Tuesday, October 28, 2008

[Event] ESEM-Conferences

From October 6th-10th the Experimental Software Engineering International Week (ESEIW) took place in Kaiserslautern, Germany. The ESEIW was organized in four joint events:
  • 16th Annual Meeting of International Software Engineering Research Network ISERN, Oct 6th-7th
  • 6th International Advanced School of Empirical Software Engineering. IASESE, Oct 8th
  • 3rd International Doctoral Symposium on Empirical Software Engineering IDoESE, Oct 8th
  • 2nd International Symposium on Empirical Software Engineering and Measurement. ESEM, Oct 9th-Oct 10th
Major topics of the ISERN Meeting were
  • aggregation opportunities from experimental results,
  • application of Empirical Software Engineering to Software Architecture
  • discussion of an Empirical Research roadmap and associated key task within a time range up to 2010
  • application opportunities of empirical investigations using simulation.
The ESEM main conference is an established forum for researchers and practitioners to report and discuss recent research results in the area of empirical software engineering and metrics. The conference focuses on topics related to processes, design and structure of empirical studies, and results of specific studies.

Paper Presentation

We gave a short paper presentation in the track "Empirical evidence and Systematic review" titled with "An Empirical Investigation of Scenarios Gained and Lost in Architecture Evaluation Meetings" (D. Winkler, S. Biffl, M. A. Babar) which reports on initial findings on team effects in scenario brainstorming processes for architecture evaluation.
Abstract: Studying the effectiveness of scenario development meetings in the software architecture process is important to improve meeting effectiveness. This paper reports initial findings from analyzing the data collected in a controlled experiment aimed at studying the effectiveness of meetings in terms of gained and lost scenarios of individuals, real and nominal (non-communicating) teams. Our findings question the effectiveness of holding meetings since more important scenarios were lost than gained in these meetings. In the study nominal teams performed better than individuals and real teams.

The slides of our presentation are available for download.

Key Note Talks

Beside presentations and discussions of academic papers, "state of the art" presentations focus on relevant topics for industry and best software engineering practice:
  1. Using empirical methods to improve industrial technology transfer. (Harald Hoenninger, Vice President Corporate Research, Robert Bosch GmbH, Germany).
  2. Empirical Challenges in Ultra Large Scale Systems (Mary Shaw, Institute for Software Research, Carnegie Mellon University (USA)

Abstracts of the key notes are available for download.

Dietmar Winkler (edited by Alexander Schatten)

Sunday, October 26, 2008

[Arch] SEDA Model and scalable enterprise applications

Scalability, Performance, Fault Tolerance are classical non functional requirements when building enterprise applications. Setting up the application in a clustered environment is a very popular approach and is often used in practice.

When building process based applications you usually deal with long and short running processes. For example a order process may take one week, whereas a save transaction is a process that takes (should take) only few seconds. Short running processs often implements the backend business logic. In Service Oriented Architectures these short running processes results in a orchestration of provided services from different systems.

Mihai Lucian describes in his article a simple scenario, where different platforms in a backend process are connected by using web service endpoints. One of the platform that is queried has a slow response time. He describes one solution approach to battle to the slow response time by using asynchronous IO in servlet container and the Staged Event Driven Architecture (SEDA) model.

He mentioned that current servlet APIs do not provide methods in order to deliver data to the client in a asynchronous way. AJAX based frameworks currently use one of the modes: Polling, Piggy back and Comet. Apache Tomcat for example provides a implementation to handle asynchronous IO by decouple the requirest and response from the worker thread. So you can prepare your response later.

Now the combination with the SEDA model is very interesting, because you can route your request to the right queue. As Mule is based one the SEDA model, Mihai Lucian illustrates how to implement such a scenario in Mule (see image).

From my point of view the example is very interesting based on the following key points:
  • Asynchronous communication in a servlet container
  • The most interesting thing is how to correlate the request with the response through different layers
  • How Mule fits in such a architecture
  • Practical example of JMS
  • Using Routers in Mule and route the message to the right Queue
  • Using Apache CXF in Mule
A full description of the example is provided on the article homepage. At the end of the article he provides some benchmarks in order to provide a clear view of the advanateges using such an architecture.

Friday, October 24, 2008

[Misc] Two new interesting SE books out

Recently two fresh books fell into my hands:

  1. The Productive Programmer, Neal Ford, 978-0596519780
  2. Clean Code, Robert C. Martin, 978-0132350884
The first book is a very ambivalent one.

