Application Provisioning
With the right system configuration in place, it’s time to install the applications. So why not use the same tools we used for the OS and middleware? Do we need yet another set of tools?”
It depends. You can use the same set of tools for middleware to install some applications. The middleware appears like an application to the OS as well. The difference is whether your application is stable enough and whether you need to customize per node. The tools like Puppet can be good for stable applications that can be deployed the same way across all nodes. If your application is still a work in progress and you need flexibility to tweak it, you need more specialized application provisioning tools.
The big technical difference between application and middleware provisioning tools is that application tools push the application to the nodes and remotely change anything as needed. The process is procedural.
The middleware provisioning tools normally have agents on the nodes to pull the software based on the prescribed configuration files. The process is declarative.
Beyond the “push” and “pull” difference, the application provisioning tools can also manage the lifecycles of applications (sometimes called services) distributed on different nodes with a single line of command or code. Given the nature of remote command dispatching framework, the application provisioning tool can do almost anything. If there has to be a limitation, it’s your imagination.
So if you develop applications by yourself, you most likely need application provisioning tools.
Let’s see what tools are there. Read more... (1601 words, 1 image, estimated 6:24 mins reading time)
Cloud computing is an evolutionary technology because it doesn’t change the computing stack at all. It simply distributes the stacks between the service providers and the users. In some sense, it is not as impactful as virtualization technology which introduced a new hypervisor layer in the computing stack and fundamentally changed people’s perception about computing with virtual machines.
But if you look closely at the latest IaaS clouds, they do leverage virtualization as a way to effectively and efficiently deploy systems. Inside one virtual machine, the computing stacks remain the same as before: from OS to middleware to application.
Keep in mind that the application is the end while the OS and middleware are the means. Customers care about applications more than the underlying infrastructure. As long as the infrastructure can support the applications, whatever the infrastructure might be is fine technically. Then the question would shift to the economic side: whatever is the most cost effective wins in infrastructure. That’s why Linux gains more shares in the cloud than in traditional IT shops.
To get to the end, you have to take a mean. In the IaaS cloud, you have to install the underlying OS and middleware before you can run your application. For the PaaS cloud, you can get away from that by focusing on application provisioning.
OS Provisioning
Remember, the software stack inside a virtual machine doesn’t change. It needs OS, middleware and application installed and configured before the application can work. Read more... (1238 words, estimated 4:57 mins reading time)
With the growth of virtualization, a new term “virtual appliance” has been coined for a special type of virtual machines that are used like applications. What does it really mean?
First, a virtual appliance is still a virtual machine. When seen in vSphere Client, the virtual appliance does not look much different from other typical virtual machines. Secondly, the functionality of the virtual machine is limited to that of an application. More often than not, the virtual machine is installed with one application. Because of this, the underlying OS is stripped down only to the minimum required to support that application. This type of OS is also called Just Enough OS (JEOS). All the existence of the JEOS is to support the application in the virtual appliance.
Now, is it a VM or an application? It could be either, depending how you look at it. For ESX/vCenter, a virtual appliance is a virtual machine. You can manage it just like any other virtual machine. For application users, it’s an application, a special one that is different from a normal application. Read more... (500 words, estimated 2:00 mins reading time)
As I quoted VMware CMO Rick Jackson in my previous blog, cloud computing is a journey. You may wonder, “If so, what are the phases for that journey?”
A great question! Understanding the phases helps us to better plan our journey and have a smooth transition from phase to phase.
In this blog, I will introduce 3 phases one by one: 100% virtualization, private cloud, and federated cloud. I will go over each of them and discuss the challenges in each. Read more... (646 words, estimated 2:35 mins reading time)
While asked how each Spring products are used in the market at the end of today’s training, the instructor showed us a nice website as a reference. Here is the diagram showing the numbers of jobs requiring skills of Spring and EJB. A great answer even though not a direct answer.
Strictly speaking, the jobs are not products, but well reflect what products are in use. So this is a good index on market shares of different products. If you have your products too easy to use, this index works against you. 
Read more... (267 words, 4 images, estimated 1:04 mins reading time)
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