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</script></head><body><div id="wrapper"><header><div id="header"><div><div><div class="logo noPrint"><a href="http://tomcat.apache.org/"><img alt="Tomcat Home" src="../images/tomcat.png"></a></div><div style="height: 1px;"></div><div class="asfLogo noPrint"><a href="http://www.apache.org/" target="_blank"><img src="../images/asf-feather.png" alt="The Apache Software Foundation" style="width: 266px; height: 83px;"></a></div><h1>Apache Tomcat 8 Configuration Reference</h1><div class="versionInfo">
Version 8.0.39,
<time datetime="2016-11-09">Nov 9 2016</time></div><div style="height: 1px;"></div><div style="clear: left;"></div></div></div></div></header><div id="middle"><div><div id="mainLeft" class="noprint"><div><nav><div><h2>Links</h2><ul><li><a href="../index.html">Docs Home</a></li><li><a href="index.html">Config Ref. Home</a></li><li><a href="http://wiki.apache.org/tomcat/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul></div><div><h2>Top Level Elements</h2><ul><li><a href="server.html">Server</a></li><li><a href="service.html">Service</a></li></ul></div><div><h2>Executors</h2><ul><li><a href="executor.html">Executor</a></li></ul></div><div><h2>Connectors</h2><ul><li><a href="http.html">HTTP</a></li><li><a href="ajp.html">AJP</a></li></ul></div><div><h2>Containers</h2><ul><li><a href="context.html">Context</a></li><li><a href="engine.html">Engine</a></li><li><a href="host.html">Host</a></li><li><a href="cluster.html">Cluster</a></li></ul></div><div><h2>Nested Components</h2><ul><li><a href="cookie-processor.html">CookieProcessor</a></li><li><a href="credentialhandler.html">CredentialHandler</a></li><li><a href="globalresources.html">Global Resources</a></li><li><a href="jar-scanner.html">JarScanner</a></li><li><a href="jar-scan-filter.html">JarScanFilter</a></li><li><a href="listeners.html">Listeners</a></li><li><a href="loader.html">Loader</a></li><li><a href="manager.html">Manager</a></li><li><a href="realm.html">Realm</a></li><li><a href="resources.html">Resources</a></li><li><a href="sessionidgenerator.html">SessionIdGenerator</a></li><li><a href="valve.html">Valve</a></li></ul></div><div><h2>Cluster Elements</h2><ul><li><a href="cluster.html">Cluster</a></li><li><a href="cluster-manager.html">Manager</a></li><li><a href="cluster-channel.html">Channel</a></li><li><a href="cluster-membership.html">Channel/Membership</a></li><li><a href="cluster-sender.html">Channel/Sender</a></li><li><a href="cluster-receiver.html">Channel/Receiver</a></li><li><a href="cluster-interceptor.html">Channel/Interceptor</a></li><li><a href="cluster-valve.html">Valve</a></li><li><a href="cluster-deployer.html">Deployer</a></li><li><a href="cluster-listener.html">ClusterListener</a></li></ul></div><div><h2>web.xml</h2><ul><li><a href="filter.html">Filter</a></li></ul></div><div><h2>Other</h2><ul><li><a href="systemprops.html">System properties</a></li></ul></div></nav></div></div><div id="mainRight"><div id="content"><h2>The HTTP Connector</h2><h3 id="Table_of_Contents">Table of Contents</h3><div class="text">
<ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Attributes">Attributes</a><ol><li><a href="#Common_Attributes">Common Attributes</a></li><li><a href="#Standard_Implementation">Standard Implementation</a></li><li><a href="#Java_TCP_socket_attributes">Java TCP socket attributes</a></li><li><a href="#BIO_specific_configuration">BIO specific configuration</a></li><li><a href="#NIO_specific_configuration">NIO specific configuration</a></li><li><a href="#NIO2_specific_configuration">NIO2 specific configuration</a></li><li><a href="#APR/native_specific_configuration">APR/native specific configuration</a></li></ol></li><li><a href="#Nested_Components">Nested Components</a></li><li><a href="#Special_Features">Special Features</a><ol><li><a href="#HTTP/1.1_and_HTTP/1.0_Support">HTTP/1.1 and HTTP/1.0 Support</a></li><li><a href="#Proxy_Support">Proxy Support</a></li><li><a href="#SSL_Support">SSL Support</a><ol><li><a href="#SSL_Support_-_BIO,_NIO_and_NIO2">SSL Support - BIO, NIO and NIO2</a></li><li><a href="#SSL_Support_-_APR/Native">SSL Support - APR/Native</a></li></ol></li><li><a href="#Connector_Comparison">Connector Comparison</a></li></ol></li></ul>
</div><h3 id="Introduction">Introduction</h3><div class="text">
<p>The <strong>HTTP Connector</strong> element represents a
<strong>Connector</strong> component that supports the HTTP/1.1 protocol.
It enables Catalina to function as a stand-alone web server, in addition
to its ability to execute servlets and JSP pages. A particular instance
of this component listens for connections on a specific TCP port number
on the server. One or more such <strong>Connectors</strong> can be
configured as part of a single <a href="service.html">Service</a>, each
forwarding to the associated <a href="engine.html">Engine</a> to perform
request processing and create the response.</p>
<p>If you wish to configure the <strong>Connector</strong> that is used
for connections to web servers using the AJP protocol (such as the
<code>mod_jk 1.2.x</code> connector for Apache 1.3), please refer to the
<a href="ajp.html">AJP Connector</a> documentation.</p>
<p>Each incoming request requires
a thread for the duration of that request. If more simultaneous requests
are received than can be handled by the currently available request
processing threads, additional threads will be created up to the
configured maximum (the value of the <code>maxThreads</code> attribute).
If still more simultaneous requests are received, they are stacked up
inside the server socket created by the <strong>Connector</strong>, up to
the configured maximum (the value of the <code>acceptCount</code>
attribute). Any further simultaneous requests will receive "connection
refused" errors, until resources are available to process them.</p>
</div><h3 id="Attributes">Attributes</h3><div class="text">
<div class="subsection"><h4 id="Common_Attributes">Common Attributes</h4><div class="text">
<p>All implementations of <strong>Connector</strong>
support the following attributes:</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">allowTrace</code></td><td>
<p>A boolean value which can be used to enable or disable the TRACE
HTTP method. If not specified, this attribute is set to false.</p>
</td></tr><tr><td><code class="attributeName">asyncTimeout</code></td><td>
<p>The default timeout for asynchronous requests in milliseconds. If not
specified, this attribute is set to the Servlet specification default of
30000 (30 seconds).</p>
</td></tr><tr><td><code class="attributeName">enableLookups</code></td><td>
<p>Set to <code>true</code> if you want calls to
<code>request.getRemoteHost()</code> to perform DNS lookups in
order to return the actual host name of the remote client. Set
to <code>false</code> to skip the DNS lookup and return the IP
address in String form instead (thereby improving performance).
By default, DNS lookups are disabled.</p>
</td></tr><tr><td><code class="attributeName">maxHeaderCount</code></td><td>
<p>The maximum number of headers in a request that are allowed by the
container. A request that contains more headers than the specified limit
will be rejected. A value of less than 0 means no limit.
If not specified, a default of 100 is used.</p>
</td></tr><tr><td><code class="attributeName">maxParameterCount</code></td><td>
<p>The maximum number of parameter and value pairs (GET plus POST) which
will be automatically parsed by the container. Parameter and value pairs
beyond this limit will be ignored. A value of less than 0 means no limit.
If not specified, a default of 10000 is used. Note that
<code>FailedRequestFilter</code> <a href="filter.html">filter</a> can be
used to reject requests that hit the limit.</p>
</td></tr><tr><td><code class="attributeName">maxPostSize</code></td><td>
<p>The maximum size in bytes of the POST which will be handled by
the container FORM URL parameter parsing. The limit can be disabled by
setting this attribute to a value less than zero. If not specified, this
attribute is set to 2097152 (2 megabytes). Note that the
<a href="filter.html#Failed_Request_Filter"><code>FailedRequestFilter</code></a>
can be used to reject requests that exceed this limit.</p>
</td></tr><tr><td><code class="attributeName">maxSavePostSize</code></td><td>
<p>The maximum size in bytes of the POST which will be saved/buffered by
the container during FORM or CLIENT-CERT authentication. For both types
of authentication, the POST will be saved/buffered before the user is
authenticated. For CLIENT-CERT authentication, the POST is buffered for
the duration of the SSL handshake and the buffer emptied when the request
is processed. For FORM authentication the POST is saved whilst the user
is re-directed to the login form and is retained until the user
successfully authenticates or the session associated with the
authentication request expires. The limit can be disabled by setting this
attribute to -1. Setting the attribute to zero will disable the saving of
POST data during authentication. If not specified, this attribute is set
to 4096 (4 kilobytes).</p>
</td></tr><tr><td><code class="attributeName">parseBodyMethods</code></td><td>
<p>A comma-separated list of HTTP methods for which request
bodies will be parsed for request parameters identically
to POST. This is useful in RESTful applications that want to
support POST-style semantics for PUT requests.
