Package: gimel
Gimela Scaleable A/B testing backend in ~100 lines of code (and for free*)What is it?an A/B testing backend using AWS Lambda/API Gateway + RedisKey Features:Highly scalable due to the nature of AWS LambdaHigh performance and low memory footprint using Redis HyperLogLogCost EffectiveEasy deployment usinggimel deploy. No need to twiddle with AWS.Looking for contributorsclick here for more infoWhat does Gimel mean?Gimel (גִּימֵל) is the 3rd letter of the Hebrew Alphabet. The letter (ג) also looks visually similar to the greek Lambda
(λ).Installation / Quick StartYou will need a live instance of redis accessible online from AWS. Then run:$pipinstallgimel
$gimelconfigure
$gimeldeployIt will automatically configure your AWS Lambda functions, API gateway and produce a JS snippet ready to use
for tracking your experiments.ArchitectureClientI suggest looking atAlephbetto get more details, but at a high level, the client runs on the end-user browser. It will randomly pick a variant and execute a javascript function to 'activate' it. When a goal is reached -- user performs a certain action, this also include the pseudo-goal ofparticipatingin the experiment -- then an event is sent to the backend. An event typically looks something like "experiment ABC, variant red, user participated", or "experiment XYZ, variant blue, check out goal reached".Alephbet might send duplicate events, but each event should include auuidto allow the backend to de-duplicate it. More belowData Store - Redis HyperLogLogThe data store keeps a tally of each event that comes into the system. Being able to count unique events (de-duplication) was important to keep an accurate count. One approach would be to store each event in an entry / database row / document, and then run some kind of a unique count on it. Or we could use a nifty algorithm calledHyperLogLog. HyperLogLog allows you to count unique counts without storing each and every item.In terms of storage space, redis HyperLogLog offers a fixed size of 12k per counter. This gives us ample space for storing experiment data with low memory footprint.Backend - AWS Lambda / API GatewayThe backend had to take care of a few simple types of requests:track an event - receive a (HTTP) request with some json data -- experiment name, variant, goal and uuid, and then push it to redis.extract the counters for a specific experiment, or all experiments into some json that can be presented on the dashboard.DashboardNew! access your dashboard withgimel dashboardHow does tracking work?Check outAlephbet.Command Referencegimel --help- prints a help screen.gimel configure- opens your editor so you can edit the config.json file. Use it to update your redis settings.gimel preflight- runs preflight checks to make sure you have access to AWS, redis etc.gimel deploy- deploys the code and configs to AWS automatically.Advancedcustom API endpointsIf you want to use different API endpoints, you can add your ownextra_wiringinto theconfig.jsonfile (e.g. usinggimel configure).for example, this will add a.../prod/my_tracking_endpointURL pointing to thegimel-tracklambda:{"redis":{...},"extra_wiring":[{"lambda":{"FunctionName":"gimel-track","Handler":"gimel.track","MemorySize":128,"Timeout":3},"api_gateway":{"pathPart":"my_tracking_endpoint","method":{"httpMethod":"GET","apiKeyRequired":false,"requestParameters":{"method.request.querystring.namespace":false,"method.request.querystring.experiment":false,"method.request.querystring.variant":false,"method.request.querystring.event":false,"method.request.querystring.uuid":false}}}}]}seeWIRINGPrivacy, Ad-blockers (GDPR etc)Gimel provides a backend for A/B test experiment data. This data is aggregated and doesnotcontain any personal information at all. It merely stores the total number of actions with a certain variation against another.As such, Gimel should meet privacy requirements of GDPR and similar privacy regulations.Nevertheless, important disclaimers:I am not a lawyer, and it's entirely up to you if and how you decide to use Gimel. Please check with your local regulations and get legal advice to decide on your own.Some ad-blockers are extra vigilent, and would block requests with thetrackkeyword in the URL. Therefore, track requests to Gimel might be blocked by default. As the library author, I make no attempts to conceal the fact that a form of tracking is necessary to run A/B tests, even if I believe it to be respecting privacy.Users who decide to use Gimel can, if they wish, assign a different endpoint that might get past ad-blockers, but that's entirely up to them. seecustom API endpointson how this can be achieved.As with almost any tool, it can be use for good or evil. Some A/B tests can be seen as manipulative, unfair or otherwise illegitimate. Again, use your own moral compass to decide whether or not it's ok to use A/B testing, or specific A/B tests.LicenseGimel is distributed under the MIT license. All 3rd party libraries and components are distributed under their
respective license terms.Copyright (C) 2016 Yoav Aner

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