1 Introduction

Manufacturing companies face several challenges nowadays. Firstly, in some industry sectors there exists an overcapacity of produced goods, for instance in the automobile industry. There is a tough competition between companies for market share, price and quality of products. Secondly, the trend for customization is growing. Companies deliver highly individualized products to customers in order to increase their competitiveness. This results in an increasing complexity in the development of products and production planning. Finally, environmental regulations, like reducing energy consumption and greenhouse gas emissions or replacement of harmful materials, force producing companies to be highly innovative in developing new technologies, materials and processes.

These challenges lead together with a highly volatile market to new requirements for manufacturing companies. To consolidate or increase the market share, the adaptability of companies has to be enhanced in many ways. The production has to be as flexible as possible to produce highly customizable products in the same production line. Changes in the factory layout have to be performed in a very short time and often with increasing frequency in order to achieve shorter lead times. Therefore, the exchange of data between product development, the digital and physical factory has to be improved. This means that the actual state of the physical factory should be reflected in the model of the digital factory at any time. This enables a faster reaction on appearing problems or failures in the physical factory. Additionally, the organization has to be adaptive as well. Hence, changes in the business processes have to be smoothly performed [1].

The first approaches to organize and provide the product data over the whole life cycle came with the Product Data Management (PDM). Introducing PDM systems enormously reduces the effort to handle product data, but the PDM systems do not consider the processes in the whole product life cycle. Therefore, the concept of PDM was extended to monitor and manage these processes and Product Lifecycle Management was introduced (PLM). The goal is to optimize and standardize the processes to execute them efficiently and therefore save time and money [2, 11].

Additionally, the tasks within a process are supported by software applications. This leads to a faster execution of single tasks and consequently reduces the execution time of the process. However, several problems arise when a high number of applications are installed. One of these problems is the emergence of information silos. Such an IT landscape can often be characterized as distributed, heterogeneous and proprietary. Coupling applications by implementing point-to-point interfaces reduces the problem of information silos, but such solutions get quickly very complex and hard to manage and maintain.

The motivation of our work is to build an architecture, which provides the needed flexibility in the IT landscape for manufacturing companies. The processes within PLM have to be continuously supported by IT systems. These systems have to be loosely coupled to provide the needed flexibility. Existing applications should be integrated into the new architecture. Additionally, the management and maintenance effort of the infrastructure has to be reduced and the availability of data within the product life cycle improved.

To realize such an architecture, a flexible solution is needed to integrate various heterogeneous applications throughout the product life cycle. A commonly used paradigm today is the Service-oriented Architecture (SOA). SOA provides a flexible integration of applications by loose coupling and reusing services, which are self-contained, platform-independent and discoverable [3]. The use of standardized technology like Web services to implement services allows the easy maintenance, extension or exchange of an interface. Moreover, Web services can be composed to workflows, which are modeled in standardized languages like Business Process Execution Language (BPEL) [4] or Business Process Model and Notation (BPMN) [5]. These workflows can be executed by corresponding workflow engines to support the business processes.

Fig. 1
figure 1

Enterprise Service Bus.

The flexible composition of Web services within workflows enables a flexible IT support of business processes, which is necessary to quickly adapt the business processes in a highly volatile environment. The platform-independence of Web services allows exchanging data and information between heterogeneous applications. Relying on standards and loosely-coupled applications simplifies maintaining, changing and extending the IT infrastructure [6].

A common middleware solution to integrate Web services is the Enterprise Service Bus (ESB) [7], shown in Fig. 1. The ESB handles the routing of messages to enable a loose coupling of applications. Most ESB solutions possess a BPEL engine, which is able to execute BPEL workflows. Additionally, the ESB can offer functionality like message queuing capabilities or monitoring services.

This paper presents a service-based integration approach for PLM. The developed architecture is based on an ESB hierarchy to integrate the product life cycle in a modular way. The results of the implemented prototype for the digital factory demonstrates the benefits of the service-based solution. The benefits include the flexible composition of IT tasks, implemented as Web services, in workflows. The workflows support the planner of the factory by automating recurring tasks and saves therefore time and money. Additionally, the management and extensibility effort of the implemented prototype is enormously enhanced compared to the previous solution with customized scripts.

