DE102020123509A1 - Method for providing and validating alternative object identifiers and for determining references of alternative object identifiers within an OPC UA-based communication environment - Google Patents

Abstract

A method is proposed for providing alternative object identifiers for objects in an address space of a server (S1, S2) within an OPC UA-based communication environment (K), with each object in the address space of the server (S1, S2) being uniquely identified by a conventional object identifier , at least one additional identifier being defined and stored in a directory of the additional identifier defined for this address space of the server (S1, S2), and an alternative object identifier likewise uniquely identifying the object being formed for each object in the address space of the server (S1, S2) by combining the additional identifier with the conventional object identifier of the respective object according to a specific scheme. A method for validating alternative object identifiers and a method for determining references of alternative object identifiers as well as a server, a system and a computer program product designed to carry out at least one of the methods are also proposed.

Description

The present invention relates to a method for providing alternative object identifiers for objects of an address space of a server within an OPC UA-based communication environment, a method for validating such alternative object identifiers and a method for determining references of such alternative object identifiers. The invention relates to a server, a system and a computer program product which are designed to carry out at least one of these methods.

IEC 62541 is a multi-part standard for the OPC Unified Architecture (OPC UA) which, for example, defines protocols for so-called machine-to-machine (M2M) communication, i.e. for the automated exchange of information between end devices such as machines or machines.

OPC UA is subject to a client-server model, i. H. Servers provide information that clients request from the servers. The functionality of a server is made available to the clients using so-called services. A service enables access to certain server aspects by means of request and response messages (request / response) which are defined for the respective service and which are exchanged between the client and the server. The information is provided by a server to the clients in an address space of the server.

Part 3 of the IEC 62541 standard (“Address Space Model”) defines an object-oriented concept of an address space, in particular in accordance with the version valid on the filing date, whereby objects are carried out in accordance with Part 4 of the standard (“Services”), in particular in accordance with the version valid on the filing date Nodes are represented. On the one hand, nodes have attributes and, on the other hand, references that point to other nodes and represent the edges of a directed graph, so that there can be forward and backward references.

Clients in a UPC UA-based communication environment can browse such an address space provided by a server in order to determine the unique identifier of another node (hereinafter also called NodeID) based on a known root node. Using the specified services such as "DataAccess", OPC UA clients receive read or write access to attribute values of a node in an address space, for example.

NodeIDs are usually made up of the three elements "namespacierendex", "identifierType" and "identifier". The "identifierType" element defines the type of the unique identifier, which can be NUMERIC, STRING, GUID or BYTESTRING. For the uniqueness of each NodeID, each node of the address space must be defined as an element "identifier" according to the defined identifier type. In order to avoid address or identifier collisions and to further subdivide the address space, an address space can comprise several name spaces. The respective namespace of the node must be specified for each node of the address space as the “namespacierendex” element of the NodeID. A directory of all namespaces or namespace indexes of an address space is stored as an attribute for a known node such as the root node.

One possible application of an OPC UA server is, for example, in the field of automation technology, to provide OPC UA clients with access to variables of a programmable logic control (PLC). For example, with controllers based on the applicant's PLCnext Technology, the variables of the components are listed as nodes of an address space of an OPC UA server, whereby the identifier type STRING is specified for the unique node identifier (cf. 8th ). The directory of all namespaces or namespace indexes of the address space is stored as the “NamespaceArray” attribute of the “Server” node (cf. 9 ).

So far, however, it has been problematic when several information models such as different semantic representations are to be implemented especially dynamically for the same database of an OPC UA address space, or changes are to be made in the address space over time that have an impact on existing NodeIDs.

The namespaces already mentioned allow structuring of an address space. However, they are of a static nature and would require a replication of nodes or node instances in a different namespace in order to implement several information models for the same database of an OPC UA address space.

The concept of the OPC UA views allows the organization and tailoring of address spaces to specific tasks and use cases. However, they serve more as entry points or filters for an address space.

One object of the present invention is therefore to provide a possibility for eliminating at least one of the disadvantages mentioned.

As a solution, the invention proposes a method with the features of independent patent claim 1, a method with the features of independent patent claim 6 and a method with the features of independent patent claim 9. Furthermore, the invention proposes a server according to independent claim 14, a system according to independent claim 15 and a computer program product according to independent claim 16.

Further advantageous configurations of the control arrangement according to the invention are specified in the dependent claims.

The invention is based on the idea of enabling several different representations of the same database of an OPC UA address space by means of a new addressing scheme, which can be implemented in addition to the conventional addressing scheme. This allows different information models and, in particular, access to objects or nodes in different contexts. The new addressing scheme is based on alternative object identifiers which essentially combine the existing conventional object identifiers with an additional identifier, the alternative identifier being understood as a representative, alias or synonym of the conventional identifier of an object or node. An essential advantage of the invention, which will be explained in more detail later, is that an OPC UA server essentially does not require any additional computing or memory resources to implement this new addressing scheme.

