Sad to see the latest outage with Gmail; how confident should individuals and companies be in web services?At their best, web services allow a concentration of expertise and best-practice that many organizations might not have internally. Many individuals and small- or even medium-sized businesses do not achieve the”99.9%” uptime in their email systems -equivalent to less than 9 hours of service interruption per year – that is often a minimum service-level standard in the web-services world. To make a simple comparison, in most countries people know that the service from their electricity company is simpler and more reliable than trying to run their own power station.Many corporate web-services users would rightly expect to go much further than 99.9%; they should look under the covers of the web-service, to see if it is structured to support a higher corporate-grade level of reliability. Typical questions include -if a service center were destroyed by a fire, would the service continue immediately at an alternative site? Would a problem be automatically isolated to a small number of users and not -as appears to be the case with this latest outage -reach every user? Is there enough capacity so if some components fail the rest are not overwhelmed? How is the service secured? What are the actual reliability results of the service, and how are they measured? And if the worst happens -for instance, a corrupted database -would there be recent copies of data that could be recovered?Happily, while no service, web-based or otherwise, can ever guarantee perfection, corporate-grade web services can be structured to achieve the best available reliability and security.by Duncan Greatwood, director of engineering, Cisco Collaboration Software Group.