Note that any setting other than <code>POST</code> causes Tomcat
to behave in a way that goes against the intent of the servlet
specification.
The HTTP method TRACE is specifically forbidden here in accordance
with the HTTP specification.
The default is <code>POST</code></p>
</td></tr><tr><td><strong><code class="attributeName">port</code></strong></td><td>
<p>The TCP port number on which this <strong>Connector</strong>
will create a server socket and await incoming connections. Your
operating system will allow only one server application to listen
to a particular port number on a particular IP address. If the special
value of 0 (zero) is used, then Tomcat will select a free port at random
to use for this connector. This is typically only useful in embedded and
testing applications.</p>
</td></tr><tr><td><code class="attributeName">protocol</code></td><td>
<p>Sets the protocol to handle incoming traffic. The default value is
<code>HTTP/1.1</code> which uses an auto-switching mechanism to select
either a non blocking Java NIO based connector or an APR/native based connector.
If the <code>PATH</code> (Windows) or <code>LD_LIBRARY_PATH</code> (on
most unix systems) environment variables contain the Tomcat native
library, the APR/native connector will be used. If the native library
cannot be found, the non blocking Java based connector will be used. Note
that the APR/native connector has different settings for HTTPS than the
Java connectors.<br>
To use an explicit protocol rather than rely on the auto-switching
mechanism described above, the following values may be used:<br>
<code>org.apache.coyote.http11.Http11Protocol</code> -
blocking Java connector<br>
<code>org.apache.coyote.http11.Http11NioProtocol</code> -
non blocking Java NIO connector<br>
<code>org.apache.coyote.http11.Http11Nio2Protocol</code> -
non blocking Java NIO2 connector<br>
<code>org.apache.coyote.http11.Http11AprProtocol</code> -
the APR/native connector.<br>
Custom implementations may also be used.<br>
Take a look at our <a href="#Connector_Comparison">Connector
Comparison</a> chart. The configuration for both Java connectors is
identical, for http and https.<br>
For more information on the APR connector and APR specific SSL settings
please visit the <a href="../apr.html">APR documentation</a>
</p>
</td></tr><tr><td><code class="attributeName">proxyName</code></td><td>
<p>If this <strong>Connector</strong> is being used in a proxy
configuration, configure this attribute to specify the server name
to be returned for calls to <code>request.getServerName()</code>.
See <a href="#Proxy_Support">Proxy Support</a> for more
information.</p>
</td></tr><tr><td><code class="attributeName">proxyPort</code></td><td>
<p>If this <strong>Connector</strong> is being used in a proxy
configuration, configure this attribute to specify the server port
to be returned for calls to <code>request.getServerPort()</code>.
See <a href="#Proxy_Support">Proxy Support</a> for more
information.</p>
</td></tr><tr><td><code class="attributeName">redirectPort</code></td><td>
<p>If this <strong>Connector</strong> is supporting non-SSL
requests, and a request is received for which a matching
<code><security-constraint></code> requires SSL transport,
Catalina will automatically redirect the request to the port
number specified here.</p>
</td></tr><tr><td><code class="attributeName">scheme</code></td><td>
<p>Set this attribute to the name of the protocol you wish to have
returned by calls to <code>request.getScheme()</code>. For
example, you would set this attribute to "<code>https</code>"
for an SSL Connector. The default value is "<code>http</code>".
</p>
</td></tr><tr><td><code class="attributeName">secure</code></td><td>
<p>Set this attribute to <code>true</code> if you wish to have
calls to <code>request.isSecure()</code> to return <code>true</code>
for requests received by this Connector. You would want this on an
SSL Connector or a non SSL connector that is receiving data from a
SSL accelerator, like a crypto card, a SSL appliance or even a webserver.
The default value is <code>false</code>.</p>
</td></tr><tr><td><code class="attributeName">URIEncoding</code></td><td>
<p>This specifies the character encoding used to decode the URI bytes,
after %xx decoding the URL. If not specified, UTF-8 will be used unless
the <code>org.apache.catalina.STRICT_SERVLET_COMPLIANCE</code>
<a href="systemprops.html">system property</a> is set to <code>true</code>
in which case ISO-8859-1 will be used.</p>
</td></tr><tr><td><code class="attributeName">useBodyEncodingForURI</code></td><td>
<p>This specifies if the encoding specified in contentType should be used
for URI query parameters, instead of using the URIEncoding. This
setting is present for compatibility with Tomcat 4.1.x, where the
encoding specified in the contentType, or explicitly set using
Request.setCharacterEncoding method was also used for the parameters from
the URL. The default value is <code>false</code>.
</p>
<p><strong>Notes:</strong> 1) This setting is applied only to the
query string of a request. Unlike <code>URIEncoding</code> it does not
affect the path portion of a request URI. 2) If request character
encoding is not known (is not provided by a browser and is not set by
<code>SetCharacterEncodingFilter</code> or a similar filter using
Request.setCharacterEncoding method), the default encoding is always
"ISO-8859-1". The <code>URIEncoding</code> setting has no effect on
this default.
</p>
</td></tr><tr><td><code class="attributeName">useIPVHosts</code></td><td>
<p>Set this attribute to <code>true</code> to cause Tomcat to use
the IP address that the request was received on to determine the Host
to send the request to. The default value is <code>false</code>.</p>
</td></tr><tr><td><code class="attributeName">xpoweredBy</code></td><td>
<p>Set this attribute to <code>true</code> to cause Tomcat to advertise
support for the Servlet specification using the header recommended in the
specification. The default value is <code>false</code>.</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="Standard_Implementation">Standard Implementation</h4><div class="text">
<p>The standard HTTP connectors (BIO, NIO, NIO2 and APR/native) all support
the following attributes in addition to the common Connector attributes
listed above.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">acceptCount</code></td><td>
<p>The maximum queue length for incoming connection requests when
all possible request processing threads are in use. Any requests
received when the queue is full will be refused. The default
value is 100.</p>
</td></tr><tr><td><code class="attributeName">acceptorThreadCount</code></td><td>
<p>The number of threads to be used to accept connections. Increase this
value on a multi CPU machine, although you would never really need more
than <code>2</code>. Also, with a lot of non keep alive connections, you
might want to increase this value as well. Default value is
<code>1</code>.</p>
</td></tr><tr><td><code class="attributeName">acceptorThreadPriority</code></td><td>
<p>The priority of the acceptor threads. The threads used to accept
new connections. The default value is <code>5</code> (the value of the
<code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
for the <code>java.lang.Thread</code> class for more details on what
this priority means.</p>
</td></tr><tr><td><code class="attributeName">address</code></td><td>
<p>For servers with more than one IP address, this attribute
specifies which address will be used for listening on the specified
port. By default, this port will be used on all IP addresses
associated with the server.</p>
</td></tr><tr><td><code class="attributeName">allowedTrailerHeaders</code></td><td>
<p>By default Tomcat will ignore all trailer headers when processing
chunked input. For a header to be processed, it must be added to this
comma-separated list of header names.</p>
</td></tr><tr><td><code class="attributeName">bindOnInit</code></td><td>
<p>Controls when the socket used by the connector is bound. By default it
is bound when the connector is initiated and unbound when the connector is
destroyed. If set to <code>false</code>, the socket will be bound when the
connector is started and unbound when it is stopped.</p>
</td></tr><tr><td><code class="attributeName">compressableMimeType</code></td><td>
<p>The value is a comma separated list of MIME types for which HTTP
compression may be used.
The default value is
<code>
text/html,text/xml,text/plain,text/css,text/javascript,application/javascript
</code>.
