Scala Stream Collector

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Introduction

The Scala Stream Collector is a Snowplow event collector for Snowplow snowplow, written in Scala. The Scala Stream Collector allows near-real time processing (Enrichment, Storage, Analytics) of a Snowplow raw event stream.

The Scala Stream Collector receives raw Snowplow events over HTTP, serializes them to a Thrift record format, and then writes them to a sink. Currently supported sinks are:

1. Amazon Kinesis
2. stdout for a custom stream collection process

Support for Apache Kafka may be added in the future - please see ticket #xxx for details.

Like the Clojure Collector, the Scala Stream Collector supports cross-domain Snowplow deployments, setting a user_id (used to identify unique visitors) server side to reliably identify the same user across domains.

How it works

User identification

The Scala Stream Collector allows the use of a third-party cookie, making user tracking across domains possible. The CloudFront Collector does not support cross domain tracking of users because user ids are set client-side, whereas the Scala Stream Collector sets them server-side.

In a nutshell: the Scala Stream Collector receives events from the [Snowplow JavaScript tracker] snowplow-js, sets/updates a third-party user tracking cookie, and returns the pixel to the client. The ID in this third-party user tracking cookie is stored in the network_userid field in Snowplow events.

In pseudocode terms:

if (request contains an "sp" cookie) {
    Record that cookie as the user identifier
    Set that cookie with a now+1 year cookie expiry
    Add the headers and payload to the output array
} else {
    Set the "sp" cookie with a now+1 year cookie expiry
    Add the headers and payload to the output array
}

Technical architecture

The Scala Stream Collector is built on top of Spray and Akka actors.

See also

• [GitHub repository] github-repo
• [Setup guide] setup-guide