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 service integration bus component
of IBM service integration technologies, 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.
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.
- TCP channel
- Used to provide client applications with persistent connections within
a Local Area Network (LAN). When configuring a TCP channel, you can specify
a list of IP addresses that are allowed to make inbound connections and a
list of IP addresses that are not allowed to make inbound connections. You
can also specify the thread pool that this channel uses, which allows you
to segregate work by the port that the application server is listening on.
- HTTP 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 server HTTP requests and to send HTTP specific information to
servlets expecting this type of information.
- 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.
- Web container channel
- Used to create a bridge in the transport chain between an HTTP inbound
channel and a servlet and JavaServer Pages (JSP) engine.
- DCS channel
- Used by the core group bridge service, the data replication service (DRS),
and the high availability manger to transfer data, objects, or events among
application servers.
- 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.
- JFAP channel
- Used by the Java Message Service (JMS) server to create connections to
JMS resources on a service integration bus.
- SSL channel
- Used to associate an SSL configuration repertoire with the transport chain.
This channel is only available when Secure Sockets Layer (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.