doc.go

//go:generate mockgen -self_package github.com/lovoo/goka -package goka -destination mockstorage.go github.com/lovoo/goka/storage Storage
//go:generate mockgen -self_package github.com/lovoo/goka -package goka -destination mocks.go github.com/lovoo/goka TopicManager,Producer,Broker
//go:generate mockgen -self_package github.com/lovoo/goka -package goka -destination mockssarama.go github.com/IBM/sarama Client,ClusterAdmin

/*
Package goka is a stateful stream processing library for Apache Kafka (version 0.9+) that eases
the development of microservices.
Goka extends the concept of consumer group with a group table, which represents the state of the
group.
A microservice modifies and serves the content of a table employing two complementary object types:
processors and views.

# Processors

A processor is a set of callback functions that modify the group table when messages arrive and may
also emit messages into other topics.
Messages as well as rows in the group table are key-value pairs.
Callbacks receive the arriving message and the row addressed by the message's key.

In Kafka, keys are used to partition topics.
A goka processor consumes from a set of co-partitioned topics (topics with the same number of
partitions and the same key range).
A group topic keeps track of the group table updates, allowing for recovery and rebalancing of
processors:
When multiple processor instances start in the same consumer group, the instances split the
co-partitioned input topics and load the respective group table partitions from the group topic.
A local disk storage minimizes recovery time by caching partitions of group table.

# Views

A view is a materialized (ie, persistent) cache of a group table.
A view subscribes for the updates of all partitions of a group table and keeps local disk storage
in sync with the group topic.
With a view, one can easily serve up-to-date content of the group table via, for example, gRPC.
*/
package goka