Monthly Archives: April 2010

Top 20 Most Popular Programming Languages

If you are a software engineer, you might have known Tiobe popularity index of programming languages. The index is updated on monthly basis. The following table shows the top 20 most popular languages this month.

The index caught many people’s attention this month because C regained its No.1 position. Java, used to be No. 1 for years, dropped to No. 2. Although percentage wise Java is still very close to C, the declining of Java popularity can be eye-catching.

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What Does DevOps Mean for Cloud Professionals?

I heard about DevOps a while back but didn’t really look into it. My initial understanding was that the roles of developer and system administrator would merge into one called devops. Last week, I attended a DevOps meet up at Palo Alto and got the chance to learn from others about DevOps.

The hosting organization even wrote up a good blog defining what a DevOps is. According to the blog,

DevOps is, in many ways, an umbrella concept that refers to anything that smoothes out the interaction between development and operations. However, the ideas behind DevOps run much deeper than that.

So the DevOps is more about a movement than merging of two roles. The basic idea behind the DevOps is to breach the wall between development and operations.

Traditionally developers ship products which are then run by operators in other companies. In this new age where much of software is delivered as services, the developers run their software directly. When there is a problem, the developers must fix it right away. That is why you see engineers at Google required to rotate on calls for support. When more companies ship software as services, it’s natural that more engineers will have two hats on their heads. The DevOps concept is not really new, but the terminology is.

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Key Takeaways from VMForce Announcement

Today VMware and announced finally after several weeks of speculations on what the joint project is about. The following diagram I captured from the live webcast of the event answered the question nicely.

The event attracted about 3,500 online viewers, not to mention the audience onsite. This was a very successful event, resulted in more media coverage than anyone can read. If you missed the live webcast, you can check out the recorded one from the website.

Among all the blogs and news coverage, I think you should read the one by Steve Herrod who has done a great job in explaining the joint adventure in a big picture. His blog also has links to other bloggers.

Looking beyond the exciting keynotes and demos, I think the key takeaways from the announcement are as follows:

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What The CTO Wants YOU to Know?

I just read a book by Ram Charan What The CEO Wants You to Know? Using Business Acumen to understand how your company really works. Having grown up in India, the author has earned D.B.A and M.B.A from Harvard Business School, and has taught at Harvard and Northwestern.

In the book, Ram coined a new term “business acumen” to describe the fundamental capabilities for business success. He claims, “Every business is the same inside, cutting through to cash margin, velocity, growth, and customers.”

Here are more quotes from the book:

When you come down to it, the business is very simple. There are universal laws of business that apply whether you sell fruit from a stand or are running a Fortune 500 company. Successful business leaders know them. They have what I call business acumen – the ability to understand the building blocks of how a one person operation or a very big business makes money. You, too, may learn the fundamentals of cash, margin, velocity, return on investment, growth, and customers.

You can develop your own business acumen. While these ideas may sound complex, they are not. Think more about your best teacher in a subject like chemistry. Once you understand that the atom was made up of protons, electrons, and neutrons, you then had the fundamentals to solve any problem in chemistry. I want to show you that it’s the same with business . When you know the fundamentals, you can “get” the basics for how any business works.

This made me think what the CTO wants you to know, and what “technical acumen” is. Here is my paraphrased version:

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Really Easy Way to Clone a Session: Yet Another Contribution from NetApp

Recently there were questions in the vSphere Java API forum on how to clone a new session from an existing one. Although vSphere Java API wraps around the basic Web Services API cloneSession() method, simply calling the method doesn’t get what you want.

Why? The signature of cloneSession() is as follows. It returns UserSession, which is embedded inside ServiceInstance managed object in vSphere Java API. While using the API, you always starts from the ServiceInstance.

public UserSession cloneSession(String cloneTicket) throws InvalidLogin, RuntimeFault, RemoteException;

In vSphere Java API, the ServiceInstance and UserSession have one to one mapping. Without a new ServiceInstance around the new UserSession, the UserSession is not much helpful.

