Transport (Server)

NetKernel provides a high-performance HTTP transport based on the Jetty HTTP server.

The NetKernel HTTP transport receives external HTTP requests. For each external request it creates and issues an internal root request into the NetKernel address space.

The HTTP Transport has been designed to provide both ease-of-use and flexibility. To achieve this, it is implemented in two parts: the HTTP Transport and the HTTP Bridge. Generally the HTTP Transport and HTTP Bridge are configured to work together as shown in the following diagram.

The front-end fulcrum running HTTP server on port 8080 is set-up so that all requests from the HTTP transport are mapped to the HTTP Bridge.

The HTTP Bridge is a declaratively configurable service. Its job is to obtain and process information from the external HTTP request and to construct and issue an internal NetKernel request to applications. It impedance matches the widely diverse ways in which HTTP provides information and unifies it into simple active URI argument values on an internal NK request.

For example, the HTTP Bridge can convert form-encoded POST data into a clean name-value pair resource structure provided as the param argument. Equally it can be configured to pass through information suitable for RESTful web-services such as HTTP Method, HTTP Headers etc etc. Or, to process the HTTP request in SOAP mode for handling SOAP web-services and the specific headers used by SOAP clients.

The HTTP bridge not only pre-processes the HTTP request before issuing to the NetKernel internal address space. It also handles the response from the NetKernel address space and interprets it before writing the response to the HTTP response stream.

For example the HTTP Bridge writes ETAG headers for each resouce served from NetKernel. Every request is examined to determine if a 304 not-modified response code can be returned if the requested resource is currently cached by NetKernel. This happens transparently for both static and dynamic application resources.

The HTTP bridge will also write protocol specific responses when in SOAP mode.

The HTTP Bridge is a simple and powerful complementary technology to the low-level HTTP server. However if you require full low-level access to the HTTPRequest and HTTPResponse objects from Java, simply remove the HTTP Bridge mapping from your fulcrum module and you will recieve the low-level HTTPRequestResponse aspect and will be able to access all of the low-level HTTP request fields but you must also take responsibility for writing the HTTP response.

Transport Configuration

HTTP Transport

The NetKernel HTTP Transport requests its configuration information from the resource ffcpl:/etc/TransportJettyConfig.xml. This contains the low-level server configuration settings such as threading, port, SSL, access control and the syntax is specific to Jetty. Refer to the HTTP Transport documentation for more details.

HTTP Bridge

The NetKernel HTTP Bridge requests its configuration information from the resource ffcpl:/etc/HTTPBridgeConfig.xml.

For specifics about the bridge configuration consult the HTTP Bridge documentation.