</p>
</td></tr><tr><td><code class="attributeName">compression</code></td><td>
<p>The <strong>Connector</strong> may use HTTP/1.1 GZIP compression in
an attempt to save server bandwidth. The acceptable values for the
parameter is "off" (disable compression), "on" (allow compression, which
causes text data to be compressed), "force" (forces compression in all
cases), or a numerical integer value (which is equivalent to "on", but
specifies the minimum amount of data before the output is compressed). If
the content-length is not known and compression is set to "on" or more
aggressive, the output will also be compressed. If not specified, this
attribute is set to "off".</p>
<p><em>Note</em>: There is a tradeoff between using compression (saving
your bandwidth) and using the sendfile feature (saving your CPU cycles).
If the connector supports the sendfile feature, e.g. the NIO connector,
using sendfile will take precedence over compression. The symptoms will
be that static files greater that 48 Kb will be sent uncompressed.
You can turn off sendfile by setting <code>useSendfile</code> attribute
of the connector, as documented below, or change the sendfile usage
threshold in the configuration of the
<a href="../default-servlet.html">DefaultServlet</a> in the default
<code>conf/web.xml</code> or in the <code>web.xml</code> of your web
application.
</p>
</td></tr><tr><td><code class="attributeName">compressionMinSize</code></td><td>
<p>If <strong>compression</strong> is set to "on" then this attribute
may be used to specify the minimum amount of data before the output is
compressed. If not specified, this attribute is defaults to "2048".</p>
</td></tr><tr><td><code class="attributeName">connectionLinger</code></td><td>
<p>The number of seconds during which the sockets used by this
<strong>Connector</strong> will linger when they are closed. The default
value is <code>-1</code> which disables socket linger.</p>
</td></tr><tr><td><code class="attributeName">connectionTimeout</code></td><td>
<p>The number of milliseconds this <strong>Connector</strong> will wait,
after accepting a connection, for the request URI line to be
presented. Use a value of -1 to indicate no (i.e. infinite) timeout.
The default value is 60000 (i.e. 60 seconds) but note that the standard
server.xml that ships with Tomcat sets this to 20000 (i.e. 20 seconds).
Unless <strong>disableUploadTimeout</strong> is set to <code>false</code>,
this timeout will also be used when reading the request body (if any).</p>
</td></tr><tr><td><code class="attributeName">connectionUploadTimeout</code></td><td>
<p>Specifies the timeout, in milliseconds, to use while a data upload is
in progress. This only takes effect if
<strong>disableUploadTimeout</strong> is set to <code>false</code>.
</p>
</td></tr><tr><td><code class="attributeName">disableUploadTimeout</code></td><td>
<p>This flag allows the servlet container to use a different, usually
longer connection timeout during data upload. If not specified, this
attribute is set to <code>true</code> which disables this longer timeout.
</p>
</td></tr><tr><td><code class="attributeName">executor</code></td><td>
<p>A reference to the name in an <a href="executor.html">Executor</a>
element. If this attribute is set, and the named executor exists, the
connector will use the executor, and all the other thread attributes will
be ignored. Note that if a shared executor is not specified for a
connector then the connector will use a private, internal executor to
provide the thread pool.</p>
</td></tr><tr><td><code class="attributeName">executorTerminationTimeoutMillis</code></td><td>
<p>The time that the private internal executor will wait for request
processing threads to terminate before continuing with the process of
stopping the connector. If not set, the default is <code>0</code> (zero)
for the BIO connector and <code>5000</code> (5 seconds) for the NIO,
NIO2 and APR/native connectors.</p>
</td></tr><tr><td><code class="attributeName">keepAliveTimeout</code></td><td>
<p>The number of milliseconds this <strong>Connector</strong> will wait
for another HTTP request before closing the connection. The default value
is to use the value that has been set for the
<strong>connectionTimeout</strong> attribute.
Use a value of -1 to indicate no (i.e. infinite) timeout.</p>
</td></tr><tr><td><code class="attributeName">maxConnections</code></td><td>
<p>The maximum number of connections that the server will accept and
process at any given time. When this number has been reached, the server
will accept, but not process, one further connection. This additional
connection be blocked until the number of connections being processed
falls below <strong>maxConnections</strong> at which point the server will
start accepting and processing new connections again. Note that once the
limit has been reached, the operating system may still accept connections
based on the <code>acceptCount</code> setting. The default value varies by
connector type. For BIO the default is the value of
<strong>maxThreads</strong> unless an <a href="executor.html">Executor</a>
is used in which case the default will be the value of maxThreads from the
executor. For NIO and NIO2 the default is <code>10000</code>.
For APR/native, the default is <code>8192</code>.</p>
<p>Note that for APR/native on Windows, the configured value will be
reduced to the highest multiple of 1024 that is less than or equal to
maxConnections. This is done for performance reasons.<br>
If set to a value of -1, the maxConnections feature is disabled
and connections are not counted.</p>
</td></tr><tr><td><code class="attributeName">maxCookieCount</code></td><td>
<p>The maximum number of cookies that are permitted for a request. A value
of less than zero means no limit. If not specified, a default value of 200
will be used.</p>
</td></tr><tr><td><code class="attributeName">maxExtensionSize</code></td><td>
<p>Limits the total length of chunk extensions in chunked HTTP requests.
If the value is <code>-1</code>, no limit will be imposed. If not
specified, the default value of <code>8192</code> will be used.</p>
</td></tr><tr><td><code class="attributeName">maxHttpHeaderSize</code></td><td>
<p>The maximum size of the request and response HTTP header, specified
in bytes. If not specified, this attribute is set to 8192 (8 KB).</p>
</td></tr><tr><td><code class="attributeName">maxKeepAliveRequests</code></td><td>
<p>The maximum number of HTTP requests which can be pipelined until
the connection is closed by the server. Setting this attribute to 1 will
disable HTTP/1.0 keep-alive, as well as HTTP/1.1 keep-alive and
pipelining. Setting this to -1 will allow an unlimited amount of
pipelined or keep-alive HTTP requests.
If not specified, this attribute is set to 100.</p>
</td></tr><tr><td><code class="attributeName">maxSwallowSize</code></td><td>
<p>The maximum number of request body bytes (excluding transfer encoding
overhead) that will be swallowed by Tomcat for an aborted upload. An
aborted upload is when Tomcat knows that the request body is going to be
ignored but the client still sends it. If Tomcat does not swallow the body
the client is unlikely to see the response. If not specified the default
of 2097152 (2 megabytes) will be used. A value of less than zero indicates
that no limit should be enforced.</p>
</td></tr><tr><td><code class="attributeName">maxThreads</code></td><td>
<p>The maximum number of request processing threads to be created
by this <strong>Connector</strong>, which therefore determines the
maximum number of simultaneous requests that can be handled. If
not specified, this attribute is set to 200. If an executor is associated
with this connector, this attribute is ignored as the connector will
execute tasks using the executor rather than an internal thread pool. Note
that if an executor is configured any value set for this attribute will be
recorded correctly but it will be reported (e.g. via JMX) as
<code>-1</code> to make clear that it is not used.</p>
</td></tr><tr><td><code class="attributeName">maxTrailerSize</code></td><td>
<p>Limits the total length of trailing headers in the last chunk of
a chunked HTTP request. If the value is <code>-1</code>, no limit will be
imposed. If not specified, the default value of <code>8192</code> will be
used.</p>
</td></tr><tr><td><code class="attributeName">minSpareThreads</code></td><td>
<p>The minimum number of threads always kept running. If not specified,
the default of <code>10</code> is used. If an executor is associated
with this connector, this attribute is ignored as the connector will
execute tasks using the executor rather than an internal thread pool. Note
that if an executor is configured any value set for this attribute will be
recorded correctly but it will be reported (e.g. via JMX) as
<code>-1</code> to make clear that it is not used.</p>
</td></tr><tr><td><code class="attributeName">noCompressionUserAgents</code></td><td>
<p>The value is a regular expression (using <code>java.util.regex</code>)
matching the <code>user-agent</code> header of HTTP clients for which
compression should not be used,
because these clients, although they do advertise support for the
feature, have a broken implementation.
The default value is an empty String (regexp matching disabled).</p>
</td></tr><tr><td><code class="attributeName">processorCache</code></td><td>
<p>The protocol handler caches Processor objects to speed up performance.
This setting dictates how many of these objects get cached.
<code>-1</code> means unlimited, default is <code>200</code>. If not using
Servlet 3.0 asynchronous processing, a good default is to use the same as
the maxThreads setting. If using Servlet 3.0 asynchronous processing, a
good default is to use the larger of maxThreads and the maximum number of
expected concurrent requests (synchronous and asynchronous).</p>
</td></tr><tr><td><code class="attributeName">restrictedUserAgents</code></td><td>
<p>The value is a regular expression (using <code>java.util.regex</code>)
matching the <code>user-agent</code> header of HTTP clients for which
HTTP/1.1 or HTTP/1.0 keep alive should not be used, even if the clients
advertise support for these features.
