

In today’s interconnected world, cloud applications often require the ability to interact with other services, which creates more work for developers.
LinkedIn set out to ease the task today by open sourcing an internal tool that is designed to automate one of the most tedious chores involved in implementing application connectivity: testing how traffic is handled. Developers need to ensure that a service can reliably respond to all the different kinds of requests it’s expected process before rolling out their code to production. The business network’s software, which goes by the name Flashback, provides the ability to run simulations that mimic real-world operating conditions so to reveal potential issues.
The Microsoft Corp.-owned service detailed in a blog post that the tool works similarly to Betamax, another open-source traffic testing tool that it had used before moving to build an alternative. They both go about running simulations by connecting to the target application or website, recording inbound requests and then replaying them offline. This approach allows developers to perform assessments even if the third-party service they’re looking to test is unavailable because of technical issues.
LinkedIn set Flashback apart by removing need for web access altogether after the initial live traffic capture. The company’s motivation was to optimize the tool for its internal test environment, which is kept offline due to security reasons. As a result, it should be a more convenient option than Betamax for other organizations that likewise block external connections to their development infrastructure.
Flashback’s other big advantage, in turn, lies with its ability to handle information that is sent over protocols other than HTTPS. The tool supports so-called match rules that developers can configure to customize traffic parameters according to their specific requirements. This feature is particularly handy for simulating security data transmitted using the OAuth authorization standard, which requires certain credentials to be refreshed after every request.
Flashback is the latest in a long series of internal projects that LinkedIn has open sourced to ease the work of developers. Previously, the social networking giant released another testing tool called Simroog that aims help identify operational conditions in which an application may crash before any damage is done.
The code for Flashback and LinkedIn’s other open-source projects is available on its GitHub page.
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