1213 To Learn More Given limited space we focused on aspects of operations that

1213 to learn more given limited space we focused on

This preview shows page 484 - 485 out of 517 pages.

12.13 To Learn More Given limited space, we focused on aspects of operations that every SaaS developer should know, even given the availability of PaaS. An excellent and more detailed book that focuses on challenges specific to SaaS and is laced with real customer stories is Michael Nygard’s Release It! ( Nygard 2007 ), which focuses more on the problems of “unexpected success” (sudden traffic surges, stability issues, and so on) than on repelling malicious attacks. Our monitoring examples are based on aggregating metrics such as latency over many requests. A contrasting approach is request tracing, which is used in conjunction with metric aggregation to pinpoint and diagnose slow requests. You can see a simplified version of request tracing in the development- mode Rails logs, which by default will report the database query time, controller action time, and rendering time for each request. True request tracing is much finer-grained, following a request through every software component in every tier and timestamping it along the way. Companies that run large sites often build their own request tracing, such as Twitter’s Big Brother Bird and Google’s Dapper. In a recent article ( Barroso and Dean 2012 ) two Google architects discuss how request tracing identifies obstacles to keeping Google’s massively-parallel systems highly responsive. James Hamilton, an engineer and architect at Amazon Web Services who previously spent many years architecting and tuning Microsoft SQL Server, writes an excellent blog that includes a great article on the cost of latency , gathering measured results from a variety of industry practitioners who have investigated the topic. Although we focused on monitoring for performance problems, monitoring can also help you understand your customers’ behavior: Clickstreams: what are the most popular sequences of pages your users visit? Think times/dwell times: how long does a typical user stay on a given page? Abandonment: if your site contains a flow that has a well-defined termination, such as making a sale, what percentage of users “abandon” the flow rather than completing it and how far do they get? Google Analytics provides free basic analytics-as-a-service: you embed a small piece of JavaScript in every page on your site (for example, by embedding it on the default layout template) that sends Google Analytics information each time a page is loaded. To help you use this information, Google’s “Speed is a Feature” site links to a breathtakingly comprehensive collection of articles about all the different ways you can speed up your SaaS apps, including many optimizations to reduce the overall size of your pages and improve the speed at which Web browsers can render them. The RailsLab blog maintained by New Relic also collects best practices and techniques for tuning Rails apps, including screencasts on Rails tuning and how to use New Relic in development mode for profiling . Be aware, though, that some of the specific code examples, especially around caching, are no longer valid because of changes between Rails 2 and Rails 3.
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  • Spring '19
  • Dr.Marcos

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