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These materials are the copyright of John Wiley & Sons, Inc. and any dissemination, distribution, or unauthorized use is strictly prohibited. 34 Platform as a Service For Dummies, Special Edition development staff in traditional environments. Some of the deployment functions built into PaaS platforms are ✓ Allocating resources ✓ Staging and testing applications ✓ Provisioning nodes on the server clusters ✓ Installing, configuring, and securing load balancers, application servers, and databases The standardization of PaaS deployment lifecycle services means that the services are both easier to deploy and maintain consistently. In a PaaS environment, all the key deployment functions are abstracted from the developer masking them from the complexities of these sophisticated features. As a result, PaaS makes the process of updating applications after they’ve been deployed faster and more efficient. PaaS takes on the responsibility of connecting applications. The integration services provided with the PaaS make this simple. Some issues still remain for consideration, including service management, access to a variety of services, and integration across environments. Staging and testing applications in PaaS The PaaS environment allows for much greater flexibility in the way that deployment teams create staging areas — environments used to test changes to a private version of an application before the new or revised application goes live — for their applications. It can take a lot of time and manual effort on the part of the IT team to get the staging area set up appropriately. The staging area needs to completely replicate the databases, web servers, connections, and other dynamic components of the application environment or you run the risk of allowing errors into your live system. All of this can be quickly and easily handled with PaaS allowing developers to focus more on meeting customer requirements and less on IT infrastructure issues. Basically with PaaS, you can take a much more logical and practical approach to the staging and testing of applications. As a user of PaaS deployment services, you expect the following in your staging environment:
These materials are the copyright of John Wiley & Sons, Inc. and any dissemination, distribution, or unauthorized use is strictly prohibited. Chapter 4: Using PaaS as a Deployment Platform 35 ✓ Full mirror of your live environment for the switch ✓ Rollback to pre-change environment if errors are found ✓ Partition existing cloud resources for phased deployment and testing within pre-defined limits How do these PaaS capabilities impact the testing process prior to rolling out a new version of an application Consider the developer who needs to roll out a new version of an online shopping application for a retailer. She has ten servers running the existing application. In the past, her approach has been to take one server offline at a time. This approach introduces operational problems: ✓ A reduction in the amount of resource currently serving the existing application to be able to introduce the new version. If the new version causes a change in load or code path, or servers are already highly utilized, users may see degradation in service. ✓ As the new application becomes more heavily loaded with real users, a stress-related issue may arise in production that was difficult to test for. So, the rollout process may need to be rolled back — quickly — and the operational processes for rollback can be at least as difficult as for rollout. These operational problems can easily be eliminated with PaaS. The new version rollout can be handled in a different way. With PaaS, the developer can create ten new instances in a completely replicated environment — the new instances have the new application but otherwise are 100 percent like the old ones. The new requests can all be routed to the new instances in a controlled manner, and you don’t need to cannibalize the existing with the live environment. If an unexpected error occurs, your full existing environment is in place, so you can guarantee no loss of service. When you’re comfortable with the new application, you can retire the old systems. In a pay-as-you-go PaaS environment, this approach is simpler, because traditionally the process involves meetings, planning, installing, and wiring.
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