Pros: It covers a wide range of areas how to be more productive. And so you can find topics like ACCERLERATION, FOCUS, AUTOMATION, Test-Diven Design, Code Analyse, up to very philosophical points. The real strong point of this book is that it has several dozen important points most programmers really forget about in their daily work. Each point might be trivial when analyzed in isolation. But to gather all productive points is a worthy issue. And even some principles as SLAP (already covered by Beck) can not be explained often enough.

Cons: The content really leaves a very diced impression. You can find the same information at several places in the book (like the "magic" unix find) and some points of uninteresting information like his words to Reflection, Exceptions, Array Indices and some flame about EJB 2 (really 2!). And thus it's not astonishing that this book gets only two stars on amazon.de.

But nevertheless: even if the book is a mixed work, if you adhere to 80% of the good rules, you will be a massively better programmer.

2. The Clean Code (subtitle: handbook of agile craftsmanship) is more a real work of craftsmanship itself. The idea is the same as for the book beautiful code I recently reviewed here. Martin has found smart authors for each chapters. And the chapters are:
  • Meaningful Names (! which is a horror in big companies with developers from different cultural and technical backgrounds to my opinion...)
  • Functions
  • Comments (you think you can not learn here?)
  • Formatting (sounds boring but is not) and
  • Error Handling, Boundaries, Unit Tests, Classes, Systems, Emergence, Concurrency, Successive Refinement, JUnit Internals, and more...
It closes with a catalog of smells and heuristics which is a little like the one we had in the Fowler refactoring book but nevertheless of great use.

Robert C. Martins Clean Code Book differs from the rest because there is a lot code in it. And a lot code that migrates from bad to good. You really feel while reading that the authors have invested in strong code examples. This makes it a really valuable resource to read. So it has my strong recommendation.

To conclude: These two books, combined with all the Fowlers and Becks (not the beer...) lead me to create a catalog of all the useful points they have written. It is still small and in beta state. But you are invited to use, contribute or link to this growing list of best practices.

So God bless all (most of?) the software developers!
(who read these books ;-)

Monday, October 20, 2008

[Conf] CEE-SET Conference

Last week I joined the CEE-SET conference in Brno. On the conference I presented a paper written by Robert Thullner, Josef Schiefer and myself: We analyse the application of Open Source frameworks in implementing enterprise integration patterns. For that matter a series of scenarios was implemented with (combinations) of different frameworks like Apache Active MQ, Apache Camel, Apache Service Mix and Mule.

The paper is available for download.

Saturday, October 11, 2008

[Arch] Introduction to REST

REST ist an architectural style on how to let distributed applications communicate. It is considered as an alternative approach to XML:RPC or SOAP webservices. I generally like that Google Talks introduction to REST:

I would also recommend additional resources to get a more complete picture on REST, check out this link.

Monday, October 06, 2008

[Arch] OpenSource ESBs

The last couple of years major Open Source ESBs, including MuleSource and ServiceMix, have been expanded and are used in critical business solutions. Tijs Rademakers and Jos Dirksen offer a book which gives an overview about Open Source ESBs and which combination of Open Source technologies with ESBs are used. The main open source solutions covered in this book are Mule and ServiceMix. Therefore most of the examples in the book are based on these two technologies. Other Open Source ESBs that will be covered are Apache Synapse, Open ESB and the new integration framework from Spring, called Spring Integration.

In the TechBrief the authors mentioned that all Open Source ESBs focus on Enterprise Integration Pattersn. If you understand these patterns its very easy to understand the implementation and handling of ESBs.

The book is divided into three parts. The first part concentrates on reader which are not familiar with an ESB:
  • Overview about ESB functionality and what Open Source ESBs are available in the Open Source market
  • Taking a deep look into the Mule and ServiceMix architecture
  • Installation of Mule and ServiceMix and how to run them
The second part focus on ESB core functioanlity which covers some of the Enterprise Integration Patterns. Here the reader becomes some connector examples, like JMS, JDBC, POP3 and Web Services.

The third part covers case studies and also illustrates integration scenarios with BPM engines, like jBPM and Apache ODE.

In the tech brief there was also a short comparison between Mule and Service Mix. When to use which one, is hard to say, it depends on your requirements. But in this interview on of the authors said that in a web service based architecture the JBI approach is often the better choice, but Mule is very often used, because you can also transfer Java objects, which is often very comfortable and faster. They also talk about integration of legacy systems, which is sometimes easier with Mule, because when you use Service Mix all messages must be transformed in XML.

You can download chapter 1 and chapter 4 for the book homepage.