communications Online, etc.
  • Platform services: This is where the Windows Azure platform itself is positioned. It serves as an application platform public cloud that developers can use to deploy next-generation, Internet-scale, and always available solutions.
  • Infrastructure services: There is a limited set of elements of the Windows Azure platform that can support cloud-based infrastructure resources.

Figure 3 illustrates the service categories related to the Windows Azure platform. Given that Windows Azure is itself a platform, let's explore it as an implementation of the PaaS delivery model.

Figure 3: A high-level representation of categories of services available in the Windows Azure cloud

The Windows Azure platform was built from the ground up using Microsoft technologies, such as the Windows Server Hyper-V-based system virtualization layer. However, the Windows Azure platform is not intended to be just another off-premise Windows Server hosting environment. It has a cloud fabric layer, called the Windows Azure Fabric Controller, built on top of its underlying infrastructure.

The Windows Azure Fabric Controller pools an array of virtualized Windows Server instances into a logical entity and automatically manages the following:

  • Resources
  • Load balancing
  • Fault-tolerance
  • Geo-replication
  • Application lifecycle

These are managed without requiring the hosted applications to explicitly deal with the details. The fabric layer provides a parallel management system that abstracts the complexities in the infrastructure and presents a cloud environment that is inherently elastic. As a form of PaaS, it also supports the access points for user and application interactions with the Windows Azure platform.

The Windows Azure platform essentially provides a set of cloud-based services that are symmetric with existing mainstream on-site enterprise application platforms (see Figure 4).

Figure 4: An overview of common Windows Azure platform capabilities

For example:

  • Storage services: A scalable distributed data storage system that supports many types of storage models, including hash map or table-like structured data, large binary files, asynchronous messaging queues, traditional file systems, and content distribution networks
  • Compute services: Application containers that support existing mainstream development technologies and frameworks, including .NET, Java, PHP, Python, Ruby on Rails, and native code.
  • Data services: Highly reliable and scalable relational database services that also support integration and data synchronization capabilities with existing on-premise relational databases
  • Connectivity services: These are provided via a cloud-based service bus that can be used as a message intermediary to broker connections with other cloud-based services and services behind firewalls within on-premise enterprise environments
  • Security services: Policy-driven access control services that are federation-aware and can seamlessly integrate with existing on-premise identity management systems
  • Framework services: Components and tools that support specific aspects and requirements of solution frameworks
  • Application services: Higher-level services that can be used to support application development, such as application and data marketplaces

All of these capabilities can be utilized individually or in combination.

Windows Azure (Application Container)
Windows Azure serves as the development, service hosting, and service management environment. It provides the application container into which code and logic, such as Visual Studio projects, can be deployed. The application environment is similar to existing Windows Server environments. In fact, most .NET projects can be deployed directly without significant changes.

A Windows Azure instance represents a unit of deployment, and is mapped to specific virtual machines with a range of variable sizes. Physical provisioning of the Windows Azure instances is handled by the cloud fabric. We are required only to specify, by policy, how many instances we want the cloud fabric to deploy for a given service.

We have the ability to manually start and shut down instances, and grow or shrink the deployment pool; however, the cloud fabric also provides automated management of the health and lifecycles of instances. For example, in the event of an instance failure, the cloud fabric would automatically shut down the instance and attempt to bring it back up on another node.

Windows Azure also provides a set of storage services that consumers can use to store and manage persistent and transient data. Storage services support geo-location and offer high durability of data by triple-replicating everything within a cluster and across data centers. Furthermore, they can manage scalability requirements by automatically partitioning and load balancing services across servers.

Also supported by Windows Azure is a VHD-based deployment model as an option to enable some IaaS requirements. This is primarily geared for services that require closer integration with the Windows Server OS. This option provides more control over the service hosting environment and can better support legacy applications.
Services deployed within Windows Azure containers and made available via Windows Azure instances establish service architectures that, on the surface, resemble typical Web service or REST service implementations. However, the nature of the back-end processing is highly extensible and scalable and can be further subject to various forms of Service Refactoring [783] over time to accommodate changing usage requirements. This highlights the need for Windows Azure hosted services to maintain the freedom to be independently governed and evolved. This, in turn, places a greater emphasis on the balanced design of the service contract and its proper separation as part of the overall service architecture.

Specifically, it elevates the importance of the Standardized Service Contract (693), Service Loose Coupling (695), and Service Abstraction (696) principles that, through collective application, shape and position service contracts to maximize abstraction and cross-service standardization, while minimizing negative forms of consumer and implementation coupling. Decoupled Contract [735] forms an expected foundation for Windows Azure-hosted service contracts, and there will generally be the need for more specialized contract-centric patterns, such as Validation Abstraction [792], Canonical Schema [718], and Schema Centralization [769].

