Using Microsoft Cloud Services

Microsoft's approach is to view cloud applications as software plus service. In this model, the cloud is another platform and applications can run locally and access cloud services or run entirely in the cloud and be accessed by browsers using standard Service Oriented Architecture (SOA) protocols.

Microsoft calls their cloud operating system the Windows Azure Platform. You can think of Azure as a combination of virtualized infrastructure to which the .NET Framework has been added as a set of .NET Services. The Windows Azure service itself is a hosted environment of virtual machines enabled by a fabric called Windows Azure AppFabric. You can host your application on Azure and provision it with storage, growing it as you need it. Windows Azure service is an Infrastructure as a Service offering.

A number of services interoperate with Windows Azure, including SQL Azure (a version of SQL
Server), SharePoint Services, Azure Dynamic CRM, and many of Windows Live Services comprising what is the Windows Azure Platform, which is a Platform as a Service cloud computing model.

Windows Live Services is a collection of applications and services that run on the Web. Some of these applications called Windows Live Essentials are add-ons to Windows and downloadable as applications. Other Windows Live Services are standalone Web applications viewable in a browser.

Exploring Microsoft Cloud Services

Microsoft Live is only one part of the Microsoft cloud strategy. The second part of the strategy is the extension of the .NET Framework and related development tools to the cloud. To enable .NET developers to extend their applications into the cloud, or to build .NET style applications that run completely in the cloud, Microsoft has created a set of .NET services, which it now refers to as the Windows Azure Platform.

Azure is a virtualized infrastructure to which a set of additional enterprise services has been layered on top, including:
• A virtualization service called Azure AppFabric that creates an application hosting environment. AppFabric (formerly .NET Services) is a cloud-enabled version of the .NET Framework.
• A high capacity non-relational storage facility called Storage.
• A set of virtual machine instances called Compute.
• A cloud-enabled version of SQL Server called SQL Azure Database.
• A database marketplace based on SQL Azure Database code-named “Dallas.”
• An xRM (Anything Relations Management) service called Dynamics CRM based on Microsoft
Dynamics.
• A document and collaboration service based on SharePoint called SharePoint Services.
• Windows Live Services, a collection of services that runs on Windows Live, which can be used in applications that run in the Azure cloud.

Defining the Windows Azure Platform

Azure is Microsoft's Infrastructure as a Service (IaaS) Web hosting service. Compared to Amazon's and Google's cloud services, Azure (the service) is a competitor to AWS. Windows Azure Platform is a competitor to Google's App Engine.

The software plus services approach 

Microsoft has a very different vision for cloud services than either Amazon or Google does. In Amazon's case, AWS is a pure infrastructure play. AWS essentially rents you a (virtual) computer on which to run your application. An Amazon Machine Image can be provisioned with an operating system, an enterprise application, or application stack, but that provisioning is not a prerequisite. An AMI is your machine, and you can configure it as you choose. AWS is a deployment enabler.

Google's approach with its Google App Engine (GAE) is to offer a cloud-based development platform on which you can add your program, provided that the program speaks the Google App Engine API and uses objects and properties from the App Engine framework. Google makes it possible to program in a number of languages, but you must write your applications to conform to Google's infrastructure. Google Apps lets you create a saleable cloud-based application, but that application can only work within the Google infrastructure, and the application is not easily ported to other environments.

Microsoft sees the cloud as being a complimentary platform to its other platforms. The company envisages a scenario where a Microsoft developer with an investment in an application wants to extend that application's availability to the cloud. Perhaps the application runs on a server, desktop, or mobile device running some form of Windows. Microsoft calls this approach software plus services.

The Windows Azure Platform allows a developer to modify his application so it can run in the cloud on virtual machines hosted in Microsoft datacenters. Windows Azure serves as a cloud operating system, and the suitably modified application can be hosted on Azure as a runtime application where it can make use of the various Azure Services. Additionally, local applications running on a server, desktop, or mobile device can access Windows Azure Services through the Windows Services Platform API.

The Azure Platform

With Azure's architecture (shown in Figure 10.4), an application can run locally, run in the cloud, or some combination of both. Applications on Azure can be run as applications, as background processes or services, or as both.

The Azure Windows Services Platform API uses the industry standard REST, HTTP, and XML
protocols that are part of any Service Oriented Architecture cloud infrastructure to allow applications to talk to Azure. Developers can install a client-side managed class library that contains functions that can make calls to the Azure Windows Services Platform API as part of their applications. These API functions have been added to Microsoft Visual Studio as part of Microsoft's Integrated Development Environment (IDE).

The Azure Service Platform hosts runtime versions of .NET Framework applications written in any of the languages in common use, such as Visual Basic, C++, C#, Java, and any application that has been compiled for .NET's Common Language Runtime (CLR). Azure also can deploy Web-based applications built with ASP.NET, the Windows Communication Foundation (WCF), and PHP, and it supports Microsoft's automated deployment technologies. Microsoft also has released SDKs for both Java and Ruby to allow applications written in those languages to place calls to the Azure Service Platform API to the AppFabric Service.

The Windows Azure service

Windows Azure is a virtualized Windows infrastructure run by Microsoft on a set of datacenters around the world.

