Users have access to desktop virtualization, which means that their desktop appears on whatever device they happen to use at a given moment.
❯❯ The use of policy-based services ensures that users must still adhere to company requirements when using computer resources.
❯❯ All required updates (software and hardware) occur automatically and without any interaction required by the client.
❯❯
❯❯ Billing can become complex because some services are billed at different rates and within different time frames. In addition, billing can include resource usage. The client must ensure that the amount on the bill actually matches real-world usage; paying too much for services that the client didn’t actually use can easily happen.
❯❯ Systems-management monitoring becomes more difficult. The client loses control over the precise manner in which activities occur.
❯❯ A lag often occurs between when a change in service is needed and when the host provides it, so the client can find that even though services are more flexible, they aren’t as responsive.
❯❯ Host downtime can affect a large group of people and prove difficult to fix, which means that a particular client may experience downtime at the worst possible time without any means to resolve it.
❯❯ Building and testing custom applications can become more difficult. Many experts recommend using in-house equipment for application-development needs to ensure that the environment is both protected and responsive.
SaaS is all about cloud-based applications. Products like online email and office suites are examples of cloud-based applications. A client typically accesses the application using a local application, such as a browser. The browser runs on local hardware, but the application runs on the host hardware. What a client sees is the application running in the browser as if it is working locally. In most cases, the application runs within a browser without any alteration to the local system. However, some applications do require the addition of plug-ins.
The difference between IaaS and SaaS is the level of service. When working with IaaS, a client typically requires detailed support that spans entire solutions. A SaaS solution may include only the application. However, it can also include the following:
❯❯ Application runtimes
❯❯ Data access
❯❯ Middleware
❯❯ Operating system support
❯❯ Virtualization
❯❯ Server access
❯❯ Data storage
❯❯ Networking
PaaS is more of a development solution than a production environment solution. A development team typically uses PaaS to create custom solutions or modify existing solutions. The development staff has full control over the application and can perform all development-related tasks, such as debugging and testing. As with the SaaS solution, the host normally maintains control over
❯❯ Middleware
❯❯ Operating system support
❯❯ Virtualization
❯❯ Server access
❯❯ Data storage
❯❯ Networking
In this case, however, the development staff can access the middleware to enhance application development without reinventing the wheel. Writing application code to make the application cloud-ready isn’t necessary because the middleware already contains these features. The development team gains access to cloud-based application features that include the following:
❯❯ Scalability
❯❯ High availability
❯❯ Multitenancy
❯❯ SaaS enablement
Determining Why You Should Use AWS
Even though AWS has a lot to offer, you still need to consider how it answers your specific needs. This consideration goes beyond simply determining whether you really want to move to cloud-based services, but also takes into account other offerings that might serve your needs just as well (if not better). Even though this book is about AWS, you should compare AWS with other cloud services. You may choose to use AWS as part of your solution rather than as the only solution. Of course, this means knowing the areas in which AWS excels. The following sections address both of these possibilities: using cloud services other than AWS, or in addition to it.
You have many ways to compare cloud services. One of the ways in which companies commonly look at services is by the market share they have. A large market share tends to ensure that the cloud service will be around for a long time and that many people find its services both useful and functional. A recent InfoWorld article (http://www.infoworld.com/article/3065842/cloud-computing/beyond-aws-the-clouds-next-stage.html) points out that AWS currently corners 70 to 80 percent of the cloud market. In addition, AWS revenues keep increasing, which lets Amazon continue adding new features while maintaining existing features at peak efficiency.