The default value is an empty String (regexp matching disabled).</p>
</td></tr><tr><td><code class="attributeName">server</code></td><td>
<p>Overrides the Server header for the http response. If set, the value
for this attribute overrides the Tomcat default and any Server header set
by a web application. If not set, any value specified by the application
is used. If the application does not specify a value then
<code>Apache-Coyote/1.1</code> is used. Unless you are paranoid, you won't
need this feature.
</p>
</td></tr><tr><td><code class="attributeName">socketBuffer</code></td><td>
<p>The size (in bytes) of the buffer to be provided for socket
output buffering. -1 can be specified to disable the use of a buffer.
By default, a buffers of 9000 bytes will be used.</p>
</td></tr><tr><td><code class="attributeName">SSLEnabled</code></td><td>
<p>Use this attribute to enable SSL traffic on a connector.
To turn on SSL handshake/encryption/decryption on a connector
set this value to <code>true</code>.
The default value is <code>false</code>.
When turning this value <code>true</code> you will want to set the
<code>scheme</code> and the <code>secure</code> attributes as well
to pass the correct <code>request.getScheme()</code> and
<code>request.isSecure()</code> values to the servlets
See <a href="#SSL_Support">SSL Support</a> for more information.
</p>
</td></tr><tr><td><code class="attributeName">tcpNoDelay</code></td><td>
<p>If set to <code>true</code>, the TCP_NO_DELAY option will be
set on the server socket, which improves performance under most
circumstances. This is set to <code>true</code> by default.</p>
</td></tr><tr><td><code class="attributeName">threadPriority</code></td><td>
<p>The priority of the request processing threads within the JVM.
The default value is <code>5</code> (the value of the
<code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
for the <code>java.lang.Thread</code> class for more details on what
this priority means. If an executor is associated
with this connector, this attribute is ignored as the connector will
execute tasks using the executor rather than an internal thread pool. Note
that if an executor is configured any value set for this attribute will be
recorded correctly but it will be reported (e.g. via JMX) as
<code>-1</code> to make clear that it is not used.</p>
</td></tr><tr><td><code class="attributeName">upgradeAsyncWriteBufferSize</code></td><td>
<p>The default size of the buffer to allocate to for asynchronous writes
that can not be completed in a single operation, specified in bytes. Data that can't be
written immediately will be stored in this buffer until it can be written.
If more data needs to be stored than space is available in the buffer than
the size of the buffer will be increased for the duration of the write. If
not specified the default value of 8192 will be used.</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="Java_TCP_socket_attributes">Java TCP socket attributes</h4><div class="text">
<p>The BIO, NIO and NIO2 implementation support the following Java TCP
socket attributes in addition to the common Connector and HTTP attributes
listed above.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">socket.rxBufSize</code></td><td>
<p>(int)The socket receive buffer (SO_RCVBUF) size in bytes. JVM default
used if not set.</p>
</td></tr><tr><td><code class="attributeName">socket.txBufSize</code></td><td>
<p>(int)The socket send buffer (SO_SNDBUF) size in bytes. JVM default
used if not set.</p>
</td></tr><tr><td><code class="attributeName">socket.tcpNoDelay</code></td><td>
<p>(bool)This is equivalent to standard attribute
<strong>tcpNoDelay</strong>.</p>
</td></tr><tr><td><code class="attributeName">socket.soKeepAlive</code></td><td>
<p>(bool)Boolean value for the socket's keep alive setting
(SO_KEEPALIVE). JVM default used if not set.</p>
</td></tr><tr><td><code class="attributeName">socket.ooBInline</code></td><td>
<p>(bool)Boolean value for the socket OOBINLINE setting. JVM default
used if not set.</p>
</td></tr><tr><td><code class="attributeName">socket.soReuseAddress</code></td><td>
<p>(bool)Boolean value for the sockets reuse address option
(SO_REUSEADDR). JVM default used if not set.</p>
</td></tr><tr><td><code class="attributeName">socket.soLingerOn</code></td><td>
<p>(bool)Boolean value for the sockets so linger option (SO_LINGER).
A value for the standard attribute <strong>connectionLinger</strong>
that is >=0 is equivalent to setting this to <code>true</code>.
A value for the standard attribute <strong>connectionLinger</strong>
that is <0 is equivalent to setting this to <code>false</code>.
Both this attribute and <code>soLingerTime</code> must be set else the
JVM defaults will be used for both.</p>
</td></tr><tr><td><code class="attributeName">socket.soLingerTime</code></td><td>
<p>(int)Value in seconds for the sockets so linger option (SO_LINGER).
This is equivalent to standard attribute
<strong>connectionLinger</strong>.
Both this attribute and <code>soLingerOn</code> must be set else the
JVM defaults will be used for both.</p>
</td></tr><tr><td><code class="attributeName">socket.soTimeout</code></td><td>
<p>This is equivalent to standard attribute
<strong>connectionTimeout</strong>.</p>
</td></tr><tr><td><code class="attributeName">socket.performanceConnectionTime</code></td><td>
<p>(int)The first value for the performance settings. See
<a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
All three performance attributes must be set else the JVM defaults will
be used for all three.</p>
</td></tr><tr><td><code class="attributeName">socket.performanceLatency</code></td><td>
<p>(int)The second value for the performance settings. See
<a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
All three performance attributes must be set else the JVM defaults will
be used for all three.</p>
</td></tr><tr><td><code class="attributeName">socket.performanceBandwidth</code></td><td>
<p>(int)The third value for the performance settings. See
<a href="http://docs.oracle.com/javase/7/docs/api/java/net/Socket.html#setPerformancePreferences(int,%20int,%20int)">Socket Performance Options</a>.
All three performance attributes must be set else the JVM defaults will
be used for all three.</p>
</td></tr><tr><td><code class="attributeName">socket.unlockTimeout</code></td><td>
<p>(int) The timeout for a socket unlock. When a connector is stopped, it will try to release the acceptor thread by opening a connector to itself.
The default value is <code>250</code> and the value is in milliseconds</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="BIO_specific_configuration">BIO specific configuration</h4><div class="text">
<p>The following attributes are specific to the BIO connector.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">disableKeepAlivePercentage</code></td><td>
<p>The percentage of processing threads that have to be in use before
HTTP keep-alives are disabled to improve scalability. Values less than
<code>0</code> will be changed to <code>0</code> and values greater than
<code>100</code> will be changed to <code>100</code>. If not specified,
the default value is <code>75</code>.</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="NIO_specific_configuration">NIO specific configuration</h4><div class="text">
<p>The following attributes are specific to the NIO connector.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">pollerThreadCount</code></td><td>
<p>(int)The number of threads to be used to run for the polling events.
Default value is <code>1</code> per processor but not more than 2.<br>
When accepting a socket, the operating system holds a global lock. So the benefit of
going above 2 threads diminishes rapidly. Having more than one thread is for
system that need to accept connections very rapidly. However usually just
increasing <code>acceptCount</code> will solve that problem.
Increasing this value may also be beneficial when a large amount of send file
operations are going on.
</p>
</td></tr><tr><td><code class="attributeName">pollerThreadPriority</code></td><td>
<p>(int)The priority of the poller threads.
The default value is <code>5</code> (the value of the
<code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
for the <code>java.lang.Thread</code> class for more details on what
this priority means.</p>
</td></tr><tr><td><code class="attributeName">selectorTimeout</code></td><td>
<p>(int)The time in milliseconds to timeout on a select() for the
poller. This value is important, since connection clean up is done on
the same thread, so do not set this value to an extremely high one. The
default value is <code>1000</code> milliseconds.</p>
</td></tr><tr><td><code class="attributeName">useComet</code></td><td>
<p>(bool)Whether to allow comet servlets or not. Default value is
<code>true</code>.</p>
</td></tr><tr><td><code class="attributeName">useSendfile</code></td><td>
<p>(bool)Use this attribute to enable or disable sendfile capability.