Six main elements are part of Windows Azure:

• Application: This is the runtime of the application that is running in the cloud.

• Compute: This is the load-balanced Windows server computation and policy engine that allows you to create and manage virtual machines that serve either in a Web role and a Worker role.

A Web role is a virtual machine instance running Microsoft IIS Web server that can accept and
respond to HTTP or HTTPS requests. A Worker role can accept and respond to requests, but doesn't run IIS in that virtual machine. Worker roles can communicate with Azure Storage or through direct connections to clients.

• Storage: This is a non-relational storage system for large-scale storage.

Azure Storage Service lets you create drives, manage queues, and store BLOBs (Binary Large
Objects). You manipulate content in Azure Storage using the REST API, which is based on
standard HTTP requests and is therefore platform-independent. Stored data can be read using GETs, written with PUTs, modified with POSTs, and removed with DELETE requests. Azure Storage plays the same role in Azure that Amazon Simple Storage Service (S3) plays in
Amazon Web Services. For relational database services, SQL Azure may be used.

• Fabric: This is the Windows Azure Hypervisor, which is a version of Hyper-V that runs on Windows Server 2008.

• Config: This is a management service.

• Virtual machines: These are instances of Windows that run the applications and services that are part of a particular deployment.

The Windows Azure Platform extends applications running on other platforms to the cloud using Microsoft infrastructure and a set of enterprise services.

Windows Azure is a virtualized infrastructure that provides configurable virtual machines, independent storage, and a configuration interface. The portion of the Azure environment that creates and manages a virtual resource pool is called the Fabric Controller. Applications that run on Azure are memory-managed, load-balanced, replicated, and backed up through snapshots automatically by the Fabric Controller.

Windows Azure AppFabric

Windows Azure AppFabric provides a comprehensive cloud middleware platform for developing, deploying and managing applications on the Windows Azure Platform. It delivers additional developer productivity, adding in higher-level Platform-as-a-Service (PaaS) capabilities on top of the familiar Windows Azure application model. It also enables bridging your existing applications to the cloud through secure connectivity across network and geographic boundaries, and by providing a consistent development model for both Windows Azure and Windows Server. Finally, it makes development more productive by providing a higher abstraction for building end-to-end applications, and simplifies management and maintenance of the application as it takes advantage of advances in the underlying hardware and software infrastructure. 

Middleware Services: platform capabilities as services, which raise the level of abstraction and reduce complexity of cloud development.

Composite Applications: a set of new innovative frameworks, tools and composition engine to easily assemble, deploy, and manage a composite application as a single logical entity

Scale-out application infrastructure: optimized for cloud-scale services and mid-tier components.

Azure Content Delivery Network

The Windows Azure Content Delivery Network (CDN) is a worldwide content caching and delivery system for Windows Azure blob content. Currently, more than 18 Microsoft datacenters are hosting this service in Australia, Asia, Europe, South America, and the United States, referred to as endpoints. CDN is an edge network service that lowers latency and maximizes bandwidth by delivering content to users who are nearby.

SQL Azure

SQL Azure is a cloud-based relational database service that is based on Microsoft SQL Server. Initially, this service was called SQL Server Data Service. An application that uses SQL Azure Database can run locally on a server, PC, or mobile device, in a datacenter, or on Windows Azure. Data stored in an SQL Azure database is accessed using the Tabular Data Stream (TDS) protocol, the same protocol used for a local SQL Server database. SQL Azure Database supports Transact-SQL statements.

Note: Because SQL Azure is managed in the cloud, there are no administrative controls over the SQL engine. You can't shut the system down, nor can you directly interact with the SQL Servers.

Windows Live Essentials

Windows Live Essentials applications are a collection of client-side applications that must be
downloaded and installed on a desktop. Some of these applications were once part of Windows and have been unbundled from the operating system; others are entirely new. Live Essentials rely on cloud-based services for their data storage and retrieval, and in some cases for their processing.

Windows Live Essentials currently includes the following:
• Family Safety
• Windows Live Messenger
• Photo Gallery
• Mail
• Movie Maker

Using Amazon Web Services

Working with the Elastic Compute Cloud (EC2)

Amazon Elastic Compute Cloud (EC2) is a virtual server platform that allows users to create and run virtual machines on Amazon's server farm. With EC2, you can launch and run server instances called Amazon Machine Images (AMIs) running different operating systems such as Red Hat Linux and Windows on servers that have different performance profiles. You can add or subtract virtual servers elastically as needed; cluster, replicate, and load balance servers; and locate your different servers in different data centers or “zones” throughout the world to provide fault tolerance. The term elastic refers to the ability to size your capacity quickly as needed.

The difference between an instance and a machine image is that an instance is the emulation of a hardware platform such as X86, IA64, and so on running on the Xen hypervisor. A machine image is the software and operating system running on top of the instance. A machine image may be thought of as the contents of a boot drive, something that you could package up with a program such as Ghost, Acronis, or TrueImage to create a single file containing the exact contents of a volume. A machine image should be composed of a hardened operating system with as few features and capabilities as possible and locked down as much as possible.

