WSO2 Complex Event Processor

WSO2 Complex Event Processor (WSO2 CEP) helps identify the most meaningful events and patterns from multiple data sources, analyze their impacts, and act on them in real time. 100% open source, it allows you a set up a more agile connected business, responding to urgent business situations with both speed and precision.

From enabling healthcare providers develop real-time clinical decision support systems, to monitoring transactions and tracking vehicles in smart cities, WSO2 CEP is highly performant, massively scalable, and offers significant savings in both cost and time.

WSO2 CEP is available on-premise, on top of WSO2 Private PaaS or on any public cloud such as Amazon AWS. It is an integral part of the WSO2 Analytics Platform, where it provides the real time analytics pipeline.

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WSO2 CEP facilitates real time event detection, correlation and notification of alerts, combined with rich visualization tools to help build monitoring dashboards.

It utilizes a high-performance streaming processing engine which is the outcome of extensive research at WSO2. Thanks to its architecture, memory optimizations and new approaches to storing event data, WSO2 CEP is one of the fastest open source solutions available today, able to find events patterns in real-time milliseconds.


At the heart of WSO2 CEP is Siddhi. Configured using a rich, compact, easy to learn SQL-like language, WSO2 CEP is especially suited for complex queries involving time windows, as well as patterns and sequences detection. CEP queries can be changed dynamically at runtime using templates. The core streaming engine is low-latency, extremely small in size and can be deployed for edge analytics - that is, the execution of event processing flows on a device or IoT gateway. This, coupled with its ability to handle extremely large volumes of event streams, makes WSO2 CEP particularly well-suited to handle IoT scenarios.

WSO2 CEP can be deployed in standalone or distributed modes. In distributed mode, it leverages Apache Storm architecture for nearly linear scalability. Pre-built solutions such as fraud detection and geo fencing leverage the power of WSO2 CEP and provide domain specific implementations on top of the core engine.


  • A single WSO2 CEP node can handle 100K+ events per second over network on commodity hardware (e.g. 4 cores, 4 GB RAM)
  • Capable of processing 6 million events per second with events generated from same JVM
  • Finalist in DEBS Grand Challenge 2014 and 2015 (based on building single-node and distributed solutions running queries across 4 billion events collected from smart homes equipped with a total of 2000 sensors)


Process data in motion, and analyze in real time

  • Works as a streaming pipeline, processing one event at a time, allowing to detect conditions and react to them in real time.
  • Handle massive amounts of streamed events (100,000 events per second and above) due to low-latency engine.
  • Detection of out-of-order events and ability to smooth event streams (remove noise) by using Kalman filtering.
  • Supports data partitioning for optimized execution of queries in a distributed deployment.

Rich configuration language

  • Uses a rich and compact SQL-like query language covering the most complex event processing flows configuration.
  • Supports event streams filtering by conditions, as well as event streams transformation.
  • Supports the aggregation and correlation of one or multiple event streams.
  • Supports temporal patterns detection, logical patterns detection, as well as events sequences.
  • Includes capability to enrich event streams with historical data stored in databases, files or external data source.
  • Supports parameterized templates for dynamic editing and deployment of queries by non-technical users.

Scalability and High availability

  • Supports standalone fault tolerant deployment, with or without event streams persistence.
  • Supports distributed deployment on top of Apache Storm architecture.
  • Includes specific streaming operators to drive parallel execution on Apache Storm.

Connect and integrate with anything

  • Event streams can be received and sent in XML , JSON, Text or Map format.
  • Supports standards transport receivers and publishers, including HTTP(s), JMS, files or SOAP, REST or Email, Apache Thrift or Web sockets.
  • Support for IoT-friendly transports such as MQTT or Apache Kafka.
  • Events can be published in data repositories such as RDBMS or Apache Cassandra.
  • Supports the addition of custom data connectors in Java.
  • Supports 100+ legacy and cloud applications when combined with the WSO2 ESB

Business Applications

  • Interactively create dashboards, including support for gadget generation from event stream definitions.
  • Configure pre-built queries via a web application, with no need to know about the underlying language.

Application Development

  • Try It capability to learn the configuration language by testing a query against a sample data set.
  • Visualize event processing flow and simulate event streams
  • Replay data sets from a file or a database
  • Embed into enterprise applications for event streams publishing

Operational Management

  • Ability to collect statistics data at several points of the event processing flow and visualize in embedded dashboards or via JMX.
  • Ability to record and replay events to troubleshoot production systems.
  • Ability to instrument, monitor and visualize operational metrics

Customer Success Stories

Pacific Controls is an innovative company delivering an IoT platform of platforms: Galaxy 2021. The platform allows to manage all kinds of devices within a building and take automated decisions such as moving an elevator or starting the air conditioning based on certain conditions. Within Galaxy2021, WSO2 CEP is used for monitoring alarms and specific conditions.

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The Cleveland Clinic, ranked among the top 3 hospitals in the US, uses a Clinical Intelligence Platform that combines big data storage, stream and batch processing to provide decision support to clinicians. Real-time analytics for the platform is provided by WSO2 CEP along with custom extensions to handle healthcare data.

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