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The Apache Tomcat servlet container provides an ideal environment for running Sakai as a web application. Tomcat implements both the Java Servlet and JavaServer Pages (JSP) specifications and can be run in standalone mode or in conjunction with a web application server such as the Apache HTTP server or JBoss. Sakai 2.6 works with the Tomcat 5.5 series. We recommend Tomcat 5.5.30 33 in order to avoid certain Tomcat security vulnerabilities present in earlier releases. Note however, that using Tomcat 5.5.27+ requires the addition of a JAVA_OPTS parameter (see below). Sakai 2.6 is not compatible with Tomcat 6.0+.
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Good: C:\opt\tomcat\, C:\sakaistuff\installs\tomcat\ 
Bad: C:\program files\tomcat\, C:\opt\apache tomcat 5.5.3033\
Tomcat permissions
Unix/Mac users should make sure that they have write permissions to the Tomcat servlet container files and directories before proceeding or startup permission errors may occur.
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Tomcat 5.5.27+ enforces strict quote escaping which causes run-time errors in certain Sakai tools that use the JavaServer Faces (JSF) UI rendering framework. See https://issues.apache.org/bugzilla/show_bug.cgi?id=45015 for more details. If you deploy Sakai using Tomcat 5.5.27+ add the following parameter to your JAVA_OPTS environment setting:
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