SQL Azure
SQL Azure is a cloud-based relational database service built on SQL Server technologies that exposes a fault-tolerant, scalable, and multi-tenant database service. SQL Azure does not exist as hosted instances of SQL Server. It also uses a cloud fabric layer to abstract and encapsulate the underlying technologies required for provisioning, server administration, patching, health monitoring, and lifecycle management. We are only required to deal with logical administration tasks, such as schema creation and maintenance, query optimization, and security ­management.

In addition to reliability and scalability improvements, SQL Azure's replication mechanism can be used to apply Service Data Replication [773] in support of the Service Autonomy (699) principle. This is significant, as individual service autonomy within cloud environments can often fluctuate due to the heavy emphasis on shared resources across pools of cloud-based services.

A SQL Azure database instance is actually implemented as three replicas on top of a shared SQL Server infrastructure managed by the cloud fabric. This cloud fabric delivers high availability, reliability, and scalability with automated and transparent replication and failover. It further supports load-balancing of consumer requests and the synchronization of concurrent, incremental changes across the replicas. The cloud fabric also handles concurrency conflict resolutions when performing bi-directional data synchronization between replicas by using built-in policies (such as last-writer-wins) or custom policies.

Because SQL Azure is built on SQL Server, it provides a familiar relational data model and is highly symmetric to on-premise SQL Server implementations. It supports most features available in the regular SQL Server database engine and can also be used with tools like SQL Server 2008 Management Studio, SQLCMD, and BCP, and SQL Server Integration Services for data migration.

Windows Azure Platform AppFabric
In Chapter 7, as part of our coverage of .NET Enterprise Services, we introduced Windows Server AppFabric. This represents the version of AppFabric that is local to the Windows Server environment. Windows Azure platform AppFabric (with the word "platform" intentionally not capitalized), is the cloud-based version of AppFabric that runs on Windows Azure.

Windows Azure platform AppFabric helps connect services within or across clouds and enterprises. It provides a Service Bus for connectivity across networks and organizational boundaries, and an Access Control service for federated authorization as a ­service.

The Service Bus acts as a centralized message broker in the cloud to relay messages between services and service consumers. It has the ability to connect to on-premise services through firewalls, NATs, and over any network topology.

Its features include:

  • Connectivity using standard protocols and standard WCF bindings
  • Multiple communication models (such as publish-and-subscribe, one-way messaging, unicast and multicast datagram distribution, full-duplex bi-directional connection-oriented sessions, peer-to-peer sessions, and end-to-end NAT traversal)
  • Service endpoints that are published and discovered via Internet-accessible URLs
  • Global hierarchical namespaces that are DNS and transport-independent
  • Built-in intrusion detection and protection against denial-of-service attacks

The Windows Azure Service Bus complies to the familiar Enterprise Service Bus [741] compound pattern, and focuses on realizing this pattern across network, security, and organizational domains. Service Bus also provides a service registry to provide registration and discovery of service metadata, which allows for the application of Metadata Centralization [754] and emphasizes the need to apply the Service Discoverability (702) principle.

Access Control acts as a centralized cloud-based security gateway that regulates access to cloud-based services and Service Bus communications, while integrating with standards-based identity providers (including enterprise directories such as Active Directory and online identity systems like Windows Live ID). Access Control and other Windows Azure-related security topics are covered in Chapter 17.

Unlike Windows Azure and SQL Azure, which are based on Windows Server and SQL Server, Access Control Service is not based on an existing server product. It uses technology included in Windows Identity Foundation and is considered a purely cloud-based service built specifically for the Windows Azure platform environment.

Summary of Key Points

  • The Windows Azure platform is primarily a PaaS deployed in a public cloud managed by Microsoft.
  • Windows Azure platform provides a distinct set of capabilities suitable for building scalable and reliable cloud-based services.
  • The overall Windows Azure platform further encompasses SQL Azure and Windows Azure platform AppFabric.

This excerpt is from the book, "SOA with .NET & Windows Azure: Realizing Service-Orientation with the Microsoft Platform", edited and co-authored by Thomas Erl, with David Chou, John deVadoss, Nitin Ghandi, Hanu Kommapalati, Brian Loesgen, Christoph Schittko, Herbjörn Wilhelmsen, and Mickie Williams, with additional contributions from Scott Golightly, Daryl Hogan, Jeff King, and Scott Seely, published by Prentice Hall Professional, June 2010, ISBN 0131582313, Copyright 2010 SOA Systems Inc. For a complete Table of Contents please visit: www.informit.com/title/0131582313

Authors
David Chou is a technical architect at Microsoft and is based in Los Angeles. His focus is on collaborating with enterprises and organizations in such areas as cloud computing, SOA, Web, distributed systems, and security.

John deVadoss leads the Patterns & Practices team at Microsoft and is based in Redmond, WA.

Thomas Erl is the world's top-selling SOA author, series editor of the Prentice Hall Service-Oriented Computing Series from Thomas Erl (www.soabooks.com), and editor of the SOA Magazine (www.soamag.com).

Nitin Gandhi is an enterprise architect and an independent software consultant, based in Vancouver, BC.

