portal server

Abstract

Embodiments of the present disclosure relate to a facade server. The facade server provides a configurable facade having a configurable address space and serving as an interface for clients, and provides a mapping between the configurable address space of the facade and a data space and / or address space of an external server.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a server providing an interface between a client and one or more external servers, a computer-implemented method, a computer program product and a computer readable medium. BACKGROUND

[0002] When providing a system comprising one or more external servers for use with a client, it often occurs that the one or more external servers each have their own address space and interface. While the client can typically interact with different interfaces and address spaces, this is very inefficient, especially when several different external servers are comprised in the system.

[0003] It is known to aggregate servers to aggregate and merge the address spaces of several external servers, such that the client can only have to deal with one address space even if several servers are involved.

[0004] However, adjusting the address space of the respective aggregation server on the client side still requires a lot of effort.

[0005] It is therefore an object of the present disclosure to provide a server that relieves the burden on the client side to adapt to the address space of one or more external servers or aggregation servers. SUMMARY

[0006] This problem is solved by the subject matter of the present application. Preferred embodiments are listed in the description and the drawings.

[0007] The present disclosure provides a facade server configured to provide a configurable facade having a configurable address space and serving as an interface for a client, and to provide a mapping between the configurable address space of the facade and a data space and / or address space of an external server.

[0008] As mentioned above, the facade server serves to solve the problem associated with different address spaces. An address space is a collection of nodes connected by references. Using references allows to step through the address space. A node is a data object that is addressable in a data space. It can be a type definition or an instance. As an example, a type can be a data type, a variable type, an object type and a reference type. An instance can include an object, a variable and a method.

[0009] One or more information models can be used to build at least part of the address space, i.e. one or more data models can specify how to build the address space.

[0010] The address space can support several information models. To this end, the address space can be organized by name spaces. The identity of a name space is linked to a URL.

[0011] The facade can be seen as a transformed representation of the address space, which differs from the address space used or expected by the client. In particular, it can be a transformed representation of the merged address space of the aggregation server.

[0012] As briefly mentioned above, the aggregation server provides an aggregation, i.e. a merged representation, of the address spaces of several external servers in a common merged address space. For example, the aggregation server can forward service requests from the client to the external servers.

[0013] The facade server can be configured to run the facade nodes. In addition, it can also optionally be configured to implement the logic for transforming the address space, including the logic required to provide the transformation of the client access of the facade nodes to the address space of the external servers or the nodes of the merged address space.

[0014] The facade is configurable. This means that the facade server does not prescribe the configuration of the interface visible to the client. Instead, it is possible for the client to configure the facade and, thus, the interface.

[0015] Thus, the facade server of the present disclosure allows seamless integration of the facade server and any external servers supported by the facade server into the client system.

[0016] One way of providing the facade configuration is to allow the client to configure one or more data models, which are used to build the facade, in particular the nodes of the facade.

[0017] Note that in the following, some features will be described with reference to the example of an OPC UA and / or OPC DA server and / or client. The reason is that the facade server is particularly suitable for this case. However, the present disclosure is not limited to use in or in the context of OPC UA / DA.

[0018] OPC DA, HDA and AE are standards of the OPC base definition for the transfer of data (DA), trends (historical DA, HDA) and alarms and events (AE), also known as OPC Classic. DA items are addressable variable objects in the data space of an OPC DA server, which are similar to a flat list of variables. OPC Classic is the predecessor of OPC UA (Unified Architecture), which is an object-oriented middleware for automation technology systems built on IP (Internet Protocol).

[0019] In the context of OPC UA, for example, the client-oriented facade server has the role of an OPC UA server. For the external servers, the facade server has the role of an OPC UA client, while the external servers have the role of OPC UA servers.

[0020] According to the present disclosure, a facade server can be configured to provide a plurality of facades as an interface for a client, each facade having a configurable address space. The facade server can be an aggregation server configured to aggregate a data space and / or an address space of each of a plurality of external servers, and can be configured to provide, for each of the plurality of external servers, a mapping between the configurable address space of one of the facades and the aggregated data space and / or address space of the external server.

[0021] This is particularly advantageous as it allows for the addition and removal of external servers and allows for easy addition or removal while still maintaining the desired interface to the client.

[0022] The facade or each of the facades can be configured by one or more node set files.

