I recently posted these as a comment over on Ben's "Software Delivery Approaches – Debunking the Myths" post and thought it worthy to reiterate the key points.
The key Pros (from my perspective) Ben articulated with SaaS were as follows:
- Ability to provision almost instantly.
- Pushes infrastructure, service, and support costs to the vendor.
- Upgrades are automatically applied to all users – all customers work with the same application.
Cons of ASP and SaaS options (which will have differing levels of risk based on who the vendor is):
- If the vendor goes out of business, then you may have a significant problem with little or no warning.
- Depending on where the data is hosted you may be subject to different laws.
- From an information/data security perspective you are placing trust in another organisation. On the flip-side for many organisations, this may however be better than what they would have anyway.
- With SaaS you are moreso at the mercy of the vendor’s roadmap changing with little or no notice. Whilst this can be a positive in terms of functionality delivered, I’ve seen this one go the other way whereby a vendor “changed the rules” and as a result this raised a number of audit/risk challenges.
- Depending on your timezone, scheduled downtime (if required) may not be at an optimal time.
- Potential for increased latency depending on the location of the service. This may however end up being closer to your customers so may in fact be a positive.
- Integration may be confined to API limits that are not suitable.