Apache ServiceMix, the Agile Open Source ESB -- Component Introduction

ServiceMix currently has the following JBI components:

Rules based routing via the Drools rule engine.
BPEL support for WS-BPEL via PXE
Cache for caching service invocations using a Map cache or a JCache provider
Groovy for clean integration with the Groovy scripting language as a component, transformer or expression language
JCA allows the Java Connector Architecture to be used for efficient thread pooling, transaction handling and consumption on JMS or other Resource Adapters
Quartz to support enterprise timer integration via the Quartz library
Scripting support to allow any JSR 223 compliant scripting engine to be used to easily create a component, perform a transformation or be an expression language.
Transformation using XSLT
Validation for schema validation of documents using JAXP 1.3 and XMLSchema or RelaxNG
XSQL for working with SQL and XML via Oracle's XSQL library

ActiveSOAP the lightweight StAX based SOAP stack
JAX WS to use the JAX-WS API to make a web service client invocation or to host a Java based web service and expose it over multiple protocols
SAAJ for Soap With Attachments and Apache Axis support
XFire for clean integration with POJOs via the XFire SOAP stack
WSIF for integration with the Apache Web Service Invocation Framework (WSIF)

Email support via JavaMail
File based components for writing messages to files and polling directories and sending files into the JBI
FTP support via the Jakarta Commons Net library
HTTP both client side GET/POST with commons httpclient and server side processing with servlets or Jetty
Jabber to provide bindings to Jabber network via the XMPP protocol
JMS via the Java Messaging Service plus all of the great, reliable and scalable transports in ActiveMQ which includes persistence, recovery and transaction support.
RSS support via Rome library for accessing and processing RSS feeds.
VFS via the Jakarta Commons Net library which provides access to file systems, jars/zips/bzip2, temporary files, WebDAV, Samba (CIFS), HTTP, HTTPS, FTP and SFTP among others