Luckily, we got yet another contribution from Eric Forgette who works at NetApp. The contributed code includes a new overloaded method cloneSession() method to return a ServiceInstance object.

As I described before, we’ve been trying very hard to keep the vSphere Java API as close to the basic Web Services as possible. In this case, we decided to break the rule a little bit for good reasons, mainly for usability.

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Zimbra Architecture Overview – A Must Read Document

It’s been a while after VMware acquired Zimbra. In a VMware Console blog, VMware CTO Steve Herrod explained how Zimbra fits in VMware’s mission to simplify IT.

After the acquisition, I actually tried the online demo at Zimbra website. The impression I had was that the Zimbra client was very much like Microsoft Outlook in a browser.

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Synchronous versus Asynchronous Calls in vSphere API

In a previous article Top 10 Best Practices Using VMware VI and vSphere SDK, I mentioned synchronous versus asynchronous calls in the second best practice “Choose Right APIs.” But no detail was provided there. In this article, which is based on my book VMware VI and vSphere SDK , I discuss all the details.

Some methods defined on managed objects in vSphere API are asynchronous, meaning they return right away whether the operations are done successfully or not. That makes sense for long-running operations; you don’t want to block your current thread by waiting for the return of the call, and you might want to cancel it before it’s done.

For these asynchronous methods, the VI SDK provides a way to track the progress and results after the invocation is returned. As a naming convention, a long-running asynchronous method has _Task as a suffix in the method name, and it returns MOR to a Task. With MOR pointing to the Task object, you can track the progress and even get the result of the operation. For example, the cloneVM_Task() method defined in VirtualMachine is a long-running method that returns MOR pointing to a Task managed object.

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SOA and Cloud Computing: Are They The Same?

SOA has been a buzzword in enterprise computing for a while. Cloud computing is relatively new one but gaining stronger momentum than SOA. With these two terms, many people get a little confused: is cloud computing just a new name for SOA? And can they play together?


Before drawing a conclusion, let’s take a look at the definitions from

Service Oriented Architecture (SOA): is a flexible set of design principles used during the phases of systems development and integration. A deployed SOA-based architecture will provide a loosely-integrated suite of services that can be used within multiple business domains.

Cloud Computing: is Internet-based computing, whereby shared resources, software and information are provided to computers and other devices on-demand, like a public utility.

What’s Common?

As we’ve read in various articles and books, SOA is mainly for enterprise; the cloud computing is, as its definition points out, Internet based services. In my previous blog, I mentioned cloud as architecture pattern (CAA), which can be leveraged in enterprises as well. If we compare the SOA and CAA, they look somewhat similar and share some core principles:

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Tutorial: Easy VMware Development with VI Java API and Groovy

Every time I google for VI(vSphere) Java API, I get something new. Here is yet another one I just found. It’s a blog article Easy VMware Development with VI Java API and Groovy by Aaron Sweemer. By reading his blog site, I came to know Aaron is actually my colleague at VMware working as a Sr. System Engineer in Cincinnati Ohio. He is the principal blogger at Virtual Insanity.

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Virtual Appliance: Is It a Virtual Machine or an Application?

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.

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Software Engineering: Do We Need Yet Another Theory?

Today I read a blog by Martin Fowler, the author of the famous Refactoring: Improving the Design of Existing Code and other books. The blog explained why he declined the invitation to be part of the SEMAT (Software Engineering Method and Theory) initiative by Ivar Jacobson, Bertrand Meyer, and Richard Soley. Ivar Jacobson is known for his contribution to the UML, together with Grady Booch and James Rumbaugh. All of them worked for Rational Software, now part of IBM, which I was part of from year 2000 to 2005.

Martin added his rationale for his declining:

…From here I got the distinct impression that the central thrust of the initiative is to create a software meta-method-kernel – essentially a set of common process elements for software developments that you can rigorously compose into a method for your own project.

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How to Use HTTP with vSphere Client?

If you have viewed the video about Onyx by Carter Shanklin (@cshanklin), you may have noticed a little trick with the vSphere Client.

