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APIs are synapse configurations in the back-end and API Manager uses accesses them using HTTP-NIO transport by default to invoke APIs. You can switch to a different transport such as PassThrough. For information on each of these transports, see ESB Transports. To change the default transport of API Manager, go to <APIM_HOME>/repository/conf/axis2 folder and rename axis2.xml_PT file to axis2.xml. Similarly, you can switch back to NHTTP by simply renaming axis2.xml_NHTTP file to axis2.xml.

The following topics explain HTTP-NIO and PassThrough transports:

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HTTP-NIO transport

HTTP-NIO transport is a module of the Apache Synapse project. Apache Synapse as well as WSO2 APIM ship the HTTP-NIO transport as the default HTTP transport implementation. The two classes that implement the receiver and sender APIs are org.apache.synapse.transport.nhttp.HttpCoreNIOListener and org.apache.synapse.transport.nhttp.HttpCoreNIOSender respectively. These classes are available in the JAR file named synapse-nhttp-transport.jar. This non-blocking transport implementation improves performance. The transport implementation is based on Apache HTTP Core - NIO and uses a configurable pool of non-blocking worker threads to grab incoming HTTP messages off the wire.

Transport receiver parameters

Info

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

Parameter Name

Description

Requried

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

 

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

hostname

The host name of the server to be displayed in service EPRs, WSDLs etc. This parameter takes effect only when the WSDLEPRPrefix parameter is not set.

No

A host name or an IP address

localhost

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>/

 

Transport sender parameters

Parameter Name

Description

Requried

Possible Values

Default Value

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 '|'

 

non-blocking

Setting this parameter to true is vital for reliable messaging and a number of other scenarios to work properly.

Yes

true

 

 

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 care about the content type and simply streams all received messages through. It also has a simpler and cleaner model for forwarding messages back and forth. It can be used as an alternative to the NHTTP transport. 

The HTTP PassThrough Transport is enabled by default. If you want to use the NHTTP transport instead, uncomment the relevant NHTTP transport entries in axis2.xml and comment out the HTTP PassThrough transport entries. The PassThrough Transport does not require the binary relay builder and expanding formatter.

Excerpt

Connection throttling

With the HTTP PassThrough and HTTP NIO transports, you can enable connection throttling to restrict the number of simultaneous open connections. To enable connection throttling, edit the <PRODUCT_HOME>/repository/conf/nhttp.properties (for the HTTP NIO transport) or <PRODUCT_HOME>/repository/conf/passthru.properties (for the PassThrough transport) and add the following line: 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.