VIATRA/CEP/Language

VIATRA-CEP User's guide

The following contents introduce the VIATRA-CEP complex event processing stack and its main features. Basic knowledge on complex event processing is advised, although not strictly required. Should this guide prove to be insufficient, please do not hesitate to ask your question on our mailing list.

Getting started

The VIATRA-CEP stack

//TODO

Language essentials

This section is a comprehensive overview on the features of the VIATRA Event Processing Language (VEPL).

Atomic event patterns

AtomicEvent name (parameters) {body}

• The name of the atomic event must be unique among the model.
• The parameters are typed and use the JVM type hierarchy. An example parameter list could be (name:String, id:int). Parameters are evaluated at runtime. To see the main motivation behind this, see the ..link:complex events...
• The body is currently not in used, but it will be soon: https://bugs.eclipse.org/bugs/show_bug.cgi?id=440748.

From this structure, two types of source code is generated: atomic events and atomic event patterns. The former ones are used by applications to be instantiated and forwarded to the engine; while the latter ones are actual patterns which can be reused in /link complex event pattern definitions or /link rules.

Complex event patterns

ComplexEvent name (parameters) {
     definition: complex pattern definition
}

Rules

Rule name {
     events: complex pattern definition
     action{
          executable code block using XBase syntax
     }
}

Rule name {
     events: complex pattern definition
     actionHandler: reference to an action handler, i.e. a class implementing the IActionHandler interface
}

Packages and Usages

package name

VEPL allows the model to be organized into different packages and reuse those packages in other ones by usages. Every model begins with a package declaration, which is a hierarchical identifier. For example: package com.company.cepproject.

uses package name with wildcard or a specific class in a package
uses-patterns IncQuery pattern package

The uses keyword imports other VEPL packages or source code packages; the uses-patterns keyword imports IncQuery patterns to be used in IncQuery event patterns.

Setting up the environment

1. Download the latest Eclipse Luna Modeling (currently SR1) package.
2. Install the following plugins or import their source plug-ins into a running Eclipse instance:

   EMF-IncQuery 0.9.0 

   CI update site

   VIATRA 0.7.0 (required components are VIATRA2-EMF and VIATRA-CEP) 

   CI update site

Examples

You can find demonstrative examples here.

Important links

• VIATRA-CEP Bugzilla
• our mailing list: viatra-dev@eclipse.org
• A paper on VIATRA-CEP from MoDELS 2014 (Available for download from here.)