A method is therefore proposed for providing alternative object identifiers for objects in an address space of a server within an OPC UA-based communication environment ( K ), each object in the address space of the server being uniquely identified by a conventional object identifier. At least one additional identifier is defined and expediently stored in a directory of the additional identifier defined for this address space of the server. In addition, an alternative object identifier that uniquely identifies the object is formed for each object in the address space of the server by combining the additional identifier with the conventional object identifier of the respective object according to a specific scheme.

Both in this and in the other methods according to the invention, the objects can be represented by nodes, so that the object identifiers are node identifiers (NodeIDs). Furthermore, an address space can be subdivided into name spaces, with the respective method being able to be used or executed for the objects or nodes of a name space or several, in particular all, name spaces of an address space.

The advantage here is that a user can clearly recognize the alternative object identifier as such and can easily differentiate it from the conventional object identifier.

The alternative object identifiers offer great flexibility with regard to any changes that may be required in the address space over time, such as the assignment of new identifiers for existing objects or nodes, because thanks to the new addressing scheme, such changes do not affect the conventional objects, but only the alternative objects - or node identifier.

Another advantage here is that the alternative object identifiers from the OPC UA protocol point of view can be treated in the same way as the conventional object identifiers.

According to a first embodiment of the method, the scheme specifies that if the conventional object identifier is of the identifier type STRING, the additional identifier is also of the identifier type STRING and comprises two additional identifier parts, the first additional identifier part being a freely definable character string and the second additional identifier part being a freely definable separator character is.

In an expedient development, the scheme specifies that the alternative object identifier is also of the identifier type STRING and is formed from the three parts of the first additional identifier part, second additional identifier part and conventional object identifier of the respective object in this or the reverse combination order.

The new addressing scheme can thus be implemented very easily for address spaces with conventional object identifiers of the identifier type STRING.

According to another embodiment of the method, the scheme specifies that if the conventional object identifier is of the identifier type NUMERIC, the additional identifier is also of the identifier type NUMERIC and a multiple of a base value, the base value being greater than the largest numerical value increased by 1 among all conventional ones Object identifiers of the objects in the address space of the server.

In an expedient development, the scheme specifies that the alternative The object identifier is also of the identifier type NUMERIC and is formed by adding the additional identifier and the conventional object identifier of the respective object. In this case, the alternative object identifier corresponds to the sum of the numerical values of the additional identifier and the conventional object identifier.

The new addressing scheme can thus also be implemented very easily for address spaces with conventional object identifiers of the identifier type NUMERIC.

• - Entnehmen eines alternativen Objektbezeichners aus einer Anfrage eines Clients,
• - Teilen des alternativen Objektbezeichners nach einem bestimmten Schema unter Anwendung eines Teilungskriteriums, so dass anschließend ein herkömmlicher Objektbezeichner und ein Zusatzbezeichner vorliegen,
• - Beurteilen des herkömmlichen Objektbezeichners als valide, wenn er in einem Verzeichnis der in diesem Adressraum des Servers vorhandenen herkömmlichen Objektbezeichner ermittelt werden kann,
• - Beurteilen des Zusatzbezeichners als valide, wenn er in einem Verzeichnis der für diesen Adressraum des Servers definierten Zusatzbezeichner ermittelt werden kann,
• - Beurteilen des alternative Objektbezeichners als valide, wenn zuvor sowohl der herkömmliche Objektbezeichner als auch der Zusatzbezeichner als valide beurteilt wurden,
• - Beurteilen des alternativen Objektbezeichners als nicht valide, wenn zuvor der herkömmliche Objektbezeichner und/oder der Zusatzbezeichner als nicht valide beurteilt wurden.

A method is also proposed for validating an alternative object identifier within an OPC UA-based communication environment, each object of an address space of a server being uniquely identified by a conventional object identifier and additionally being uniquely identified by at least one alternative object identifier, comprising the steps:

• - Extracting an alternative object identifier from a request from a client,
• - Split the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier and an additional identifier are then available,
• - Assessment of the conventional object identifier as valid if it can be determined in a directory of the conventional object identifier present in this address space of the server,
• - Assessment of the additional identifier as valid if it can be determined in a directory of the additional identifier defined for this address space of the server,
• - Assessment of the alternative object identifier as valid if both the conventional object identifier and the additional identifier were previously assessed as valid,
• - Assessment of the alternative object identifier as not valid if the conventional object identifier and / or the additional identifier were previously assessed as not valid.

Since the request from an OPC UA client could basically contain any object identifier, it must first be validated, in particular by the OPC UA server, that the requested alternative object identifier is actually a valid one by validating that the additional identifier contained therein is valid and the conventional object identifier it contains is actually part of the address space.

