I've spotted a bit of a worrying trend around SOA and package delivery namely that people seem to be thinking that SOA magically means that you can now customise packages safely. The goal becomes once again "fit the package to the business" this unfortunately is the road to ruin. It doesn't matter what the package is, whether Finance, ERP, niche or even a small off the shelf thing for a point solution the basic rule remains the same. You are going package because it doesn't differentiate you, it isn't an area where you will gain competitive advantage and if everyone in your sector ran the same package, it really wouldn't matter.
This is a critical starting point. If you want to use a package solution you have to accept that this means you have chosen to take a non-differentiated route. If your content is the thing that is your USP then this doesn't mean that you shouldn't use a CMS it just means you should recognise that it is the content that is the USP, not the publishing and managing of the content.
Too often people go through extensive requirements gathering before selecting a package and then try and find the "best fit" to those requirements. The project kicks off and they try and implement the remaining requirements. This is suicide, don't do it.
First off start with a set of objectives and principles that will guide the package selection. One of these principles must be that the goal will be to change the business approach to fit the selected package. Then choose the package. The next state is then to ask "how can I cope with what the package does" this leads to the understanding of what business change can be done.
So how does SOA help in this process? Well first off you can use a Business Service Architecture to understand the drivers and interactions at a high level, this really helps to clarify where the package will be used and to make clear the broad business context in which it fits. So if you are looking at packages across multiple areas you should still be thinking about the different areas based on their different business context and drivers, one size doesn't fit all.
So SOA doesn't mean that you can customise the package anymore today that you could before. There is a rough calculation that I've seen a few times around package implementations (the numbers vary a bit but the thought is important)
So basically the more you customise the more likely you are to fail. Now while it looks okay down the bottom end, don't be fooled.
Now these aren't hard and fast numbers, indeed they could be under playing the impact of customisation.
SOA doesn't help in terms of package customisation. A decent BSA can help you understand how the package will work (if at all) and the boundaries that it will have, but the same rules on customising the box remain.
There is however a new choice when it comes to adding differentiation into a business service which is partly implemented using a package.... but not in this post.