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Hybrid cloud: The best of public and private clouds

Hybrid clouds are gaining acceptance in the enterprise. With three ways to build a hybrid cloud, you need to know which integration method is best.

While the term “private cloud” means custom cloud technology for enterprises, most believe their own data centers already provide private cloud services. Since these companies also expect to adopt at least some public cloud services, the next step clearly is to build a hybrid cloud

But if hybridization isn’t a partnership between a public cloud and a private cloud that are built on common technologies, how does it happen? Companies expect worker application experiences to be transparent to where the application runs, which means either the experiences or the applications must be integrated in a hybrid cloud regardless of how the “private” portion is created.

A hybrid cloud’s success begins by selecting the right integration method.

Building a hybrid cloud with a front-end application

The dominant strategy in creating a hybrid cloud that ties traditional data centers with public cloud services involves the use of a front-end application. Most companies have created Web-based front-end applications that give customers access to order entry and account management functions, for example. Many companies have also used front-end application technologies from vendors like Citrix Systems Inc. to assemble the elements of several applications into a single custom display for end users. You can use either of these front-end methods to create a hybrid cloud.

In front-end application-based hybrid models, applications located in the cloud and the data center run normally; integration occurs at the front end. There are no new or complicated processes for integrating data or sharing resources between public and private clouds.

The application front-end integration method can be used with all three public cloud models—Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). If a new application is cloudsourced or an existing application is moved from the cloud back into the data center, you can easily alter the front-end application and transfer data from the new location.

Using the integrated workflow model for hybrid clouds

The front-end application-based hybrid cloud model has some limitations; it doesn’t allow for resource sharing between the data center and the public cloud. A user sees a composite view of applications, but each runs independently. If an admin wants the public cloud to back up critical applications or provide overflow capacity in peak periods, admins should use the integrated workflow model.

To create an integrated workflow model, you can use either enhance virtualization software with cloud resource management components such as vCloud from VMware, or expand the resource-allocation tools associated with most SOA platforms -- Microsoft, Oracle and IBM offer this capability -- to recognize cloud-hosted resources as well as those located in the data center.

All distributed-workflow models for hybrid cloud presume that some element monitors resource availability and assigns resources to tasks as needed. This process will move applications and components within and between the cloud and data center, so it requires a directory function to link a dynamic application’s location to end users.

It’s also essential to ensure the data that applications need is available in the data center and the cloud. This, according to enterprises, is the most problematic issue with distributing workflow in hybrid clouds. Relatively static data can be hosted in both locations, but dynamic data access requires that data center applications and cloud applications are connected to a common repository.

Tightly coupled workflows magnify any delays the communication connection creates between the enterprise data center and the public cloud; this connection will be more costly if you need to improve performance and reduce delays. Any additional costs could limit the value of a hybrid model for some companies; however, Windows Azure is moving toward an integrated workflow model, and it is likely that most PaaS clouds will follow suit.

Nontraditional hybrid cloud: VPN-integrated access

A third way to build a hybrid cloud is by using a VPN-integrated access mode in which public cloud and data center resources are connected to the corporate VPN, allowing end users to access them independently. For some, this isn’t a true hybrid cloud model because the cloud and the data center remain completely independent. But many businesses don’t provide an integrated view of their internal applications, and the VPN-integrated hybrid cloud model replicates their current practices.

VPN integration is usually the cheapest and easiest of the three hybrid cloud models. When enterprises examine the practical business costs and benefits of public cloud, they often find it’s most suitable for niche applications that don’t access the company’s core data.

Hosting customer relationship management (CRM) applications as well as payroll, personnel, communications and collaboration apps in the cloud doesn’t require admins to integrate any data or application. It allows companies to focus IT hardware and software investments on core, business-critical applications.

Picking the winning hybrid cloud model 

To choose the most appropriate hybrid cloud model, you need to determine which applications can be cloudsourced from a financial perspective. If these applications don’t use large quantities of mission-critical data, then any of the three hybrid approaches will work. However, either the front-end model or the VPN-integrated model will be the most effective, quickest to adopt and least expensive option.

The workflow integration model is a better choice for enterprises that have cloud applications that must access core data. In such instances, this option can be more cost effective and secure.

All three of these hybrid cloud models will work with any data center applications -- whether or not they use cloud-specific technology. Enterprises could safely adopt either model and develop it as the company advances its private cloud strategy and expands public cloud usage. That’s a win-win for the cloud.

About the author:
Tom Nolle is president of CIMI Corporation, a strategic consulting firm specializing in telecommunications and data communications since 1982.

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