According to a first embodiment of the method, the scheme specifies that if the alternative object identifier is of the identifier type STRING, a separator character is used as the division criterion and the separator character is identified within the entire character string of the alternative object identifier as the second additional identifier part, and the part of the character string is specified the separator character as the first additional identifier part and the part of the character string after the separator character is identified and further processed as a conventional object identifier or the part of the character string before the separator character is identified as a conventional object identifier and the part of the character string after the separator character is identified and further processed as the first additional identifier part.

According to another embodiment of the method, the scheme specifies that if the alternative object identifier is of the identifier type NUMERIC, a base value is used as the division criterion and the alternative object identifier is divided by the base value, the integer quotient of this division, in particular after repeated multiplication by the base value Base is identified as an additional identifier and the rest of this division is identified and processed as a conventional object identifier.

In this way, requested object identifiers of the identifier type STRING but also of the identifier type NUMERIC can be validated.

If the alternative object identifier is of the identifier type STRING, the separator to be used as the division criterion for dividing the alternative object identifier can be specified, for example, in the source code, in particular in the source code for a so-called NodeID parser. Alternatively, the division criterion to be used can also be set up as a configurable parameter, for example.

Even if the alternative object identifier is of the identifier type NUMERIC, the basis to be used as the division criterion for dividing the alternative object identifier can be defined, for example, in the source code, in particular in the source code for a so-called NodeID parser. The value of the base should be selected as large as possible, so that an overlap of the NodeIDs of different information models of a namespace is as unlikely as possible. OPC UA specifies UINT32 as the data type for numeric NodeIDs, so that (2 ^ 32-1) / Y can be selected as the maximum value of the base, where Y indicates the maximum possible number of different dimensions or information models. If, on the other hand, the value of the base is to be set to be minimally small, the maximum number of nodes in the address space must be known and observed. Alternatively, the division criterion to be used can also be set up as a configurable parameter, for example.

If the alternative object identifier is of the identifier type STRING, a directory of the defined additional identifiers can be specified, for example, as a list or array in the source code, in particular in the source code for a so-called NodeID parser.

Even if the alternative object identifier is of the identifier type NUMERIC, a directory of the defined additional identifiers can be specified, for example, as a list or array in the source code, in particular in the source code for a so-called NodeID parser.

• - Entnehmen eines alternativen Objektbezeichners aus einer Anfrage eines Clients,
• - Teilen des alternativen Objektbezeichners nach einem bestimmten Schema unter Anwendung eines Teilungskriteriums, so dass anschließend ein herkömmlicher Objektbezeichner und ein Zusatzbezeichner vorliegen,
• - Ermitteln der dem herkömmlichen Objektbezeichner zugeordneten Referenzen in einem Verzeichnis der in diesem Adressraum des Servers vorhandenen Referenzen, wobei jede Referenz einen herkömmlichen Objektbezeichner eines zugeordneten anderes Objekts umfasst,
• - für jede ermittelte Referenz Bilden eines alternativen Objektbezeichners durch Kombinieren des Zusatzbezeichners mit dem von der Referenz umfassten herkömmlichen Objektbezeichner des zugeordneten anderen Objekts nach einem bestimmten Schema.

A method is also proposed for determining references of an alternative object identifier within an OPC UA-based communication environment, each object of an address space of a server being uniquely designated by a conventional object identifier and additionally being uniquely designated by at least one alternative object identifier, comprising the steps:

• - Extracting an alternative object identifier from a request from a client,
• - Split the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier and an additional identifier are then available,
• - Determination of the references assigned to the conventional object identifier in a directory of the references present in this address space of the server, each reference comprising a conventional object identifier of an assigned other object,
• - For each identified reference, formation of an alternative object identifier by combining the additional identifier with the conventional object identifier of the assigned other object, which is comprised by the reference, according to a specific scheme.

The request from an OPC UA client can be aimed at determining the references to a requested alternative object identifier. This method generates an alternative object identifier for each identified reference using the additional identifier contained in the requested alternative object identifier. When answering the request, the information model used by the client is taken into account. The method can advantageously be used or carried out both for forward references and for backward references.

According to a first embodiment of the method, the scheme specifies that if the alternative object identifier whose references are to be determined is of the identifier type STRING, a separator character is used as the division criterion and the separator character is identified within the character string of the alternative object identifier as the second additional identifier part, and the part of the character string before the separator character as the first additional identifier part and the part of the character string after the separator character as a conventional object identifier and processed further, or the part of the character string before the separator character as a conventional object identifier and the part of the character string after the separator character as the first additional identifier part is further processed.

According to a development of the method, the scheme specifies that the alternative object identifier for each identified reference is also of the identifier type STRING and is formed from three parts, namely in the order of the first additional identifier part, second additional identifier part and conventional object identifier of the respective assigned other object or in the Order of conventional object identifiers of the respective assigned other object, second additional identifier part and first additional identifier part.

