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Apache JServ Protocol
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<p>The Apache JServ Protocol (AJP) is a <a href="/facts/Binary_protocol/Nmj0lyxI">binary protocol</a> that can <a href="/facts/Proxy_server/ArhwQE74">proxy</a> inbound requests from a <a href="/facts/Web_server/A4GS6thA">web server</a> through to an <a href="/facts/Application_server/wHYtgYK5">application server</a> that sits behind the web server. AJP is a highly trusted protocol and should never be exposed to untrusted clients, which could use it to gain access to sensitive information or execute code on the application server. </p><p>It also supports some monitoring in that the web server can <a href="/facts/Ping_(networking_utility)/BoyaWck6">ping</a> the application server. Web implementors typically use AJP in a <a href="/facts/Load_balancing_(computing)/jddk6ang">load-balanced</a> deployment where one or more front-end web servers feed requests into one or more application servers. Sessions are redirected to the correct application server using a routing mechanism wherein each application server instance gets a name (called a <i>route</i>). In this scenario the web server functions as a <a href="/facts/Reverse_proxy/bN4HFUEC">reverse proxy</a> for the application server. Lastly, AJP supports request attributes which, when populated with environment-specific settings in the reverse proxy, provides for secure communication between the reverse proxy and application server. </p><p>AJP runs in <a href="/facts/Apache_HTTP_Server/tcmWYYUq">Apache HTTP Server</a> 1.x using the <a href="/facts/Mod_jk/T73N57Ph">mod_jk</a> <a href="/facts/Plug-in_(computing)/351Du3Wu">plugin</a> and in Apache 2.x using mod_proxy_ajp, <a href="/facts/Mod_proxy/7jAPevA5">mod_proxy</a> and proxy balancer modules together. Other web server implementations exist for: <a href="/facts/Lighttpd/NTJLA4H6">lighttpd</a> 1.4.59, <a href="/facts/Nginx/AlTYUuTp">nginx</a>, <a href="/facts/Eclipse_Grizzly/HWTcuv4s">Grizzly</a> 2.1, and the <a href="/facts/Internet_Information_Services/nqmfJr3T">Internet Information Services</a>. </p><p><a href="/facts/Web_container/Pv06YKvB">Web container</a> application servers supporting AJP include: <a href="/facts/Apache_Tomcat/psmVfM2B">Apache Tomcat</a>, <a href="/facts/WildFly/sdwoM5jn">WildFly</a> (formerly JBoss AS), and <a href="/facts/GlassFish/Y45eWxx3">GlassFish</a>. </p>