The remainder of the paper is structured as follows: In Sect. 2, the challenges in PLM and the problems of inadequate integration of applications are discussed. Furthermore, the service-based approach for PLM integration is presented and the current solutions in application integration are described. The implemented prototype for the integration of production planning tools is depicted in Sect. 3. In Sect. 4, the benefits and problems as well as further extensions are discussed before related work is presented. Finally, a summary and outlook is given in Sect. 5.

2 Service-Oriented PLM Architecture

An efficient and effective IT support of PLM processes is one of the major challenges in today’s manufacturing companies. Using IT systems, especially in the product development and production planning phase, can reduce the time-to-market of new products tremendously. At the same time failures and ramp-up-time of production are reduced as well as the quality of planning results is improved. Today, the time between deciding to develop a new product and its production start can be further reduced by a seamless integration of the various tools in the product life cycle. These IT systems are often legacy applications or information silos difficult to integrate. In order to enhance the efficiency of production, the challenge is to enable an efficient exchange of information within the plethora of heterogeneous and distributed IT systems used during the product life cycle.

The adoption of the SOA paradigm eases the needed information exchange between heterogeneous applications by using standardized interfaces like Web services and decoupling service functionality from its implementation. Hence, a modular integration of the various product life cycle phases is presented in Sect. 2.2. Modularity reduces the implementation and maintenance effort of the IT infrastructure. Data exchange between the Web service as well as their compositions is accomplished by an ESB. Workflows are capable of automatically executing recurring tasks within PLM and therefore save valuable time, as well as reducing errors.

In Sect. 2.1, the separation of the product life cycle in six phases, which is used in this paper, is presented. The service-based PLM architecture is described in Sect. 2.2 and possible integration of security and safety features are discussed in Sect. 2.3. The ideas of a service-based PLM integration to supply chains are extended in Sect. 2.4. Subsequently, the motivation for an improved data exchange between the digital and physical factory as well as the current state of integration at the Learning Factory’s digital learning shell of the Institute of Industrial Manufacturing and Management (IFF) at the University of Stuttgart is presented in Sect. 2.5.

The architecture for the production planning and its prototypical implementation is given in Sect. 3. This prototype realizes a seamless service-based integration of systems in the production planning at the IFF and eases the data management thanks to automating the data exchange between the applications by implementing the process in a BPEL workflow.

2.1 Product Life Cycle

The product life cycle is heterogeneous in many ways. Therefore, it is split in different phases, each of them represent a characteristic activity. In Fig. 2, the different phases of the product life cycle can be seen. The separation of the product life cycle considers not only the different activities in each phase, but also the support with tools and the management of data.

In the first phase, the concept phase (C), ideas for new products are generated and market analyses are conducted. Therefore, wikis, blogs or social networks are used and often unstructured data has to be handled and interpreted.

The design & development phase (DD) is determined by developing and designing the various parts of the products. Tools like Computer-aided Design (CAD) and Product Data Management systems (PDM) manage the high volume of data within this phase.

In the next phase, the production planning (PP) is carried out, where process and resource data are added to the product data and linked among each other. This data is linked in Digital Factory Tools, which generate a plan for the factory. The planned production processes are simulated with simulation tools to verify the sequence. The data volume, which has to be handled, increases enormously in this phase compared to the design and development phase.

Fig. 2
figure 2

Phases and Tools of the Product Life Cycle.

Once the product development and production planning are completed, the production can start in phase four, the production phase (P). Here, Manufacturing Execution Systems (MES) are responsible for executing the production orders in the production. The control unit provides a real-time control of the manufacturing facilities. Feedback of the manufacturing facilities is gathered and stored by the production data acquisition unit (PDA) for later analysis.

Selling the products, their maintenance and the customers comprise are the main tasks of phase five, the distribution & support phase (DS). Customer Relationship Management Systems (CRM) are used for the linking of sold products and customers for any kind of complaints or warranty issues.

The retire & dispose phase (RD) deals with the disposal of products. Information about assembly and material composition of the product can help to regain valuable material or to simplify the separation of material for recycling.

