Links Top Level Elements Connectors Containers Nested Components | | Introduction |
The HTTP Connector element represents a
Connector 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 Connectors can be
configured as part of a single Service, each
forwarding to the associated Engine to perform
request processing and create the response.
If you wish to configure the Connector that is used
for connections to web servers using the AJP protocol (such as the
mod_jk 1.2.x connector for Apache 1.3), see
here instead.
At server startup time, this Connector will create a
number of request processing threads (based on the value configured for
the minSpareThreads attribute). 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 maxThreads attribute).
If still more simultaneous requests are received, they are stacked up
inside the server socket created by the Connector, up to
the configured maximum (the value of the acceptCount
attribute. Any further simultaneous requests will receive "connection
refused" errors, until resources are available to process them.
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| Attributes |
| Common Attributes |
All implementations of Connector
support the following attributes:
| Attribute | Description |
|---|
allowTrace |
A boolean value which can be used to enable or disable the TRACE
HTTP method. If not specified, this attribute is set to false.
| emptySessionPath |
If set to true, all paths for session cookies will be set
to /. This can be useful for portlet specification implementations,
but will greatly affect performance if many applications are accessed on a given
server by the client.
If not specified, this attribute is set to false.
| enableLookups |
Set to true if you want calls to
request.getRemoteHost() to perform DNS lookups in
order to return the actual host name of the remote client. Set
to false to skip the DNS lookup and return the IP
address in String form instead (thereby improving performance).
By default, DNS lookups are enabled.
| maxPostSize |
The maximum size in bytes of the POST which will be handled by
the container FORM URL parameter parsing. The feature can be disbled by
setting this attribute to a value inferior or equal to 0.
If not specified, this attribute is set to 2097152 (2 megabytes).
| protocol |
This attribute value must be HTTP/1.1 to use the HTTP
handler, which is the default.
| proxyName |
If this Connector is being used in a proxy
configuration, configure this attribute to specify the server name
to be returned for calls to request.getServerName().
See Proxy Support for more
information.
| proxyPort |
If this Connector is being used in a proxy
configuration, configure this attribute to specify the server port
to be returned for calls to request.getServerPort().
See Proxy Support for more
information.
| redirectPort |
If this Connector is supporting non-SSL
requests, and a request is received for which a matching
<security-constraint> requires SSL transport,
Catalina will automatically redirect the request to the port
number specified here.
| scheme |
Set this attribute to the name of the protocol you wish to have
returned by calls to request.getScheme(). For
example, you would set this attribute to "https"
for an SSL Connector. The default value is "http".
See SSL Support for more information.
| secure |
Set this attribute to true if you wish to have
calls to request.isSecure() to return true
for requests received by this Connector (you would want this on an
SSL Connector). The default value is false.
| URIEncoding |
This specifies the character encoding used to decode the URI bytes,
after %xx decoding the URL. If not specified, ISO-8859-1 will be used.
| useBodyEncodingForURI |
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 explicitely set using
Request.setCharacterEncoding method was also used for the parameters from
the URL. The default value is false.
| xpoweredBy |
Set this attribute to true to cause Tomcat to advertise
support for the Srevlet specification using the header recommended in the
specification. The default value is false.
|
|
| Standard Implementation |
The standard implementation of the HTTP
Connector is
org.apache.coyote.tomcat5.CoyoteConnector.
It supports the following additional attributes (in addition to the
common attributes listed above):
| Attribute | Description |
|---|
acceptCount |
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 10.
| address |
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.
| bufferSize |
The size (in bytes) of the buffer to be provided for input
streams created by this connector. By default, buffers of
2048 bytes will be provided.
| compressableMimeType |
The value is a comma separated list of MIME types for which HTTP
compression may be used.
The default value is text/html,text/xml,text/plain.
| compression |
The Connector 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".
| connectionLinger |
The number of milliseconds during which the sockets used by this
Connector will linger when they are closed.