According to another embodiment of the method, the scheme specifies that if the alternative object identifier whose references are to be determined is of the identifier type NUMERIC, a base value is used as the division criterion and the alternative object identifier is divided by the base value, the integer quotient of this division, in particular-after repeated multiplication with the base value base, is processed further as an additional identifier and the remainder of this division as a conventional object identifier.

According to a further development of the method, the scheme specifies that the alternative object identifier for each identified reference is also of the identifier type NUMERIC and is formed by adding the additional identifier and the conventional object identifier of the respective assigned other object.

In this way, references can effectively be determined for requested object identifiers of the identifier type STRING but also of the identifier type NUMERIC.

A server is also proposed, in particular an OPC UA server, which is used for Implementation of at least one of the above-described methods according to the invention is designed.

A system is also proposed comprising an OPC UA-based communication environment with at least one server according to the invention as described above and with at least one client which are connected to one another via a network.

Finally, a computer program product is also proposed, comprising instructions which, when executed by a computer, in particular a server, cause the computer to execute at least one of the previously described methods according to the invention.

The features and advantages specified for the method according to the invention, including their embodiments and developments, also apply mutatis mutandis to the server according to the invention and to the system and the computer program product.

• 1 ein System mit einer OPC-UA-basierenden Kommunikationsumgebung;
• 2 ein erstes Beispiel eines Verfahrens zum Bereitstellen eines alternativen Objektbezeichners;
• 3 ein erstes Beispiel eines Verfahrens zum Validieren eines alternativen Objektbezeichners;
• 4 ein erstes Beispiel eines Verfahrens zum Ermitteln von Referenzen eines alternativen Objektbezeichners;
• 5 ein zweites Beispiel eines Verfahrens zum Bereitstellen eines alternativen Objektbezeichners;
• 6 ein zweites Beispiel eines Verfahrens zum Validieren eines alternativen Objektbezeichners;
• 7 ein zweites Beispiel eines Verfahrens zum Ermitteln von Referenzen eines alternativen Objektbezeichners;
• 8 einen Adressraum eines OPC-UA-Servers, worin die Komponentenvariablen einer Steuerung als Knoten mit eindeutigen Knotenbezeichner des Bezeichnertyp STRING aufgeführt sind;
• 9 einen Adressraum eines OPC-UA-Servers, worin das Verzeichnis aller Namensräume bzw. Namensraumindizies des Adressraums als Attribut „NamespaceArray“ des Knotens „Server“ hinterlegt ist;
• 10 ein erstes Beispiel einer Auflistung von herkömmlichen Objektbezeichnern und alternativen Objektbezeichnern für Objekte bzw. Knoten eines Adressraums, welche Variablen der Steuerungskomponente „Arp.PLC.Eclr“ in unterschiedlichen Informationsmodellen repräsentieren;
• 11 ein zweites Beispiel einer Auflistung von herkömmlichen Objektbezeichnern und alternativen Objektbezeichnern für Objekte bzw. Knoten eines Adressraums, welche Variablen der Steuerungskomponente „Arp.PLC.Eclr“ in unterschiedlichen Informationsmodellen repräsentieren.

These and other features and advantages of the present invention also emerge from the exemplary embodiments, which are explained in more detail below with reference to the accompanying drawings. It shows in a schematic representation

• 1 a system with an OPC UA-based communication environment;
• 2 a first example of a method for providing an alternative object identifier;
• 3rd a first example of a method for validating an alternative object identifier;
• 4th a first example of a method for determining references of an alternative object identifier;
• 5 a second example of a method for providing an alternative object identifier;
• 6th a second example of a method for validating an alternative object identifier;
• 7th a second example of a method for determining references of an alternative object identifier;
• 8th an address space of an OPC UA server, in which the component variables of a controller are listed as nodes with a unique node identifier of the identifier type STRING;
• 9 an address space of an OPC UA server, in which the directory of all namespaces or namespace indices of the address space is stored as the “NamespaceArray” attribute of the “Server” node;
• 10 a first example of a list of conventional object identifiers and alternative object identifiers for objects or nodes of an address space, which variables of the control component “Arp.PLC.Eclr” represent in different information models;
• 11 a second example of a list of conventional object identifiers and alternative object identifiers for objects or nodes in an address space, which variables of the control component "Arp.PLC.Eclr" represent in different information models.

1 shows an example of a system with an OPC UA-based communication environment K which here are two servers S1 and S2 as well as two clients C1 and C2 having which over a network N are connected to each other. The clients are designed as OPC UA clients and the servers as OPC UA servers. The servers are also designed to carry out the method according to the invention for providing, validating and determining references of alternative object identifiers, the individual methods being explained in more detail below. The servers S1 and S2 present your information to the clients C1 and C2 ready in an address space.

The 8th shows an example of part of the address space of the OPC UA server S1 . This contains the component variables of a PLCnext Technology controller, not shown, with which at least the server S1 is in connection, listed as nodes with unique conventional node identifiers of the identifier type STRING. 9 shows another part of the address space of the OPC UA server S1 It can be seen here that the directory of all namespaces or namespace indexes of the address space is stored as the “NamespaceArray” attribute of the “Server” node.

