Brothers in arms - SOA and Product Line Engineering
Now, compare all this to Software Product Line Engineering (SPLE, see my special posting on that issue):
- Services and other common parts (such as legacy applications or platforms) are core assets
- Applications (composite applications and business processes) denote the members of a product line
- Service engineering resembles domain engineering and application engineering is identical.
Sooner or later you'll reconginze that SOA engineering is best organized as a SPLE process.
Scoping might be a little more difficult but you should read my last posting how we could cope with this challenge. You might also consider to provide a generative architecture as described in another recent posting as well as in what I wrote on ULS.
From my viewpoint the only conclusion to draw is that SPLE and SOA engineering should be considered as two sides of the same coin.