The 'provides' tag was not added to subsequent newer versions of java as the gcj was gcj specific and is now for all intents and purposes retired. Sun, Oracle, IBM maintainers have no reason to add in this tag as a 'provides' and thus to satisfy the requirement pulls in the only java that satisfies it.. 1.5.0
There are ['ways'] of tricking the rpm dependency database into thinking it already has this requirement satisfied.. but they are not supported or approved by Red Hat.
Installing Tomcat without enabling the "Optional Subscription Channel" in RHN will result in a Tomcat service which has broken dependencies between java classes and java services in code written for the Tomcat service.
RHN Channel Subscription:
Subscribed Channels (Alter Channel Subscriptions)
[x] Red Hat Enterprise Linux Server (v.6 for x86_64)
+-> RHEL Server Optional (v.6 64-bit x86_64)
In particular the following package is only available from the "Optional Channel"
Pulling in Java 1.5.0 is suboptimal because Java 1.5.0 is no longer supported by its upstream provider.jakarta-taglibs-standard rhel-x86_64-server-optional-6
However Java 1.8.0 changed and removed many of the java classes in use by a large portion of the web service code in common use today (i.e. Hashmaps).
Therefore it is more desirable to install Java 1.6.0 or Java 1.7.0
However while this is possible (and because the Alternatives symlinking will result in Tomcat running on the designated version of Java once it is installed) java 1.5.0 cannot be removed with the YUM package manager without causing a catastrophic "unwinding" that removes all packages that have the java-gcj-compat requirement.
To paraphrase the most recent statement from bug 1175457
2015-05-12This bug is not fixed, however a workaround is provided for rhel7.The true fix will probably never go into rhel6
With these issues in mind the barest base install of Tomcat on RHEL 6.6 can be made with the command:
# yum groupinstall web-servletWhich will install the following:
It will provide a webservice, but serve a completely [blank] page.
[ don't forget about - iptables and selinux ]
The following packages [will not be installed] but you may expect and wish to install them:
One reason is that these other packages pull in even more dependencies for supporting the Example and Sample JSP and Servlet applications, which "people tend to install tomcat because they want to serve JSP and Servlet applications.."
If you install only the group web-servlet, your very secure.. but most of your JSP and Servlet apps will not work unless you selectively install supporting packaged versions of support software for JSP and Servlet apps. Kind of a knock on side-effect. Figuring out which packages contain those support services.. is "fun"
Upon enabling the Optional Channel and installing all of the packages, Tomcat behaves more like a freshly compiled source code distribution.
By installing an alternate version of java [before] the java_1.5.0 version is pulled in by a dependency (i.e. on a freshly installed server) the later version of java will take priority and keep the alternatives pointers fixed on the newer version of java [ alternatively the "alternatives" command can be used to manually adjust the pointers, however its just easier to install a different java version before 1.5.0 is pulled in ] [ the non-devel package will pull in only the java runtimes JRE, the "-devel" package will pull in the java development kit javac compiler JDK which could be useful ]
# yum install java-1.7.0-openjdk java-1.7.0-openjdk-devel
# yum install tomcat6 tomcat6-el-2.1-api tomcat6-jsp-2.1-api tomcat6-lib tomcat6-servlet-2.5-api tomcat6-admin-webapps tomcat6-docs-webapp tomcat6-javadoc tomcat6-log4j tomcat6-webappsThe APR, OpenSSL, JNI - libtcnative.so or tomcat-native component is apparently not available as a packaged option on RHEL6. While facility to accomodate it was made in the /etc/sysconfig/tomcat6 file under JAVA_OPTS= it was never packaged for the x86_64 architecture.
It can in theory be compiled and inserted into the /usr/lib64 path "since it is in fact a C" library. But then you run the risk of further maintenance addressing CVEs and other Security audits.
For RHEL7 and Tomcat 7.0 it appears libtcnative may be available as a packaged option.
EPEL and RHSCL also do not appear to offer much support for Tomcat6 on RHEL6.
JBoss however, if contracted and installed, does appear to have a libtcnative however that is not to my knowlege a generally supported option unless you are running that platform.