The OPC UA standard does not specify how a server has to manage the nodes. It is assumed that the address space is subdivided into namespaces N [x], the conventional node identifiers NodeID in a namespace N [x] of the identifier type identifierType = STRING or identifierType = NUMERIC. It is also assumed that the server uses an array-like structure called NodeIDArray to store valid node identifier NodeID, and one called Forward- / BackwardReferenceMap Uses card-like structure to store references, ie arrays of node identifiers NodeIDs of the references to each node identifier NodeID. However, these assumptions were made only to simplify the description of the invention, but not to limit the invention.

The invention aims to expand an existing address space, in particular within a namespace N [x], by a dimension y with y = 1... Y, at low cost or with little effort, ie without replicating node instances in a memory, especially without adding new elements to the NodeIDArray or to the Forward- / BackwardReferenceMaD. The invention thus enables the implementation of Y additional information models or contexts for a database.

For this purpose, the invention proposes a new addressing scheme already mentioned at the beginning.

In the case of a conventional node identifier NodeID of the identifier type identifierType = STRING in a namespace N [x], a new or alternative node identifier PrefixedNodeID of the same identifier type is defined, which is defined as in 2 shown is formed by the combination or concatenation (see Prefix Concatenator) of a first part of an additional identifier Prefix [y] and a second part of an additional identifier in the form of a literal separator with the conventional node identifier NodeID, where Prefix [y] is an element of the set Prefix [Y] with the index y = 1: Y is.

In the case of a conventional node identifier NodeID of the identifier type identifierType = NUMERIC in a namespace N [x], a new or alternative node identifier BiasedNodeID of the same identifier type is defined, which is defined as in 5 is formed by the combination or addition (see Bias Adder) of an additional identifier Bias [y] and the conventional node identifier NodeID, where Bias [y] is an element of the set Bias [Y] with the index y = 1: Y, and where Bias [y] is the product of the multiplication of a base value Base by y (cf. Base Multiplier), where the base value Base is greater than the largest numerical value increased by 1 among all conventional node identifiers NodeID in the namespace N [x].

For example, if the namespace N [x] includes 10 nodes with the node identifiers NodeID = 1 ... 9, the base value can be Base = 100, since 100> max (0 ... 9), so that Y = 3 alternative node identifiers Biased NodeID = (100 ... 109, 200 ... 209, 300 ... 309) result.

In general terms, there is thus a method for providing alternative object identifiers for objects of an address space, in particular a namespace, of a server S1 , S2 within an OPC UA-based communication environment K provided, each object being the address space of the server S1 , S2 uniquely identified by a conventional object identifier, with at least one additional identifier being defined and in a directory for the address space of the server S1 , S2 defined additional identifier is stored, and for each object of the address space of the server S1 , S2 an alternative object identifier that also uniquely identifies the object is formed by combining the additional identifier with the conventional object identifier of the respective object according to a specific scheme.

In a first embodiment of the method, the scheme specifies that if the conventional object identifier is of the identifier type STRING, the additional identifier is also of the identifier type STRING and comprises two additional identifier parts, the first additional identifier part being a freely definable character string and the second additional identifier part being a freely definable separator character is. In addition, the scheme specifies that the alternative object identifier is also of the identifier type STRING and is formed from the three parts of the first additional identifier part, the second additional identifier part and the conventional object identifier of the respective object in this combination order (cf. 2 ).

Exemplary results of this procedure are shown in 10 and 11 shown.

Can be seen in 10 a list of conventional object identifiers and alternative object identifiers for objects or nodes in an address space, which variables of the control component "Arp.PLC.Eclr" represent in different information models. On the one hand, the additional identifier "PlcOpen.Programs" was defined to provide an information model for program variables. On the other hand, the additional identifier "PlcOpen.GlobalVars" was defined to provide an information model for global variables. In both cases, the additional identifier also includes the separator ":".

In 11 a further list of conventional object identifiers and alternative object identifiers for objects or nodes of an address space can be seen which variables of the control component “Arp. PLC. Eclr ”in yet another information model. On the one hand, the additional identifier "History.SessionA" was defined here for an information model for accessing historical values of these variables, which are stored in of a session A with a first sampling rate. On the other hand, the additional identifier “History.SessionB” was defined for an information model for accessing historical values of these variables, which were recorded in session B with a second sampling rate. In both cases, the additional identifier also includes the separator ":".

In the examples according to 2 , 10 and 11 the additional identifier is provided as a prefix to the conventional object identifier. However, it would also be conceivable to provide the additional identifier as a suffix to the conventional object identifier.