The pricing of these different AMI types depends on the operating system used, which data center the AMI is located in (you can select its location), and the amount of time that the AMI runs. Rates are quoted based on an hourly rate. Additional charges are applied for:
• the amount of data transferred
• whether Elastic IP Addresses are assigned
• your virtual private server's use of Amazon Elastic Block Storage (EBS)
• whether you use Elastic Load Balancing for two or more servers
• other features

System images and software

You can choose to use a template AMI system image with the operating system of your choice or create your own system image that contains your custom applications, code libraries, settings, and data. Security can be set through passwords, Kerberos tickets, or certificates.

These operating systems are offered:
• Red Hat Enterprise Linux
• OpenSuse Linux
• Ubuntu Linux
• Sun OpenSolaris
• Fedora
• Gentoo Linux
• Oracle Enterprise Linux
• Windows Server 2003/2008 32-bit and 64-bit up to Data Center Edition
• Debian

Most of the system image templates that Amazon AWS offers are based on Red Hat Linux, Windows Server, Oracle Enterprise Linux, and OpenSolaris. When you create a virtual private server, you can use the Elastic IP Address feature to create what amounts to a static IP v4 address to your server. This address can be mapped to any of your AMIs and is associated with your AWS account. You retain this IP address until you specifically release it from your AWS account. Should a machine instance fail, you can map your Elastic IP Address to fail over to a different AMI. You don't need to wait until a DNS server updates the IP record assignment, and you can use a form to configure the reverse DNS record of the Elastic IP address change.

 

Working with Amazon Storage Systems

When you create an Amazon Machine Instance you provision it with a certain amount of storage. That storage is temporal, it only exists for as long as your instance is running. All of the data contained in that storage is lost when the instance is suspended or terminated, as the storage is reassigned to the pool for other AWS users to use. For this and other reasons you need to have access to persistent storage. The Amazon Simple Storage System provides block storage, but is set up in a way that is somewhat unique from other storage systems you may have worked with in the past.

Amazon Simple Storage System (S3)

Amazon S3's cloud-based storage system allows you to store data objects ranging in size from 1 byte up to 5GB in a flat namespace. In S3, storage containers are referred to as buckets, and buckets serve the function of a directory, although there is no object hierarchy to a bucket, and you save objects and not files to it. It is important that you do not associate the concept of a filesystem with S3, because files are not supported; only objects are stored. Additionally, you do not “mount” a bucket as you do a filesystem.

The S3 system allows you to assign a name to a bucket, but that name must be unique in the S3 namespace across all AWS customers. Access to an S3 bucket is through the S3 Web API (either with SOAP or REST) and is slow relative to a real-world disk storage system. S3's performance limits its use to non-operational functions such as data archiving and retrieval or disk backup. The REST API is preferred to the SOAP API, because it is easier to work with large binary objects with REST.

The S3 service is used by many people as the third level backup component in a 3-2-1 backup strategy. That is, you have your original data (1), a copy of your data (2), and an off-site copy of your data (3); the latter of these may be S3.

Note: Keep in mind that while Amazon S3 is highly reliable, it is not highly available. You can definitely get your data back from S3 at some point with guaranteed 100% fidelity, but the service is not always connected and experiences service outages. 

Amazon Elastic Block Store (EBS)

The third of Amazon's data storage systems are devoted to Amazon Elastic Block Storage (EBS), which is a persistent storage service with a high operational performance. Advantages of EBS are that it can store file system information and its performance is higher and much more reliable than Amazon S3. That makes EBS valuable as an operational data storage medium for AWS. The cost of creating an EBS volume is also greater than creating a similarly sized S3 bucket.

CloudFront

Amazon CloudFront is referred to as a content delivery network (CDN), and sometimes called edge computing. In edge computing, content is pushed out geographically so the data is more readily available to network clients and has a lower latency when requested. You enable CloudFront through a selection in the AWS Management Console.

You can think of a CDN as a distributed caching system. CloudFront servers are located throughout the world—in Europe, Asia, and the United States. As such, CloudFront represents yet another level of Amazon cloud storage. A user requesting data from a CloudFront site is referred to the nearest geographical location. CloudFront supports “geo-caching” data by performing static data transfers and streaming content from one CloudFront location to another.

Understanding Amazon Database Services

Amazon offers two different types of database services: Amazon SimpleDB, which is non-relational, and Amazon Relational Database Service (Amazon RDS).

Amazon SimpleDB

Amazon SimpleDB is an attempt to create a high performance data store with many database features but without the overhead. To create a high performance “simple” database, the data store created is flat; that is, it is non-relational and joins are not supported. Data stored in SimpleDB domains doesn't require maintenances of a schema and is therefore easily scalable and highly available because replication is built into the system. Data is stored as collections of items with attribute-value pairs, and the system is akin to using the database function within a spreadsheet.

Amazon Relational Database Service (RDS)

Amazon Relational Database Service is a variant of the MySQL5.1 database system, but one that is somewhat simplified. The purpose of RDS is to allow database applications that already exist to be ported to RDS and placed in an environment that is relatively automated and easy to use. RDS automatically performs functions such as backups and is deployable throughout AWS zones using the AWS infrastructure.

In RDS, you start by launching a database instance in the AWS Management Console and assigning the DB Instance class and size of the data store. Any database tool that works with MySQL 5.1 will work with RDS. Additionally, you can monitor your database usage as part of Amazon CloudWatch.

