Transport chains represent a network protocol stack that is used
for I/O operations within an application server environment.
Transport chains are part of the channel framework function
that provides a common networking service for all components, including the
WebSphere Secure Caching Proxy, and the high availability manager core group
bridge service.
A transport chain consists of one or more types of channels, each of which
supports a different type of I/O protocol, such as TCP, DCS. or HTTP. Network
ports can be shared among all of the channels within a chain. The channel
framework function automatically distributes a request arriving on that port
to the correct I/O protocol channel for processing.
For transitioning users: If
you have a routine that issues a call to start transports during server startup,
unless you have a mixed-node environment and that server is running in either
a V5.1 or V6.0.x, you must modify your routine to issue a call to start transport
chains instead of the transports. WebSphere Application Server issues an error
message if it receives a call to start transports for a server that is not
running in a V5.x or V6.0.x node.
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The transport chain configuration settings determine which I/O protocols
are supported for that chain. Following are some of the more common types
of channels. Custom channels that support requirements unique to a particular
customer or environment can also be added to a transport chain.
- DCS channel
- Used in a Network Deployment environment by the core group bridge service,
the data replication service (DRS), and the high availability manager to transfer
data, objects, or events among application servers.
- HTTP inbound channel
- Used to enable communication with remote servers. It implements the HTTP
1.0 and 1.1 standards and is used by other channels, such as the Web container
channel, to serve HTTP requests and to send HTTP specific information to servlets
expecting this type of information.
HTTP inbound channels
are used instead of HTTP transports to establish the request queue between
a WebSphere Application Server plug-in for Web servers and a Web container
in which the Web modules of an application reside.
- HTTP proxy inbound channel
- Used to handle HTTP requests between a proxy server and application server
nodes.
- HTTP Tunnel channel
- Used to provide client applications with persistent HTTP connections to
remote hosts that are either blocked by firewalls or require an HTTP proxy
server (including authentication) or both. An HTTP Tunnel channel enables
the exchange of application data in the body of an HTTP request or response
that is sent to or received from a remote server. An HTTP Tunnel channel also
enables client-side applications to poll the remote host and to use HTTP requests
to either send data from the client or to receive data from an application
server. In either case, neither the client nor the application server is aware
that HTTP is being used to exchange the data.
- JFAP channel
- Used by the Java Message Service (JMS) server to create connections to
JMS resources on a service integration bus.
This type
of channel cannot be used as a transport for Web services.
- MQ channel
- Used in combination with other channels, such as a TCP channel, within
the confines of WebSphere MQ support to facilitate communications between
a WebSphere System Integration Bus and a WebSphere MQ client or queue manager.
This type of channel cannot be used as a transport
for Web services.
- ORB Service channel
- Used in combination with other channels, such as a TCP channel, to handle
CORBA and RMI/IIOP messages for the ORB Service. It enables clients to make
requests and receive responses from servers in a network-distributed environment.
- SIP channel
- Used to create a bridge in the transport chain between a session initiation
protocol (SIP) inbound channel, and a servlet and JavaServer Page engine.
- SIP container inbound channel
- Used to handle communication between the SIP inbound channel and the SIP
servlet container.
- SIP inbound channel
- Used to handle inbound SIP requests from a remote client.
- SSL channel
- Used to associate an Secure Sockets Layer (SSL) configuration repertoire
with the transport chain. This channel is only available when SSL support
is enabled for the transport chain. An SSL configuration repertoire is defined
in the administrative console, under security, on the SSL configuration
repertoires > SSL configuration repertoires page.
- TCP channel
- Used to provide client applications with persistent connections within
a Local Area Network (LAN) when a node uses transmission control protocol
(TCP) to retrieve information from a network.
- UDP channel
- Used to provide client applications with persistent connections within
a Local Area Network (LAN) when a node uses user datagram protocol (UDP) to
retrieve information from a network.
- Web container channel
- Used to create a bridge in the transport chain between an HTTP inbound
channel and a servlet and JavaServer Page (JSP) engine.