I have been reading Martin Fowler’s book Domain-Specific Language during last two months. Now I am not fully done with the book but have a good idea because the rest of the book is about individual DSL patterns, which I think are better read when used.
I got two key points from the book. One is that the key to DSL is semantic model (“The semantics of a program is what it means – that is, what it does when it executes”). You can implement semantic model as APIs/frameworks in system languages like Java. If you are confused by the question, “what is the difference between DSL and normal code on top of high level APIs? Read more...
After Shreyas shared his experience with Vaadin in his comment on my previous post, I started to play with the web framework. As it advertises, it’s “a Java framework for building modern web applications that look great, perform well and make you and your users happy.”
Based on my experience, I think it’s a great framework that is very intuitive yet powerful. All you need to do is to write Java code in a similar way to using Java AWT and Swing for standalone applications. The minor different is Read more...
Many APIs have emerged since the inception of computer software. Its root can be traced back to the layered software architecture in which high layer calls to low layer. The low layer is not necessarily called APIs, but the other way is mostly true.
Initial APIs were inside a single or multiple vertical call stacks that share same memory space. As a result, you have good performance and ease of use. After that, inter-process communication (IPC) emerged and allowed API services to run in a different process for better Read more...
After I touted the idea to have a meetup last week, I got quite positive feedbacks from the community. More importantly, I secured sponsorship from my employer VMware so that we can have the event at VMware headquarter. Due to a little time conflict, we will have it on May 18, instead of May 25 as I planned before. It’s still a Wednesday and food/drinks will be served with no charge.
This event was designed for professionals like developers, system administrators. Even if you are not but interested in virtualization and cloud computing in general, you are still very welcome to join us.
The first 100 registers for onsite will have chance to win Read more...
If you want to read information about a virtual machine from the guest OS running on it, the vSphere Guest API is for you. It’s a C library coming with VMware Tools. Unlike the vSphere API which can be used anywhere, the vSphere Guest API is only available in the guest OS.
High Level Characteristics Read more...
- It’s read only. You can use it to retrieve state and performance of a virtual machine running on ESX, but you can NOT
If you think vSphere Client exposes everything, you are wrong. The vSphere APIs actually expose more features than the vSphere Client, which is a great product. This is one reason why system administrators should learn vSphere APIs.
While writing my book, for example, I noticed that vSphere APIs actually allow you to change guest OS screen size with a simple call setScreenResolution(int width, int height).
Given the time pressure, I didn’t summarize these API only features at that time. To be honest, Read more...
By this May, the open source VI Java API will turn 3 year old. While there is a big community out there, we haven’t organized any event for people to meet each other in person.
I think now is a good time to do so. How about a meet up in the silicon valley around May 25(Update: 18 as new date) which is a Wednesday?
Agenda Read more...
- 6:30PM-7PM. Reception and Networking.
It has become a conventional wisdom in software development that you should NOT re-invent a new wheel – reuse an existing one instead. There are many compelling cases in which re-inventing wheels had caused catastrophic failures as described in Joel’s article Things You Shoud Never Do (Great article BTW). One famous example there was the NetScape’s loss to Microsoft in the browser war more than a decade ago.
Nothing is absolute in software however. You can find opposite cases like Microsoft’s successful re-inventing Windows from Window 95 to Windows XP. Actually in a longer term, you cannot stick with a wheel forever; otherwise we are still using wooden wheels in the pre-industrial age. Same is true for software.
I think the question is really not whether to invent a new wheel, but when. In other words, Read more...
I was working at Rational Software when IBM bought it almost 10 years ago. After the acquisition, we got emails and trainings encouraging us to file patent disclosures. As you may have known, IBM has been the top patent holder in the USA, maybe worldwide as well. At that time, I coined the term “non-patentable software architecture.”
Pattern system was invented to protect and encourage innovations. There are three criteria for a valid pattern: novelty, usefulness, and non-obviousness. Those are all in relative terms. As I can tell, there is rarely anything Read more...
Google Web Toolkit is an interesting project. It’s basically an AJAX toolkit but presents itself as a Java toolkit. The idea is that you still write Java code as you would with Java AWT, SWING, and the GWT converts it to JavaScript code for you.
But why don’t write JavaScript code directly? Well, you may know Java better than JavaScript. More importantly, Java is a typed language and easier to develop a large system than JavaScript.
Using GWT for Java developers is mostly Read more...
