Add the Jersey servlet configuration before your </web-app> closing tag
<servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <init-param>
        <!-- Tell Jersey where to find your REST classes -->
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>com.dan.rest</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>
After deploying to Tomcat, you should be able to hit:
bash
http://localhost:8080/testmavenproject/rest/a
This should return:
nginx
Hello World
How about it?