DE102019202134A1 - Method and device for transmitting and providing data in a publish-subscribe system - Google Patents

Abstract

A method for transmitting and providing data in a topic-based publish-subscribe system (1) comprising at least one server device (20) and a number of client devices (31-34) is proposed, with: a ) Receiving (S1) a message sent by a specific client device (31-34) of the number on a specific topic, b) deriving (S2) metadata from the received message, and c) providing (S3) a knowledge base (W) for the client devices (31-34) using the derived metadata. The knowledge base provided improves the transmission and provision of data in the publish-subscribe system. Furthermore, a computer program product and a device for transmitting and providing Data in a publish-subscribe system and such a publish-subscribe system are proposed.

Description

The present invention relates to a method and a computer program product for transmitting and providing data in a publish-subscribe system. The present invention also relates to a device for transmitting and providing data in a publish-subscribe system and to such a publish-subscribe system.

The technical field of the invention relates to publish-subscribe systems. With the opening of closed systems to open IoT systems (IoT; Internet of Things), there are requirements for communication in industrial networks that are familiar from the telecommunications environment and the public Internet. Due to the increasing decentralization of the systems, components are also located behind firewall systems and are therefore not directly accessible from the Internet.

For example, so-called publish-subscribe systems are used here, which on the one hand support the discovery phase, i.e. finding the communication partner, but also support the establishment of an end-to-end communication relationship. Publish-subscribe systems can also be referred to as publication and subscription systems. In the case of publish-subscribe systems, both classic point-to-point communication and group communication can be used in order to reach a large number of systems in the most efficient way possible.

Message broker systems such as MQTT (Message Queuing Telemetry Transport) are used as publish-subscribe systems in order to distribute data from a publishing client to various subscribed clients using a topic. A typical scenario for this is that sensor data, such as temperature, fill level and the like, are transmitted from various sensors that act as publishing clients in a cloud-based system that includes a plurality of subscribed clients.

Furthermore, a message broker can also be set up in such a way that actor-based action, e.g. B. controlling a pump or adjusting the brightness of a lamp can be implemented. The actor assumes the role of a subscribed client with a specific topic and waits for a message from a publishing client on this topic, for B. to change its state, d. H. to switch a pump from ON to OFF.

However, with the standard means of message brokers such as MQTT, a system image can only be recognized with difficulty from the outside. For example a Discovery, i. H. It is not possible to determine which topics originate from an actuator or a sensor. This makes it more difficult, for example, to add (on-board) new IoT devices to an existing system and requires implicit knowledge in order to participate in the existing system and implement an IoT application.

The importance of a topic, e.g. B. which topic offers which sensor data or controls which actuators is difficult to derive both for a person and for a computer system and thus in fact cannot be used if further external knowledge is not available.

Against this background, an object of the present invention is to improve the transmission and provision of data in a publish-subscribe system.

1. a) Empfangen einer von einer bestimmten Client-Vorrichtung der Anzahl gesendeten Nachricht zu einem bestimmten Topic,
2. b) Ableiten von Metadaten aus der empfangenen Nachricht, und
3. c) Bereitstellen einer Wissensbasis für die Client-Vorrichtungen unter Verwendung der abgeleiteten Metadaten.

According to a first aspect, a method for transmitting and providing data in a topic-based publish-subscribe system comprising at least one server device and a number of client devices is proposed. The procedure consists of the following steps:

1. a) receiving a message sent by a specific client device of the number on a specific topic,
2. b) deriving metadata from the received message, and
3. c) providing a knowledge base for the client devices using the derived metadata.

According to a step d), data can be provided in the topic-based publish-subscribe system using the knowledge base provided, for example by the server device for a specific one of the client devices, and can be transmitted. The client device can also be referred to as a client or a communication device. The client device is designed, for example, as a PC, laptop, tablet, smartphone or microcontroller, for example systems-on-chip (SoC).

