Mt collector failed updating entry in message tracking store
This means site activity (page views, searches, or other actions users may take) is published to central topics with one topic per activity type.These feeds are available for subscription for a range of use cases including real-time processing, real-time monitoring, and loading into Hadoop or offline data warehousing systems for offline processing and reporting.It builds upon important stream processing concepts such as properly distinguishing between event time and processing time, windowing support, exactly-once processing semantics and simple yet efficient management of application state.Kafka Streams has a low barrier to entry: You can quickly write and run a small-scale proof-of-concept on a single machine; and you only need to run additional instances of your application on multiple machines to scale up to high-volume production workloads.Kafka works well as a replacement for a more traditional message broker.Message brokers are used for a variety of reasons (to decouple processing from data producers, to buffer unprocessed messages, etc).Such processing pipelines create graphs of real-time data flows based on the individual topics.Starting in 0.10.0.0, a light-weight but powerful stream processing library called Kafka Streams is available in Apache Kafka to perform such data processing as described above.
For an overview of a number of these areas in action, see this blog post.
This allows for lower-latency processing and easier support for multiple data sources and distributed data consumption.
In comparison to log-centric systems like Scribe or Flume, Kafka offers equally good performance, stronger durability guarantees due to replication, and much lower end-to-end latency.
Apart from Kafka Streams, alternative open source stream processing tools include Apache Storm and Apache Samza.
Event sourcing is a style of application design where state changes are logged as a time-ordered sequence of records.
The ecosystem page lists many of these, including stream processing systems, Hadoop integration, monitoring, and deployment tools.