HTTP Servlet Transport

The transport receiver implementation of the HTTP transport is available in the Carbon core component. The transport sender implementation comes from the Tomcat http connector. This transport is shipped with WSO2 Carbon and all WSO2 Carbon-based products, which use this transport as the default transport, except WSO2 ESB and WSO2 Enterpise Integrator. By default, we use non-blocking Tomcat Java connector, org.apache.coyote.http11.Http11NioProtocol.

This is a non-blocking HTTP transport implementation, which means that I/O the threads does not get blocked while received messages are processed.
Although the axis2.xml file contains configurations for HTTP/S transports by default, they are not used by WSO2 products. Instead, the products use the HTTP/S transport configurations in Tomcat-level; therefore, changing the HTTP/S configurations in the axis2.xml file has no effect.

In the transport parameter tables, the literals displayed in italics under the "Possible Values" column should be considered as fixed literal constant values. Those values can be directly put into the transport configurations.

Transport Connector Parameters

Parameter Name	Description	Required	Possible Values	Default Value
port	The port number on which this transport receiver should listen for incoming messages.	Yes	A positive integer less than 65535
proxyPort	When used, this transport listener will accept messages arriving througha HTTPproxy server which listens on the specified proxy port. Apache mod_proxy should be enabled in the proxy server. All the WSDLs generated will contain the proxy port value as the listener port.	No	A positive integer less than 65535

HTTP servlet transport should be configured in the <EI_HOME>/conf/tomcat/catalina-server.xml file. The transport class that should be specified in the catalina-server.xml file is as follows:

<Connector protocol="org.apache.coyote.http11.Http11NioProtocol"/>

Parameter Name	Description	Possible Values	Default Value
port	The port over which this transport receiver listens for incoming messages.	A positive integer less than 65535	9763 for HTTP Connector 9443 for HTTPS Connector
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.	A positive integer less than 65535	9443
bindOnInit	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 `false`, the socket will be bound when the connector is started and unbound when it is stopped.		false
proxyPort	When used, this transport listener will accept messages arriving through a HTTP proxy server which listens on the specified proxy port. Apache `mod_proxy` should be enabled on the proxy server. All the WSDLs generated will contain the proxy port value as the listener port.	A positive integer less than 65535
maxHttpHeaderSize	The maximum size of the HTTP request and response header in bytes.	A positive integer	4096
acceptorThreadCount	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 `2`. Also, with a lot of non keep-alive connections, you might want to increase this value as well.		2
maxThreads	The maximum number of worker threads created by the receiver to handle incoming requests. This parameter largely determines the number of concurrent connections that can be handled by the transport.	A positive integer	40
minSpareThreads	The minimum number of threads always kept running. If not specified, the default will be used.		50
enableLookups	Use this parameter to enable DNS lookups in order to return the actual host name of the remote client. Disabling DNS lookups at transport level generally improves performance. By default, DNS lookups are disabled.	true, false	false
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.	true, false	true
connectionUploadTimeout	Specifies the timeout, in milliseconds, to use while a data upload is in progress. This only takes effect if `disableUploadTimeout` is set to `false`.
clientAuth	Set to true if you want the SSL stack to require a valid certificate chain from the client before accepting a connection. Set to want if you want the SSL stack to request a client Certificate, but not fail if one is not present. 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.	true, false, want	false
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.	-1 or any positive integer	100
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.	A positive integer	10
server	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.	Any string	WSO2 Carbon Server
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".	on, off, force	off
compressionMinSize	If compression is set to "on" then this attribute may be used to specify the minimum amount of data before the output is compressed.	A positive integer	2048
noCompressionUserAgents	Indicate a 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.	A comma separatedlist of regular expressions	empty string
compressableMimeType	Use this parameter to indicate a list of MIME types for which HTTP compression may be used.	A comma separated list of valid mime types	text/html, text/xml, text/plain
URIEncoding	This specifies the character encoding used to decode the URI bytes, after %xx decoding the URL.	URI encoding Character set name	ISO-8859-1

This servlet transport implementation can be further tuned up using the following parameters.

This is only a subset of all the supported parameters. The servlet HTTP transport uses the org.apache.catalina.connector.Connector implementation from Apache Tomcat. So the servlet HTTP transport actually accepts any parameter accepted by the connector implementation. For a complete list of supported parameters, see Apache Tomcat's connector configuration reference.

Transport Sender Parameters

Parameter Name	Description	Requried	Possible Values	Default Value
PROTOCOL	The version of HTTP protocol to be used for outgoing messages.	No	HTTP/1.0, HTTP/1.1	HTTP/1.1
Transfer-Encoding	Effective only when the HTTP version is 1.1 (i.e. the value of the PROTOCOL parameter should be HTTP/1.1). Use this parameter to enable chunking support for the transport sender.	No	chunked	Not Chunked
SocketTimeout	The socket timeout value in milliseconds, for out bound connections.	No	A positive integer	60000 ms
ConnectionTimeout	The connection timeout value in milliseconds, for out bound connections.	No	A positive integer	60000 ms
OmitSOAP12Action	Set this parameter to "true" if you need to disable the soap action for SOAP 1.2 messages.	No	true, false	false

Defining multiple tomcat connectors

You have the option of defining multiple tomcat connectors in the catalina-server.xml file. Note that when you define multiple connectors, all the endpoints of the applications deployed in your WSO2 server will still be exposed through all the connector ports. However, you can configure your load balancer to ensure that only the relevant applications are exposed through the required connector port.

Therefore, you can use multiple connectors to strictly separate the applications deployed in your server as explained below.

See the example given below where two connectors are defined in the catalina-server.xml file.

<!-- Connector using port 9763 -->
 <Connector protocol="org.apache.coyote.http11.Http11NioProtocol"
                   port="9763"
                   ......
                   ....../>
<!-- Connector using port 9764 -->
 <Connector protocol="org.apache.coyote.http11.Http11NioProtocol"
                   port="9764"
                   ......
                   ....../>

Configure your load balancer so that the relevant applications are exposed through the required connector port.