[0023] An advantage of the node set files is that they allow for a simple direct configuration of the facade by simply selecting the corresponding node set file for the configuration. The node set files comprise the information required to configure the address space of the facade such that no specific knowledge is required on the client side to perform the appropriate configuration. For example, the node set files are suitable to provide various information including data propagation for each node. Furthermore, the use of node set files allows for a high compatibility of the facade server with client systems. Moreover, the addition of additional facade nodes by using node set files allows for an easy implementation of the addition of external servers to the system and the removal of external servers from the system.

[0024] The node set files describe the address space. For example, in case the address space of the facade implements multiple information models, multiple node files can be used. The node set is a standardized data format based on xml.

[0025] For example, the node set files are typically used in the context of OPC UA. Thus, in one embodiment, the facade server can be an OPC UA server and the client can be an OPC UA client and the node set files can be used to configure the facade.

[0026] For example, the node set files are specified in the OPC UA standard OPC 10000-6.

[0027] Configuring the facade or each of the facades by one or more node set files can comprise implementing one or more data models to obtain the address space of the facade, the address space being defined by the one or more node set files.

[0028] An advantage thereof is that due to the use of configurable facades, in particular when the configuration is performed using node set files, a significant flexibility in terms of data models is provided.

[0029] The facade can be configured to provide a transformed representation of the data space and / or address space of the external server, and the logic for transformation for providing the transformed representation can be configurable. The logic for transformation for configuring can comprise configuring a bidirectional link of data of the facade and data of the external server, e.g. to provide a data forwarding functionality. Alternatively or additionally, the logic for transformation for configuring comprises configuring a unidirectional link to provide a forwarding functionality, in particular forwarding alarms and / or events sent by the external server.

[0030] Thus, whenever the two address spaces are incompatible per se for instant communication, still an effective propagation of data can be ensured.

[0031] In particular, the logic for transformation can comprise a scripted logic allowing data conversion, e.g. when a method call needs to be converted into data to be read and / or written, and / or allowing business logic when the external server does not provide the business logic prescribed by the information model under the facade.

[0032] This allows to overcome potential incompatibilities and to adapt lost functionality, thus ensuring compatibility and supporting a wide range of functionality.

[0033] The facade server can be an OPC UA server, the client can be an OPC UA client, and the external server can be an OPC UA server or an OPC DA server.

[0034] As mentioned above, configurable facades are particularly advantageous when used in OPC systems, as they are frequently used in environments where the functionality of the facades is particularly useful, i.e. allowing an effective data exchange between multiple external servers and clients associated with devices of a plant. In particular, the facade server can be an aggregation server as described above, which allows an improved data exchange in a system with multiple external servers.

[0035] It is noted that the facade server outlined above can comprise one or more processing units and / or one or more storage units.

[0036] The present application can also provide a system comprising one of the above-mentioned facade servers, in particular an aggregation server, and one or more, in particular aggregated, external servers. Alternatively or additionally, the system can comprise a client, e.g. an OPC UA client, which in particular communicates with the facade server configured to perform read and / or write operations on the aggregation server via the facade.

[0037] The present disclosure also provides a computer-implemented method, comprising: at a facade server, in particular at any of the above-mentioned facade servers, providing a configurable facade having a configurable address space and serving as an interface for a client; and providing a mapping between the configurable address space of the facade and a data space and / or address space of an external server.

[0038] It is noted that the facade server can comprise one or more processing units configured to perform the method steps. The facade server can comprise or have access to one or more storage units in which information for the facade configuration is stored, for example a configuration file which can comprise a node set file.

[0039] The facade server can be an aggregation server configured to aggregate a data space and / or address space of each of a plurality of external servers, and the method can further comprise providing a plurality of facades as an interface for a client server, each facade having a configurable address space; and providing, for each of the plurality of external servers, a mapping between the configurable address space of one of the facades and the aggregated data space and / or address space of the external server.

[0040] The method can further comprise configuring the facade or each of the facades by one or more node set files.

[0041] Configuring the facade or each of the facades by one or more node set files can comprise implementing one or more data models to obtain an address space of the facade, the address space being defined by the one or more node set files.

[0042] The facade can provide a transformed representation of the data space and / or address space of the external server, and the method can comprise configuring logic for providing the transformation. Configuring the logic for the transformation can comprise configuring a bidirectional link of data of the facade and data of the external server, for example to provide a data forwarding function. Alternatively or additionally, configuring the logic for the transformation can comprise configuring a unidirectional link to provide a forwarding function, in particular to forward alerts and / or events sent by the external server.