2.2 Service-Oriented Integration

PLM extends the concept of PDM by adding management and control of business processes for the whole life cycle. The problem today is that IT systems poorly support business processes. Especially the flexible IT support of business processes is of great importance [8]. Therefore, a service-based architecture is needed, which allows to implement a continuous IT support along the whole product life cycle. Additionally, business processes must be adapted in an easy manner as part of the IT infrastructure.

Therefore, a modular service-based architecture was developed with different integration layers, to efficiently integrate the plethora of applications, used in the product life cycle, as well as to flexibly support the business processes. The developed architecture, which is presented in Fig. 3, uses a pillar for every phase of the product life cycle. Furthermore, the six phases are integrated with an additional pillar for the overall PLM [9].

Each pillar is represented by a phase-specific ESB that integrates all the applications of the corresponding phase. These phase-specific characteristics can be supported directly. A distinction is made between phase-specific ESBs and the phase-overlapping PLM-Bus. This solution with multiple ESBs builds a hierarchy to efficiently manage all the processes in the whole product life cycle.

Fig. 3
figure 3

Service-based Integration Architecture for Product Lifecycle Management.

The vertical integration of each product life cycle phase is clearly structured by distinguishing different levels of abstraction [10]. Hence, the functionality and data, provided by each application, is exposed as Web service in small, functional units. These units can be composed to workflows, which support the execution of business processes. The five layers are explained in Sect. 3.1 in more details.

The horizontal, phase-overlapping integration is performed by the PLM-Bus, which connects the phase-specific ESBs as a central backbone. The separation of phase-specific integration and holistic PLM integration contains several advantages [9]. Particularly, the possibility of adapting the ESB to the requirements of each phase like availability, data throughput and time requirements are of great importance.

The PLM-Bus is responsible to manage the phase-overlapping data exchange, tasks and processes. The PLM-Bus should provide information about available Web services of all phases as well as authorization and authentication as a single sign-on service. Processes like change and failure management have to be coordinated by the PLM-Bus. Additionally, Enterprise Resource Planning systems and other applications, which cannot be assigned to a specific phase, should be directly integrated by the PLM-Bus.

2.3 Security and Safety Issues in the Product Life Cycle

This subsection deals with security and safety issues in PML and how the presented service-based architecture can support these issues. Due to the high number of employees involved and vast quantity of different tasks executed in the product life cycle, security and safety management should be naturally supported by the IT architecture. Therefore, a uniform authentication and authorization is needed, which can be provided by accordant Web services. Additionally, a rights and roles management has to be introduces, which restricts the access of each employee to the systems and data they need for their work. For this reason, different security levels were defined, which are presented in Fig. 4 and discussed in the following.

The objective is to securely maintain the product data [11]. The demand for a consistent rights management over the whole product life cycle, including authentication and authorization services, can be accomplished by the PLM-Bus, as the central instance in the service-oriented PLM architecture. This level of security belongs to the Enterprise Level of Fig. 4.

Fig. 4
figure 4

Security levels in the service-oriented PLM architecture.

The other three security levels take place in the whole architecture, that means on the PLM as well as the phase-specific layers. The phase-specific integration of the product life cycle phases reflects an organizational separation of the IT infrastructure, which leads to a naturally defined security level, the Domain Level, because the field of activity of most employees is restricted to a single domain. Therefore, it is sufficient to give them admission to this domain, which can be further detailed on the Service/Application Level. The lowest and most detailed security level is described as Data Level, where access of users can be restricted to specific databases or other data sources.

Beside the access control other aspects like a secure communication of messages has to be considered. For the secure and reliable exchange of messages between Web services, the Organization for the Advancement of Structured Information Standards (OASIS) defined the WS-Security standard, which should be used to sign and encrypt the contend of each message [12].

To ensure data safety, three different approaches are conceivable to backup or replicate the enterprise data. Firstly, each application is responsible for the safety of its dedicated data. Secondly, a data backup is done centrally in each phase, by using a backup service deployed in each ESB. Finally, the safety of enterprise data can be accomplished by the PLM-Bus. This would implicate an uniform backup and replication strategy over the whole IT-infrastructure, but comes along with an increased number of messages to perform data safety.