In the present case, the publish-subscribe system is in particular a system which comprises at least one publisher as a client device that publishes data, and a subscriber as a client device that can subscribe to and receive data. Subscribing can also be understood as subscribing, for example. The publish-subscribe system can also be referred to as a publication and subscription system. Publishing and subscribing to data is topic-based. The topic of the publish Subscribe system is, for example, a topic or a service of the publish-subscribe system. The topic can also be structured hierarchically, for example by means of a topic tree, for example topic 1 , Topic 2 , Topic 3 .

The knowledge base is represented in particular by means of a semantic model, preferably by means of a W3C Web-of-Things Thing Description (TD). The semantic model is preferably machine-interpretable and also understandable for humans. The semantic model of the knowledge base can thus be interpreted by a machine, such as a computer, as well as read by a person.

The method is in particular a computer-implemented method. The semantic knowledge base is automatically generated from the data or messages transmitted via the publish-subscribe system using the derived metadata and made available to the publish-subscribe system, in particular the connected client devices. The semantic knowledge base is generated in a topic-specific manner. In particular, the semantic knowledge base includes metadata assigned to each topic of the publish-subscribe system.

The knowledge base provided, for example, makes it much easier to add new devices, for example client devices, since they transfer knowledge about the publish-subscribe system, in particular about the topics, the client devices and the information about the publish-subscribe system Provides data, in particular their data formats.

As stated above, the knowledge base is represented in particular by means of a Thing Description (TD). The TD offers the possibility of a thing, e.g. B. a topic to characterize and describe with their data and functions in properties, actions and events. Actor-based topics of an active client device can, for example, be declared as an action and sensor-based data as an event within the TD. Further information can also be stored, e.g. B. which data types are used or which coding format is used, for example JSON, XML or the like. The TD itself is preferably implemented in JSON-LD and is therefore easy to understand for people and also suitable for machines to interpret.

With the proposed method, clients, such as PCs, have the option of searching through the knowledge base provided in order to identify topics with metadata, e.g. B. which data is sensor-based or what can be used to control a certain actuator. Furthermore, a manually managed knowledge base can advantageously be avoided.

• Ableiten der Metadaten aus einer aktuellen empfangenen Nachricht, zumindest einer älteren empfangenen Nachricht und/oder aus einer Relation zwischen der aktuellen empfangenen Nachricht und der zumindest einen älteren empfangenen Nachricht.

According to one embodiment, step b) comprises:

• Deriving the metadata from a current received message, at least one older received message and / or from a relation between the current received message and the at least one older received message.

The metadata can advantageously be generated not only from a current message, but also from older messages and from relations between messages. This advantageously increases the information content of the knowledge base.

According to a further embodiment, the metadata comprise client-specific metadata, message-specific metadata and / or topic-specific metadata.

According to a further embodiment, the client-specific metadata includes classification information for classifying the particular client device as a particular one of a plurality of client types, a role specification for specifying a role of the particular client device within the publish-subscribe System, identification information for identifying the specific client device, an address of the specific client device and / or a functionality description for specifying the functionality of the specific client device.

According to a further embodiment, the client types include a number of active client types, which offer at least one service in the publish-subscribe system, and a number of passive client types, which exclusively rely on at least one in the publish-subscribe system. System offered service are subscribed.

According to a further embodiment, the active client types include at least one sensor type, which offers the provision of sensor data as a service in the publish-subscribe system, and at least one actuator type, which is set up to provide an actuator system depending on a to control the topic-based message transmitted to the publish-subscribe system.

According to a further embodiment, the message-specific metadata comprise a data type specification for specifying a data type supported by the specific client device and / or a data format indicator to indicate a data format supported by the particular client device.

According to a further embodiment, the topic-specific metadata includes a name of the specific topic, a classification specification for classifying the specific topic, in particular as a sensor-specific topic or as an actuator-specific topic, and / or a description of the specific topic.

According to a further embodiment, the knowledge base is represented by means of a semantic model.

As already stated above, the knowledge base is represented, for example, by means of the semantic description W3C Web of Things Thing Description (TD) or by W3C Semantic Sensor Network (SSN).

