METHOD AND APPARATUS FOR USING A COMMAND DESIGN PATTERN TO ACCESS AND CONFIGURE NETWORK ELEMENTS
An XML accessible network device is capable of performing functions in response to an XML encoded request transmitted over a network. It includes a network data transfer service, coupled to a network, that is capable of receiving XML encoded requests from a client also connected to the network. A service engine is capable of understanding and parsing the XML encoded requests according to a corresponding DTD. The service engine further instantiates a service using parameters provided in the XML encoded request and launches the service for execution on the network device in accordance with a command design parameter. A set of device APIs interacts with hardware and software on the network device for executing the requested service on the network device. If necessary, a response is further collected from the device and provided to the client in a response message.
1 . A method of causing a network device to perform a service at the network device, the method comprising:
sending a service request from a requesting client to the network device, the service request comprising a request identifier and a markup language document, the markup language document identifying a document type definition; and
at the network device:
receiving the service request;
retrieving the document type definition identified by the markup language document;
parsing the service request using the retrieved document type definition;
determining whether an object corresponding to the service has already been instantiated; and
when no object corresponding to the service has already been instantiated, instantiating an object corresponding to the service, and calling an operate method of the instantiated object to launch the service.
2 . The method of claim 1 , wherein the markup language document comprises parameter values and parsing the service request comprises extracting parameter values from the markup language document.
3 . The method of claim 2 , wherein the parameter values comprise class, source and identifier parameter values.
4 . The method of claim 3 , wherein the identifier parameter value indicates the document type definition.
5 . The method of claim 3 , wherein the class parameter value indicates a service class.
6 . The method of claim 5 , wherein instantiating the object corresponding to the service comprises instantiating the object based on the service class.
7 . The method of claim 6 , wherein the operate method is instantiated by each of a plurality of service classes.
8 . The method of claim 6 , wherein instantiating the object based on the service class comprises identifying a byte code for the service based on the class parameter value.
9 . The method of claim 1 , wherein the markup language document comprises tags, at least some of the tags being defined by the document type definition.
10 . The method of claim 9 , comprising generating events for each tag in the markup language document which is defined by the document type definition.
11 . The method of claim 1 , comprising keeping track of services that require responses.
12 . The method of claim 11 , comprising, at the network device:
receiving response messages associated with services;
formatting response messages for transmission to clients requesting the services; and
transmitting the response messages to the clients requesting the services.
13 . The method of claim 12 , comprising, at the network device, for services requiring multiple responses, receiving multiple responses and correlating the multiple responses for the requesting client.
14 . The method of claim 1 , wherein the service is associated with an HTTP server.
15 . The method of claim 1 , wherein the markup language comprises XML.
16 . The method of claim 15 , wherein the document type definition comprises an XML DTD.
17 . The method of claim 1 , wherein the service configures a packet forwarding architecture in the network device.
18 . The method of claim 17 , wherein the service causes changes in packet forwarding behavior at the network device.
19 . The method of claim 18 , wherein the service filters packets at the network device.
20 . The method of claim 1 , wherein the service monitors packet forwarding at the network device.