GB2251358A

GB2251358A - Data processing network

Info

Publication number: GB2251358A
Application number: GB9123691A
Authority: GB
Inventors: Mark Anthony Nagaitis
Original assignee: Fujitsu Services Ltd
Current assignee: Fujitsu Services Ltd
Priority date: 1990-12-14
Filing date: 1991-11-07
Publication date: 1992-07-01
Anticipated expiration: 2011-11-07
Also published as: GB2251358B; AU8976491A; GB9123691D0; AU642563B2; ZA918848B; GB9027186D0

Abstract

A data processing network consists of a number of data processing nodes 20, i.e. computers, with an interconnection network consisting of dedicated connections and switched connections eg dial-up lines. Each node includes a connection manager 24 which, when requested, selects and sets up connections over the network, performing the necessary dial-up operations in respect of switched connections. The provision of a connection manager removes the need for programs that require to transfer messages to other nodes to know whether the connections to those nodes are dedicated or switched. The connection manager also terminates the connection when requested. <IMAGE>

Description

DATA PROCESSING NETWORK Background to the Invention This invention relates to data processing networks. A data processing network generally comprises a number of data processors (referred to herein as processing nodes), connected together by a communication network which allows the nodes to send messages to each other. The network may consist of dedicated connections (eg leased lines) or switched connections (eg dial-up lines), or a combination of these.

In known systems of this kind, before a program in one node can send a message to a program in a remote node, it must know whether the connection to the remote node is a dedicated or switched connection, so that it can take the necessary action eg to perform a dial-up operation. The need to build this knowledge into each program presents a problem, in that it reduces the portability of programs between different computer types.

The object of the invention is to overcome this problem.

Summary of the invention According to the invention there is provided a data processing network comprising a plurality of processing nodes and an interconnection network interconnecting the nodes, wherein each node includes a connection manager which, in response to a connection request specifying a particular destination node, selects and sets up a connection over the network to that destination node, and then returns a confirmation message, and which, in response to a completion message specifying a particular node, terminates the connection to that node.

It will be seen that the provision of the connection manager removes the need for programs that require to transfer messages to other nodes to know whether the connections to those nodes are dedicated or switched.

Brief description of the drawings Figure 1 is a block diagram of a data processing network embodying the invention.

Figure 2 is a block diagram of one of the nodes within the network.

Figures 3 and 4 flow charts showing the operation of a connection manager within one of the nodes.

Description of an embodiment of the invention One data processing network in accordance with the invention will now be described by way of example with reference to the accompanying drawings.

Referring to Figure 1, the data processing network comprises a plurality of processing nodes 10 interconnected by a connection network 12. In this example, the connection network 12 comprises a mixture of dedicated connections and switched connections. The dedicated connections comprise, in this example, a local area network (LAN) using the standard X.25 protocol. The switched connections are dial-up lines.

Referring to Figure 2, this shows one of the processing nodes 10 in more detail.

The node comprises a computer 20 which, in this example, is DRS 6000, manufactured by International Computers Limited, running under the DRS/NX operating system.

The computer 20 contains a number of software modules, including: a file transfer manager 21, file transfer service programs 22, protocol programs 23, and a connection manager 24. The connection manager 24 has access to a connection management database 25. The connection management database is initially set up by the system user, by way of an operator interface 26, and holds information about other nodes in the system, and routes to those nodes, as will be described.

Each node also includes a number of link devices 27, for physically connecting the computer 20 to the network 12. The link devices comprise one or more LAN interface circuits, for connection to the LAN lines, and one or more modems, for connection to the dial-up lines.

When the file transfer manager 21 requires to transfer a file to a remote node, it first passes a "connection request" message to the connection manager 24. This message specifies the identity of the desired destination node. Figure 3 shows the operation of the connection manager in response to this message.

First, the connection manager searches the database 25 to find a route to the desired destination node. The route may be one of the LAN lines or one of the dial-up lines, Where there is more than one possible route, one of these routes is selected. For example, the cheapest route may be selected, taking into account variations in charges according to the time of day. The connection manager also checks the availability of the selected route. A route may not be available, for example, because it is out of service or because it is currently fully loaded. If the connection manager cannot find an available route, it returns a report message to the file transfer manager 21.

Assuming that an available route has been selected, the connection manager now selects one of the file transfer service programs 22 to support the connection. The connection manager also consults the database 25 to check whether the same service program is also available at the remote destination node. In other words, the connection manager ensures that the same service program is available at both ends of the connection. If a suitable service program is not available, the connection manager returns a report message to the file transfer manager 21.

The connection manager then selects one of the link devices27, and a corresponding protocol 23, to support this file transfer service. If a suitable link device is not available, the connection manager returns a report message to the file transfer manager 21.

If the selected route is a switched line, the connection manager now performs the necessary dial-up operation to establish the connection to the remote node.

Finally, the connection manager returns G "connection ready" message to the file transfer manager 21. The file transfer manager can then go ahead with performing the desired file transfer, using the selected service 22, protocol 23 and link 27.

When the file transfer is complete, the file transfer manager 21 passes a "disconnect" message to the connection manager 24. Figure 4 shows the operation of the connection manager in response to this message.

First, the connection manager waits for a predetermined time-out period.

Then, when the time-out period expires, the connection manager check whether any other connections have been set up using the same route. If not, then the connection is terminated, and a confirmation message is returned to the file transfer manager.

It should be noted that the file transfer manager 21 does not need to know whether any particular connection is by way of a dedicated line or a switched line; as far as the file transfer manager is concerned, all connections look like dedicated lines.

Claims

1. A data processing network comprising a plurality of processing nodes and an interconnection network interconnecting the nodes, wherein each node includes a connection manager which, in response to a connection request specifying a particular destination node, selects and sets up a connection over the network to that destination node, and then returns a confirmation message specifying a particular node, terminates the connection to that node.

2. A network according to claim 1, wherein in response to the connection request, the connection manager selects a route to the destination node and, if that route is a switched connection, performs a dial-up operation to establish the connection over that route.

3. A network according to claim 1 or 2 wherein each node includes a plurality of file transfer services and wherein, in response to the connection requests, the connection manager checks whether the same file transfer service is available at both ends of the connection.

4. A data processing network substantially as hereinbefore described with reference to the accompanying drawings.

5. A data processing node for use in a network in accordance with any preceding claim.

Amendments to the claims have been filed as follows 1. A data processing network comprising a plurality of processing nodes and an interconnection network interconnecting the nodes, wherein each node includes a connection manager which, in response to a connection request specifying a particular destination node, selects and sets up a connection over the network to that destination node, and then returns a confirmation message, and which, in response to a completion message specifying a particular node, terminates the connection to that node.