Selectively forced redirection of network traffic

Details Selectively forced redirection of network traffic Selectively forced redirection of network traffic

1999-01-05

2004-04-06

Follansbee, John (Department: 2126)

Electrical computers and digital processing systems: multicomput

Computer-to-computer session/connection establishing

Network resources access controlling

C709S203000, C709S246000, C713S152000

Reexamination Certificate

active

06718390

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to data processing. The invention relates more specifically to selectively forcing network communications, such as HTML results generated by a Web server, to go a particular location.
BACKGROUND OF THE INVENTION
In a client/server computing environment a need may arise to enable a client to communicate with two servers, each of which provide functions that represent a portion of a service desired by the client. In some cases, it is desirable to permit the client to communicate with only a first one of the two servers and to prevent direct contact between the client and the other of the two servers.
FIG. 1
is a block diagram of a networked computer system in which the foregoing general problem may arise. Client
102
is a computer device such as a workstation, server, router, or switch. Client
102
is coupled to network
104
, which is an interconnected combination of computers, terminals, or peripherals used to provide communications a between two or more points. A first server
106
and a second server
108
are coupled to network
104
, logically separated from client
102
. In one embodiment, client
102
, network
104
, and servers
106
,
108
communicate using TCP/IP network protocols, and using HTTP protocol messages that comprise requests and responses. Such protocols are exemplary and not required.
Client
102
may communicate an HTTP request for a service to network
104
. The request includes a name or other identifier of server
106
, which client
102
expects to provide the requested service. Network
104
locates server
106
and routes the request to server
106
, thereby establishing a logical connection
110
from client
102
to the server. Server
106
determines that it cannot provide the function or service solicited in the request, but that server
108
can provide the function or service. Accordingly, software elements in server
106
automatically divert or “redirect” the request to server
108
over a logical connection
112
, which may physically travel through the network
104
. Server
108
processes the request, generates a response message, and sends the response message back to client
102
over logical connection
114
, which may pass through network
104
.
In this scenario, when the client and the servers use HTTP, the response message may include a document formatted using a structured markup language, such as HTML. The HTML document may contain hyperlinks or other references to resources within server
108
, or other servers or network elements. As a result, client
102
may select one of the hyperlinks or references, and thereby attempt to request a service of server
108
directly along connection
114
. Server
106
would not be involved in processing such a request.
This result is undesirable in several circumstances. The server
106
may have been designated as authoritative for certain kinds of transactions. The server
106
may have redirected the original request to server
108
solely because server
106
cannot directly process the request, whereas server
108
can, but server
106
may need to remain in control of the overall transaction. For example, server
106
may have redirected the original request to server
108
just to carry out a specialized or subordinate task, although server
106
remains responsible for the total transaction or for presenting a consistent interface to the client
102
.
Accordingly, there is a need in this field for a mechanism that allows a client request to be redirected from a first server to a second server, while keeping the first server in control of subsequent requests by the client for services of the second server.
In particular, there is a need for a mechanism that prevents the client from directly communicating with the second server even after the first server has redirected a request of the client to the second server.
There is a specific need in Internet protocol networks, such as Intranets or the Internet in which clients and servers use TCP/IP and HTTP, to force subsequent requests resulting from HTML generated by the second server to come back to the first server for further redirection.
SUMMARY OF THE INVENTION
The foregoing needs and objects, and other needs and objects that will become apparent from the following description, are achieved by the present invention, which comprises, in one aspect, a method of redirecting a request from a client that may be served by a first server to a second server. Generally, the method involves the computer-implemented steps of receiving a client request at the second server; automatically forwarding the client request to the first server; receiving a result message from the first server; identifying, in the result message, references to resources of the first server; replacing the references to resources of the first server with translated references that reference the second server; and sending the translated references to the client as a response to the client request.
One feature of this embodiment further involves receiving, at the second server, a second client request based on the response; and for the second client request, repeating the steps of automatically forwarding, receiving a result message, identifying, replacing, and sending. According to another feature, the identifying step involves parsing the result message to identify one or more tags that are associated with references to resources of the first server; and matching the tags to attributes that identify resources of the first server.
According to another feature, the replacing step involves attaching, to each of the references to resources of the first server, a value that identifies a process of the second server that carries out the identifying step and the replacing step. A related feature is that the replacing step comprises attaching, to each of the references to resources of the first server, a value that identifies a process of the second server that carries out the identifying step and the replacing step.
In yet another feature, the step of receiving a client request at the second server involves receiving a client HTTP request at a second Web server; the step of automatically forwarding the client request to the first server is redirecting the client HTTP request to a first Web server; and the step of receiving a result message from the first server involves receiving an HTTP response message from the first Web server that contains an HTML document. A related feature is that the step of identifying, in the result message, references to resources of the first server comprises parsing the HTML document to identify one or more URLs. Another related feature is that the step of identifying, in the result message, references to resources of the first server comprises parsing the HTML document to identify one or more relative URLs that lack an explicit reference to the first server or one or more URLs that explicitly reference the first server. Yet another related feature is that the steps of identifying and replacing are carried out using a CGI script that may contain one or more associated software elements, and the step of replacing involves attaching, to each of the references to resources of the first server, a value that identifies the CGI script.
According to another feature, the steps of identifying, replacing and sending involve stream tokenizing the result message into a plurality of tags, each of the tags having zero or more attributes; storing in an output message any tags that are not associated with references to resources of the first server; for each tag that is associated with a reference to a resource of the first server: identifying a resource attribute associated with the tag that identifies the resource; prepending a value, which identifies a software element that carries out the steps of identifying and replacing, to the resource attribute; and storing the tag, value, and resource attribute in the output message.
In one embodiment, a function resides at a first Web server. The function r

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