Computing in the clouds

Many people might perceive Amazon as THE online store for books, music, gadgets and many other things with advanced market place capabilities and as one of the trail blazers on the Web. But the company from the Pacific Northwest is much more. Amazon is a high-tech company when it comes to very large distributed architectures and technologies based on web services. The “Mechanical Turk” is one example, an impressive idea to use human beings as “end points” in a Service-Oriented Architecture in order to let them do what human beings can do best. I really like this concept.
Another great thing is Cloud Computing as currently (21-April-2008) covered by an article on wired.com. It’s a must read! The company offers computing capabilities for everyone. This is good news for young enterprises that don’t want to spend too much on hardware. In essence, it is a lesson and a serious example at the same time how to offer computing power (and hardware, of course) as a service. I strongly believe we can expect much more from Amazon in the future. These guys are working on a real new computing platform on the web. The vision that the network is the computer, as verbalized by other companies, might turn into reality …

Transactional Memory …

… is most likely one solution to overcome parallel programming issues. Currently, it is very difficult (and error prone) to use locks properly when accessing shared memory sections. Lock-free programming is much more difficult. All these issues are already covered in earlier posts.
Talking about transactional memory, this concept is not that new but not part of mainstream development platforms. Not yet, but transactional memory could be available in hardware and software soon. Basically, software-based transactional memory solutions do already exist. The concept is similar to mechanisms used in database systems controlling concurrent access to data. A transaction in the scope of software-based transactional memory is a section of code that covers a series of reads and writes to shared memory. Logically, this occurs at a single point in time. In addition, a log and a final operation, called commit, are also part of the concept. Sounds familiar? Published concepts (of software-based transactional memory) using an optimistic approach free of locks. It is up to the reader in the scope of the transaction to verify based on the logs that data in the shared memory has not been altered (by other threads). If so, a roll-back will be performed and give him another try …
This sounds really simple and desirable, right? What’s the drawback, why not using this technology for solving existing problems in parallel computing? It is the performance, decreased by maintaining logs and doing the commits. But those issues should be solved soon. It would make life easier pertaining to the understanding of multi-threading code and could prevent the pitfalls coming with lock-based programming. Each transaction could be perceived as a single-threaded, isolated operation.

UML and Domain Specific Languages

I joined an interesting conversation on the utilization of UML recently. The talk was about code generation out of UML (tools). Mmmh. Pro and cons will always exist when it comes to UML. I use UML for sketching and for my architecture and design documents. Use case, class, deployment and sequence diagrams are important tools to me. They create a better understanding in the team on the expected outcome based on a unified description - much better than proprietary pictures which often lead to different views in the minds of the team members. UML models do not cover non-functional requirements sufficiently. This is a real drawback when is comes to code generation. My hope is that Domain Specific Languages (DSL) will improve, gain more acceptance and will be extended to areas and domains where they appropriate.

Prioritize your non-functional requirements

Non-functional requirements (like usability, security, performance, fidelity) are important success criterions in software architecture and development. It is a misconception that all requirements can be covered by functional requirements. Many requirements are of twofold nature, say security, that typical consists of functional and non-functional types. If this has been recognized and accepted, prioritization is the next important step. It should be not acceptable to have TWO non-functional requirements (also known as Quality Attributes) with the very same high level of priority. This is a critical contradiction that must be communicated and resolved. If not, you might be end with a beast that is highly secured and comfortable to use (let’s call it digital monkey wrench) – which is basically not feasible. It is always a challenge to make compromises for each Quality Attribute and to communicate and explain this. Utility Trees are a great tool to list, depicts and prioritize non-functional requirements.

F Sharp (F#) – a functional programming language in the scope of the .NET ecosystem

C# is a well known programming language designed to be used in the scope of the Microsoft .NET framework. It is an imperative and object-oriented programming language and widely accepted in this managed environment.But there is another “sharp-language”: F# - developed by Microsoft Research. F Sharp is a functional programming language with imperative and object-oriented aspects. It is part of the .NET environment and can be used within the Visual Studio development environment. Programs written in functional programming languages are easier to parallelize because of missing side-effects. Concerning this characteristic (which is basically an advantage), it is worth checking on F# in order to solve parallelization problems. The language can be obtained from the Microsoft Research website and is covered by the Microsoft Research Shared Source License Agreement.

Seattle in April

One day of snow, one day of rain, and three sunny days in the Pacific Northwest.