[0043] The logic for the transformation can comprise scripted logic allowing data conversion, for example when a method call needs to be transformed into data to be read and / or written, and / or when the external server does not provide business logic prescribed by an information model under the facade.

[0044] The facade server can be an OPC UA server, the client can be an OPC UA client, and the external server can be an OPC UA server or an OPC DA server.

[0045] The present disclosure also provides a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out any of the above methods.

[0046] The present disclosure also provides a computer readable medium comprising instructions which, when executed by a computer, cause the computer to carry out any of the above methods.

[0047] The features and advantages described in the context of the system above apply analogously to the method, computer program product and computer readable medium described herein.

[0048] Other features, examples and advantages will become apparent from the detailed description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0049] In the drawings,

[0050] Figure 1a An example of a facade server is shown, as well as exemplary interactions with a client and an external server;

[0051] Figure 1b A facade server is shown having a different configuration than in Figure 1a

[0052] An example of a facade server is shown, as well as exemplary interactions with a client and an external server when the facade server is an aggregation server; Figure 2

[0053] Another example of a facade server is shown, as well as exemplary interactions with a client and an external server when the facade server is an aggregation server; and Figure 3

[0054] An example of steps involved in configuring a facade server is shown. Figure 4 DETAILED DESCRIPTION

[0055] An embodiment of a facade server 1 running a configurable facade 2 having a configurable address space 3 is shown, in which Figure 1a In the configuration shown, the configurable address space 3 comprises a node 3a and a node 3b, where reference sign 3a denotes an instance and reference sign 3b denotes a type definition. Figure 1a

[0056] ​The facade service is the interface for the client 4. The client is not part of the facade server, but is shown in figure 1 for better understanding of the functionality of the facade server.

[0057] Furthermore, indicated by reference signs 5, 5a-1, 5a-2 and 5a-3 is the logic for transformation within the facade server, which will be described in more detail below.

[0058] Reference sign 6 indicates the address space of the external server 7, which is not part of the facade server, and in Figure 1a is shown for illustrative purposes. Figure 1a The arrows in

[0059] Furthermore, a plurality of node set files 9a is shown in figure 1, the arrows indicating that the address space is built using the node set files.

[0060] Reference sign 10a indicates a configuration file for configuring the transformation 5. Indicated by reference signs 5a-1 and 5a-2 are logic blocks, one for reading data and one for writing data. These blocks can be provided, for example, by scripted logic. Reference sign 5a-3 indicates read / write not involving a logic block.

[0061] Figure 1b Basically corresponds to Figure 1a , the only difference being that the address space 3 is built up by a different set of node set files 9a-1, and thus, the facade comprises a different set of nodes 3a-1 and 3b-1.

[0062] In other words, Figure 1a and Figure 1b shows the same facade server with two different facade configurations, more specifically, two different configurations of the facade address space.

[0063] Although Figure 1b the transformation logic shown in Figure 1a is the same as in

[0064] Note that for simplicity, Figure 1b the client shown is the same as the client shown in Figure 1a However, it can also be the case that different clients can apply different facade configurations to meet client-specific technical requirements.

[0065] Figure 2An embodiment of a facade server 1 configured as an aggregation server is shown. In this case, the address space 6 is a merged address space on the aggregation server, which merges the address space 6a of the first external server 7 and the address space 6b of the second external server 8.

[0066] The address space 6a of the external server 7 comprises nodes 7a and 7b representing instance and type definitions, respectively. The address space of the external server 8 comprises nodes 8a and 8b representing instance and type definitions, respectively.

[0067] The facade server is shown to run two facades, which together provide the interface for the client 4.

[0068] The first facade is configured substantially as shown and explained in the context of Figure 1a and Figure 1b , the address space 3 having nodes 3a and 3b. The address space of the first facade is based on the node set file 9a. The logic 5 of the first facade is based on the configuration file 10a. The first facade essentially provides the client with the functionality to interact with the address space of the server 7.

[0069] The second facade is similar to the first facade. Its address space 3 comprises a node 3c representing an instance and a node 3d representing a type definition. The address space of the second facade is based on the node set file 9b, the logic 5 of the second facade is based on the configuration file 10b. The second facade essentially provides the client with the functionality to interact with the address space of the server 8.

[0070] It will be appreciated that each of the facades shown in Figure 1a and Figure 1b , Figure 2 may be configured differently depending on the node set files used to build them.