Hanu Kommalapati is a Principal Platform Strategy Advisor for a Microsoft Developer and Platform Evangelism team based in North America.

Brian Loesgen is a Principal SOA Architect with Microsoft, based in San Diego. His extensive experience includes building sophisticated enterprise, ESB and SOA solutions.

Christoph Schittko is an architect for Microsoft, based in Texas. His focus is to work with customers to build innovative solutions that combine software + services for cutting edge user experiences and the leveraging of service-oriented architecture (SOA) solutions.

Herbjörn Wilhelmsen is a consultant at Forefront Consulting Group, based in Stockholm, Sweden. His main areas of focus are Service-Oriented Architecture, Cloud Computing and Business Architecture.

Mickey Williams leads the Technology Platform Group at Neudesic, based in Laguna Hills,

Contributors
Scott Golightly is currently an Enterprise Solution Strategist with Advaiya, Inc; he is also a Microsoft Regional Director with more than 15 years of experience helping clients to create solutions to business problems with various technologies.

Darryl Hogan is an architect with more than 15 years experience in the IT industry. Darryl has gained significant practical experience during his career as a consultant, technical evangelist and architect.

As a Senior Technical Product Manager at Microsoft, Kris works with customers, partners, and industry analysts to ensure the next generation of Microsoft technology meets customers' requirements for building distributed, service-oriented solutions.

Jeff King has been working with the Windows Azure platform since its first announcement at PDC 2008 and works with Windows Azure early adopter customers in the Windows Azure TAP

Scott Seely is co-founder of Tech in the Middle, www.techinthemiddle.com, and president of Friseton, LLC,

More Stories By Thomas Erl

Thomas Erl is a best-selling IT author and founder of Arcitura Education Inc., a global provider of vendor-neutral educational services and certification that encompasses the Cloud Certified Professional (CCP) and SOA Certified Professional (SOACP) programs from CloudSchool.com™ and SOASchool.com® respectively. Thomas has been the world's top-selling service technology author for nearly a decade and is the series editor of the Prentice Hall Service Technology Series from Thomas Erl, as well as the editor of the Service Technology Magazine. With over 175,000 copies in print world-wide, his eight published books have become international bestsellers and have been formally endorsed by senior members of many major IT organizations and academic institutions. To learn more, visit: www.thomaserl.com

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


IoT & Smart Cities Stories
The challenges of aggregating data from consumer-oriented devices, such as wearable technologies and smart thermostats, are fairly well-understood. However, there are a new set of challenges for IoT devices that generate megabytes or gigabytes of data per second. Certainly, the infrastructure will have to change, as those volumes of data will likely overwhelm the available bandwidth for aggregating the data into a central repository. Ochandarena discusses a whole new way to think about your next...
DXWorldEXPO LLC announced today that Big Data Federation to Exhibit at the 22nd International CloudEXPO, colocated with DevOpsSUMMIT and DXWorldEXPO, November 12-13, 2018 in New York City. Big Data Federation, Inc. develops and applies artificial intelligence to predict financial and economic events that matter. The company uncovers patterns and precise drivers of performance and outcomes with the aid of machine-learning algorithms, big data, and fundamental analysis. Their products are deployed...
Dynatrace is an application performance management software company with products for the information technology departments and digital business owners of medium and large businesses. Building the Future of Monitoring with Artificial Intelligence. Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more busine...
All in Mobile is a place where we continually maximize their impact by fostering understanding, empathy, insights, creativity and joy. They believe that a truly useful and desirable mobile app doesn't need the brightest idea or the most advanced technology. A great product begins with understanding people. It's easy to think that customers will love your app, but can you justify it? They make sure your final app is something that users truly want and need. The only way to do this is by ...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO are the world's most influential, independent events where Cloud Computing was coined and where technology buyers and vendors meet to experience and discuss the big picture of Digital Transformation and all of the strategies, tactics, and tools they need to realize their goals. Sponsors of DXWorldEXPO | CloudEXPO benefit from unmatched branding, profile building and lead generation opportunities.
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
Cell networks have the advantage of long-range communications, reaching an estimated 90% of the world. But cell networks such as 2G, 3G and LTE consume lots of power and were designed for connecting people. They are not optimized for low- or battery-powered devices or for IoT applications with infrequently transmitted data. Cell IoT modules that support narrow-band IoT and 4G cell networks will enable cell connectivity, device management, and app enablement for low-power wide-area network IoT. B...
The hierarchical architecture that distributes "compute" within the network specially at the edge can enable new services by harnessing emerging technologies. But Edge-Compute comes at increased cost that needs to be managed and potentially augmented by creative architecture solutions as there will always a catching-up with the capacity demands. Processing power in smartphones has enhanced YoY and there is increasingly spare compute capacity that can be potentially pooled. Uber has successfully ...
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things'). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing. IoT is not about the devices, its about the data consumed and generated. The devices are tools, mechanisms, conduits. This paper discusses the considerations when dealing with the...