If you have a mobile phone and travel to other areas or countries, you can still use it to make and receive a call. Your phone number does not change. This is called roaming in the wireless telecommunications.
In the cloud environment, your virtual machine can “travel” around as well, maybe from one datacenter to another, from your enterprise to one of your service providers or the other way around, or from one service provider to another.
It’s relatively easy for a virtual machine Read more...
Chargeback is an important feature for computing infrastructures. Even inside an enterprise where IT users are not charged with real money, it’s still nice to see the usage patterns and sometimes avoid wasting resources. As I mentioned in IBM RC2, applying chargeback reduced unnecessary usage overnight.
VMware vCenter Chargeback is a component for this purpose. It can run standalone with Web GUI, and surface to vSphere Client as a plug-in. Although its name includes vCenter, it can also work with vCloud Director (see Using vCenter Chargeback with VMware Cloud Director).
I just spent some time over the weekend reading the API documentation, including vCenter Chargeback API Programming Guide, API Reference. The version 1.5 of the API Read more...
Communication is always important in any teamwork environment. This is especially true in software development where changes are constant. There are two levels of possible communications in software development: soft communication and hard communication. Let’s go over them one by one.
Soft Communication
It happens among people, those who work on a software project. Two popular forms of soft communication are Read more...
VMware ESX and ESXi (a.k.a. vSphere Hypervisor) support the most guest operating systems among all the hypervisors. From the vSphere API, you can determine what operating system is installed on a virtual machine.
The related managed object is the VirtualMachine and there are multiple ways to Read more...
If you are a software engineer, you may move from project to project over the time. How to quickly ramp up with a new project is always a challenge. The term “new” I use here does not mean that the project is new and you need to start from scratch, but that the project is new to you.
Although we all like to start from scratch, the reality is that 80% of engineers are actually doing maintenance works on existing projects: fixing bugs, adding new features, etc.
When you move to a new project, you have to Read more...
If you develop FLEX with Java backend, you most likely know BlazeDS already. It’s a web application running with Tomcat that exposes Java objects on the server side as services to the Flex Client written in ActionScript. It combines the best of Flex on the client side and Java on the server side. As a result, it becomes one of the most popular architectural styles for web development these days.
It’s less known that you can also develop Java code on the client that consumes the services on the server side. Check out this wiki page by Adobe on the original design. The implementation of Java AMF Client is added to BlazeDS as of July 2008.
Because I had to hack Read more...
Many folks talk about developer enablement today because it’s a key success factor for a platform company. If you haven’t watched this video by Microsoft CEO Steve Ballmer, you want to check it out. Also, my previous blog: CO2: The Formula For A Successful Developer Ecosystem.
To empower developers, we got to figure out who the developers are and what they want. It’s hard, if ever possible, to identify every developer in VMware community. But it’s normally easy to find out the types of the developers. In my observation, there are two types of developers (The title of this article is not that accurate, but Read more...
After working on this for weeks, I am pleased to announce the first release of VMware vSphere API and SDK Frequently Asked Questions. It includes 70+ questions and trustable answers in 6 different categories: General, Getting Started, Language Bindings, VI Java API, API Usage, Troubleshooting.
From now on, before posting any question to any forum please read this FAQ page. For the best readability, I decided not to allow comments on that page. But your feedbacks and suggestions are always important. Please feel free to use this post for comments and discussions. Based on your inputs, I will continue to enhance the FAQs.
The open source VI Java API has implemented typing which makes it much easier to use and possible to catch errors in compile time. To use these types, you have to get hold of these objects. Normally you don’t need to worry about this because you navigate the system from the top ServiceInstance and get the managed objects through VI Java API calls.
There are some rare cases in which you get the object id first, for example, a task id as asked in the VI Java API forum. A bit more common case is when you develop vSphere Client plug-ins. The URL string your web application gets has object id and type for a virtual machine or host, etc.
Although coming from different use cases, Read more...
Per community requests, two methods were added into VI Java API 2.1 (GAed last summer) for changing the default connection and read timeouts. Both methods are defined in WSClient.java.
The first method setConnectTimeout() sets a specified timeout in milliseconds. It intends to be used when opening a communications link to the resource referenced by the URLConnection inside the WSClient object. If the timeout expires before the connection can be established, a java.net.SocketTimeoutException is raised. A timeout of zero is interpreted as an infinite timeout.
The second method setReadTimeout() Read more...
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