Choosing a database for AWS

In choosing a database solution for your AWS solutions, consider the following factors in making your selection:
• Choose SimpleDB when index and query functions do not require relational database support.
• Use SimpleDB for the lowest administrative overhead.
• Select SimpleDB if you want a solution that autoscales on demand.
• Choose SimpleDB for a solution that has a very high availability.
• Use RDS when you have an existing MySQL database that could be ported and you want to
minimize the amount of infrastructure and administrative management required.
• Use RDS when your database queries require relation between data objects.

Using Google App Engine

Google App Engine (GAE) is a Platform as a Service (PaaS) cloud-based Web hosting service on Google's infrastructure.

This service allows developers to build and deploy Web applications and have Google manage all the infrastructure needs, such as monitoring, failover, clustering, machine instance management, and so forth. For an application to run on GAE, it must comply with Google's platform standards, which narrows the range of applications that can be run and severely limits those applications' portability.

GAE supports the following major features:
• Dynamic Web services based on common standards
• Automatic scaling and load balancing
• Authentication using Google's Accounts API
• Persistent storage, with query access sorting and transaction management features
• Task queues and task scheduling
• A client-side development environment for simulating GAE on your local system
• One of either two runtime environments: Java or Python

When you deploy an application on GAE, the application can be accessed using your own domain name or using the Google Apps for Business URL.

Google App Engine currently supports applications written in Java and in Python, although there are plans to extend support to more languages in the future. The service is meant to be language-agnostic. A number of Java Virtual Machine languages are compliant with GAE, as are several Python Web frameworks that support the Web Server Gateway Interface (WSGI) and CGI. Google has its own Webapp framework designed for use with GAE. The AppScale (http://appscale.cs.ucsb.edu/) open-source framework also may be used for running applications on GAE.

To encourage developers to write applications using GAE, Google allows for free application
development and deployment up to a certain level of resource consumption. Resource limits are described on Google's quota page at http://code.google.com/appengine/docs/quotas.html, and the quota changes from time to time.

When you enable billing for an application deployed to GAE, you pay for consumption of CPU, network I/O, and other usage above the level of the free quotas that GAE allows.

Applications running in GAE are isolated from the underlying operating system, which Google
describes as running in a sandbox. This allows GAE to optimize the system so Web requests can be matched to the current traffic load. It also allows applications to be more secure because applications can connect only to computers using the specified URLs for the e-mail and fetch services using HTTP or HTTPS over the standard well-known ports. URL fetch uses the same infrastructure that retrieves Web pages on Google. The mail service also supports Gmail's messaging system.

Applications also are limited in that they can only read files; they cannot write to the file system
directly. To access data, an application must use data stored in the memcache (memory cache), the datastore, or some other persistent service. Memcache is a fast in-memory key-value cache that can be used between application instances. For persistent data storage of transactional data, the datastore is used. Additionally, an application responds only to a specific HTTP request—in real-time, part of a queue, or scheduled—and any request is terminated if the response requires more than 30 seconds to complete.

The App Engine relies on the Google Accounts API for user authentication, the same system used when you log into a Google account. This provides access to e-mail and display names within your app, and it eliminates the need for an application to develop its own authentication system. Applications can use the User API to determine whether a user belongs to a specific group and even whether that person is an administrator for your application.

Exploring Platform as a Service

With Platform as a Service systems, you are given a toolkit to work with, a virtual machine to run your software on, and it is up to you to design the software and its user-facing interface in a way that is appropriate to your needs. So PaaS systems range from full-blown developer platforms like Windows Azure Platform to systems like Drupal, Squarespace, Wolf, and others where the tools are modules that are very well developed and require almost no coding.

Many Content Management Systems (CMS) are essentially PaaS services where you get standard parts and can build Web sites and other software like Tinker Toys.

The services provided by PAAS model is:

• Application development: A PaaS platform either provides the means to use programs you create in a supported language or offers a visual development environment that writes the code for you.
• Collaboration: Many PaaS systems are set up to allow multiple individuals to work on the same projects.
• Data management: Tools are provided for accessing and using data in a data store.
• Instrumentation, performance, and testing: Tools are available for measuring your applications
and optimizing their performance.
• Storage: Data can be stored in either the PaaS vendor's service or accessed from a third-party storage service.
• Transaction management: Many PaaS systems provide services such as transaction managers or brokerage service for maintaining transaction integrity.

PaaS systems exist to allow you to create software that can be hosted as SaaS systems or to allow for the modification of existing SaaS applications.

A good PaaS system has certain desirable characteristics that are important in developing robust, scalable, and hopefully portable applications. On this list would be the following attributes:
• Separate of data management from the user interface
• Reliance on cloud computing standards
• An integrated development environment (IDE)
• Lifecycle management tools
• Multi-tenant architecture support, security, and scalability
• Performance monitoring, testing, and optimization tools
 

Salesforce.com versus Force.com: SaaS versus PaaS

Force.com. Salesforce.com is a Web application suite that is an SaaS. Force.com is Salesforce.com's PaaS platform for building your own services.