2.4 Service-Based PLM Architecture Applied to Supply Chains

Previously not considered was the fact, that most companies are not involved in the whole product life cycle. The Original Equipment Manufacturers (OEMs) treat the product life cycle from the development to the recycling of the product. Small and Medium-sized Enterprises (SMEs), in particular suppliers of OEMs, often focus their work on one or two phases of the presented product life cycle. Therefore, a phase-specific integration is often sufficient to cover their whole business area. This is not only profitable for the SMEs, which benefit from the advantages of a service-based IT infrastructure. Especially for the OEMs, the change of the SMEs IT landscape to an SOA can be valuable.

A service-based communication between OEM and SME improves the quality of the data exchange, due to standardized Web service interfaces, workflow definition or data exchange formats. Additional, asynchronous communication eases the loose coupling systems of the companies.

Therefore, the integration of SMEs in the business process of an OEM is useful to have a defined way of communication between the companies. E.g. changes in the design of a product, made by an SME, can be necessary due to inconsistencies in assembly tests of the OEM. The OEM can describe the problems and send them to the SME, where automatically an exposed process is triggered to solve the resulting problem.

Therefore, the presented architecture can be easily extended to manage data and processes in the supply chain covering all involved companies, e.g., from OEM to all suppliers. The challenge would be to convince all suppliers and customers of a company to migrate their IT infrastructure to SOA. Beside the technical challenge it poses an organizational challenge.

2.5 Digital and Physical Factory

Today, one key to a more efficient factory is the coupling of the digital and physical factory. The vision is to have an up-to-date digital copy of the physical factory available at any time. Based on the current state, different simulations could be executed to forecast the short and medium term development of the factory and its production.

The problem is to provide status information of the production environment in real-time to the digital factory in order to automatically run a simulation model out of that data [13]. The presented architecture improves the availability of data in the production environment by exposing Web service interfaces and loosely coupling of applications in the infrastructure, which allows a faster data exchange between the digital and physical factory.

The IFF at the University of Stuttgart has built a Learning Factory, which contains a digital learning shell and a physical factory. The digital learning shell contains many tools for planning and optimizing the digital model of the factory. The central application is a database to store product, process and resource (PPR) data, also called PPR-Hub. Around this PPR-Hub, there are several tools for the factory optimization. Amongst others, there is a layout planning table, where a group of people can cooperatively optimize the factory layout [14]. In the next step, a logistic simulation tool is used to verify the new layout and planned production processes by simulating various scenarios [15].

Currently, these tools and others can exchange data with the PPR-Hub by executing (Visual Basic) scripts. These scripts are customized point-to-point connections. Therefore, the inclusion of new tools or substitution of an existent tool is associated with a great effort. Substituting a tool leads to a complete reimplementation of the script.

The physical factory of the IFF, called iTRAME, consists of modular manufacturing units, which are connected with a universal plug-and-play mechanism and can be easily exchanged [16].

The factory layout of the physical factory can already be automatically detected and copied with a script to the digital planning environment. Due to the high effort for implementing these scripts, no further information is used in the planning environment, e.g. process data and time information of the production. This information would help to understand the current situation in the production, when planning and real data are compared, and thus would enhance the planning accuracy, but also increases the planning effort.

The goal of implementing an SOA is to replace the tight coupling of the applications with scripts by Web service interfaces, which can be flexibly composed into workflows. The workflows can support the planner by automatically or semi-automatically executing recurring tasks in the product life cycle, e.g. when new products are introduced, changes in the product mix are detected, or machine failures appear.

3 Implementation of a Service-Based Integration for Production Planning

This section describes, how the service-based architecture is applied to the production planning phase. Subsequently, the implementation details of the prototype are described, where two applications of the Learning Factory’s digital learning shell were integrated by the presented approach. Therefore, the databases of each application were equipped with Web service interfaces and a web-based portal was developed to control and manage workflows executed in the production planning environment. Additionally, the implemented integration workflow is presented.

Fig. 5
figure 5

Integration Pillar for the Production Planning Phase.

3.1 Production Planning

The implementation of the presented service-based architecture for PLM in the production planning is illustrated in Fig. 5.

Fig. 6
figure 6

Architecture of Integrated IT systems.

