Local area network for digital data processing system
First Claim
1. A local area network (10) including a server (24) and a node (34) interconnected by a communications link (16),A. said node (34) transmitting node messages each including a data field (140, 162) for containing data to be transferred to said server and a response requested flag field (80) having a set condition and a clear condition;
- B. said server (24) including;
i. timing means (92) for performing a timing operation to assert a timing signal at the end of a predetermined timing interval;
ii. data storage means (106) for storing data for transmission to said node;
iii. data waiting flag means (86
108), having a set condition and a clear condition;
iv. message transmission means (60, 66,
100) for generating server messages for transmission over the communications link (16), each said server message being generated only when said timing signal (92) is asserted and the data waiting flag means (86) is in said set condition, said message transmission means (60, 66,
100) further resetting said timing means (92) and enabling said timing means 92 to begin said timing operation in response to the transmission of each said server message;
v. server message receiving means (60, 66,
100) for connection to said communications link 16 for receiving node messages; and
vi. first data waiting flag condition establishment means connected (108) to said data storage means for setting said data waiting flag means (86) into said set condition, in response to said data storage means (106) containing data to be transmittedvii. second data waiting flag condition establishment means (60, 62, 66,
80) for setting said data waiting flag means (86) into said set condition, in response to receipt by said server message receiving means of a node message in which said response requested flag field has said set condition,and said timing means (92) and said data waiting flag means (86) together regulate transmission of messages onto said communications link both from said server (24) and from said node (34).
4 Assignments
0 Petitions
Accused Products
Abstract
A local area network for interconnecting terminals and other users and data processing systems and other service providers over a communications link. The users and providers connect to the communications link by means of interface units each of which may connect to several users or providers. The interface units communicate over the communications link by means of messages. When a user requires the use of a service, the interface unit establishes a virtual circuit between it and the interface unit connected to the service provider and a service session which allows the user and the service provider to communicate over the virtual circuit. If several users connected to the one interface unit as the first user require services provided by providers which connected to the same interface unit as the first provider, they communicate in sessions over the same virtual circuits. The session messages are accumulated into single virtual circuit messages that are acknowledged in unison by the receiving interface unit. Each virtual circuit in the users'"'"' interface units includes a timer which reset when a message is transmitted over the virtual circuit and a data waiting flag set whenever data is present to be transitted over the virtual circuit. The interface units are inhibited from transmitting over a virtual circuit unless the timer has timed out and the data waiting flag is set.
92 Citations
32 Claims
-
1. A local area network (10) including a server (24) and a node (34) interconnected by a communications link (16),
A. said node (34) transmitting node messages each including a data field (140, 162) for containing data to be transferred to said server and a response requested flag field (80) having a set condition and a clear condition; -
B. said server (24) including; i. timing means (92) for performing a timing operation to assert a timing signal at the end of a predetermined timing interval; ii. data storage means (106) for storing data for transmission to said node; iii. data waiting flag means (86
108), having a set condition and a clear condition;iv. message transmission means (60, 66,
100) for generating server messages for transmission over the communications link (16), each said server message being generated only when said timing signal (92) is asserted and the data waiting flag means (86) is in said set condition, said message transmission means (60, 66,
100) further resetting said timing means (92) and enabling said timing means 92 to begin said timing operation in response to the transmission of each said server message;v. server message receiving means (60, 66,
100) for connection to said communications link 16 for receiving node messages; andvi. first data waiting flag condition establishment means connected (108) to said data storage means for setting said data waiting flag means (86) into said set condition, in response to said data storage means (106) containing data to be transmitted vii. second data waiting flag condition establishment means (60, 62, 66,
80) for setting said data waiting flag means (86) into said set condition, in response to receipt by said server message receiving means of a node message in which said response requested flag field has said set condition,and said timing means (92) and said data waiting flag means (86) together regulate transmission of messages onto said communications link both from said server (24) and from said node (34). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A local area network of the type having a server and a node interconnected by a communications link, comprising:
-
A. said node transmitting node messages each having a data field for containing data to be transferred to said server and a response requested flag having a set condition and a clear condition; B. said server having; i. timing means for performing a timing operation to assert a timing signal at the end of a predetermined timing interval; ii. data storage means for storing data for transmission to said node; iii. data waiting flag means having a set condition and a clear condition; iv. message transmission means for generating server messages for transmission over the communications link, each said server message being generated only when said timing signal is asserted and the data waiting flag means is in said set condition; v. server message receiving means for connection to said communications link for receiving node messages; and vi. data waiting flag condition establishment means connected to said data storage means for setting said data waiting flag means in response to said data storage means containing data to be transmitted vii. second data waiting flag condition establishment means for setting said data waiting flag means into said set condition, in response to receipt by said server message receiving means of a node message in which said response requested flag field has said set condition, and said timing means and said data waiting flag means together regulate transmission of messages onto said communication link both from said server and from said node. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
-
17. A local area network for interconnecting a service user an a service provider, comprising:
-
