Event Stream Intelligence: Esper & NEsper
NEsper is a CLR-based component for building CEP and ESP engines. NEsper is based upon the Esper baseline, but includes customizations that are specific to the .NET CLR.
NEsper is derived from Esper and to that end we want to ensure that NEsper is inline with the design, spirit and influence that drives Esper. However, NEsper strives to provide a CEP-ESP component for .NET applications. To that end, we strive to ensure that the APIs, interfaces and other constructs that we use properly reflect the way that the CLR is designed.
NEsper and Esper share the same grammar. Users should find the two environments to be compatible. However, users should keep in mind that NEsper and Esper are case sensitive and canonization practices differ between the Java and .NET.
All of the features found in Esper are also available in NEsper. A NEsper version is feature-equivalent to the same-version Esper (Java) component.
Like its namesake, NEsper was created to make it easier to build CEP and ESP applications. NEsper is open-source software available under the GNU General Public License (GPL) license.
NEsper has been tested with both ADO.NET and ODBC drivers to relational database access. As part of the regular build, NEsper tests against a MySQL database and Microsoft SQL Server 2005.
The ADO.NET database model has one huge quirk: In ADO.NET parameters and their format are dictated by the driver. As such, you can end up with a driver like the MySQL driver which is a named-parameter driver. Parameters have to be written as @name in order to be processed. ODBC is a positional-parameter driver which means that parameters must be written using ? as their parameter.
What makes this even worse is that the prefix (the ? or @) is defined by the driver. Oracle, SQL Server and MySQL all have potentially different prefixes. The NEsper tests exercise code that allows the user to change the the provider and positional parameter style.
About Esper for Java
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Last Published: Mar 04, 2013