According to a further embodiment, the semantic model is both machine-interpretable and understandable for a person.

The knowledge provided by the knowledge base can thus be interpreted both directly by a machine, such as a client device, and by a person, such as an operator.

1. 1. Es wird vorausgesetzt, dass es eine Möglichkeit gibt, am Message-Broker neue aktive Clients mit ihren Topics zu detektieren. Dabei wird insbesondere detektiert, welche Topics gepublished sind und auf welche Topics eine Subskription besteht, insbesondere auch welche. Dies kann auch durch einen zu dem Message-Broker externen Service bereitgestellt werden, welcher dazu geeignet ist, das Verhalten des Message-Brokers zu detektieren.
2. 2. Des Weiteren wird vorzugsweise vorausgesetzt, dass jedes Topic der aktiven Clients individuell ist.

The following example can illustrate the structure of the knowledge base. The following two preconditions apply in particular:

1. 1. It is assumed that there is a possibility of detecting new active clients with their topics on the message broker. In particular, it is detected which topics are published and which topics are subscribed to, and in particular which ones. This can also be provided by a service external to the message broker, which service is suitable for detecting the behavior of the message broker.
2. 2. Furthermore, it is preferably assumed that each topic of the active clients is individual.

Now to build the knowledge base:

1. 1. Die aktiven Clients registrieren ihre Topics beim Message-Broker. Dabei wird ein Sensor (Client vom Sensor-Typ) detektiert, wenn eine Publikation auf ein Topic durchgeführt wird. Demgegenüber wird ein Aktor (Client vom Aktor-Typ) detektiert, wenn eine Subskription auf einem nicht existierenden Topic durchgeführt wird.
2. 2. Optional wird detektiert, welche Datentypen und welche Datenformate bei dem jeweiligen Topic verwendet werden. Hierbei können Algorithmen der Mustererkennung und/oder Lernalgorithmen eingesetzt werden.
3. 3. Die gewonnenen Informationen werden in eine TD überführt. Dabei werden vorzugsweise die folgenden Teilschritte i) bis iv) durchgeführt:
   1. i) Topics, die als Sensor deklariert wurden, werden in ein Event überführt. Dabei kann optional der letzte Topic-Pfad-Eintrag als Name des Events verwendet werden. Bei Namenskollisionen kann optional auch das vollständige Topic als Name vergeben werden.
   2. ii) Topics, welche als Aktor deklariert wurden, werden als Aktion deklariert. Der Name kann dann wie unter i) zugewiesen werden.
   3. iii) Weitere Metadaten des Publish-Subscribe-Systems, z. B. die Broker-Adresse oder der Broker-Name des Message-Brokers, können mit in die TD aufgenommen werden.
   4. iv) Die Events und Actions werden vorzugsweise mit weiteren Metadaten angereichert, wie z. B. Media-Typ und konkrete Datentypen.

With the defined roles and preconditions, the following steps can be used to build a knowledge base. B. be mapped in a TD:

1. 1. The active clients register their topics with the message broker. A sensor (sensor-type client) is detected when a publication is carried out on a topic. In contrast, an actor (client of the actor type) is detected when a subscription is carried out on a topic that does not exist.
2. 2. Optionally, it is detected which data types and which data formats are used for the respective topic. Pattern recognition algorithms and / or learning algorithms can be used here.
3. 3. The information obtained is transferred to a TD. The following sub-steps i) to iv) are preferably carried out:
   1. i) Topics that have been declared as sensors are transferred to an event. The last topic path entry can optionally be used as the name of the event. In the event of name collisions, the complete topic can optionally be assigned as a name.
   2. ii) Topics that have been declared as actors are declared as actions. The name can then be assigned as under i).
   3. iii) Further metadata of the publish-subscribe system, e.g. B. the broker address or the broker name of the message broker can be included in the TD.
   4. iv) The events and actions are preferably enriched with further metadata, such as B. Media type and concrete data types.

According to a second aspect, a computer program product is proposed which causes the method as explained above to be carried out on a program-controlled device.

