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Changing the Default Transport¶

APIs are made up of Apache Synapse configurations that WSO2 API Manager accesses through a transport protocol. The default API Manager transport is the PassThrough transport, but you can configure a different default transport in your deployment.toml file.

Info

WSO2 API Manager does not use the HTTP/S servlet transport protocol configurations that are in the axis2.xml file. Instead, WSO2 API Manager's Management Console uses the Tomcat-level servlet transport protocols that are available in the <API-M_HOME>/repository/conf/tomcat/catalina-server.xml file.

The following topics provide more information on these transports:

HTTP PassThrough Transport
Transport Receiver Parameters
Transport Sender Parameters
Connection Throttling

HTTP PassThrough Transport¶

HTTP PassThrough Transport is the default, non-blocking HTTP transport implementation based on HTTP Core NIO and is specially designed for streaming messages. It is similar to the old message relay transport, but it does not take the content type into consideration and simply streams all the messages that it receives. It also has a simpler and cleaner model for forwarding messages back and forth. The two classes that implement the receiver and sender APIs are org.apache.synapse.transport.passthru.PassThroughHttpListener and org.apache.synapse.transport.passthru.PassThroughHttpSender, respectively. The PassThrough Transport does not require the binary relay builder and expanding formatter.

Transport Receiver Parameters¶

Parameter Name	Description	Required	Possible Values	Default Value
port	The port on which this transport receiver should listen for incoming messages.	No	A positive integer less than 65535	8280
non-blocking	Setting this parameter to true is vital for reliable messaging and a number of other scenarios to work properly.	Yes	`true` or `false`	`true`
bind-address	The address of the interface to which the transport listener should bind.	No	A host name or an IP address	127.0.0.1
WSDLEPRPrefix	A URL prefix which will be added to all service EPRs and EPRs in WSDLs etc.	No	A URL of the form <protocol>://<hostname>:<port>/
httpGetProcessor	An extension point used to execute a special interceptor for HTTP GET requests.	Yes	An extension point	`org.wso2.carbon.mediation.transport.handlers .PassThroughNHttpGetProcessor`
priorityConfigFile	The location of the file containing the configuration for priority based dispatching.	No	A file location

Transport Sender Parameters¶

Parameter Name	Description	Required	Possible Values	Default Value
non-blocking	Setting this parameter to true is vital for reliable messaging and a number of other scenarios to work properly.	Yes	`true` or `false`	`true`
warnOnHTTP500	Logs warnings for HTTP 500 responses only for the specified content-types. For example, `<parameter name="warnOnHTTP500 locked="false">x-application/hessian\|none</parameter>` would log warnings for HTTP 500 responses of content-type 'x-application/hessian' or messages missing a content-type.	No	A list of content types separated by "\|"
http.proxyHost	If the outgoing messages should be sent through an HTTP proxy server, use this parameter to specify the target proxy.	No	A host name or an IP address
http.proxyPort	The port through which the target proxy accepts HTTP traffic.	No	A positive integer less than 65535
http.nonProxyHosts	The list of hosts to which the HTTP traffic should be sent directly without going through the proxy.	No	A list of host names or IP addresses separated by '\|'

Connection Throttling¶

Using the HTTP PassThrough transport protocol, you can enable connection throttling to restrict the number of simultaneous open connections. To enable connection throttling, edit the <APIM_HOME>/repository/conf/deployment.toml and add the following configuration under passthough_http configurations.

    [passthru_http]
    max_open_connections = 2

This will restrict simultaneous open incoming connections to 2. To disable throttling, delete the max_open_connections setting or set it to -1.

Info

Connection throttling is never exact. For example, setting this property to 2 will result in roughly two simultaneous open connections at any given time.

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