Thinking of migrating applications to the cloud? Don’t know where to start? Fear not, Gartner is here to guide you.
Put simply, you have five choices, according to the analyst house: "Rehost on infrastructure as a service (IaaS), refactor for platform as a service (PaaS), revise for IaaS or PaaS, rebuild on PaaS, or replace with software as a service (SaaS)."
"When the CIO issues the simple directive: ‘Move some applications to the cloud’, architects face bewildering choices about how to do this, and their decision must consider an organisation’s requirements, evaluation criteria, and architecture principles," said Richard Watson, research director at Gartner.
"However, no alternative offers a silver bullet: all require architects to understand application migration from multiple perspectives and criteria, such as IT staff skills, the value of existing investments, and application architecture," he added.
Let’s dive down into more detail about those:
Rehost: This means redeploying applications to a different hardware environment and change the application’s infrastructure configuration. It’s certainly a fast way of migrating apps to the cloud but you will miss out on one of the primary advantages of IaaS in scalability, Gartner reckons.
Refactor: meaning run applications on a cloud provider’s infrastructure. Benefits of this approach include the ability to reuse languages, frameworks and containers they have invested in, says Gartner. Missing capabilities and framework lock-in are the disadvantages though.
Revise: This means modifying or extending existing code base to support legacy modernisation requirements before use rehosting or refactoring options to deploy to cloud. The obvious drawback to this method is the upfront cost of a major development process and the time it could take. Gartner believes this enables businesses to, "optimise the application to leverage the cloud characteristics of providers’ infrastructure," the company said in its report.
Rebuild: Essentially this means discarding the code for an existing application and re-architect the application specifically for a PaaS environment. You’ll lose the familiarity of existing code, says Gartner, but you’ll be able to rebuild an app to take advantage of the provider’s platform.
Replace: Does exactly what it says on the tin; discard an existing application (or set of applications) and use commercial software delivered as a service. "This option avoids investment in mobilising a development team when requirements for a business function change quickly. Disadvantages can include inconsistent data semantics, data access issues, and vendor lock-in," says Gartner’s report.
"Choosing the optimal application-migration option is a decision that cannot be made in isolation," said Watson. "Any cloud-migration decision is, in essence, an application or infrastructure modernisation decision and needs to be approached in the broader context of related application portfolio management and infrastructure portfolio management programmes."
"This decision is not solely an issue of migration but is truly one of optimisation: Which cloud platform and migration techniques offer the chance to optimise the application’s contribution to stated and implied business and IT goals? Those business and supporting IT goals, described next, should be driving any cloud migration decision — not a rush to experiment with new toys," he adds.
There are companies out there that will help with cloud migration, including CIMtrek, founded by ex-Staffware, The Process Factory and Cordys man Jon Pyke. Its initial focus is on helping companies to automatically migrate their Lotus Notes databases to the cloud, in a common format that could be hosted on the likes of Amazon, Google or salesforce.com’s cloud platforms.
You can read our interview with Jon Pyke about CIMtrek’s launch here.
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