REAL-TIME PUBLISH-SUBSCRIBE SYSTEM
First Claim
1. A real-time protocol executable on a computer network having a plurality of nodes, wherein the nodes can include applications, a network stack, an operating system, and middleware capable of executing real-time operations, where the real-time protocol uses group objects to model physical and logical devices connected to the network wherein each group object comprises at least one variable and wherein the real-time protocol uses communication objects to communicate information about the variables in the form of variable change messages.
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Abstract
A real-time protocol for real-time network programming applications is disclosed. The protocol is executable on a computer network having a plurality of nodes that include applications, a network stack, an operating system, and middleware capable of executing real-time operations. The protocol can use group objects to model physical and logical devices connected to the network wherein each group object comprises at least one variable. Changes in these variables are encapsulated in variable change messages which are propagated in the network using communication objects. Also described is a real-time messaging format useful for implementing the protocol.
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Citations
35 Claims
- 1. A real-time protocol executable on a computer network having a plurality of nodes, wherein the nodes can include applications, a network stack, an operating system, and middleware capable of executing real-time operations, where the real-time protocol uses group objects to model physical and logical devices connected to the network wherein each group object comprises at least one variable and wherein the real-time protocol uses communication objects to communicate information about the variables in the form of variable change messages.
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17. A real-time protocol executable on a computer network having a plurality of nodes, wherein the nodes include real-time middleware capable of executing real-time operations, the middleware of each node further including:
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a write object; a read object; the write object is capable of writing variable change messages having a topic to associated read objects that are registered to receive variable change messages having the topic; a message interpreter that receives and interprets the variable change messages so that they can be read by a read object; a variable reference table which a write object uses to track variable information; and a remote reader reference table for each reader that has registered to receive information from the writer so that the writer can determine a message status for each reader registered to receive information from the writer. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A real-time publish-subscribe (RTPS) message format for use on a real-time computer network where the RTPS messages are sent between communication objects, each RTPS message comprising:
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a modular message format having a RTPS message header of a uniform length; a variable number of RTPS submessages where each RTPS submessage includes a RTPS submessage header of uniform length; and a RTPS submessage payload comprised of a variable number of RTPS submessage elements. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for writing a variable change message from a writer to a registered reader using a real-time protocol on a real-time computer network having a plurality of nodes, wherein the nodes include at least one writer, at least one registered reader, and middleware capable of executing real-time operations, the method comprising:
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A. determining if there is a new reader; B. where there is no new reader; 1) determining if there has been a change to a variable; (a) if there are changes to the variable, (i) the changes are saved as a variable change message; (ii) a change sequence number is modified to reflect the addition of a new saved variable change message; (iii) return to Step A, determining if there is a new reader; (b) if there are no changes to the variable then return to Step A, determining if there is a new reader; and C. where there is a new reader, a remote reader process is activated to update a registered reader. - View Dependent Claims (33)
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34. A method for a registered reader to read variable change message sent by a writer to the registered reader using a real-time protocol on a real-time computer network having a plurality of nodes, wherein the nodes include at least one writer, a registered reader, and middleware capable of executing real-time operations, the method comprising:
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A. determining if there is a writer for which the reader is registered to receive variable change messages; B. where there is no writer, returning to Step A, determining if there is a writer; and C. where there is a writer, a remote writer process is activated to update the registered reader. - View Dependent Claims (35)
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Specification