a device server unit which connects to a service user and a node which connects to a service provider and a communications link to effect transfers of messages between the node and device server unit, each message comprising a message data field for containing message data, a message identification field containing a value identifying the message and a message acknowledgement field containing a value identifying an acknowledged message, each message from said node to said device server unit further comprising a response requested indicator field having a set condition and a clear condition; A. said node comprising; i. a node message counter for generating a message identification value; ii. a node message acknowledgment counter for generating a message acknowledgment value; iii. node data store for storing data to be transmitted over said communications link; iv. a node retry timer for generating a node retry indication at the end of a predetermined node retry timing interval; v. a node message receiver for receiving messages from said communications link and modifying the message identification value generated by said node message counter and the message acknowledgment value generated by said node message acknowledgment counter in response to the contents of said message acknowledgment field of each received message, said node message receiver enabling said node retry timer in response to a message not being acknowledged; and vi. a node message transmitter for transmitting a message over said communications link comprising a message identification value from said node message counter and a message acknowledgment value from said message acknowledgment counter, and conditioning said response requested indicator field to a selected condition, in response to the last sent message requiring a response; B. said device server unit comprising a device server communications link message control portion comprising; i. a message interval timer for asserting a message interval timing indication at the end of a predetermined message timing interval; ii. a device server message counter for generating a message identification value; iii. a device server data store for accumulating data from said service user for transmission over said communication link; iv. a data waiting indicator having a set condition when data is stored in said data store and a reset condition; v. a device server message acknowledgment counter for generating a message acknowledgment value; vi. a device server retry timer for generating a device server retry indication at the nd of a predetermined device server retry timing interval longer than said message timing interval; vii. a keep alive timer for generating a keep alive timing indication at the end of a predetermined keep alive timing interval longer than said message timing interval; viii. a device server message receiver for (I) receiving messages from said communications link, (II) modifying the message identification value generated by said device server message counter and the message acknowledgement value generated by said device server message acknowledgment counter in response to the contents of said message acknowledgment field of each received message, (III) disabling said device server retry timer in response to a message being acknowledged, and (IV) setting said data waiting indicator in response to said response requested indicator field having a predetermined value; ix. a device server message generator for generating a message containing data from said data store in response to any of the following events;
(I) the coincidence of said data waiting indicator having a set condition and said message interval timer generating the message interval timing indication, (II) the generation of a device server retry indication by said device server retry timer, and (III) the generation of a keep alive timing indication by said keep alive timer; andx. a device server message transmitter for transmitting messages generated by said device server message generator over the communications link, said message transmitter controlling timing of its transmission of messages after receipt from said message generator in response to conditions over said communications link.
-
-
18. A method of operating a local area network including a server and a node interconnected by a communications link, comprising the steps of:
-
A. transmitting node messages from said node each including a data field for containing data to be transferred to said server and a response requested flap field having a set condition and a clear condition; B. in said server performing the steps of; i. conducting a timing operation with a timer to assert a timing signal at the end of a predetermined timing interval; ii. storing data for transmission to said node in a data store; iii. providing a data waiting flag having a set condition and a clear condition; iv. generating server messages for transmission over the communications link, each said server message being generated only when said timing signal is asserted and the data waiting flag is in said set condition; v. receiving node messages via said communications link; and vi. setting said data waiting flag in response to said data store containing data to be transmitted; and vii. setting said data waiting flag in response to receipt by said server via the link of a node message in which said response requested flag field has said set condition. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
-
-
26. A local area network for establishing a communications session between a user and a node, said local area network of the type having a server for communicating said user'"'"'s data to said node, comprising:
-
said node having; means for said node to send a message to said server in response to receipt of a message from said server; means, in response to said node requiring a response from said server, for sending a message to said server; and
,said server having; timing means for indicating a passage of a predetermined time interval; means, in response to said apparatus receiving data from said user OR in response to said apparatus receiving a node message from said node, for sending a server message for receipt by said node after an expiration of said predetermined time interval, said server message containing any data received from said user if there is any, and containing no data if there is no data received from said user; whereby said timing means regulates both said server sending data from said user to said node and regulates said node in sending messages for receipt by said server.
-
-
27. A local area network for establishing a communications session between a user and a node, said local area network of the type having a server for communicating said user'"'"'s data to said node, comprising:
-
said node having; means for said node to send a message to said server in response to receipt of a message from said server; means, in response to said node requiring a response from said server, for sensing a message to said server having a response requested flag field set to indicate that a response is required by said node; and
,said server having; timing means for indicating a passage of a predetermined time interval; means, in response to said apparatus receiving data from said user OR in response to said apparatus receiving a message from said node having a response requested flag field set to indicate that a response is required by said node, for sending a message for receipt by said node after an expiration of said predetermined time interval, said server message containing any data received from said user if there is any, and containing no data if there is no data received from said user, whereby said timing means regulates both said server sending data from said user to said node and regulates said node in sending messages for receipt by said server. - View Dependent Claims (28, 29, 30, 31, 32)
-
Specification