The default value is <code>true</code>. Note that the use of sendfile
will disable any compression that Tomcat may otherwise have performed on
the response.</p>
</td></tr><tr><td><code class="attributeName">socket.directBuffer</code></td><td>
<p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
ByteBuffers. If <code>true</code> then
<code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
the buffers, if <code>false</code> then
<code>java.nio.ByteBuffer.allocate()</code> is used. The default value
is <code>false</code>.<br>
When you are using direct buffers, make sure you allocate the
appropriate amount of memory for the direct memory space. On Sun's JDK
that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
</p>
</td></tr><tr><td><code class="attributeName">socket.directSslBuffer</code></td><td>
<p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
ByteBuffers for the SSL buffers. If <code>true</code> then
<code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
the buffers, if <code>false</code> then
<code>java.nio.ByteBuffer.allocate()</code> is used. The default value
is <code>false</code>.<br>
When you are using direct buffers, make sure you allocate the
appropriate amount of memory for the direct memory space. On Oracle's JDK
that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
</p>
</td></tr><tr><td><code class="attributeName">socket.appReadBufSize</code></td><td>
<p>(int)Each connection that is opened up in Tomcat get associated with
a read ByteBuffer. This attribute controls the size of this buffer. By
default this read buffer is sized at <code>8192</code> bytes. For lower
concurrency, you can increase this to buffer more data. For an extreme
amount of keep alive connections, decrease this number or increase your
heap size.</p>
</td></tr><tr><td><code class="attributeName">socket.appWriteBufSize</code></td><td>
<p>(int)Each connection that is opened up in Tomcat get associated with
a write ByteBuffer. This attribute controls the size of this buffer. By
default this write buffer is sized at <code>8192</code> bytes. For low
concurrency you can increase this to buffer more response data. For an
extreme amount of keep alive connections, decrease this number or
increase your heap size.<br>
The default value here is pretty low, you should up it if you are not
dealing with tens of thousands concurrent connections.</p>
</td></tr><tr><td><code class="attributeName">socket.bufferPool</code></td><td>
<p>(int)The NIO connector uses a class called NioChannel that holds
elements linked to a socket. To reduce garbage collection, the NIO
connector caches these channel objects. This value specifies the size of
this cache. The default value is <code>500</code>, and represents that
the cache will hold 500 NioChannel objects. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">socket.bufferPoolSize</code></td><td>
<p>(int)The NioChannel pool can also be size based, not used object
based. The size is calculated as follows:<br>
NioChannel
<code>buffer size = read buffer size + write buffer size</code><br>
SecureNioChannel <code>buffer size = application read buffer size +
application write buffer size + network read buffer size +
network write buffer size</code><br>
The value is in bytes, the default value is <code>1024*1024*100</code>
(100MB).</p>
</td></tr><tr><td><code class="attributeName">socket.processorCache</code></td><td>
<p>(int)Tomcat will cache SocketProcessor objects to reduce garbage
collection. The integer value specifies how many objects to keep in the
cache at most. The default is <code>500</code>. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">socket.keyCache</code></td><td>
<p>(int)Tomcat will cache KeyAttachment objects to reduce garbage
collection. The integer value specifies how many objects to keep in the
cache at most. The default is <code>500</code>. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">socket.eventCache</code></td><td>
<p>(int)Tomcat will cache PollerEvent objects to reduce garbage
collection. The integer value specifies how many objects to keep in the
cache at most. The default is <code>500</code>. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">selectorPool.maxSelectors</code></td><td>
<p>(int)The max selectors to be used in the pool, to reduce selector
contention. Use this option when the command line
<code>org.apache.tomcat.util.net.NioSelectorShared</code> value is set
to false. Default value is <code>200</code>.</p>
</td></tr><tr><td><code class="attributeName">selectorPool.maxSpareSelectors</code></td><td>
<p>(int)The max spare selectors to be used in the pool, to reduce
selector contention. When a selector is returned to the pool, the system
can decide to keep it or let it be GC'd. Use this option when the
command line <code>org.apache.tomcat.util.net.NioSelectorShared</code>
value is set to false. Default value is <code>-1</code> (unlimited).</p>
</td></tr><tr><td><code class="attributeName">command-line-options</code></td><td>
<p>The following command line options are available for the NIO
connector:<br>
<code>-Dorg.apache.tomcat.util.net.NioSelectorShared=true|false</code>
- default is <code>true</code>. Set this value to <code>false</code> if you wish to
use a selector for each thread. When you set it to <code>false</code>, you can
control the size of the pool of selectors by using the
<strong>selectorPool.maxSelectors</strong> attribute.</p>
</td></tr><tr><td><code class="attributeName">oomParachute</code></td><td>
<p>(int)The NIO connector implements an OutOfMemoryError strategy called
parachute. It holds a chunk of data as a byte array. In case of an OOM,
this chunk of data is released and the error is reported. This will give
the VM enough room to clean up. The <code>oomParachute</code> represents
the size in bytes of the parachute(the byte array). The default value is
<code>1024*1024</code>(1MB). Please note, this only works for OOM errors
regarding the Java Heap space, and there is absolutely no guarantee
that you will be able to recover at all. If you have an OOM outside of
the Java Heap, then this parachute trick will not help.
</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="NIO2_specific_configuration">NIO2 specific configuration</h4><div class="text">
<p>The following attributes are specific to the NIO2 connector.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">useCaches</code></td><td>
<p>(bool)Use this attribute to enable or disable object caching to
reduce the amount of GC objects produced.
The default value is <code>false</code>.</p>
</td></tr><tr><td><code class="attributeName">useComet</code></td><td>
<p>(bool)Whether to allow comet servlets or not. Default value is
<code>true</code>.</p>
</td></tr><tr><td><code class="attributeName">useSendfile</code></td><td>
<p>(bool)Use this attribute to enable or disable sendfile capability.
The default value is <code>true</code>. Note that the use of sendfile
will disable any compression that Tomcat may otherwise have performed on
the response.</p>
</td></tr><tr><td><code class="attributeName">socket.directBuffer</code></td><td>
<p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
ByteBuffers. If <code>true</code> then
<code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
the buffers, if <code>false</code> then
<code>java.nio.ByteBuffer.allocate()</code> is used. The default value
is <code>false</code>.<br>
When you are using direct buffers, make sure you allocate the
appropriate amount of memory for the direct memory space. On Sun's JDK
that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
</p>
</td></tr><tr><td><code class="attributeName">socket.directSslBuffer</code></td><td>
<p>(bool)Boolean value, whether to use direct ByteBuffers or java mapped
ByteBuffers for the SSL buffers. If <code>true</code> then
<code>java.nio.ByteBuffer.allocateDirect()</code> is used to allocate
the buffers, if <code>false</code> then
<code>java.nio.ByteBuffer.allocate()</code> is used. The default value
is <code>false</code>.<br>
When you are using direct buffers, make sure you allocate the
appropriate amount of memory for the direct memory space. On Oracle's JDK
that would be something like <code>-XX:MaxDirectMemorySize=256m</code>.
</p>
</td></tr><tr><td><code class="attributeName">socket.appReadBufSize</code></td><td>
<p>(int)Each connection that is opened up in Tomcat get associated with
a read ByteBuffer. This attribute controls the size of this buffer. By
default this read buffer is sized at <code>8192</code> bytes. For lower
concurrency, you can increase this to buffer more data. For an extreme
amount of keep alive connections, decrease this number or increase your
heap size.</p>
</td></tr><tr><td><code class="attributeName">socket.appWriteBufSize</code></td><td>
<p>(int)Each connection that is opened up in Tomcat get associated with
a write ByteBuffer. This attribute controls the size of this buffer. By
default this write buffer is sized at <code>8192</code> bytes. For low
concurrency you can increase this to buffer more response data. For an
extreme amount of keep alive connections, decrease this number or
increase your heap size.<br>
The default value here is pretty low, you should up it if you are not
dealing with tens of thousands concurrent connections.</p>
</td></tr><tr><td><code class="attributeName">socket.bufferPoolSize</code></td><td>
<p>(int)The NIO2 connector uses a class called Nio2Channel that holds
elements linked to a socket. To reduce garbage collection, the NIO2
connector caches these channel objects. This value specifies the size of
this cache. The default value is <code>500</code>, and represents that
the cache will hold 500 Nio2Channel objects. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">socket.processorCache</code></td><td>
<p>(int)Tomcat will cache SocketProcessor objects to reduce garbage
collection. The integer value specifies how many objects to keep in the
cache at most. The default is <code>500</code>. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">socket.socketWrapperCache</code></td><td>
<p>(int)Tomcat will cache SocketWrapper objects to reduce garbage
collection. The integer value specifies how many objects to keep in the
cache at most. The default is <code>500</code>. Other values are
<code>-1</code> for unlimited cache and <code>0</code> for no cache.</p>
</td></tr><tr><td><code class="attributeName">oomParachute</code></td><td>
<p>(int)The NIO2 connector implements an OutOfMemoryError strategy called
parachute. It holds a chunk of data as a byte array. In case of an OOM,
this chunk of data is released and the error is reported. This will give
the VM enough room to clean up. The <code>oomParachute</code> represents
the size in bytes of the parachute(the byte array). The default value is
<code>1024*1024</code>(1MB). Please note, this only works for OOM errors
regarding the Java Heap space, and there is absolutely no guarantee
that you will be able to recover at all. If you have an OOM outside of
the Java Heap, then this parachute trick will not help.