Normally on the login dialog box, you enter a hostname or IP address. By default, the vSphere Client use HTTPS to communicate with the server. That means you cannot easily see what’s passed back and forth on the wire. As shown in the Onyx video, Carter showed how to use HTTP instead of the default HTTPS with the following in the IP Address / Name field:


So the vSphere Client does support HTTP. In Onyx case, it points to localhost on which the Onyx is installed. You can actually point to a real vCenter or ESX/ESXi server directly – just change the localhost to the IP address of the server and the port to the default port 80 or remove the port part.

Before connecting the server, you need to change the server a bit for it to support HTTP. 

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Amazon AWS SDK for Java: It’s Not Quite There Yet

Amazon released its SDK for Java last month. It’s a complete set of APIs that cover almost all the services from EC2, S3, SQS, RDS to SimpleDB. Overall Amazon has done a consistent job, but the SDK is NOT really object oriented. And that I think is critical for higher development productivity. 

Structure of the SDK

Before explaining why it’s not quite there, let’s take a look at the structure of the API itself. The SDK includes many packages. For each service, you find two or three packages: basic, model, and possibly util package.

In each of the basic packages you can find the two interfaces, and two implementation classes. Let’s pick EC2 as a sample here. The AmazonEC2 and AmazonEC2Async are two interfaces and implemented by AmazonEC2Client and AmazonEC2AsyncClient respectively. More methods are defined in the synchronous than the asynchronous versions with the majority of them overlapping with similar method names.

AllocateAddressResult allocateAddress()
AllocateAddressResult allocateAddress(AllocateAddressRequest allocateAddressRequest)
Future<AllocateAddressResult> allocateAddressAsync(AllocateAddressRequest allocateAddressRequest)

The first two versions wait and get you results upon return. The third version doesn’t wait and gets the result later.

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Invalid property? A Trick With vSphere PropertyCollector

As I discussed extensively in my book, the PropertyCollector is very powerful yet not easy to use. There was a question posted at vSphere Java API forum related to the property collector which I think worths sharing here. Although it’s found using vSphere Java API, but it really goes beyond the API to the vSphere API itself.

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Virtual Machine, IP Address, and MAC Address: Frequently Confused Concepts

Having answered many questions about IP addresses of virtual machines at different occasions, I still see more are coming. I think it’s time to write a blog about it. Hopefully people would search the Internet before raising the question.

First of all, there is a big confusion on the relationship of IP addresses and virtual machines. Many people tend to associate IP addresses with virtual machines, and want to retrieve/change the IP address of a virtual machine.

In fact, a virtual machine is very much like its physical counterpart. It does not have an IP address by itself. In other words, an IP address is NOT an intrinsic attribute of a machine, either virtual or physical. It might have one or more only after an OS is installed. In most cases, it does have one or more IP addresses, which gives the impression that every machine has an IP address.

A virtual machine does have intrinsic attributes such as MAC addresses if NIC cards are configured. Unlike its physical counterpart, a virtual machine’s MAC address can be re-configured. Some software vendors rely on MAC addresses to lock down their licensed software on particular machines. This mechanism can be, therefore, compromised in virtual environments.

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Will Service Providers Dominate? A Business Outlook of Cloud EcoSystem

When talking about cloud computing, people normally refer it as services provided by service providers over the Internet. These services are normally, at least in theory, elastic and with no limits on resource usage.

To differentiate the levels of services, the cloud computing is categorized into three different types of services: IaaS (Infrastructure As A Service), PaaS(Platform As A Service), and SaaS(Software As A Service).

Why is it layered as such? Simple. These three layers correspond to the traditional computing stack: machine, OS/Middleware platform, application. In light of this mapping, shouldn’t we call SaaS as AaaS?  I think that’s a right change technically. But which service providers would like to be called AaaS?