A computer program product such as a computer program means, for example, as a storage medium, e.g. Memory card, USB stick, CD-ROM, DVD, Blue-Ray or in the form of a downloadable file can be provided or delivered from a server in a network. This can be done, for example, in a wireless communication network by transmitting a corresponding file with the computer program product or the computer program means.

• eine Empfangs-Einheit zum Empfangen einer von einer bestimmten Client-Vorrichtung der Anzahl gesendeten Nachricht zu einem bestimmten Topic,
• eine Ableitungs-Einheit zum Ableiten von Metadaten aus der empfangenen Nachricht, und
• eine Bereitstellungs-Einheit zum Bereitstellen einer Wissensbasis für die Client-Vorrichtungen unter Verwendung der abgeleiteten Metadaten.

According to a third aspect, a device for transmitting and providing data in a topic-based publish-subscribe system, which comprises at least one server device and a number of client devices, is proposed. The device comprises:

• a receiving unit for receiving a message sent by a certain client device of the number on a certain topic,
• a derivation unit for deriving metadata from the received message, and
• a providing unit for providing a knowledge base for the client devices using the derived metadata.

The device is preferably a computer implemented device. In particular, it is part of a server device.

The respective unit, for example the derivation unit, can be implemented in terms of hardware and / or also in terms of software. In the case of a hardware implementation, the respective unit can be designed as a device or as part of a device, for example as a computer or as a microprocessor or as a control computer of a vehicle. In a software implementation, the respective unit can be designed as a computer program product, as a function, as a routine, as part of a program code or as an executable object.

The embodiments and features described for the proposed method apply accordingly to the proposed device.

According to a fourth aspect, a topic-based publish-subscribe system with at least one server device, a number of client devices and a device according to the third aspect is proposed.

According to one development, the server device is designed as a message broker, the device being integrated in the message broker.

According to another development, the server device is designed as a message broker and the device is external to the message broker.

Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with regard to the exemplary embodiments. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

• 1 zeigt ein schematisches Ablaufdiagramm eines Ausführungsbeispiels eines Verfahrens zum Übertragen und zum Bereitstellen von Daten in einem Topic-basierten Publish-Subscribe-System;
• 2 zeigt ein schematisches Blockdiagramm eines Ausführungsbeispiels einer Vorrichtung zum Übertragen und zum Bereitstellen von Daten in einem Topic-basierten Publish-Subscribe-System;
• 3 zeigt ein schematisches Blockdiagramm eines ersten Ausführungsbeispiels eines Publish-Subscribe-Systems; und
• 4 zeigt ein schematisches Blockdiagramm eines zweiten Ausführungsbeispiels eines Publish-Subscribe-Systems.

Further advantageous refinements and aspects of the invention are the subject matter of the subclaims and of the exemplary embodiments of the invention described below. In the following, the invention is explained in more detail on the basis of preferred embodiments with reference to the attached figures.

• 1 shows a schematic flow chart of an embodiment of a method for transmitting and providing data in a topic-based publish-subscribe system;
• 2 shows a schematic block diagram of an embodiment of a device for transmitting and providing data in a topic-based publish-subscribe system;
• 3 shows a schematic block diagram of a first embodiment of a publish-subscribe system; and
• 4th FIG. 3 shows a schematic block diagram of a second exemplary embodiment of a publish-subscribe system.

In the figures, elements that are the same or have the same function have been provided with the same reference symbols, unless otherwise stated.

1 FIG. 10 shows a schematic flow diagram of an exemplary embodiment of a method for transmitting and providing data in a topic-based publish-subscribe system 1 . The 2 an embodiment of a device 10 for transmitting and making data available in a topic-based publish-subscribe system 1 . The device 10 of the 2 is suitable for the process of 1 execute. Furthermore, the 3 a schematic block diagram of a first embodiment of a topic-based publish-subscribe system 1 .