</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="APR/native_specific_configuration">APR/native specific configuration</h4><div class="text">
<p>The following attributes are specific to the APR/native connector.</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">deferAccept</code></td><td>
<p>Sets the <code>TCP_DEFER_ACCEPT</code> flag on the listening socket
for this connector. The default value is <code>true</code> where
<code>TCP_DEFER_ACCEPT</code> is supported by the operating system,
otherwise it is <code>false</code>.</p>
</td></tr><tr><td><code class="attributeName">pollerSize</code></td><td>
<p>Amount of sockets that the poller responsible for polling kept alive
connections can hold at a given time. Extra connections will be closed
right away. The default value is 8192, corresponding to 8192 keep-alive
connections. This is a synonym for maxConnections.</p>
</td></tr><tr><td><code class="attributeName">pollerThreadCount</code></td><td>
<p>Number of threads used to poll kept alive connections. On Windows the
default is chosen so that the sockets managed by each thread is
less than 1024. For Linux the default is 1. Changing the default on
Windows is likely to have a negative performance impact.</p>
</td></tr><tr><td><code class="attributeName">pollTime</code></td><td>
<p>Duration of a poll call in microseconds. Lowering this value will
slightly decrease latency of connections being kept alive in some cases,
but will use more CPU as more poll calls are being made. The default
value is 2000 (2ms).</p>
</td></tr><tr><td><code class="attributeName">sendfileSize</code></td><td>
<p>Amount of sockets that the poller responsible for sending static
files asynchronously can hold at a given time. Extra connections will be
closed right away without any data being sent (resulting in a zero
length file on the client side). Note that in most cases, sendfile is a
call that will return right away (being taken care of "synchronously" by
the kernel), and the sendfile poller will not be used, so the amount of
static files which can be sent concurrently is much larger than the
specified amount. The default value is 1024.</p>
</td></tr><tr><td><code class="attributeName">sendfileThreadCount</code></td><td>
<p>Number of threads used service sendfile sockets. On Windows the
default is chosen so that the sockets managed by each thread is
less than 1024. For Linux the default is 1. Changing the default on
Windows is likely to have a negative performance impact.</p>
</td></tr><tr><td><code class="attributeName">threadPriority</code></td><td>
<p>(int)The priority of the acceptor and poller threads.
The default value is <code>5</code> (the value of the
<code>java.lang.Thread.NORM_PRIORITY</code> constant). See the JavaDoc
for the <code>java.lang.Thread</code> class for more details on what
this priority means.</p>
</td></tr><tr><td><code class="attributeName">useComet</code></td><td>
<p>(bool)Whether to allow comet servlets or not. Default value is
<code>true</code>.</p>
</td></tr><tr><td><code class="attributeName">useSendfile</code></td><td>
<p>(bool)Use this attribute to enable or disable sendfile capability.
The default value is <code>true</code>. Note that the use of sendfile
will disable any compression that Tomcat may otherwise have performed on
the response.</p>
</td></tr></table>
</div></div>
</div><h3 id="Nested_Components">Nested Components</h3><div class="text">
<p>None at this time.</p>
</div><h3 id="Special_Features">Special Features</h3><div class="text">
<div class="subsection"><h4 id="HTTP/1.1_and_HTTP/1.0_Support">HTTP/1.1 and HTTP/1.0 Support</h4><div class="text">
<p>This <strong>Connector</strong> supports all of the required features
of the HTTP/1.1 protocol, as described in RFC 2616, including persistent
connections, pipelining, expectations and chunked encoding. If the client
(typically a browser) supports only HTTP/1.0, the
<strong>Connector</strong> will gracefully fall back to supporting this
protocol as well. No special configuration is required to enable this
support. The <strong>Connector</strong> also supports HTTP/1.0
keep-alive.</p>
<p>RFC 2616 requires that HTTP servers always begin their responses with
the highest HTTP version that they claim to support. Therefore, this
<strong>Connector</strong> will always return <code>HTTP/1.1</code> at
the beginning of its responses.</p>
</div></div>
<div class="subsection"><h4 id="Proxy_Support">Proxy Support</h4><div class="text">
<p>The <code>proxyName</code> and <code>proxyPort</code> attributes can
be used when Tomcat is run behind a proxy server. These attributes
modify the values returned to web applications that call the
<code>request.getServerName()</code> and <code>request.getServerPort()</code>
methods, which are often used to construct absolute URLs for redirects.
Without configuring these attributes, the values returned would reflect
the server name and port on which the connection from the proxy server
was received, rather than the server name and port to whom the client
directed the original request.</p>
<p>For more information, see the
<a href="../proxy-howto.html">Proxy Support HOW-TO</a>.</p>
</div></div>
<div class="subsection"><h4 id="SSL_Support">SSL Support</h4><div class="text">
<p>You can enable SSL support for a particular instance of this
<strong>Connector</strong> by setting the <code>SSLEnabled</code> attribute to
<code>true</code>.</p>
<p>You will also need to set the <code>scheme</code> and <code>secure</code>
attributes to the values <code>https</code> and <code>true</code>
respectively, to pass correct information to the servlets.</p>
<p>The BIO, NIO and NIO2 connectors use the JSSE SSL whereas the APR/native
connector uses OpenSSL. Therefore, in addition to using different attributes
to configure SSL, the APR/native connector also requires keys and certificates
to be provided in a different format.</p>
<p>For more information, see the
<a href="../ssl-howto.html">SSL Configuration HOW-TO</a>.</p>
<div class="subsection"><h4 id="SSL_Support_-_BIO,_NIO_and_NIO2">SSL Support - BIO, NIO and NIO2</h4><div class="text">
<p>The BIO, NIO and NIO2 connectors use the following attributes to configure SSL:
</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">algorithm</code></td><td>
<p>The certificate encoding algorithm to be used. This defaults to
<code>KeyManagerFactory.getDefaultAlgorithm()</code> which returns
<code>SunX509</code> for Sun JVMs. IBM JVMs return
<code>IbmX509</code>. For other vendors, consult the JVM
documentation for the default value.</p>
</td></tr><tr><td><code class="attributeName">allowUnsafeLegacyRenegotiation</code></td><td>
<p>Is unsafe legacy TLS renegotiation allowed which is likely to expose
users to CVE-2009-3555, a man-in-the-middle vulnerability in the TLS
protocol that allows an attacker to inject arbitrary data into the user's
request. If not specified, a default of <code>false</code> is used. This
attribute only has an effect if the JVM does not support RFC 5746 as
indicated by the presence of the pseudo-ciphersuite
TLS_EMPTY_RENEGOTIATION_INFO_SCSV. This is available JRE/JDK 6 update 22
onwards. Where RFC 5746 is supported the renegotiation - including support
for unsafe legacy renegotiation - is controlled by the JVM configuration.
</p>
</td></tr><tr><td><code class="attributeName">useServerCipherSuitesOrder</code></td><td>
<p>
Set to <code>true</code> to enforce the server's cipher order
(from the <code>ciphers</code> setting). Set to <code>false</code>
to choose the first acceptable cipher suite presented by the client.
<b>Use of this feature requires Java 8 or later.</b>
Default is <i>undefined</i>, leaving the choice up to the JSSE
implementation.
</p>
</td></tr><tr><td><code class="attributeName">ciphers</code></td><td>
<p>If specified and using ',' as a separator, only the ciphers that are
listed and supported by the SSL implementation will be used.
The ciphers are specified using the JSSE cipher naming convention. The
special value of <code>ALL</code> will enable all supported ciphers. This
will include many that are not secure. <code>ALL</code> is intended for
testing purposes only.</p>
<p>The list can also use ':' as a separator, in that case
it will use the OpenSSL syntax (see OpenSSL documentation for the list
of ciphers supported and the syntax). The behaviour of this filtering is
kept aligned with the behaviour of the OpenSSL 1.0.2 stable branch.</p>
<p>If not specified, a default (using the OpenSSL notation) of
<code>HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!kRSA</code> will be used
when running on Java 8 or later. On Java 7, <code>!DHE</code> will be
added to this default when using a JSSE based connector.</p>
<p>Note that Java does not treat the order in which ciphers are defined as
an order of preference. See <code>useServerCipherSuitesOrder</code>.</p>
</td></tr><tr><td><code class="attributeName">clientAuth</code></td><td>
<p>Set to <code>true</code> if you want the SSL stack to require a
valid certificate chain from the client before accepting a connection.
