One of the fundamental tenants of IBM Workload Deployer is a choice of cloud deployment models. Starting in v3.0, users will be able to deploy to the cloud using virtual appliances (OVA files), virtual system patterns, or virtual application patterns. The ability to provision plain virtual appliances is a way to rapidly bring your own images, as they currently exist, into the provisioning realm of the appliance. As such, I think the use cases and basis for deciding to use this deployment model are fairly evident. However, when comparing the two patterns-based approaches, virtual system patterns and virtual application patterns, the decision requires a bit more scrutiny.
Our pattern approach is a good thing for you, the user. Basically, when we refer to patterns in the context of cloud, we are referring to the encapsulation of installation, configuration, and integration activities that make deploying and managing environments in a cloud much easier. Regardless of what kind of pattern you end up using, you benefit from treating a potentially complex middleware infrastructure environment or middleware application as a single atomic unit throughout its lifecycle (creation, deployment, and management). In turn, you benefit from decreased costs (administrative and operational) and increased agility via rapid, meaningful deployments of your environments. That said, it is imperative to understand the differences between virtual system and virtual application patterns, and more importantly, it is important to understand what those differences mean to you. Let’s start by considering the admittedly simple ‘Cloud Tradeoff’ continuum below.
In the above graph, the X-axis represents the degree to which you have customization control over the resultant environment. The degree of control gets lower as we move from left to right. The left Y-axis represents total cost of ownership (TCO), which decreases as we move up the axis. The right Y-axis represents time to value, which similarly decreases as we go up the axis. Naturally, enterprises want to move up the Y-axis, but, and it can be quite a big but, they are sometimes hesitant to relinquish much control (move to the right on the X-axis) in order to do so. In that light, I think it helps to explore our two patterns-based approaches a bit more.
The most important thing to understand about this continuum is that the X-axis really represents the customization control ability from the point of view of the deployer andconsumer of the environment. An example is probably the best way to explain. Let’s consider a fairly simple web service application that we want to deploy to the cloud. If we were to use a virtual system pattern to achieve this, we would probably start by using parts from the WebSphere Application Server Hypervisor Edition image to layout our topology. We may have a deployment manager, two custom nodes, and a web server. After establishing the topology, we would add custom script packages to install the web service application and then configure any resources the application depended on. Users that wanted to deploy the virtual system pattern would access it, provide configuration details such as the WAS cell name, node names, virtual resource allocation, and custom script parameters, and then deploy. Once deployed, users could access the environment and middleware infrastructure as they always have. That means they could run administrative scripts, access the administrative console provided by the deployed middleware software, and any other thing one would normally do. The difference in using virtual system patterns is not necessarily the operational model for deployed environments (though IBM Workload Deployer makes some things, like patching environments, much easier). Instead, the difference is primarily in the delivery model for these environments.
Using a virtual application pattern to support the same web service application results in a markedly different experience from both a deployment and management standpoint. In using this approach, a user would start by selecting a suitable virtual application pattern based on the application type. This may be one shipped by IBM, such as the IBM Workload Deployer Pattern for Web Applications, or it may be one created by the user through the extensibility mechanisms built into the appliance. After selecting the appropriate pattern, a user would supply the web service application, define functional and non-functional requirements for the application via policies, and then deploy. The virtual application pattern and IBM Workload Deployer provide the knowledge necessary to install, configure, and integrate the middleware infrastructure and the application itself. Once deployed, a user manages the resultant application environment through a radically simplified lens provided by IBM Workload Deployer. It provides monitoring and ongoing management of the environment in a context appropriate for the application. This means that there are typically no administrative consoles (as in the case of the virtual application pattern IBM ships), and users can only alter well-defined facets of the environment. It is a substantial shift in the mindset of deploying and managing middleware applications.
Okay, with that explanation in the bag, let’s revisit the diagram I inserted above. I hope it’s clear that, all things being equal, virtual application patterns indeed provide the lowest TCO and shortest TTV because of the degree to which they encapsulate the steps involved in setting up complex middleware application environments. So, let’s get back to my assertion that the customization control continuum really applies to the deployer and consumer. Why do I say that? It’s simple. In the case of either the virtual system pattern or the virtual application pattern, the pattern composer has quite a bit of liberty in how they construct things. Sure, we enable you right out of the chute by shipping pre-built, pre-configured IBM Hypervisor Edition images, as well as pre-built virtual system and virtual application patterns. The key is though, that the IBM Workload Deployer’s design and architecture also enables you to build your own patterns — be they the virtual system or virtual application type. With anywhere from a little to a lot of work, you can build virtual system and virtual application patterns tailored to your use cases and needs.
At this point, you may be saying, “Well now you have really confused things! How am I supposed to decide what kind of patterns-based approach fits my needs?” I have some advice in that regard. First, map your needs to things that we enable with the assets you get right out of the box with IBM Workload Deployer. If your application fits into the functional scope of one of the virtual application patterns that we ship, use it. If you can support the application by using IBM Hypervisor Edition images, virtual system patterns, and custom scripts, do it. In this way, you benefit most from the value offered by IBM Workload Deployer. However, if you find that you cannot use any of the assets we provide right out of the box (e.g. you want to deploy your environment on software not offered in IBM Hypervisor Edition form or in a virtual application pattern), then ask yourself one simple question: “What do I want my user’s experience to be?”
In this sense, I primarily mean a user to be a deployer or consumer of your patterns. You need to decide whether you favor the middleware infrastructure centric approach afforded by virtual system patterns, or if you prefer the application centric approach proffered by virtual application patterns. There is no way to answer this generically for all potential IBM Workload Deployer users. Instead, you have to look at your use case, understand what’s available to help you accomplish that use case, and finally, decide on what you want your user’s experience to be.