The Salesforce.com team created hosted software based on a cloud computing model: pay as you go, simple to use, and multifunctional. The Salesforce.com platform looks like a typical Web site such as Amazon.com, with a multi-tabbed interface—each tab being an individual application.
 
Some of the applications included in the site are:
• Accounts and Contact
• Analytics and Forecasting
• Approvals and Workflow
• Chatter (Instant Messaging/Collaboration)
• Content Library
• E-mail and Productivity
• Jigsaw Business Data
• Marketing and Leads
• Opportunities and Quotes
• Partner Relationship
• Sales
• Service and Support

Because Salesforce.com is browser-based, it is platform-independent. However, the company has extended its audience to mobile devices, such as the Android, Blackberry, iPhone, and Windows Mobile Devices. It also has a server product that supports Salesforce.com applications in-house called the Resin Application Server.

The PAAS platform Force.com uses a Java-based programming language called Apex for its application building, and it has an interface builder called Visualforce that allows a developer to create interfaces using HTML, Flex, and AJAX. Visualforce uses an XML-type language in its visual interface builder.

Application development

A PaaS provides the tools needed to construct different types of applications that can work together in the same environment. These are among the common application types:
• Composite business applications
• Data portals
• Mashups of multiple data sources

A mashup is a Web page that displays data from two or more data sources. The various landmarks and overlays you find in Google Earth, or annotated maps, are examples of mashups.

These applications must be able to share data and run in a multi-tenant environment. To make applications work together more easily, a common development language such as Java or Python is usually offered. The more commonly used the language is, the more developers and developer services are going to be available to help users of platform applications. The use of application frameworks such as Ruby on Rails is useful in making application building easier and more powerful.

All PaaS application development must take into account lifecycle management. As an application ages, it must be upgraded, migrated, grown, and eventually phased out or ported. Many PaaS vendors offer systems that are integrated lifecycle development platforms. That is, the vendor provides a full software development stack for the programmer to use, and it isn't expected that the developer will need to go outside of the service to create his application.

An integrated lifecycle platform includes the following:
• The virtual machine and operating system (often offered by an IaaS)
• Data design and storage
• A development environment with defined Application Programming Interfaces
• Middleware
• Testing and optimization tools
• Additional tools and services

Google AppEngine, Microsoft Windows Azure Platform, Eccentex AppBase, LongJump, and Wolf are examples of integrated lifecycle platforms.

Some PaaS services allow developers to modify existing software. These services are referred to as anchored lifecycle platforms. Examples of an anchored lifecycle platform are QuickBooks.com and Salesforce.com. The applications in these two services are fixed, but developers can customize which applications the users see, how those applications are branded, and a number of features associated with the different applications. 

Using PaaS Application Frameworks

Application frameworks provide a means for creating SaaS hosted applications using a unified
development environment or an integrated development environment (IDE).

Many Web sites are based on the notion of information management and organization; they are referred to as content management systems (CMS). A database is a content management system, but the notion of a Web site as a CMS adds a number of special features to the
concept that includes rich user interaction, multiple data sources, and extensive customization and extensibility.

Some examples of Paas Application frameworks are:

• Drupal

The Drupal CMS is an example of this type of PaaS. It is extensively used and has broad industry impact, and it is a full-strength developer tool.

Note: The portability of the applications you create in a PaaS is an extremely valuable feature. If your service goes out of business, being able to port an application by simply redeploying that application to another IaaS can be a lifesaver. 

• Squarespace

Squarespace (http://www.squarespace.com/), is an example of a next-generation Web site builder and deployment tool that has elements of a PaaS development environment.

• Eccentex

Eccentex is a Culver City, California, company founded in 2005 that has a PaaS development platform for Web applications based on SOA component architecture to create what it calls Cloudware applications using its AppBase architecture.

• LongJump

LongJump (http://www.longjump.com/) is a Sunnyvale, California, company hosting service created in 2003 with a PaaS application development suite. Its development environment is based on Java and uses REST/SOAP APIs. LongJump's PaaS is based on standard Java/JavaScript, SOAP, and REST.

• WaveMaker

WaveMaker (http://www.wavemaker.com/) is a visual rapid application development environment for creating Java-based Web and cloud Ajax applications. The software is open-source and offered under the Apache license. WaveMaker is a WYSIWYG (What You See is What You Get) drag-and-drop environment that runs inside a browser. The metaphor used to build applications is described as the Model-View-Controller system of application architecture.

• Wolf Frameworks

Many application frameworks like Google AppEngine and the Windows Azure Platform are tied to the platform on which they run. You can't build an AppEngine application and port it to Windows Azure without completely rewriting the application. There isn't any particular necessity to build an application framework in this way, but it suits the purpose of these particular vendors: for Google to have a universe of Google applications that build on the Google infrastructure, and for Microsoft to provide another platform on which to extend .NET Framework applications for their developers.

If you are building an application on top of an IaaS vendor such as AWS, GoGrid, or RackSpace, what you really want are application development frameworks that are open, standards-based, and portable. Wolf Frameworks is an example of a PaaS vendor offering a platform on which you can build an SaaS solution that is open and cross-platform.