When more people and more companies use cloud computing as services, we will see a rapid growth of service provider sector. In my previous blog, I made an analog between the cloud services and office rental business, and predict the growth pattern of cloud computing would be similar to the office rental. Size matters when it comes to the scale of economy. The bigger the enterprises, the more likely own their offices and their cloud datacenters.

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Cloud Computing: As Service or As Architecture?

Last week I saw an incoming link at my blog site from, a website promoting private cloud computing inside enterprises backed by EMC. Due to curiosity, I browsed the website and found a video by VMware CEO Paul Maritz on cloud computing. BTW, my website is also featured at the home page. Thanks!

In the video, Paul talked about the cloud computing, mostly referring to services over the Internet, can also be an architecture pattern for enterprises. When that architecture is implemented, you will have a private cloud on premise. Although not using cloud services from any service provider, you still get almost all the benefits in a private cloud.

From the system architecture perspective, your applications built within a private cloud aren’t much different than those built using external cloud services. If both of the services follow the same interface spec, your application may switch between public cloud and private cloud either statically or dynamically.

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Video on vSphere Java API Released at InfoQ

While searching Twitter on “vSphere Java”, I found my presentation available today online at InfoQ (many thanks to @arm1433 and @toya256ForRSS). It has both video and slides for more than one hour. The voice was not quite clear in the first one or two minutes. After that it’s pretty good.

This presenation is a complete overview of the open source vSphere Java API. Because the audience then was new to virtualization, the first several minutes covered a little virtualization basics. You can scroll over if you know virtualization already.

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I18N vs. vSphere

With today’s global market, a software vendor has to consider the internationalization (I18N) issue to better serve users in different areas and maximize the return on the product investment. This article introduces the I18N basics of vSphere. Much of the content is based on my book VMware VI and vSphere SDK by Prentice Hall.

There are two basic meanings. First, you have to design your software so that it is localizable. In other words, you have to use the right APIs that can handle double byte characters. Sometimes people call this globalization (G11N).

Second, you should provide localized versions of your software so that users can read and use their native languages. Sometimes people call this localization.

In most cases, you externalize all the text strings that are visible to end users from the code to the resource files and translate them into different languages. Then localizing the software is as easy as combining the code and localized resource files. This is the way VirtualCenter server is localized. Depending on the programming language and platform, the resource files can be organized differently and might have another format. For example, Java uses properties files, yet C++ on Windows uses resource dlls.

That said, I18N is a broad topic that does much more than what is briefly covered here. Further discussion is beyond the scope of this book, but you can find more detailed information online.

As discussed, the VI SDK is essentially a set of Web Services interfaces. The WS-I18N summarizes four internationalization patterns that can be applied with Web Services when deployed.

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How to Import and Export OVF Packages

This article is based on a similar one at vSphere Java API home page. At that time, one of VMware community members sent me an email for samples of using OvfManager APIs. Then I went to office on a Saturday writing two samples, which have been validated by several folks as “working” samples.

The purpose of the samples are to illustrate the vSphere APIs. Let’s take a look at them one by one.

First, This sample shows how to download either a VM or vApp to your local machine. The typical flow is:

  • Find the VM or vApp
  • Call their exportVm() or exportVApp() methods and get HttpNfcLease
  • Set lease time out
  • Wait for HttpNfcLease until it’s ready
  • From the property, find the all URLs from which you download the vmdk files
  • Call OvfManager.createDescriptor() API to create the content of ovf and save it to a file along with downloaded vmdk files.
  • Release the lease by calling httpNfcLeaseComplete() method
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    My company has created products like vSearch ("Super vCenter"), vijavaNG APIs, EAM APIs, ICE tool. We also help clients with virtualization and cloud computing on customized development, training. Should you, or someone you know, need these products and services, please feel free to contact me: steve __AT__

    Me: Steve Jin, VMware vExpert who authored the VMware VI and vSphere SDK by Prentice Hall, and created the de factor open source vSphere Java API while working at VMware engineering. Companies like Cisco, EMC, NetApp, HP, Dell, VMware, are among the users of the API and other tools I developed for their products, internal IT orchestration, and test automation.