Loose­ly-cou­pled de­ploy­ment vs loose­ly-cou­pled de­sign

I have talked to a num­ber of peo­ple who claim to be do­ing SOA, when in the end all they do is loose­ly-cou­pled de­sign. Let me ex­plain what I mean by an ex­am­ple.

A team of en­ter­prise ar­chi­tects was de­sign­ing an SOA in­fra­struc­ture for a bank I know. The sys­tem they were build­ing would be based on in­ter­faces, so that it would be pos­si­ble to de­ploy parts of the sys­tem as sep­a­rate in­stances lat­er on. This was their no­tion of SOA...

The good thing about it is that there are in­ter­faces in their de­sign, mean­ing it is like­ly to be loose­ly-cou­pled. The bad news is that this is not SOA, at least not in my view: one of the biggest ad­van­tages of SOA - reuse in place - is nev­er re­al­ized in this way. So, where­as this ap­proach to 'SOA' may be loose­ly cou­pled in de­sign, it is not loose­ly cou­pled in de­ploy­ment (which is at least as im­por­tant).

The con­se­quence? When­ev­er a 'ser­vice' is up­grad­ed, they will need to up­grade all the de­pen­dent ser­vices and re­de­ploy them. This is be­cause each 'ser­vice' is re­al­ly an em­bed­ded mod­ule in­side oth­er parts of the sys­tem.

I guess this also holds for the de­bate on cloud vs grid com­put­ing: in my view, a cloud is more loose­ly cou­pled than a grid in its de­ploy­ment.