legacy apps
The Trouble with Legacy Apps
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BuzzBy Ellen Rubin
Last week, I was on a panel at the CompTIA Breakaway conference in DC, with Scott Crenshaw from RedHat and Ron Culler from Secure Designs. Scott made an interesting comment about the three types of applications out there: (1) new apps that are being architected from scratch for the cloud; (2) legacy apps that are being re-architected for the cloud; and (3) everything else. It was a useful framework for our discussion about cloud migration and security, but it also made me think a bit about the issue of legacy apps and why these remain so controversial for the cloud industry.
If I had a dime for every panel discussion that led to a heated debate around whether or not to re-architect for the cloud… I think the heat around this issue reflects some underlying confusion about how to handle all those “annoying” legacy apps. It’s an area of particular interest to us here at CloudSwitch, so I’d like to share our thoughts and hopefully generate some additional productive discussion in the industry.
Let’s start with (1) new apps. High-profile customer stories from companies like Netflix are creating momentum around the idea of building enterprise apps – even mission-critical ones – to run specifically in the cloud. Of course, start-ups and SMB’s have been doing this for years, since they quickly realized that the cloud provides a low-capital way to get their businesses started and frees them from long-term expensive contracts with hosters and colos. But the idea of building greenfield enterprise apps that take advantage of the cloud’s agility & scalability is only slowly gaining traction.
This is due to several concerns of enterprise stakeholders. While individual developers love the idea of coding directly for the cool new platform of the cloud (without fighting corporate IT for access to servers), corporate IT often feels threatened by a new process/platform that may make them less relevant or able to set policies and standards. Corporate IT also recognizes that as the cloud apps go into production, all the serious issues around reliability, performance and integration will fall on them and may be extremely complex and difficult to manage. Security and networking teams have the expected concerns about changes to existing policies and access, and overall loss of control. And all groups share a fear of cloud lock-in since you’ve essentially built your app to run in a specific cloud.
Next there’s (2) teaching old legacy apps new tricks by re-architecting them for the cloud. This is appealing because it allows enterprises to move off outdated (and often costly) OS’s and hardware. It also allows the app to get true benefit from the scalability, geographic distribution and rapid provisioning of the cloud—and to run better in an environment where server performance and availability can be highly variable. Traditional legacy apps are often limited to scaling up vs out, and have requirements for network and storage configurations that may not exist in the cloud.
So why not re-architect? Most of the legacy apps we see at enterprise customers are either non-mission-critical (tier II, III) or less frequently used, with occasional bursts during peak periods. It’s not always economical to re-architect these or to spend precious developer resources on building/testing/supporting the new apps. Plus, the apps themselves may have some inherent limitations due to the age of their architectures (think SAP, SAS, Oracle Apps, etc. – apps that were designed long before the cloud gained attention, and that may not behave well if re-architected or may pose licensing challenges).
And finally, there’s (3) the “everything else” category – legacy apps that include all sorts of custom apps designed for specific purposes and business uses that may or may not still be important to the enterprise. You’d be amazed at how many of these there are. A typical F1000 enterprise can have hundred or even thousands of apps, and very few are mission-critical or worth the effort to re-architect. But there they are, sitting in your data center, still important for some particular group or maybe for compliance reasons, so you don’t want to get rid of them, either. The cloud is a great place to relocate these apps, and provides options for closer geographic proximity to the actual users, as well as the cost benefits of shutting down apps when not in use.
I find that among the “clouderati” there’s often a lack of interest in this last category of apps, mainly because they’re not very sexy or high profile. Enterprises, on the other hand, are pretty interested in them since they represent a large plurality (if not majority) of the apps that need to be considered in a broader cloud strategy. Also, since by definition these are not the critical apps that the enterprise depends on, they’re the easiest to try first in the cloud to show a low-risk success story to potential cloud users.
Large cloud providers and cloud enablement vendors are starting to take greater notice of legacy apps (both the kinds that should be re-architected as well as those that should be left alone). Amazon’s VPC strategy and VM migration tool reflect a growing recognition of legacy app requirements, as does VMware’s vCloud Director strategy, and Citrix’s CloudStack/CloudBridge. The industry as a whole has begun to focus on making it easier to migrate legacy apps and keeping them integrated with the enterprise environment they rely on.
This is good news for enterprise customers, and no surprise to us at CloudSwitch, where legacy apps have always been part of the vision. We believe that unless legacy apps can be safely and seamlessly run in any cloud environment with full enterprise control, enterprises will hold off adopting cloud in a major way. For every Netflix out there, there are hundreds of enterprises that will not build apps specifically for the cloud, or will only do this for a tiny percent of their application portfolios. And regardless of which category of app we’re discussing, you still need these apps to tie into enterprise management/monitoring systems, data, networking and security. Legacy apps are the proving ground for the cloud’s enterprise-readiness and maturity, and the industry should embrace this challenge head-on.
Legacy Apps Make the Case for the Cloud
By 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.
Legacy Apps: The Next Frontier in the Cloud
Although cloud computing momentum continues to build and scarcely a day goes by without a new cloud announcement or study, there’s been little real enterprise adoption and almost no meaningful case studies. In part, that’s because early cloud providers and vendors were focused on developers and technology start-ups when they designed their offerings, and larger, more established organizations were rarely on their radar screen. While start-ups can easily embrace new technologies and architectures, enterprises have far more constraints and have been largely limited to “tire kicking” the cloud with small applications that aren’t particularly meaningful for the business.
Cloud computing is now entering a new stage as CIOs and IT managers recognize that cloud computing is going to become an integral part of the enterprise computing environment. For it to be strategic as opposed to experimental, they need to know that the cloud can integrate with their existing data center infrastructure and incorporate the legacy applications that reside there. That’s where the major pain points, complexity, and costs have always been, and where the cloud can potentially offer its greatest returns. In our discussions with CIOs, we hear this theme over and over.
Legacy apps cover the entire installed base of applications running on a company’s internal infrastructure. They include everything from highly-used apps that are optimized for particular hardware to older versions of apps that must be maintained for specific customers as well as test and development environments, and apps used for internal purposes such as training. The true enterprise payoff for cloud computing will come from the ability to offload a wide range of legacy apps that don’t need to run in the data center to a cloud environment where they can be managed more cost-effectively. Not all legacy apps will make sense to move to the cloud initially (or perhaps ever), so the trick will be to select the right ones.
As Bernard Golden points out, the conundrum is that while putting legacy apps into the cloud can provide huge value for the enterprise, it’s also where the biggest hurdles lie. While a new application designed specifically for a cloud can usually be rolled out fairly easily, legacy apps come with a whole new set of challenges. Many of today’s cloud offerings were built for serving up web apps and Amazon-type storefronts, and have attributes that were not originally designed with the enterprise in mind (non-standard storage, isolated networking, and multi-tenancy are some examples). The result is lots of manual re-configuring, complex engineering, and trial and error before the enterprise application is able to run in the cloud. And once the app is in the cloud, it’s completely separate from the existing management tools and policies, and potentially locked-in to the cloud for which it has been re-architected. This lack of fast, incredibly simple ways to migrate legacy apps to the cloud and back without modification is one of the major factors holding back enterprise cloud adoption today.
CloudSwitch is focused on eliminating the barriers to moving legacy apps to the cloud. We believe applications should be able to run in the cloud “as is”, without worrying about the technical hurdles that today makes cloud deployments complex, time-consuming and expensive. We’re excited to be part of the “next frontier” in cloud adoption, working closely with enterprise customers and cloud providers.