Wolf Frameworks is based on the three core Windows SOA standard technologies of cloud computing:
• AJAX, asynchronous Java
• XML
• .NET Framework

Wolf Frameworks uses a C# engine and supports both Microsoft SQL Server and MySQL database. Applications that you build in Wolf are 100-percent browser-based and support mashable and multisource overlaid content.





 

Capacity Planning

A capacity planner seeks to meet the future demands on a system by providing the additional capacity to fulfill those demands. Many people equate capacity planning with system optimization (or performance tuning, if you like), but they are not the same. System optimization aims to get more production from the system components you have. Capacity planning measures the maximum amount of work that can be done using the current technology and then adds resources to do more work as needed. 

If system optimization occurs during capacity planning, that is all to the good; but capacity planning efforts focus on meeting demand. If that means the capacity planner must accept the inherent inefficiencies in any system, so be it.

Capacity planning is an iterative process with the following steps:
1. Determine the characteristics of the present system.
2. Measure the workload for the different resources in the system: CPU, RAM, disk, network, and so forth.
3. Load the system until it is overloaded, determine when it breaks, and specify what is required to maintain acceptable performance. Knowing when systems fail under load and what factor(s) is responsible for the failure is the critical step in capacity planning.
4. Predict the future based on historical trends and other factors.
5. Deploy or tear down resources to meet your predictions.
6. Iterate Steps 1 through 5 repeatedly.

Performance Monitoring

Performance should be monitored to understand the capacity.  Capacity planning must measure system-level statistics, determining what each system is capable of, and how
resources of a system affect system-level performance.

Below is a list of some LAMP performance tools:
Alertra - Web site monitoring service
Cacti - Open source RRDTool graphing module
Collectd - System statistics collection daemon
Dstat - System statistics utility; replaces vmstat, iostat, netstat, and ifstat
Ganglia - Open source distributed monitoring system
RRDTool - Graphing and performance metrics storage utility
ZenOSS - Operations monitor, both open source and commercial versions

Load testing

Examining your server under load for system metrics isn't going to give you enough information to do meaningful capacity planning. You need to know what happens to a system when the load increases. That is the aim of Load Testing. Load testing is also referred to as performance testing, reliability testing, stress testing, and volume testing.


If you have one production system running in the cloud, then overloading that system until it breaks isn't going to make you popular with your colleagues. However, cloud computing offers virtual solutions. One possibility is to create a clone of your single system and then use a tool to feed that clone a recorded set of transactions that represent your application workload.

Two examples of applications that can replay requests to Web servers are HTTPerf
(http://hpl hp.com/research/linux/httperf/) and Siege (http://www.joedog.org/JoeDog/Siege), but both of these tools run the requests from a single client, which can be a resource limitation of its own. You can run Autobench (http://www xenoclast.org/autobench/) to run HTTPerf from multiple clients against your Web server, which is a better test.

You may want to consider these load generation tools as well:

• HP LodeRunner
• IBM Rational Performance Tester
• JMeter
• OpenSTA (http://opensta.org/)
• Micro Focus (Borland) SilkPerfomer

Resource Ceiling

During load testing over a certain load for a particular server, the CPU, RAM, and Disk I/O utilization rates rise but do not reach their resource ceiling. In this instance, the Network I/O reaches its maximum 100-percent utilization at about 50 percent of the tested load, and
this factor is the current system resource ceiling.

Network I/O is often a bottleneck in Web servers, and this is why, architecturally, Web sites prefer to scale out using many low-powered servers instead of scaling up with fewer but more powerful servers.

Let's consider a slightly more complicated case that you might encounter in MySQL database systems. Database servers are known to exhibit resource ceilings for either their file caches or their Disk I/O performance. To build high-performance applications, many developers replicate their master MySQL database and create a number of slave MySQL databases. All READ operations are performed on the slave MySQL databases, and all WRITE operations are performed on the master MySQL database. A master/slave database system has two competing processes and the same server that are sharing a common resource: READs and WRITEs to the master/slave databases, and replication traffic between the master database and all the slave databases.

These types of servers reach failure when the amount of WRITE traffic in the form of INSERT, UPDATE, and DELETE operations to the master database overtakes the ability of the system to replicate data to the slave databases that are servicing SELECT (query/READ) operations.

Network Capacity

There are three aspects to assessing network capacity:
• Network traffic to and from the network interface at the server, be it a physical or virtual interface or server
• Network traffic from the cloud to the network interface
• Network traffic from the cloud through your ISP to your local network interface (your computer)

To measure network traffic at a server's network interface, you need to employ what is commonly known as a network monitor, which is a form of packet analyzer. Microsoft includes a utility called the Microsoft Network Monitor as part of its server utilities, and there are many third-party products in this area.

Alternative names for network analyzer include packet analyzer, network traffic monitor, protocol analyzer, packet sniffer, and Ethernet sniffer, and for wireless networks, wireless or wifi sniffer, network detector, and so on.

Scaling

In capacity planning, after you have made the decision that you need more resources, you are faced with the fundamental choice of scaling your systems. You can either scale vertically (scale up) or scale horizontally (scale out), and each method is broadly suitable for different types of applications.

To scale vertically, you add resources to a system to make it more powerful. For example, during scaling up, you might replace a node in a cloud-based system that has a dual-processor machine instance equivalence with a quad-processor machine instance equivalence. You also can scale up when you add more memory, more network throughput, and other resources to a single node. Scaling out indefinitely eventually leads you to an architecture with a single powerful supercomputer.