In an alternative embodiment of the method, the scheme specifies that if the conventional object identifier is of the identifier type NUMERIC, the additional identifier is also of the identifier type NUMERIC and a multiple of a base value, the base value being greater than the largest numerical value increased by 1 among all conventional ones Object identifiers of the objects in the address space of the server S1 , S2 . In addition, the scheme specifies that the alternative object identifier is also of the identifier type NUMERIC and is formed by adding the additional identifier and the conventional object identifier of the respective object (cf. 5 ).

• - Entnehmen eines alternativen Objektbezeichners PrefixedNodeID bzw. BiasedNodeID aus einer Anfrage eines Clients C1, C2,
• - Teilen des alternativen Objektbezeichners nach einem bestimmten Schema unter Anwendung eines Teilungskriteriums, so dass anschließend ein herkömmlicher Objektbezeichner NodeID und ein Zusatzbezeichner Prefix bzw. Bias vorliegen,
• - Beurteilen des herkömmlichen Objektbezeichners NodeID als valide, wenn er in einem Verzeichnis NodeIDArray der in diesem Adressraum des Servers S1, S2 vorhandenen herkömmlichen Objektbezeichner ermittelt werden kann (vgl. Node Validator),
• - Beurteilen des Zusatzbezeichners als valide, wenn er in einem Verzeichnis Prefix[Y] bzw. Bias[Y] der für diesen Adressraum des Servers S1, S2 definierten Zusatzbezeichner ermittelt werden kann (vgl. Prefix Validator bzw. Bias Validator),
• - Beurteilen des alternativen Objektbezeichners als valide, wenn zuvor sowohl der herkömmliche Objektbezeichner als auch der Zusatzbezeichner als valide beurteilt wurden (vgl. Logical AND),
• - Beurteilen des alternativen Objektbezeichners als nicht valide, wenn zuvor der herkömmliche Objektbezeichner und/oder der Zusatzbezeichner als nicht valide beurteilt wurden.

The 3rd and 6th show two examples of a method for validating an alternative object identifier within an OPC UA-based communication environment K , where each object is an address space of a server S1 , S2 is uniquely designated by a conventional object identifier and is also uniquely designated by at least one alternative object identifier. In general, the procedure includes the following steps:

• - Extracting an alternative object identifier PrefixedNodeID or BiasedNodeID from a client request C1 , C2 ,
• - Dividing the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier NodeID and an additional identifier Prefix or Bias are then available,
• - Assessment of the conventional object identifier NodeID as valid if it is in a directory NodeIDArray in this address space of the server S1 , S2 existing conventional object identifier can be determined (see Node Validator),
• - Assessment of the additional identifier as valid if it is in a directory Prefix [Y] or Bias [Y] for this address space of the server S1 , S2 defined additional identifier can be determined (see Prefix Validator or Bias Validator),
• - Assessment of the alternative object identifier as valid if both the conventional object identifier and the additional identifier were previously assessed as valid (see Logical AND),
• - Assessment of the alternative object identifier as not valid if the conventional object identifier and / or the additional identifier were previously assessed as not valid.

According to an initial development of the procedure (cf. 3rd ) specifies the scheme that if the alternative object identifier is of the identifier type STRING, a literal separator character is used as the division criterion and the separator character within the entire character string of the alternative object identifier PrefixedNodeID is identified as the second additional identifier part, with the part of the character string in front of the separator character being the first Additional identifier part Prefix and the part of the character string after the separator character is identified and further processed as a conventional object identifier NodeID (see Prefix Splitter).

In a case not shown in the figures, provision could instead be made for the part of the character string before the separator character to be identified and further processed as a conventional object identifier and the part of the character string after the separator character as the first additional identifier part.

According to another development of the procedure (cf. 6th ) the scheme specifies that if the alternative object identifier is of the identifier type NUMERIC, a base value Base is used as the division criterion and the alternative object identifier BiasedNodeID is divided by the base value Base, the integer quotient of this division, especially after repeated multiplication with the base value, as an additional identifier Bias and the remainder of this division is identified and processed as a conventional object identifier NodeID (see Base Modulo). In the 6th the repeated multiplication of the integer cruotient with the base value is not shown.

The integer quotient itself corresponds to the index y of the dimension or of the information model.

Because of this step-by-step validation according to the invention, the validation of alternative object identifiers can be carried out very efficiently. And since, with the provision according to the invention, alternative object identifiers for an additional Information model only a new additional identifier is entered in the directory of additional identifiers, but no node instances are replicated, the validation of alternative object identifiers hardly requires any additional storage space and computing power or computing time. Thus, the invention enables the implementation of Y additional information models or contexts for a database without the need for storage space and computing power or computing time increasing by a factor of Y + 1.