[0071] Furthermore, depending on the configuration of the merged address space 6, it can not be necessary to provide two facades as interfaces, but it can be possible to use only one common facade. This is shown in Figure 3 .

[0072] It is possible to selectively aggregate only parts of the address spaces of the external servers, and to map the partially aggregated address spaces to the facades, given the functional compatibility between the partially aggregated address spaces and the facades.

[0073] It is noted that different numbers and types of external servers can be used. Similarly, the facade server can be used with different clients. Furthermore, there can be a different number of facades than shown in the figures, and each of the facades can have a different configuration than shown in the figures, e.g. a different kind and number of nodes. The conversion logic 5 is optional, depending on the address spaces involved, and can also be configured differently than shown in the figures.

[0074] All of the above embodiments can be implemented, for example, in an OPC architecture, wherein the client is an OPC UA client and is facing an OPC UA client, the facade server has the functionality of an OPC UA server and is facing an external server, and the facade server has the functionality of an OPC UA client. If the system comprises an OPC DA, HDA, AE server as external server, the facade server can have the functionality of an OPC DA client facing said external server, while the facade server still has the functionality of an OPC UA server facing the OPC UA client, i.e. the facade is still modelled by an OPC UA server.

[0075] Examples of a computer-implemented method performed at a facade server will be described in the following. The facade server described in the context of Figures 1 to Figure 3 may be used. Alternatively, any suitable facade server can be used.

[0076] The method comprises providing, at the facade server, a configurable facade having a configurable address space and serving as an interface for a client. The address space can comprise a plurality of nodes, e.g. as shown in Figures 1 to Figure 3 For configuring the facade, one or more configuration files, e.g. the node set files 9a or 9b, can be accessed and the address space of the facade can be built based thereon.

[0077] The method can further comprise providing a mapping between the configurable address space of the facade and a data space and / or address space of an external server. For example, the above-mentioned logic 5 can be used for providing the mapping.

[0078] The method can further comprise reconfiguring the facade by accessing one or more configuration files, e.g. the above-mentioned node set files 9a-1, and building the facade based thereon.

[0079] The method can further comprise configuring and optionally reconfiguring the above-mentioned logic 5, e.g. by means of the above-mentioned configuration file 10b.

[0080] If the method is performed at a facade server that is an aggregation server, the method can aggregate a data space and / or address space of each of a plurality of external servers. The method can further comprise providing a plurality of facades as interfaces for a client, each of the facades having a configurable address space, in the above-mentioned manner, e.g. as shown in Figures 1 to Figure 2

[0081] For each of the plurality of external servers, a mapping between the configurable address space of one of the facades and an aggregated data space and / or address space of said external server can be provided. This allows for efficient communication between the client and the external servers.​

[0082] From the above it can be understood that the disclosed gateway server allows to wrap a control center model of a DCS (Distributed Control System) with a configurable address space that follows any customer selected model standard (e.g. any OPC UA specified model standard).

[0083] Furthermore, from the above it can be understood that in case of an aggregation server, the gateway provides a flexible embedded model transformation layer. The embedded scripted logic can overcome incompatibilities between the aggregation node and the gateway node.

[0084] A more detailed example of a gateway server and method is provided below, where the gateway server is an aggregation server. During its start-up phase, the aggregation server (e.g. an OPC UA server) creates a merged image of any address space of external servers (e.g. other aggregation OPC UA servers). The result is an aggregation address space that represents all nodes from the remote other servers.

[0085] At the end of the start-up phase, the aggregation server uses 1..n node set files to describe the gateway model that shall be seen before the aggregation address space. Sometimes, it can need more than one node set file, because the gateway model can be related to existing OPC UA companion specifications, which means that the aggregation OPC UA server has to import any node set file defined by the applied OPC UA companion specification.

[0086] The import of these node set files usually leads to finding metadata in the type definitions in the address space. Another node set file will describe any instance nodes that represent the interactive part of the gateway model. Included in this node set file are references that describe the data propagation. These reference links of the aggregation address space(s) point to the nodes of the gateway model.

[0087] Using the reference types that describe the corresponding nodes, the aggregation UA server is able to transfer data bi-directionally between the corresponding nodes according to the actual OPC UA services that access the gateway nodes.