Vertical scaling allows you to use a virtual system to run more virtual machines (operating system instance), run more daemons on the same machine instance, or take advantage of more RAM (memory) and faster compute times. Applications that benefit from being scaled up vertically include those applications that are processor-limited such as rendering or memory-limited such as certain database operations—queries against an in-memory index, for example.

Horizontal scaling or scale out adds capacity to a system by adding more individual nodes. In a system where you have a dual-processor machine instance, you would scale out by adding more dual-processor machines instances or some other type of commodity system. Scaling out indefinitely leads you to an architecture with a large number of servers (a server farm), which is the model that many cloud and grid computer networks use.

Horizontal scaling allows you to run distributed applications more efficiently and is effective in using hardware more efficiently because it is both easier to pool resources and to partition them. Although your intuition might lead you to believe otherwise, the world's most powerful computers are currently built using clusters of computers aggregated using high speed interconnect technologies such as InfiniBand or Myrinet. Scale out is most effective when you have an I/O resource ceiling and you can eliminate the communications bottleneck by adding more channels. Web server connections are a classic example of this situation.

Understanding Abstraction and Virtualization

Load Balancing and Virtualization

One characteristic of cloud computing is virtualized network access to a service. No matter where you access the service, you are directed to the available resources. The technology used to distribute service requests to resources is referred to as load balancing.

Load balancing is an optimization technique; it can be used to increase utilization and throughput, lower latency, reduce response time, and avoid system overload.

Load balancer uses different types of algorithm to decide where the traffic is routed. It also creates a session so that subsequent traffic related to that session is routed to the same resource.

Advanced load balancing

The more sophisticated load balancers are workload managers. They determine the current utilization of the resources in their pool, the response time, the work queue length, connection latency and capacity, and other factors in order to assign tasks to each resource.

An Application Delivery Controller (ADC) is a combination load balancer and application server that is a server placed between a firewall or router and a server farm providing Web services. An Application Delivery Controller is assigned a virtual IP address (VIP) that it maps to a pool of servers based on application specific criteria. An ADC is a combination network and application layer device. You also may come across ADCs referred to as a content switch, multilayer switch, or Web switch.

An ADC is considered to be an advanced version of a load balancer as it not only can provide the features described in the previous paragraph, but it conditions content in order to lower the workload of the Web servers.

Understanding Hypervisors

Load balancing virtualizes systems and resources by mapping a logical address to a physical address. Another fundamental technology for abstraction creates virtual systems out of physical systems.

Given a computer system with a certain set of resources, you can set aside portions of those resources to create a virtual machine. From the standpoint of applications or users, a virtual machine has all the attributes and characteristics of a physical system but is strictly software that emulates a physical machine. A system virtual machine (or a hardware virtual machine) has its own address space in memory, its own processor resource allocation, and its own device I/O using its own virtual device drivers. Some virtual machines are designed to run only a single application or process and are referred to as process virtual machines.

Virtual machines provide the capability of running multiple machine instances, each with their own operating system.

From the standpoint of cloud computing, these features enable VMMs to manage application
provisioning, provide for machine instance cloning and replication, allow for graceful system failover, and provide several other desirable features. The downside of virtual machine technologies is that having resources indirectly addressed means there is some level of overhead.

Virtual machine types

A low-level program is required to provide system resource access to virtual machines, and this program is referred to as the hypervisor or Virtual Machine Monitor (VMM). A hypervisor running on bare metal is a Type 1 VM or native VM. Examples of Type 1 Virtual Machine Monitors are LynxSecure, RTS Hypervisor, Oracle VM, Sun xVM Server, VirtualLogix VLX, VMware ESX and ESXi, and Wind River VxWorks, among others. The operating system loaded into a virtual machine is referred to as the guest operating system, and there is no constraint on running the same guest on multiple VMs on a physical system. Type 1 VMs have no host operating system because they are installed on a bare system.

Some hypervisors are installed over an operating system and are referred to as Type 2 or hosted VM. Examples of Type 2 Virtual Machine Monitors are Containers, KVM, Microsoft Hyper V, Parallels Desktop for Mac, Wind River Simics, VMWare Fusion, Virtual Server 2005 R2, Xen, Windows Virtual PC, and VMware Workstation 6.0 and Server, among others.

On a Type 2 VM, a software interface is created that emulates the devices with which a system would normally interact. This abstraction is meant to place many I/O operations outside the virtual environment, which makes it both programmatically easier and more efficient to execute device I/O than it would be inside a virtual environment. This type of virtualization is sometimes referred to as paravirtualization, and it is found in hypervisors such as Microsoft's Hyper-V and Xen. It is the host operating system that is performing the I/O through a para-API.

 

There is a difference between emulation, paravirtualization, and full virtualization. In emulation, the virtual machine simulates hardware, so it can be independent of the underlying system hardware. A guest operating system using emulation does not need to be modified in any way. Paravirtualization requires that the host operating system provide a virtual machine interface for the guest operating system and that the guest access hardware through that host VM. An operating system running as a guest on a paravirtualization system must be ported to work with the host interface. Finally, in a full virtualization scheme, the VM is installed as a Type 1 Hypervisor directly onto the hardware. All operating systems in full virtualization communicate directly with the VM hypervisor, so guest operating systems do not require any modification.
Guest operating systems in full virtualization systems are generally faster than other virtualization schemes.

