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Wayeb is a Complex Event Processing and Forecasting (CEP/F) engine written in Scala. It is based on symbolic automata and Markov models.

Quick start


Assuming $WAYEB_HOME is the root directory of Wayeb, then go inside:


Let's build a fat jar:

$ sbt assembly


In $WAYEB_HOME/data/demo/data.csv you may find a very simple dataset, consisting of 100 events. The event type is either A, B or C. In $WAYEB_HOME/patterns/demo/a_seq_b_or_c.sre you may find a simple complex event definition for the above dataset. It detects an event of type A followed by another event of type B or C. If we want to run this pattern over the stream, we must first compile this pattern into an automaton (make sure you have created a results folder under $WAYEB_HOME):

$ java -jar cef/target/scala-2.12/wayeb-0.2.0-SNAPSHOT.jar compile --patterns:patterns/demo/a_seq_b_or_c.sre --declarations:patterns/demo/declarations.sre --outputFsm:results/a_seq_b_or_c.fsm

Now, results/a_seq_b_or_c.fsm is the produced serialized finite state machine. Note that we also provided as input a declarations.sre file. This file simply lets the engine know that the three predicates IsEventTypePredicate(A), IsEventTypePredicate(B) and IsEventTypePredicate(C) are mutually exclusive (i.e., an event can have only one type). This helps the compiler create a more compact automaton. We can use this FSM to perform event recognition on this simple dataset:

$ java -jar cef/target/scala-2.12/wayeb-0.2.0-SNAPSHOT.jar recognition --fsm:results/a_seq_b_or_c.fsm --stream:data/demo/data.csv --statsFile:results/recstats


For forecasting, we first need to use a training dataset in order to learn a probabilistic model for the FSM. For this simple guide, we will use $WAYEB_HOME/data/demo/data.csv both as a training and as a test dataset, solely for convenience. Normally, you should use different datasets.

We first run maximum likelihood estimation:

$ java -jar cef/target/scala-2.12/wayeb-0.2.0-SNAPSHOT.jar mle --fsm:results/a_seq_b_or_c.fsm --stream:data/demo/data.csv --outputMc:results/

The file results/ is the serialized Markov model. The final step is to use the FSM and the Markov model to perform forecasting:

$ java -jar cef/target/scala-2.12/wayeb-0.2.0-SNAPSHOT.jar forecasting --modelType:fmm --fsm:results/a_seq_b_or_c.fsm --mc:results/ --stream:data/demo/data.csv --statsFile:results/forestats --threshold:0.5 --maxSpread:10 --horizon:20 --spreadMethod:classify-nextk


Copyright (c) Elias Alevizos


Wayeb follows a dual licensing scheme.

For use by individuals, Wayeb is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA. This license is provided exclusively for research purposes. The results of any such research involving Wayeb must be made publicly available.

For commercial/institutional/governmental use or any other use by private or public legal entities, sharing, modifying and distributing Wayeb or any derivatives of it in any form, such as source code, libraries and executables, requires the written permission of its author(s) (Elias Alevizos), possibly accompanied by a request for licensing fees.


Citing Wayeb

If you want to cite Wayeb, use the following references:

  author    = {Elias Alevizos and
               Alexander Artikis and
               George Paliouras},
  title     = {Event Forecasting with Pattern Markov Chains},
  booktitle = {Proceedings of the 11th {ACM} International Conference on Distributed
               and Event-based Systems, {DEBS} 2017, Barcelona, Spain, June 19-23,
  pages     = {146--157},
  publisher = {{ACM}},
  year      = {2017},
  url       = {},
  doi       = {10.1145/3093742.3093920}
  author    = {Elias Alevizos and
               Alexander Artikis and
               Georgios Paliouras},
  editor    = {Gilles Barthe and
               Geoff Sutcliffe and
               Margus Veanes},
  title     = {Wayeb: a Tool for Complex Event Forecasting},
  booktitle = {{LPAR-22.} 22nd International Conference on Logic for Programming,
               Artificial Intelligence and Reasoning, Awassa, Ethiopia, 16-21 November
  series    = {EPiC Series in Computing},
  volume    = {57},
  pages     = {26--35},
  publisher = {EasyChair},
  year      = {2018},
  url       = {}



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