Open Source Enterprise Service Bus in Java

Open source services framework for building SOAP and REST services. JAX-WS, JAX-RS; multiple transports (HTTP, JMS, JBI); WS-* support. Deploy in containers or as standalone; integrates with ESBs such as ServiceMix and Petals.

Lightweight integration platform and ESB. Message routing, transformation, orchestration; multiple transports and protocols; flow-based design; Mule runtime is open source (MuleSoft).

Extension of the Spring model for Enterprise Integration Patterns. Lightweight messaging, declarative adapters for external systems; channels, gateways, and many protocol adapters (HTTP, JMS, Kafka, etc. ).

Lightweight ESB: mediation, routing, transformation. HTTP/SOAP/REST, JMS, VFS, mail; WS-Addressing, WS-Security, WS-RM; extensible with Java and scripting.

Application integration platform; plug-in architecture, transformation and routing. Runs on J2EE servers; JCA connectivity; flow design separated from technical implementation.

OSGi-based ESB integrating ActiveMQ, Camel, CXF, and Karaf. Lightweight, embeddable; Spring support; legacy JBI support via NMR. Apache License 2.

Lightweight ESB based on Apache Synapse. Connect, transform, and mediate services (SOAP, REST, JMS, file, DB); WS-Security, graphical admin; now part of WSO2 Integrator (MI/SI/ICP).

JBI-compliant ESB with Eclipse-based GUI. Component Flow Editor for visual JBI design; support for EDI X12 and fixed/variable formats.

JBoss ESB: messaging, BPM, connectors, transaction manager, security. Part of Red Hat SOI; superseded by other integration offerings.

ESB runtime with service engines and binding components. Integrates enterprise apps and web services as loosely coupled composite applications (SOA).

JBI-compliant ESB (JSR-208) from ObjectWeb/OW2. Lightweight, distributed, clustering; built on Fractal and JORAM.