Set to <code>want</code> if you want the SSL stack to request a client
Certificate, but not fail if one isn't presented. A <code>false</code>
value (which is the default) will not require a certificate chain
unless the client requests a resource protected by a security
constraint that uses <code>CLIENT-CERT</code> authentication.</p>
</td></tr><tr><td><code class="attributeName">clientCertProvider</code></td><td>
<p>When client certificate information is presented in a form other than
instances of <code>java.security.cert.X509Certificate</code> it needs to
be converted before it can be used and this property controls which JSSE
provider is used to perform the conversion. For example it is used with
the <a href="ajp.html">AJP connectors</a>, the HTTP APR connector and
with the <a href="valve.html#SSL_Authenticator_Valve">
org.apache.catalina.valves.SSLValve</a>. If not specified, the default
provider will be used.</p>
</td></tr><tr><td><code class="attributeName">crlFile</code></td><td>
<p>The certificate revocation list to be used to verify client
certificates. If not defined, client certificates will not be checked
against a certificate revocation list. The file may be specified using a
URL, an absolute path or a relative (to CATALINA_BASE) path.</p>
</td></tr><tr><td><code class="attributeName">keyAlias</code></td><td>
<p>The alias used for the server key and certificate in the keystore. If
not specified, the first key read from the keystore will be used. The
order in which keys are read from the keystore is implementation
dependent. It may not be the case that keys are read from the keystore in
the same order as they were added. If more than one key is present in the
keystore it is strongly recommended that a keyAlias is configured to
ensure that the correct key is used.</p>
</td></tr><tr><td><code class="attributeName">keyPass</code></td><td>
<p>The password used to access the server certificate from the
specified keystore file. The default value is "<code>changeit</code>".
</p>
</td></tr><tr><td><code class="attributeName">keystoreFile</code></td><td>
<p>The pathname of the keystore file where you have stored the
server certificate to be loaded. By default, the pathname is
the file "<code>.keystore</code>" in the operating system home
directory of the user that is running Tomcat. If your
<code>keystoreType</code> doesn't need a file use <code>""</code>
(empty string) for this parameter. The file may be specified using a
URL, an absolute path or a relative (to CATALINA_BASE) path.</p>
</td></tr><tr><td><code class="attributeName">keystorePass</code></td><td>
<p>The password used to access the specified keystore file. The default
value is the value of the <code>keyPass</code> attribute.
</p>
</td></tr><tr><td><code class="attributeName">keystoreProvider</code></td><td>
<p>The name of the keystore provider to be used for the server
certificate. If not specified, the list of registered providers is
traversed in preference order and the first provider that supports the
<code>keystoreType</code> is used.
</p>
</td></tr><tr><td><code class="attributeName">keystoreType</code></td><td>
<p>The type of keystore file to be used for the server certificate.
If not specified, the default value is "<code>JKS</code>".</p>
</td></tr><tr><td><code class="attributeName">sessionCacheSize</code></td><td>
<p>The number of SSL sessions to maintain in the session cache. Use 0 to
specify an unlimited cache size. If not specified, a default of 0 is
used.</p>
</td></tr><tr><td><code class="attributeName">sessionTimeout</code></td><td>
<p>The time, in seconds, after the creation of an SSL session that it will
timeout. Use 0 to specify an unlimited timeout. If not specified, a
default of 86400 (24 hours) is used.</p>
</td></tr><tr><td><code class="attributeName">sslEnabledProtocols</code></td><td>
<p>The comma separated list of SSL protocols to support for HTTPS
connections. If specified, only the protocols that are listed and
supported by the SSL implementation will be enabled. If not specified,
the JVM default (excluding SSLv2 and SSLv3 if the JVM enables either or
both of them by default) is used. The permitted values may be obtained
from the JVM documentation for the allowed values for
<code>SSLSocket.setEnabledProtocols()</code> e.g.
<a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#jssenames">
Oracle Java 7</a>. Note: There is overlap between this attribute and
<code>sslProtocol</code>.</p>
</td></tr><tr><td><code class="attributeName">sslImplementationName</code></td><td>
<p>The class name of the SSL implementation to use. If not specified, the
default of <code>org.apache.tomcat.util.net.jsse.JSSEImplementation</code>
will be used which wraps JVM's default JSSE provider. Note that the
JVM can be configured to use a different JSSE provider as the default.</p>
</td></tr><tr><td><code class="attributeName">sslProtocol</code></td><td>
<p>The SSL protocol(s) to use (a single value may enable multiple
protocols - see the JVM documentation for details). If not specified, the
default is <code>TLS</code>. The permitted values may be obtained from the
JVM documentation for the allowed values for algorithm when creating an
<code>SSLContext</code> instance e.g.
<a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#SSLContext">
Oracle Java 7</a>. Note: There is overlap between this attribute and
<code>sslEnabledProtocols</code>.</p>
</td></tr><tr><td><code class="attributeName">trustManagerClassName</code></td><td>
<p>The name of a custom trust manager class to use to validate client
certificates. The class must have a zero argument constructor and must
also implement <code>javax.net.ssl.X509TrustManager</code>. If this
attribute is set, the trust store attributes may be ignored.
</p>
</td></tr><tr><td><code class="attributeName">trustMaxCertLength</code></td><td>
<p>The maximum number of intermediate certificates that will be allowed
when validating client certificates. If not specified, the default value
of 5 will be used.</p>
</td></tr><tr><td><code class="attributeName">truststoreAlgorithm</code></td><td>
<p>The algorithm to use for truststore. If not specified, the default
value returned by
<code>javax.net.ssl.TrustManagerFactory.getDefaultAlgorithm()</code> is
used.</p>
</td></tr><tr><td><code class="attributeName">truststoreFile</code></td><td>
<p>The trust store file to use to validate client certificates. The
default is the value of the <code>javax.net.ssl.trustStore</code> system
property. If neither this attribute nor the default system property is
set, no trust store will be configured. The file may be specified using a
URL, an absolute path or a relative (to CATALINA_BASE) path.</p>
</td></tr><tr><td><code class="attributeName">truststorePass</code></td><td>
<p>The password to access the trust store. The default is the value of the
<code>javax.net.ssl.trustStorePassword</code> system property. If that
property is null, no trust store password will be configured. If an
invalid trust store password is specified, a warning will be logged and an
attempt will be made to access the trust store without a password which
will skip validation of the trust store contents.</p>
</td></tr><tr><td><code class="attributeName">truststoreProvider</code></td><td>
<p>The name of the truststore provider to be used for the server
certificate. The default is the value of the
<code>javax.net.ssl.trustStoreProvider</code> system property. If
that property is null, the value of <code>keystoreProvider</code> is used
as the default. If neither this attribute, the default system property nor
<code>keystoreProvider</code>is set, the list of registered providers is
traversed in preference order and the first provider that supports the
<code>truststoreType</code> is used.