• Das Publish-Subscribe-Systems 1 der 3 hat eine Vorrichtung 10 (siehe auch 2), eine Server-Vorrichtung 20 sowie eine Anzahl N von Client-Vorrichtungen 31 - 34. Ohne Einschränkung der Allgemeinheit ist N = 4 in 3 (N = 4).

In the following, the 1 to 3 Referred to:

• The publish-subscribe system 1 of the 3 has a device 10 (see also 2 ), a server device 20th and a number N of client devices 31-34. Without loss of generality, N = 4 in 3 (N = 4).

• In Schritt S1 wird eine von einer bestimmten Client-Vorrichtung 31 - 34 der Anzahl gesendete Nachricht zu einem bestimmten Topic empfangen, insbesondere durch die Empfangs-Einheit 11 der Vorrichtung 10 (siehe 2).

Continue with reference to 1 . The procedure of 1 includes the following procedural steps S1 - S4 :

• In step S1 a message sent by a specific client device 31-34 of the number on a specific topic is received, in particular by the receiving unit 11 the device 10 (please refer 2 ).

In step S2 is metadata from the received message by the device 10 derived. In particular, the metadata are obtained from a current received message, at least one older received message and / or from a relation between the current received message and the at least one older received message Message derives. The metadata include in particular client-specific metadata, message-specific metadata and topic-specific metadata.

The client-specific metadata include, in particular, classification information for classifying the specific client device 31-34 as a specific one of a plurality of client types.

The respective client type can be an active client type or a passive client type. In particular, a plurality of different active client types is provided. The same applies to a large number of passive client types. An active client type is one that has at least one service in the publish-subscribe system 1 offers. In contrast, a passive client type is one that does not have any active service in the publish-subscribe system 1 offers, but exclusively on at least one in the publish-subscribe system 1 the service offered is subscribed.

The active client types include, for example, sensor types that enable the provision of sensor data as a service in the publish-subscribe system 1 to offer. In addition, the active client types also include, in particular, actuator types which are set up to provide an actuator system as a function of the publish-subscribe system 1 to control the transmitted topic-based message.

The client-specific metadata further include, for example, a role specification for specifying a role of the respective client device 31-34 within the publish-subscribe system 1 .

The client-specific metadata can also include identification information for identifying the specific client device 31-34. This identification information can also be referred to as “ID” for short. Furthermore, the client-specific metadata can include an address of the particular client device 31-34. The address can be, for example, an Internet address or a specific intranet address. In addition, the client-specific metadata can be a functionality description for specifying the functionality of the particular client device 31-34 in the publish-subscribe system 1 include. The functionality description can, for example, indicate that a specific client device 31-34 is a temperature sensor which detects a temperature at a specific point of a gas turbine.

Furthermore, the in step S2 Derived metadata also include topic-specific metadata. The topic-specific metadata include, in particular, a name of the particular topic, e.g. B. a temperature of the gas turbine. A classification .... Furthermore, the topic-specific metadata can also include classification information for classifying the specific topic. The classification information states, for example, whether it is a sensor-specific topic or an actuator-specific topic. A description of the specific topic can also be part of the topic-specific metadata.

In step S3 of the 1 becomes a knowledge base W. through the device 10 (please refer 3 ) is provided to the client device 31-34 using the derived metadata. The knowledge base W. can for example be represented by means of a semantic model. For example, the knowledge base W. as a thing description (TD). An alternative representation for the knowledge base W. is the description language W3C SSN.

In step S4 can data in the topic-based publish-subscribe system 1 using the knowledge base provided W. provided, for example by the server device 20th for a particular one of the client devices 31-34, and are transmitted.

The server device 20th is designed, for example, as a message broker. In the example of the 3 is the device 10 in the server device 20th integrated.

The exemplary embodiment is detailed below 10 the device 10 to 2 explained. The device 10 of the 2 comprises a receiving unit 11 , a dissipation unit 12 , a deployment unit 13th as well as a storage unit 14th .

The receiving unit 11 is set up to receive a message sent by a specific client device 31-34 of the number on a specific topic.

The derivative unit 12 is set up to derive metadata from the received message.

