Legacy Apps Make the Case for the Cloud
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BuzzBy John Considine
We often talk about CloudSwitch moving legacy applications to the cloud in a simple and secure way; this raises the question of what exactly we mean by “legacy.” To be more specific, we mean a broad range of apps—including third-party, custom and customized off-the-shelf applications—basically any application that has been developed in your current environment without specific design for a cloud.
It turns out that these existing applications are very important in cloud computing. When we started building CloudSwitch, we were focused on the hybrid cloud computing model; that is, some components must stay in the data center and other applications and functions can move to the cloud. However, it became apparent that “stretching” applications between the data center and cloud only works for certain types of deployments due to the added latency between the data center and the cloud. For this reason, we recommend moving as much of a multi-tier application to the cloud as you can. This allows the application to continue to run with low latencies between the different components. Sounds obvious, but this is where a whole new set of problems arise, and it’s what causes people to start talking about the challenges of moving legacy applications to the cloud.
In order to operate a multi-tier application in the cloud, you need to be able to control the application(s), infrastructure, and operating system, including things like a database tier, middleware, and custom applications. This also means that you have to “cloudify” each of these components. Suddenly you are looking at a lot of work, and potentially facing failure because some of those tiers can’t be modified to run in the cloud.
We saw a great example of this when Microsoft’s Azure service first launched. The initial release of Azure allowed application developers to build .NET applications and run them seamlessly on their local machines or in the Azure cloud. However, people trying to use this cloud usually had other applications/databases/etc. that were part of their solution, and there was no way to run these in Azure. This meant that there were a lot of things that could not be moved to Azure since “stretching” the application caused unacceptable latency and there was no way to connect the Azure deployment to the data center-side applications. Microsoft has since expanded the capabilities of Azure, but there are still many types of applications and services that cannot run in their environment.
Given all the challenges, why is it worth bothering to move legacy applications to the cloud? For most enterprises (as opposed to new ventures and SMBs), legacy apps by definition occupy the majority of the existing IT footprint, far more than newer applications, let alone those designed specifically to run in a cloud. In many of the companies we’ve worked with, legacy apps are well over 75% of the data center footprint, and they’re constantly expanding and creating needs for more capacity. Legacy apps tie up internal processing and storage resources, sometimes continually, sometimes in a “spiky” way to meet occasional massive needs. Their demand for computing power is usually growing (or skyrocketing), and contending with other applications. The enterprise then has to make tough choices about whether to buy more equipment or put up with degraded performance.
By providing access to virtually unlimited resources on demand, the cloud can bring a new level of elasticity and efficiency to a company’s IT environment. Legacy apps are often the best candidates for moving to the cloud, especially in cases where they’re infrequently used, or only need to scale for new releases or for seasonal/marketing-driven events. One of the best use cases for the cloud so far is the ability to offload this type of resource-consuming set of apps to a lower-cost cloud infrastructure, freeing IT to focus limited internal resources where they’re needed most.
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