</p>
</td></tr><tr><td><code class="attributeName">truststoreType</code></td><td>
<p>The type of key store used for the trust store. The default is the
value of the <code>javax.net.ssl.trustStoreType</code> system property. If
that property is null, the value of <code>keystoreType</code> is used as
the default.</p>
</td></tr></table>
</div></div>
<div class="subsection"><h4 id="SSL_Support_-_APR/Native">SSL Support - APR/Native</h4><div class="text">
<p>When APR/native is enabled, the HTTPS connector will use a socket poller
for keep-alive, increasing scalability of the server. It also uses OpenSSL,
which may be more optimized than JSSE depending on the processor being used,
and can be complemented with many commercial accelerator components. Unlike
the HTTP connector, the HTTPS connector cannot use sendfile to optimize static
file processing.</p>
<p>The HTTPS APR/native connector has the same attributes than the HTTP
APR/native connector, but adds OpenSSL specific ones. For the full details on
using OpenSSL, please refer to OpenSSL documentations and the many books
available for it (see the <a href="http://www.openssl.org">Official OpenSSL
website</a>). The SSL specific attributes for the APR/native connector are:
</p>
<table class="defaultTable"><tr><th style="width: 15%;">
Attribute
</th><th style="width: 85%;">
Description
</th></tr><tr><td><code class="attributeName">SSLCACertificateFile</code></td><td>
<p>See <a href="http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#sslcacertificatefile">
the mod_ssl documentation</a>.</p>
</td></tr><tr><td><code class="attributeName">SSLCACertificatePath</code></td><td>
<p>See <a href="http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#sslcacertificatepath">
the mod_ssl documentation</a>.</p>
</td></tr><tr><td><code class="attributeName">SSLCARevocationFile</code></td><td>
<p>See <a href="http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#sslcarevocationfile">
the mod_ssl documentation</a>.</p>
</td></tr><tr><td><code class="attributeName">SSLCARevocationPath</code></td><td>
<p>See <a href="http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#sslcarevocationpath">
the mod_ssl documentation</a>.</p>
</td></tr><tr><td><code class="attributeName">SSLCertificateChainFile</code></td><td>
<p>See <a href="http://httpd.apache.org/docs/2.2/mod/mod_ssl.html#sslcertificatechainfile">
the mod_ssl documentation</a>.</p>
</td></tr><tr><td><code class="attributeName">SSLCACertificateFile</code></td><td>
<p>Name of the file that contains the concatenated certificates for the
trusted certificate authorities. The format is PEM-encoded.</p>
</td></tr><tr><td><code class="attributeName">SSLCACertificatePath</code></td><td>
<p>Name of the directory that contains the certificates for the trusted
certificate authorities. The format is PEM-encoded.</p>
</td></tr><tr><td><code class="attributeName">SSLCARevocationFile</code></td><td>
<p>Name of the file that contains the concatenated certificate revocation
lists for the certificate authorities. The format is PEM-encoded.</p>
</td></tr><tr><td><code class="attributeName">SSLCARevocationPath</code></td><td>
<p>Name of the directory that contains the certificate revocation lists
for the certificate authorities. The format is PEM-encoded.</p>
</td></tr><tr><td><code class="attributeName">SSLCertificateChainFile</code></td><td>
<p>Name of the file that contains concatenated certifcates for the
certificate authorities which form the certifcate chain for the server
certificate. The format is PEM-encoded.</p>
</td></tr><tr><td><strong><code class="attributeName">SSLCertificateFile</code></strong></td><td>
<p>Name of the file that contains the server certificate. The format is
PEM-encoded.</p>
<p>In addition to the certificate, the file can also contain as optional
elements DH parameters and/or an EC curve name for ephemeral keys, as
generated by <code>openssl dhparam</code> and <code>openssl ecparam</code>,
respectively. The output of the respective OpenSSL command can simply
be concatenated to the certificate file. This feature needs APR/native
version 1.1.34 or later.</p>
</td></tr><tr><td><code class="attributeName">SSLCertificateKeyFile</code></td><td>
<p>Name of the file that contains the server private key. The format is
PEM-encoded. The default value is the value of "SSLCertificateFile" and in
this case both certificate and private key have to be in this file (NOT
RECOMMENDED).</p>
</td></tr><tr><td><code class="attributeName">SSLCipherSuite</code></td><td>
<p>Ciphers which may be used for communicating with clients. The default
is <code>HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5</code>. See the OpenSSL
documentation for details of the syntax for this attribute.</p>
</td></tr><tr><td><code class="attributeName">SSLDisableCompression</code></td><td>
<p>Disables compression if set to <code>true</code> and OpenSSL supports
disabling compression. Default is <code>false</code> which inherits the
default compression setting in OpenSSL.</p>
</td></tr><tr><td><code class="attributeName">SSLHonorCipherOrder</code></td><td>
<p>Set to <code>true</code> to enforce the server's cipher order
(from the <code>SSLCipherSuite</code> setting) instead of allowing
the client to choose the cipher (which is the default).</p>
</td></tr><tr><td><code class="attributeName">SSLPassword</code></td><td>
<p>Pass phrase for the encrypted private key. If "SSLPassword" is not
provided, the callback function should prompt for the pass phrase.</p>
</td></tr><tr><td><code class="attributeName">SSLProtocol</code></td><td>
<p>The names of the protocols to support when communicating with clients.
This should be a list of any combination of the following:
</p>
<ul><li>SSLv2</li><li>SSLv3</li><li>TLSv1</li>
<li>TLSv1.1</li><li>TLSv1.2</li><li>all</li></ul>
<p>Each token in the list can be prefixed with a plus sign ("+")
or a minus sign ("-"). A plus sign adds the protocol, a minus sign
removes it form the current list. The list is built starting from
an empty list.</p>
<p>The token <code>all</code> is an alias for
<code>TLSv1+TLSv1.1+TLSv1.2</code>.</p>
<p>If more than one protocol is specified for an OpenSSL
based secure connector it will always support <code>SSLv2Hello</code>. If a
single protocol is specified it will not support
<code>SSLv2Hello</code>.</p>
<p>Note that <code>SSLv2</code> and <code>SSLv3</code> are inherently
unsafe.</p>
<p>If not specified, the default value of <code>all</code> will be
used.</p>
</td></tr><tr><td><code class="attributeName">SSLVerifyClient</code></td><td>
<p>Ask client for certificate. The default is "none", meaning the client
will not have the opportunity to submit a certificate. Other acceptable
values include "optional", "require" and "optionalNoCA".</p>
</td></tr><tr><td><code class="attributeName">SSLVerifyDepth</code></td><td>
<p>Maximum verification depth for client certificates. The default is
"10".</p>
</td></tr><tr><td><code class="attributeName">SSLDisableSessionTickets</code></td><td>
<p>Disables use of TLS Session Tickets (RFC 4507) if set to
<code>true</code>. Default is <code>false</code>.</p>
</td></tr></table>
</div></div>
</div></div>
<div class="subsection"><h4 id="Connector_Comparison">Connector Comparison</h4><div class="text">
<p>Below is a small chart that shows how the connectors differ.</p>
<table class="defaultTable" style="text-align: center;">
<tr>
<th></th>
<th style="text-align: center;">Java Blocking Connector<br>BIO</th>
<th style="text-align: center;">Java Nio Connector<br>NIO</th>
<th style="text-align: center;">Java Nio2 Connector<br>NIO2</th>
<th style="text-align: center;">APR/native Connector<br>APR</th>
</tr>
<tr>
<th>Classname</th>
<td><code class="noHighlight">Http11Protocol</code></td>
<td><code class="noHighlight">Http11NioProtocol</code></td>
<td><code class="noHighlight">Http11Nio2Protocol</code></td>
<td><code class="noHighlight">Http11AprProtocol</code></td>
</tr>
<tr>
<th>Tomcat Version</th>
<td>3.x onwards</td>
<td>6.x onwards</td>
<td>8.x onwards</td>
<td>5.5.x onwards</td>
</tr>
<tr>
<th>Support Polling</th>
<td>NO</td>
<td>YES</td>
<td>YES</td>
<td>YES</td>
</tr>
<tr>
<th>Polling Size</th>
<td>N/A</td>
<td><code class="noHighlight">maxConnections</code></td>
<td><code class="noHighlight">maxConnections</code></td>
<td><code class="noHighlight">maxConnections</code></td>
</tr>
<tr>
<th>Read Request Headers</th>
<td>Blocking</td>
<td>Non Blocking</td>
<td>Non Blocking</td>
<td>Blocking</td>
</tr>
<tr>
<th>Read Request Body</th>
<td>Blocking</td>
<td>Blocking</td>
<td>Blocking</td>
<td>Blocking</td>
</tr>
<tr>
<th>Write Response Headers and Body</th>
<td>Blocking</td>
<td>Blocking</td>
<td>Blocking</td>
<td>Blocking</td>
</tr>
<tr>
<th>Wait for next Request</th>
<td>Blocking</td>
<td>Non Blocking</td>
<td>Non Blocking</td>
<td>Non Blocking</td>
</tr>
<tr>
<th>SSL Support</th>
<td>Java SSL</td>
<td>Java SSL</td>
<td>Java SSL</td>
<td>OpenSSL</td>
</tr>
<tr>
<th>SSL Handshake</th>
<td>Blocking</td>
<td>Non blocking</td>
<td>Non blocking</td>
<td>Blocking</td>
</tr>
<tr>
<th>Max Connections</th>
<td><code class="noHighlight">maxConnections</code></td>
<td><code class="noHighlight">maxConnections</code></td>
<td><code class="noHighlight">maxConnections</code></td>
<td><code class="noHighlight">maxConnections</code></td>
</tr>
</table>
</div></div>
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