The provision unit is set up to provide a knowledge base W. (please refer 3 ) to the client devices 31-34 using the derived metadata.

In the 4th Figure 3 is a schematic block diagram of a second embodiment of a publish-subscribe system 1 shown. The second embodiment of the publish-subscribe system 1 of the 4th differs from the first embodiment of FIG 3 to the effect that in the 4th the device 10 external to the server device 20th is arranged. Here is the device 10 for example via a network connection with the server device 20th coupled. Alternatively or additionally, the device 10 also be coupled to one of the client devices 31-34.

Although the present invention has been described on the basis of exemplary embodiments, it can be modified in many ways.

List of reference symbols

1

Publish-subscribe system

10

contraption

11

Receiving unit

12

Dissipation unit

13

Provisioning unit

14th

Storage unit

20th

Server device

31 - 34

Client device

S1 - S4

Procedural steps

W.

Knowledge base

Claims (15)

A method for transmitting and providing data in a topic-based publish-subscribe system (1) comprising at least one server device (20) and a number of client devices (31-34), with: a) receiving (S1) one of the number of messages sent by a specific client device (31 - 34) on a specific topic, b) deriving (S2) metadata from the received message, and c) providing (S3) a knowledge base (W) for the client devices (31-34) using the derived metadata. Procedure according to Claim 1 , characterized in that step b) comprises: deriving the metadata from a current received message, at least one older received message and / or from a relation between the current received message and the at least one older received message. Procedure according to Claim 1 or 2 , characterized in that the metadata comprises client-specific metadata, message-specific metadata and / or topic-specific metadata. Procedure according to Claim 3 , characterized in that the client-specific metadata includes classification information for classifying the specific client device (31 - 34) as a specific one of a plurality of client types, a role specification for specifying a role of the specific client device ( 31 - 34) within the publish-subscribe system (1), identification information for identifying the specific client device (31 - 34), an address of the specific client device (31 - 34) and / or a functionality Description to indicate the functionality of the particular client device (31-34). Procedure according to Claim 4 , characterized in that the client types a number of active client types, which offer at least one service in the publish-subscribe system (1), and a number of passive client types, which exclusively on at least one in the publish -Subscribe system (1) service offered include subscribed. Procedure according to Claim 5 , characterized in that the active client types a sensor type, which offers the provision of sensor data as a service in the publish-subscribe system (1), and an actuator type, which is set up, an actuator depending on a to control the topic-based message transmitted via the publish-subscribe system (1). Method according to one of the Claims 3 to 6th , characterized in that the message-specific metadata includes a data type specification for specifying a data type supported by the specific client device (31-34) and / or a data format indicator for specifying one of the specific client device (31-34 ) supported data format. Method according to one of the Claims 3 to 7th , characterized in that the topic-specific metadata include a name of the specific topic, a classification specification for classifying the specific topic, in particular as a sensor-specific topic or as an actuator-specific topic, and / or a description of the specific topic. Method according to one of the Claims 1 to 8th , characterized in that the knowledge base (W) is represented by means of a semantic model. Procedure according to Claim 9 , characterized in that the semantic model is machine-interpretable as well as understandable for a human. Computer program product which, on a program-controlled device, enables the method according to one of the Claims 1 to 10 caused. Device (10) for transmitting and providing data in a topic-based publish-subscribe system (1), which comprises at least one server device (20) and a number of client devices (31-34), with: a receiving unit (11) for receiving a message sent by a specific client device (31 - 34) of the number on a specific topic, a derivation unit (12) for deriving metadata from the received message, and a provision unit (13) for providing a knowledge base (WB) for the client devices (31-34) using the derived metadata. Topic-based publish-subscribe system (1) with at least one server device (20), a number of client devices (31-34) and one device (10) Claim 12 . Publish-subscribe system Claim 13 , characterized in that the server device (20) is designed as a message broker, the device (10) being integrated in the message broker. Publish-subscribe system Claim 13 , characterized in that the server device (20) is designed as a message broker, the device (10) being arranged external to the message broker.

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