Grady Booch
IBM Fellow

Podcast 1: Current trends in software architecture  (5 min 23 sec)

IBM software architect kit
http://www.ibm.com/developerworks/architecture/kits/index.html


In civil engineering, we can identify a variety of movements or genres of
architecture. Going back many centuries we can name Egyptian, Grecian, 
Roman or Romanesque architectures. As the centuries unfolded, new architectural
styles emerged which today we label as gothic or Renaissance or Palladian. Around
the turn of the century, yet new styles emerged, such as art nouveau or modernism.
In contemporary civil engineering, we have the work of Frank Gerry and others that
have led to entirely new styles. Being an engineering activity, civil architecture
involves the resolution of a variety of forces. First there are the obvious physics
forces of tension and compression and all the attendant issues of deadloads and 
liveloads. There are also the business issues -- cost, schedule, and functionality
-- and finally other less tangible issues, such as beauty. 

In software engineering, being an engineering activity, we can identify a variety of
similar movements. For example in web-centric systems going back, in this case, a few
decades, the earliest web sites, around the work of Tim Burners-Lee, were very simple
ones involving basic formatting and basic hypertext. This led eventually to colorful
clients in which we had much more graphics. This then led to simple scripting -- the
beginnings of vbscript and Javascript. As those kind of scripting mechanisms became 
codified, this led to the next generation of web-centric systems and the rise of middleware
such as J2EE as manifest in WebSphere and .NET. These then led to the rise of simple
frameworks such as Struts, and today, for many web systems, dynamic frameworks such
as what we find in Ajax or Java Server Faces or Rubion Rails. As we project forward 
we can see the beginnings of a new kind of web architecture such as surrounding the
semantic web. Just like civil engineering, software engineering involves the resolution
of a variety of forces. There are business forces, environmental forces, development forces,
operational forces, and even legal and ethical forces. Being an engineering activity, it 
is the case that in software engineering fundamentals never go out of style, and by those
fundamentals I mean the simple principles of building crisp abstractions, devising a clear
separation of concerns, building a system with a balanced distribution responsibility, and
above all, simplicity, this later of which is the hardest for most organizations to achieve.

One thing I observe about watching many organizations, especially the hyper-productive ones,
is that there's a very common practice I find among those organizations that are successful 
and notably absent from those who are not successful. And it's simply this -- those 
hyper-productive organizations tend to grow a systems architecture through the incremental
and iterative release of executables. Now let's tease that observation apart here. First, we
see that we have a focus upon executables. Second, we see that these executables are grown
through an incremental and iterative release process. And third and the focus of the rest
of our discussion here is that those executables are centered around the growing of an 
architecture. 

Well, then what is an architecture? We can be sure that every system has an architecture, 
although in many cases those architectures are accidental and simply grow because of their 
incremental and iterative development, whereas in some cases those architectures are truly 
intentional. We can also observe that all architecture is design, but not necessarily the 
reverse, not all design is architecture. Rather we observe that significant design decisions
are the ones that encompass architecture, and by significant I mean those decisions that are
costly to change. There is an IEEE standard regarding the description of architectures -- 
IEEE standard 1472 -- and it states it this way. "Software architecture is the fundamental 
organization of a system embodied in its components, their relationships to each other, and 
the environment and the principles governing its design and evolution. Why do we care about 
software architecture? A process that is centered around growing an architecture is one that
is risk confrontive, it's one that focuses upon simplicity and it's one that deals with building
systems that are resilient to change. In short, in software engineering, an activity that focuses
 around the growing of an architecture is very much one that is a fundamental engineering process.