The Virtual Machine Interface (VMI) open standard (http://vmi ncsa.uiuc.edu/) that VMware has
proposed is an example of a paravirtualization API.

 

Process or application virtual machines

Most folks run the Java Virtual Machine or Microsoft's .NET Framework VM (called the Common Language Runtime or CLR) on their computers. A process virtual machine instantiates when a command begins a process, the VM is created by an interpreter, the VM then executes the process, and finally the VM exits the system and is destroyed. During the time the VM exists, it runs as a high-level abstraction.

Operating system virtualization

Some operating systems such as Sun Solaris and IBM AIX 6.1 support a feature known as operating system virtualization. This type of virtualization creates virtual servers at the operating system or kernel level. Each virtual server is running in its own virtual environment (VE) as a virtual private server (VPS). Different operating systems use different names to describe these machine instances, each of which can support its own guest OS. However, unlike true virtual machines, VPS must all be running the same OS and the same version of that OS. Sun Solaris 10 uses VPS to create what is called Solaris Zones. With IBM AIX, the VPS is called a System Workload Partition (WPAR). This type of virtualization allows for a dense collection of virtual machines with relatively low overhead.

Understanding Machine Imaging

As it is apparent by now abstraction in cloud computing can be achieved through redirection and virtualization. A third mechanism is commonly used to provide system portability, instantiate applications, and provision and deploy systems in the cloud. This third mechanism is through storing the state of a systems using a system image.

A system image makes a copy or a clone of the entire computer system inside a single container such as a file. The system imaging program is used to make this image and can be used later to restore a system image. Some imaging programs can take snapshots of systems, and most allow you to view the files contained in the image and do partial restores.

A prominent example of a system image and how it can be used in cloud computing architectures is the Amazon Machine Image (AMI) used by Amazon Web Services to store copies of a virtual machine. An AMI is a file system image that contains an operating system, all appropriate device drivers, and any applications and state information that the working virtual machine would have.

Porting Applications

Cloud computing applications have the ability to run on virtual systems and for these systems to be moved as needed to respond to demand. Systems (VMs running applications), storage, and network assets can all be virtualized and have sufficient flexibility to give acceptable distributed WAN application performance.

Developers who write software to run in the cloud will undoubtedly want the ability to port their applications from one cloud vendor to another, but that is a much more difficult proposition. Cloud computing is a relatively new area of technology, and the major vendors have
technologies that don't interoperate with one another.

The Simple Cloud API
If you build an application on a platform such as Microsoft Azure, porting that application to Amazon Web Services or GoogleApps may be difficult, if not impossible. In an effort to create an interoperability standard, Zend Technologies has started an open source initiative to create a common application program interface that will allow applications to be portable.

The initiative is called the Simple API for Cloud Application Services (http://www.simplecloud.org/), and the effort has drawn interest from several major cloud computing companies. Among the founding supporters are IBM, Microsoft, Nivanix, Rackspace, and GoGrid.


AppZero Virtual Application Appliance
Applications that run in datacenters are captive to the operating systems and hardware platforms that they run on. So moving an application from one platform to another isn't nearly as simple as moving a machine image from one system to another.

The situation is further complicated by the fact that applications are tightly coupled with the operating systems on which they run. An application running on Windows, for example, isn't isolated from other applications. When the application loads, it often loads or uses different Dynamic Link Libraries (DLL), and it is through the sharing or modification of DLLs that Windows applications get themselves in trouble. Further modifications include modifying the registry during installation. These factors make it difficult to port applications from one platform to another without lots of careful work. If you are a Platform as a Service (PaaS) application developer, you are packaging a complete software stack that includes not only your application, but the operating system and application logic and rules as well.0Vendor lock-in for you application is assured.

The ability to run an application from whatever platform you want is not one of the characteristics of cloud computing, but you can imagine that it is a very attractive proposition. While the Simple Cloud API is useful for applications written in PHP, other methods may be needed to make applications easily portable. One company working on this problem is AppZero (http://www.appzero.com/), and its solution is called the Virtual Application Appliance (VAA). The AppZero solution creates a virtual application appliance as an architectural layer between the Windows or the UNIX operating system and applications. The virtualization layer serves as the mediator for file I/O, memory I/O, and application calls and response to DLLs, which has the effect of sandboxing the application. The running application in AppZero changes none of the registry entries or any of the files on the Windows Server.

VAA creates a container that encapsulates the application and all the application's dependencies within a set of files; it is essentially an Application Image for a specific OS. Dependencies include DLL, service settings, necessary configuration files, registry entries, and machine and network settings. This container forms an installable server-side application stack that can be run after installation, but has no impact on the underlying operating system. VAAs are created using the AppZero Creator wizard, managed with the AppZero Admin tool, and may be installed using the AppZero Director, which creates a VAA runtime application. If desired, an application called AppZero Dissolve removes the VAA virtualization layer from the encapsulated application and installs that application directly into the operating system.