• - Entnehmen eines alternativen Objektbezeichners PrefixedNodeID bzw. BiasedNodeID aus einer Anfrage eines Clients C1, C2,
• - Teilen des alternativen Objektbezeichners nach einem bestimmten Schema unter Anwendung eines Teilungskriteriums, so dass anschließend ein herkömmlicher Objektbezeichner NodeID und ein Zusatzbezeichner Prefix bzw. Bias vorliegen,
• - Ermitteln der dem herkömmlichen Objektbezeichner NodeID zugeordneten Referenzen in einem Verzeichnis ForwardReferenceMap der in diesem Adressraum des Servers S1, S2 vorhandenen Referenzen, wobei jede Referenz einen herkömmlichen Objektbezeichner eines zugeordneten anderes Objekts umfasst (vgl. NodeID Lookup),
• - für jede ermittelte Referenz ForwardReferences Bilden eines alternativen Objektbezeichners PrefixedForwardReferences bzw. BiasedForwardReferences durch Kombinieren des Zusatzbezeichners Prefix bzw. Bias mit dem von der Referenz ForwardReferences umfassten herkömmlichen Objektbezeichner des zugeordneten anderen Objekts nach einem bestimmten Schema (vgl. Prefix Concatenator bzw. Bias Adder).

The 4th and 7th show two examples of a method for determining references of an alternative object identifier within an OPC UA-based communication environment K , where each object is an address space of a server S1 , S2 is uniquely designated by a conventional object identifier and is also uniquely designated by at least one alternative object identifier. In general, the procedure includes the following steps:

• - Extracting an alternative object identifier PrefixedNodeID or BiasedNodeID from a client request C1 , C2 ,
• - Dividing the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier NodeID and an additional identifier Prefix or Bias are then available,
• - Determination of the references assigned to the conventional object identifier NodeID in a directory ForwardReferenceMap in this address space of the server S1 , S2 existing references, each reference comprising a conventional object identifier of an assigned other object (see NodeID Lookup),
• - For each determined reference ForwardReferences formation of an alternative object identifier PrefixedForwardReferences or BiasedForwardReferences by combining the additional identifier Prefix or Bias with the conventional object identifier of the assigned other object included in the reference ForwardReferences according to a certain scheme (see Prefix Concatenator or Bias Adder)

According to an initial development of the procedure (cf. 4th ) specifies the scheme that if the alternative object identifier PrefixedNodeID, whose references are to be determined, is of the identifier type STRING, a literal separator character is used as the division criterion and the separator character within the character string of the alternative object identifier is identified as the second additional identifier part, and the part the character string before the separator character as the first additional identifier part Prefix and the part of the character string after the separator character is identified and further processed as the conventional object identifier NodeID.

In a case not shown in the figures, provision could instead be made for the part of the character string before the separator character to be identified and further processed as a conventional object identifier and the part of the character string after the separator character as the first additional identifier part.

Furthermore, the scheme specifies that for each identified ForwardReferences reference, the alternative object identifier PrefixedForwardReferences is also of the identifier type STRING and is formed from three parts, namely in the order of the first additional identifier part prefix, second additional identifier part separator literal and conventional object identifier of the other assigned object or the sequence of conventional object identifiers of the respective assigned other object, second additional identifier part and first additional identifier part.

In the example according to the 4th the additional identifier occurs as a prefix to the conventional object identifier. It is also conceivable that the additional identifier appears as a suffix to the conventional object identifier.

According to another development of the procedure (cf. 7th ) specifies the scheme that if the alternative object identifier BiasedNodeID, whose references are to be determined, is of the identifier type NUMERIC, a base value Base is used as the division criterion and the alternative object identifier is divided by the base value, the integer quotient of this division after repeated multiplication by the base value Base is processed further as the additional identifier Bias and the remainder of this division as the conventional object identifier NodeID. In the 7th the repeated multiplication of the integer quotient by the base value is not shown. The integer quotient itself corresponds to the index y of the dimension or of the information model.

Furthermore, the scheme specifies that for each determined reference ForwardReferences the alternative object identifier BiasedForwardReferences is also of the identifier type NUMERIC and is formed by adding the additional identifier Bias and the conventional object identifier of the respective assigned other object.

Even if the procedure is carried out according to the 4th and 7th is shown and described for determining forward references, this can also be used for determining backward references.

List of reference symbols

K

OPC UA-based communication environment

S1, S2

Server, OPC UA server

C1, C2

Client, OPC UA client

N

network

Claims (16)

