Cloud Computing - ABC

If you only need milk, would you buy a cow? If not, please consider the cloud computing stack for your IT requirements.

There are 3 top flavors of cloud computing (new models are emerging like BpaS, DaaS etc.) – Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and the mother of all Software as a Service (SaaS). Let’s have a geek dive into these flavors.

SaaS is the most enhanced category of cloud services and so far the only segment of cloud computing that has proven useful as a business model. With SaaS, software applications are rented from a provider as opposed to purchased for enterprise installation and deployment. Typically the services are provided in a 'pay-as-you-go' model with payments charged on a monthly basis based on the number of users or services consumed. The key segments within the SaaS segments include messaging, collaboration and Customer Relationship Management (CRM). Salesforce.com is an example of a SAAS where ERP is used as an on demand service. Microsoft BPOS provides SharePoint, Exchange and CRM as a service over internet.

In simple terms, IaaS is selling hardware as a service over the cloud. The hardware includes processing power, firewalls, network load balancing, availability, storage and so on. The IaaS customer is the owner of software that has some SLA’s for end users. To meet these SLA’s (e.g. Availability, Performance, Security etc.) the software needs to be hosted in an environment that is built to provide the failover, compute power and security. The IaaS customer now needs a service provider who shall provide the hosting environment that meets the SLA’s. The IaaS service provider leverages virtualization to provide the computing power. The software owner needs to deploy the software in a virtual environment locally and then upload the Virtual Machine to the hosting environment of the IaaS service provider. From here, based on the SLA’s, the service provider configures and host the software application as per the SLA’s required.
The leading IaaS service providers are Amazon and Rackspace. The billing is generally based on processor usage, storage and data transfer. However, the additional billing items may include- security, compliance, usage reports etc.

PaaS provides an application platform in the cloud that lets you deploy any application you develop, or any application you acquire from another vendor. PaaS offerings generally include facilities for software application design, development, testing, deployment and hosting. PaaS may also include - database integration, security, scalability, storage, persistence, state management, application versioning, application instrumentation and developer community facilitation.
In short, PaaS makes all the required facilities that support the full software life cycle of building or delivering applications through the Web, while assuring the availability of services from the Internet
Windows Azure is an example of Platform as a Service. Azure is a foundation for running Windows applications and storing data in the cloud.
To run an application, a developer accesses the Windows Azure portal through her Web browser, signing in with a Windows Live ID. She then chooses whether to create a hosting account for running applications, a storage account for storing data, or both. Once the developer has a hosting account, she can upload her application, specifying how many instances the application needs. Windows Azure then creates the necessary Virtual Machines and runs the application.

I think it's getting complex now. I’ll take a pause and try to make it simple enough in upcoming posts.

Let’s Talk About SaaS

Before I write a blog post, I spend some time on understanding the concept from a geeks perspective. The intention is to simplify the concept and make it easier to understand / imagine (abstracting hi-tech lingo).

Let’s talk about SaaS… SaaS stands for Software as Service, which is becoming very popular trend in the software industry. Let’s try to understand how it’s different from have we have now (& had in past).

Hotmail.com, one of the most used online email software that is delivered as a service to end users. Now what is wrong in the hotmail that stops me tagging it as SaaS ? Salesforce.com is offering in-the-cloud version of CRM software that can be accessed over Internet. Both salesforce.com and hotmail doesn’t require any installation at user side and serves multiple users from single instance.

Salesforce delivers CRM, a line of business application and changes $59.00 per user per month, with no upfront cost. On the other side hotmail is a generic free email service available to internet users. The nature of the service is what differentiates a SaaS applications with other internet based (consumer) applications. A line of business SaaS application is a paid solution that addresses a business problem and requires a customized delivery channel.

When you want to get a line-of-business (LOB) application like an ERP; Currently, you will have to check for an ERP vendor, finalize the best fit solution, buy the hardware to install and plan for maintenance and customization. In the SaaS world the software is paid as it is consumed and the end user required no software or infrastructure to buy, install and maintain.

Though the concept sounds very exciting, there are lot of challenges that needs to be addressed for achieving the SaaS delivery model. There is a complete lifecycle considerations starting from Discovery, SLA, Security, Performance, Deployment etc.; which is beyond the scope of this topic; I’ll only mention the key considerations.

On the top is the multitenancy concept. This is like you have tenants in different apartments of a housing complex, sharing some common facilities (Beside having their private amenities). In SaaS, each tenant is the customer/ consumer of the hosted service instance. The multitenant-efficient SaaS offering supports a data model that allows sharing of the database and resources, while protecting data access to each of the individual tenants.

Next thing to consider is the ability to provide customized service based on the tenant while running a single instance of the service. This can be achieved by using metadata that describes the attributes of a tenant and map it with service. In other words, the behavior of service is defined by the metadata associated with each tenant. The level/ effort of customization required for each tenant is reduced by having the metadata.