Software Engineering Radio - the podcast for professional software developers

Variability is one of the key concerns in software product line engineering. The episode introduces the concepts of structural and non-structural (or configurative) variability. It also discusses how to find and model variability, and especially how to implement variability in the solution artifacts. Michael and Markus discuss a series of variability mechanisms that can be used with today's programming languages and technologies.

This episode is about compile-time metaprogramming, and specifically, about implementing DSLs via compile-time metaprogramming. Our guest, Laurence Tratt, illustrates the idea with his (research) programming language called Converge. We started by talking about the importance of a custom syntax for DSL and took a brief look at the definition of DSLs by a chap called Paul Hudak. We then briefly covered the disctinction between internal and external DSLs. More to the point of this episode, we discussed the concept of compile-time metaprogramming, and the language features necessary to achieve it: in converge, these concepts are called splice, quasi-quote and insertion. We then looked at how the Converge compiler works, and at the additional features that are required to implement DSLs based on the metaprogramming features mentioned above. Using an example, we then walked through how to implement a simple DSL. Looking at some of the more technical details, we discussed the difference between the parse tree and the abstract syntax tree and at different kinds of parsers - specifically, the Earley parser used by Converge. In multi-stage languages (i.e. languages that execute programs and meta programs) error reporting is important, but non trivial. We discussed how this is done in Converge. We finally looked at how to integrate Converge's expression language into your DSL and how to package DSL definition for later use. The last segment look at the process of implementing a DSL in converge and about some of the history and practical experience with Converge. Lessons learned from building Converge wrap up the episode.

In this episode we discuss sensor networks with our guest Steffen Schaefer, who is the Technical Thought Leader for Sensors & Actuator Solutions at IBM. The discussion resolves around the TREC device, which can be mounted on containers to track them on their journey over seas, railway tracks and roads. The TREC is a small embedded device developed by Steffen's employer, IBM, that has various sensors and communications channels. In the episode we first talked about container transport in general, and then looked at how the TREC device works - specifically, it's hardware, software and power management. We then looked at the necessary backend infrastructure. The main part of the discussion covered the communication between the device and the backend, using technologies such as Zigby, GSM and satellite communications. We also looked at the middleware infrastructures used, such as the MQtt messaging tool. We closed the episode with a little discussion of the "Internet of Things" and some discussion about embedded software devleopment in general. Note that SE Radio will feature more embedded topics in the future - an introduction to embedded development will be put online soon.

In the first episode on Refactoring we talked about the basic ideas behind refactoring and some base principles why refactoring is a key part of software engineering. Now we move on to more complicated refactorings and discuss three major situations, their problems and possible solutions: advanced refactorings in large projects that can hardly be finished in a few minutes or hours and refactoring in larger teams. Also covered are the refactoring of published APIs and how merciless refactoring could be aligned with backward compatibility of published APIs, and refactorings that affect more than just code like for example database schemas.

This episode is an interview with Frank Buschmann, one of the pioneers of the pattern movement in Europe. Michael and Frank discuss how it all began: the first conferences on patterns and the first publications by the Gang-of-Four and the POSA 1 team. Frank then elaborates on the new volumes in the Pattern-Oriented Software Architecture book series - POSA 4 and POSA 5 - and gives some examples from the books. The episode concludes with a general discussion on software design and architecture, and best practices on software development.

Michael Kircher and Markus Voelter introduce the topic of software product line engineering. They motivate when and why product lines are important to consider and what makes them so special. Further, they introduce some key terminology, such as platform, core asset, feature model, commonality, and variability.

In this episode, we're talking to Obie Fernandez about agile DSL development in Ruby. We started our discussion by defining what a DSL is, the difference between internal and external DSLs as well as the importance of the flexibly syntax of the host language in order to make DSLs worthwhile. We then looked at a couple of real world examples for DSLs, specifically, at Business Natural Languages. We then progressed to the main part of the discussions, which centered around the features of Ruby that are important for building DSLs. These include the flexible handling of parentheses, symbols, blocks as well as literal arrays and hashes. We then discussed Ruby's meta programming feautures and how they are important for building DSLs: instantiation, method_missing callback, class macros, top level functions and sandboxing. Features like eval, class_eval, instance_eval and define_method are also important for DSLs in Ruby, as well as using alias_method for simple AOP.

In this episode, Arno and Michael take a look at Design by Contract, a programming technique formalized by Bertrand Meyer. The idea is that an interface is more than method signatures - it is also about specifying the expected behavior that implementations must provide. While some languages include direct support for this style of programming, it is a useful mindset when desiging interfaces even without such language features.

This is another episode where we mainly announce topics related to the podcast itself.

In this Episode we talk about dynamic languages for statically-typed minds, or in other words: which are the interesting features people should learn when they go from a langauge such as Java or C# to a language like Python or Ruby. We used Ruby as the concrete example language. We started the discussion about important features with the concept of dynamically changing an object's type and the idea of message passing. We then looked at the concepts of blocks and closures. Next in line is a discussion about functions that create functions as well as currying. This lead into a quick discussion about continuations. Open classes, aliasing and the relationship to AOP was next on our agenda. We then looked considered a somewhat more engineering-oriented view and looked at the importance of testing and what are the best steps of getting from static programming to dynamic programming. Finally, we discussed a bit about the current (as of October 2006) state of dynamic languages on mainstream platforms.