[0088] If needed, the aggregation UA server loads configuration data to add scripted logic. Both start working, if the data end that shall be connected is technically not compatible, so the data cannot be simply copied from one end to the other. In this case, the scripted logic can provide a logical bridge between the nodes in the aggregation address space and the nodes in the gateway model.

[0089] The proposed server can provide a reference type that describes the propagation (direction) that is bound to the OPC UA services that access the gateway nodes.

[0090] When reading the facade nodes, the read request is forwarded to the corresponding nodes in the chain until the aggregated node has been found that has to be read from the remote aggregated OPC UA server.

[0091] The result of the read access is then automatically propagated to the face nodes.

[0092] When writing, the modified value of the facade node is forwarded to any corresponding nodes. When hitting an aggregated node, the modified value is written to the remote aggregated OPC UA server.

[0093] With this generic service binding data propagation path, the aggregated OPC UA server allows to insert scripted logic into the data propagation path. This way, the aggregated OPC UA server supports conversion logic in both directions, which is advantageous, because the logic to convert a value "a" to "b" is not always the same in the opposite direction.

[0094] Another detailed example is provided below to illustrate the sequence of steps that can be involved in setting up and configuring a facade server, with reference to Figure 4 . The numbers used in the subsequent numbered sections correspond to the numbers used on the connection lines in Figure 4 . Here, as an example, the external server is an OPC DA server, the facade server is an OPC UA server, and the client is an OPA UA client.

[0095] (1) The existing engineering tool can be used to create the control application. The development process (engineering) makes use of existing programming libraries that are suitable for the application area like the mineral, oil and gas industry. Any kind of library can be used. However, the libraries are mentioned to emphasize that the (approved) libraries are not affected by the approach of the example.

[0096] (2) The control application can be downloaded to the controller.

[0097] (3) The designed control application also produces an IO configuration for the OPC DA server that enables access to the data by naming "OPC DA items" ("OPC DA items" is a term for variables that can be read or written by an OPC DA client).

[0098] (4) The IO configuration is loaded into the OPC DA server.

[0099] (5) The engineering tool selects the OPC UA compatible / specified information model by selecting the relevant node set file, i.e. an XML file that applies the XSD schema specified by OPC UA.

[0100] (6) The engineering tool creates a representation of the control system within the node set file describing a part of the address space matching the previously selected information model. (See (5)) The engineering tool applies the model definition rules from the previously selected information model.

[0101] (7) The engineering tool describes the mapping between the address space of the OPC DA server and the address space of the OPC UA server. This description allows to translate between the OPC UA server's address space and the OPC DA server's OPC DA items in the OPC UA service access unit.

[0102] (8) The OPC UA Server loads the selected node set file describing the standardized model (<Information Model>.Nodeset2.xml) to prepare the address space based on the imported node set file. Similarly, the node set file <Application Model>.Nodeset2.xml is loaded to represent the control system specific part of the address space.

[0103] (9) The conversion layer part is configured by the imported DA / UA Mapping.xml. The DA client uses the information about the OPC DA items in the OPC DA server that should be addressed. The OPC UA server uses the information about the address space nodes that should be linked to the OPC DA items. The gateway gets the information about how to translate between the OPC UA server and the OPC DA client.

[0104] (10) With the commissioned configuration, the DA client is able to run the communication with the OPC DA server. This communication is triggered by the OPC DA client (see (11)).

[0105] (11) With the commissioned configuration, the OPC UA server enables the exchange of information representing the enterprise level with the OPC UA client. This OPC DA client is fed with information from the OPC DA server that is transmitted and translated by the gateway in the back end of the OPC UA server.

[0106] As will be appreciated from the present disclosure, the gateway server and method described herein can have one or more of the following advantages. This can enable flexible selection of information models for OPC UA front-ends of DCS, creation of information model compatible representations of control systems, inferring a mapping between an address space of an OPC UA server and a functionality of a control system, bidirectional conversion between OPC DA (AE, HDA) servers and OPC UA servers, optionally adding business logic to the transformation functionality if the OPC UA specified information model defines behaviors that do not exist in the control system, optionally adding data type dependent conversion logic when a conversion between data items on either side is required that are semantically the same but have different data types applied.

[0107] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered exemplary and not restrictive in character. The disclosure is not limited to the disclosed embodiments. Various modifications can be made to the disclosure by those skilled in the art without departing from the scope of the disclosure as defined by the claims.

