Tutorial: open source enterprise application integration - introducing the event processing capabilities of apache camel

Reviewer: Christoph F. Strnadl

The functionality of a message-passing software system such as Camel can be reformulated in an event-centric manner. This is the main result of this work, although from a theoretical viewpoint, the result is fairly trivial. Furthermore, the paper does not fully live up to the high standards of a tutorial because of the sloppy way it describes the more advanced (and, hence, more difficult to explain) concepts of Camel. The basic concept of the paper is promising. The authors first introduce implementation-independent basic notions of an event-driven architecture (EDA), such as event objects and types, event consumers and producers, event processing network, and a reference use case (parcel delivery), to provide the semantics for short examples. After the introduction of related terms, the authors immediately reflect on the particular way Camel implements these concepts, such as using a "message" as its basic construct for capturing an event. Short Extensible Markup Language (XML) or Java code examples demonstrate how a developer would actually work with notions such as a Camel component or endpoint. Capabilities of event-processing agents are introduced using a pattern-oriented approach for filtering, aggregation, splitting, and translating messages. However, it is with the more elaborate concepts (like Camel's route and routebuilder) that I miss the clarity that would make the paper a true tutorial. For instance, the authors suddenly switch to the Java Domain Specific Language (DSL) without explaining this step. Additionally, the paper spends too much time explaining fairly basic ideas such as filtering of messages (= events) without highlighting the basic building blocks of the Java DSL. In summary, an enterprise integration software architect or developer new to event processing will find about half the paper quite useful. For an introduction to the more advanced concepts of Camel or an EDA, however, the reader will need to consult additional sources. Online Computing Reviews Service