Method for providing alternative object identifiers for objects in an address space of a server (S1, S2) within an OPC UA-based communication environment (K), each object of the address space of the server (S1, S2) being uniquely identified by a conventional object identifier, at least one additional identifier being defined and stored in a directory of the additional identifier defined for this address space of the server (S1, S2), and an alternative object identifier that also uniquely identifies the object is formed for each object in the address space of the server (S1, S2) by combining the additional identifier with the conventional object identifier of the respective object according to a specific scheme. Procedure according to Claim 1 The scheme stipulates that if the conventional object identifier is of the identifier type STRING, the additional identifier is also of the identifier type STRING and comprises two additional identifier parts, the first additional identifier part being a freely definable character string and the second additional identifier part being a freely definable separator character. Procedure according to Claim 2 The scheme stipulates that the alternative object identifier is also of the identifier type STRING and is formed from the three parts first additional identifier part, second additional identifier part and conventional object identifier of the respective object in this or the reverse combination order. Procedure according to Claim 1 The scheme stipulates that if the conventional object identifier is of the identifier type NUMERIC, the additional identifier is also of the identifier type NUMERIC and a multiple of a base value, the base value being greater than the largest numerical value increased by 1 among all conventional object identifiers of the objects in the address space of the server (S1, S2). Procedure according to Claim 4 , whereby the scheme specifies that the alternative object identifier is also of the identifier type NUMERIC and is formed by adding the additional identifier and the conventional object identifier of the respective object. Procedure for validating an alternative object identifier within an OPC UA-based communication environment (K), wherein each object of an address space of a server (S1, S2) is uniquely designated by a conventional object identifier and is also uniquely designated by at least one alternative object identifier, comprehensive the steps: - Extracting an alternative object identifier from a request from a client (C1, C2), - Dividing the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier and an additional identifier are then available, - Assessment of the conventional object identifier as valid if it can be determined in a directory of the conventional object identifier present in this address space of the server (S1, S2), - Assessment of the additional identifier as valid if it can be determined in a directory of the additional identifier defined for this address space of the server (S1, S2), - Assessment of the alternative object identifier as valid if both the conventional object identifier and the additional identifier were previously assessed as valid, - Assessment of the alternative object identifier as not valid if the conventional object identifier and / or the additional identifier were previously assessed as not valid. Procedure according to Claim 6 , whereby the scheme specifies that if the alternative object identifier is of the identifier type STRING, a separator character is used as the division criterion and the separator character is identified within the entire character string of the alternative object identifier as the second additional identifier part, and the part of the character string before the separator character as the first additional identifier part and the part of the character string after the separator character is identified and processed further as a conventional object identifier or the part of the character string before the separator character as a conventional object identifier and the part of the character string after Separator characters are identified and processed further as the first additional identifier part. Procedure according to Claim 6 , whereby the scheme specifies that if the alternative object identifier is of the identifier type NUMERIC, a base value is used as the division criterion and the alternative object identifier is divided by the base value, the integer quotient of this division, in particular after repeated multiplication with the base value, as an additional identifier and the rest of this division is identified and processed further as a conventional object identifier. Method for determining references of an alternative object identifier within an OPC UA-based communication environment (K), wherein each object of an address space of a server (S1, S2) is uniquely designated by a conventional object identifier and is also uniquely designated by at least one alternative object identifier, comprehensive the steps: - Extracting an alternative object identifier from a request from a client (C1, C2), - Split the alternative object identifier according to a certain scheme using a division criterion, so that a conventional object identifier and an additional identifier are then available, - Determination of the references assigned to the conventional object identifier in a directory of the references present in this address space of the server (S1, S2), each reference comprising a conventional object identifier of another assigned object, - For each identified reference, formation of an alternative object identifier by combining the additional identifier with the conventional object identifier of the assigned other object, which is comprised by the reference, according to a specific scheme. Procedure according to Claim 9 , whereby the scheme stipulates that if the alternative object identifier whose references are to be determined is of the identifier type STRING, a separator character is used as the division criterion and the separator character is identified within the character string of the alternative object identifier as the second additional identifier part, and the part of the character string before the separator character as the first additional identifier part and the part of the character string after the separator character is identified and further processed as a conventional object identifier or the part of the character string before the separator character is identified as a conventional object identifier and the part of the character string after the separator character is identified and further processed as the first additional identifier part. Procedure according to Claim 10 , whereby the scheme stipulates that for each identified reference the alternative object identifier is also of the identifier type STRING and is formed from three parts, namely in the order of the first additional identifier part, second additional identifier part and conventional object identifier of the respective assigned other object or in the order of conventional object identifier of the respective assigned other object, second additional identifier part and first additional identifier part. Procedure according to Claim 9 , whereby the scheme specifies that if the alternative object identifier whose references are to be determined is of the identifier type NUMERIC, a base value is used as the division criterion and the alternative object identifier is divided by the base value, the integer quotient of this division, in particular after repeated multiplication by the base value Base, as an additional identifier and the rest of this division as a conventional object identifier. Procedure according to Claim 12 The scheme stipulates that the alternative object identifier for each identified reference is also of the identifier type NUMERIC and is formed by adding the additional identifier and the conventional object identifier of the respective assigned other object. Server (S1, S1) designed to carry out the method according to one of the Claims 1 to 13th . System comprising an OPC UA-based communication environment (K) with at least one server (S1, S1) Claim 14 and at least one client (C1, C2), which are connected to one another via a network (N). Computer program product, comprising instructions which, when executed by a computer, cause the computer to execute the method according to one of the Claims 1 to 13th to execute.

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