Sateri Systems have all the required expertise in Java/J2EE.
A few of those are listed below.
Core Java, Threadpool, JNDI, RMI, JMS, JTA, JDO, JNI, JMX, JAAS, JSSE, JCE
Java TimerService, Applets, Swing, Java Web Start-JNLP, JSF, JSP/Servlets, Struts, EJB, GWT,
Ext-GWT, GWT-Ext, Vaadin, Seam, Tapestry, Velocity, Spring, Hibernate, Toplink, Quartz
Jasper Reports, Lucene, Solr, OpenAM, JAX-WS, JAX-RS, Apache Axis, Jersey, ActiveMQ,
ESB, Terracotta, GigaSpace, Logback.