The default value is -1 (socket linger is disabled).
| connectionTimeout |
The number of milliseconds this Connector will wait,
after accepting a connection, for the request URI line to be
presented. The default value is 60000 (i.e. 60 seconds).
| disableUploadTimeout |
This flag allows the servlet container to use a different, longer
connection timeout while a servlet is being executed, which in the end
allows either the servlet a longer amount of time to complete its
execution, or a longer timeout during data upload. If not specified,
this attribute is set to "false".
| maxHttpHeaderSize |
The maximum size of the request and response HTTP header, specified
in bytes.
If not specified, this attribute is set to 4096 (4 KB).
| maxKeepAliveRequests |
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.
| maxSpareThreads |
The maximum number of unused request processing threads that
will be allowed to exist until the thread pool starts stopping the
unnecessary threads. The default value is 50.
| maxThreads |
The maximum number of request processing threads to be created
by this Connector, which therefore determines the
maximum number of simultaneous requests that can be handled. If
not specified, this attribute is set to 200.
| minSpareThreads |
The number of request processing threads that will be created
when this Connector is first started. The connector
will also make sure it has the specified number of idle processing
threads available. This attribute should be set to a value smaller
than that set for maxThreads. The default value is 4.
| noCompressionUserAgents |
The value is a comma separated list of regular expressions matching
user-agents 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).
| port |
The TCP port number on which this Connector
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.
| restrictedUserAgents |
The value is a comma separated list of regular expressions matching
user-agents 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).
| server |
The Server header for the http response.
Unless your paranoid, you won't need this feature.
| socketBuffer |
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.
| strategy |
The thread pooling strategy which will be used. The default strategy does
not use a master thread, but a more conventional strategy using a
master listener thread can be used by setting "ms" as this attribute's value.
The master strategy will work significantly better using the threadPriority
attribute, which will apply only to the thread which listens on the server socket.
This is set to lf by default.
| tcpNoDelay |
If set to true, the TCP_NO_DELAY option will be
set on the server socket, which improves performance under most
circumstances. This is set to true by default.
| threadPriority |
The priority of the request processing threads within the JVM.
The default value is java.lang.Thread#NORM_PRIORITY.
See the JavaDoc for the java.lang.Thread class for more details on
what this priority means.
|
|
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| Special Features |
| HTTP/1.1 and HTTP/1.0 Support |
This Connector 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
Connector will gracefully fall back to supporting this
protocol as well. No special configuration is required to enable this
support. The Connector also supports HTTP/1.0
keep-alive.
RFC 2616 requires that HTTP servers always begin their responses with
the highest HTTP version that they claim to support. Therefore, this
Connector will always return HTTP/1.1 at
the beginning of its responses.
|
| Proxy Support |
The proxyName and proxyPort attributes can
be used when Tomcat is run behind a proxy server. These attributes
modify the values returned to web applications that call the
request.getServerName() and request.getServerPort()
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.
For more information, see the
Proxy Support HOW-TO.
|
| SSL Support |
You can enable SSL support for a particular instance of this
Connector by setting the secure attribute to
true. In addition, you may need to configure the following
attributes:
| Attribute | Description |
|---|
algorithm |
The certificate encoding algorithm to be used. If not
specified, the default value is SunX509.
| clientAuth |
Set to true if you want the SSL stack to
require a valid certificate chain from the client before
accepting a connection. A false value (which
is the default) will not require a certificate chain unless
the client requests a resource protected by a security constraint
that uses CLIENT-CERT authentication.
| keystoreFile |
The pathname of the keystore file where you have stored the
server certificate to be loaded. By default, the pathname is
the file ".keystore" in the operating system home
directory of the user that is running Tomcat.
| keystorePass |
The password used to access the server certificate from the
specified keystore file. The default value is "changeit".
| keystoreType |
The type of keystore file to be used for the server certificate.
If not specified, the default value is "JKS".
| sslProtocol |
The version of the SSL protocol to use. If not specified,
the default is "TLS".
| ciphers |
A comma seperated list of the encryption ciphers that may be used.
If not specified, then any available cipher may be used.
|
For more information, see the
SSL Configuration HOW-TO.
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