Claims

1. A facade server (1), configured as A configurable facade (2) is provided, the configurable facade having a configurable address space (3) and serving as an interface for a client (4) to an external server, wherein the interface is configured by the client by configuring one or more data models for constructing the configurable facade, and Provides a mapping between the configurable address space (3) of the facade (2) and the data space and / or address space (6, 6a, 6b) of the external server (7, 8).

2. The storefront server (1) according to claim 1. The facade server (1) is configured to provide multiple facades (2) as interfaces for the client, each facade (2) having a configurable address space (3). The facade server (1) is an aggregation server configured to aggregate the data space and / or address space (6, 6a, 6b) of each of a plurality of external servers, and The facade server is configured to provide a mapping between the configurable address space (3) of one facade (2) and the aggregated data space and / or address space (6, 6a, 6b) of the external servers (7, 8) for each of the plurality of external servers (7, 8).

3. The facade server (1) according to claim 1, wherein the facade (2) or each facade in the facade (2) can be configured via one or more node set files (9a, 9b).

4. The facade server (1) according to claim 3, wherein configuring the facade (2) or each facade in the facade (2) via one or more node set files (9a, 9b) comprises: Implement one or more data models to obtain the configurable address space (3) of the facade (2), the configurable address space (3) being defined by the one or more node set files (9a, 9b).

5. The storefront server (1) according to any one of claims 1-4. The facade (2) is configured to provide a transformed representation of the data space and / or address space (6, 6a, 6b) of the external servers (7, 8), and the logic of the transformation (5) for providing the transformed representation is configurable. The logic configured for the transformation (5) includes: Configure a bidirectional link between the data of the facade (2) and the data of the external servers (7, 8) to provide data forwarding functionality, and / or The logic configured for the transformation (5) includes: configuring a unidirectional link to provide forwarding of alarms and / or events sent by the external servers (7, 8).

6. The facade server (1) according to claim 5, wherein the logic for transformation (5) includes scripted logic that allows data transformation when a method call needs to be transformed into data to be read and / or written, and / or allows the business logic to be accommodated when the external server does not provide business logic defined by the information model under the facade (2).

7. The facade server (1) according to any one of claims 1-4, wherein the facade server (1) is an OPC UA server, the client (4) is an OPC UA client, and the external server (7, 8) is an OPC UA server or an OPC DA server.

8. A computer-implemented method, the method comprising: At the storefront server (1), A configurable facade (2) is provided, the configurable facade having a configurable address space (3) and serving as an interface for a client (4) to an external server, wherein the interface is configured by the client by configuring one or more data models for constructing the configurable facade, and Provides a mapping between the configurable address space (3) of the facade (2) and the data space and / or address space (6, 6a, 6b) of the external servers (7, 8).

9. The method according to claim 8, in, The facade server (1) is an aggregation server configured to aggregate the data space and / or address space (6, 6a, 6b) of each of a plurality of external servers (7, 8), and the method further includes: providing a plurality of facades (2) as interfaces for the client (4), each facade having a configurable address space (3); and for each of the plurality of external servers, providing a mapping between the configurable address space (3) of one facade in the facade (2) and the aggregated data space and / or address space (6, 6a, 6b) of the external servers (7, 8).

10. The method of claim 8, further comprising: The facade (2) or each facade in the facade (2) is configured by one or more node set files (9a, 9b).

11. The method of claim 10, wherein configuring the facade (2) or each facade (2) via the one or more node set files (9a, 9b) comprises: Implement one or more data models to obtain the configurable address space (3) of the facade (2), the configurable address space (3) being defined by the one or more node set files (9a, 9b).

12. The method according to any one of claims 8 to 11, The facade (2) provides a transformed representation of the data space and / or address space (6, 6a, 6b) of the external servers (7, 8), and the method includes configuring logic for a transformation (5) to provide the transformed representation. The logic configured for the transformation (5) includes: Configure a bidirectional link between the data of the facade (2) and the data of the external servers (7, 8) to provide data forwarding functionality, and / or The logic configured for the transformation (5) includes: configuring a unidirectional link to provide forwarding of alarms and / or events sent by the external servers (7, 8).

13. The method of claim 12, wherein the logic for transformation (5) includes scripting logic that allows data transformation when a method call needs to be transformed into data to be read and / or written, and / or allows the inclusion of the business logic when the external server (7, 8) does not provide the business logic defined by the information model under the facade (2).

14. A computer program product comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 8 to 13.

15. A computer-readable medium comprising instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 8 to 13.

Images