Layer 0 contains the various applications of the production planning, e.g. digital factory tools, layout planning table, simulation tools. The data and functionality of the applications is exposed to other tools by means of Web service interfaces, which are placed in Layer 1. The ESB in the integration layer (Layer 2) routes the messages sent and received by the Web service interfaces to the desired destination. Additionally, it performs the data transformations from proprietary data formats to a common message format of the ESB. The business services in Layer 3 compose the Web services to small processes, which manage the data exchange between two applications. The business process layer at the top of the pillar (Layer 4) represents the IT implementation of the business processes.

Web service technologies are platform independent, which is a great advantage when integrating proprietary heterogeneous systems like the current IT infrastructure at the IFF. In the implemented prototype, the messages are exchanged over Message Queues (MQ), which allow a reliable, asynchronous communication between the participating applications and improve the loose coupling of applications [17]. More details on our prototype implementation will be given in the subsequent section.

3.2 Example of Service-Based Production Planning

In the first phase of the implementation, the central data hub, which stores the PPR data, should be integrated with a layout planning tool [14]. The developed architecture is shown in Fig. 6.

The core of this architecture is the Production Planning Service Bus (PPSB), which is based on the OpenESB, an open source implementation of an ESB [18]. BPEL workflows can be executed in the workflow engine of the OpenESB. To administrate the workflows, the Workflow Management Portal was developed, where the production planner can start, control and if necessary restart or stop the available workflows. The usage of the implemented planning workflow is described in Sect. 3.3.

Using asynchronous communication improves the loose coupling between the applications. They do not communicate directly with each other; instead the messages are sent over MQs. An MQ enables a reliable communication between the participants by receiving messages and storing them persistently until the MQ has successfully delivered the message to the receiver. This way, the receiver can be temporarily unavailable without disrupting the whole system or blocking the sender of a message. Therefore, the usage of MQs makes the system more robust against network or application failures and improves the loose coupling of the applications.

In the presented prototype, Microsoft Message Queuing (MSMQ) is used to connect the systems with the OpenESB. To enable the OpenESB to communicate with the MSMQs, an MSMQ Binding Component is provided by the developers of the OpenESB.

To integrate the applications within the architecture, Web service interfaces were developed to enable the exchange of messages with other applications. For the Workflow Management Portal, PPR-Hub and Layout Planning Table a Web service interface was implemented for each. Due to the fact that no source code was available for the Layout Planning Table, the only way to exchange data with this tool was an interface to its Microsoft Access database.

All the messages exchanged in the system rely on the same common message format. Thus, all the messages have the same structure and don’t have to be transformed between the different systems. The only effort is to generate a correct message, including the data provided by the data source. To reduce the effort, a common library that automatically generates the messages in the correct format is implemented to be used by all Web services.

The loose coupling of the integrated applications is ensured by using a content-based router [17]. This means, an application must not know the network address or endpoint of the destination system of a message. The message can just be sent to the ESB, where the content-based router determines the destination by inspecting the content of the message. Therefore, the endpoint can be looked up in a database, when the destination system is known. This allows transferring applications to other servers or changing their endpoints without affecting other applications. The only thing to do is to change the corresponding endpoint in the database of the content-based router and all other applications can communicate again with the changed application. The purpose of the content-based router is to decouple applications and to enhance adaptability.

The presented approach to integrate applications of the production planning allows the production planner to manage the data of the integrated applications at a single point, the Workflow Management Portal. In the portal, the planner can see the available workflows and start, stop or restart them. The portal can be easily extended to include new workflows, when more application are integrated into the infrastructure.

Fig. 7
figure 7

BPMN Workflow for Layout Planning.

3.3 Layout Planning Workflow

The workflow implemented for the prototype controls the data flow between the systems presented in the previous subsection. A BPMN model of this workflow is presented in Fig. 7.

The first task Load Projects of the workflow sends all projects, which are stored in the PPR-Hub, in a message to the Workflow Management Portal. The message is extracted and the projects are presented in the portal.

The user is asked in the second task Select Project, to select the project he wants to modify in the Layout Planning Table. The human icon in the top left corner of the task indicates that a human interaction is necessary in this task.

After selecting a project, the third task Load Resource Data to Planning Table is started, which sends a message containing the selected project to the PPR-Hub. The resource information of this project is thereupon sent over the ESB to the Layout Planning Table and stored in its database.

In the fourth task Perform Layout Planning, the user can perform the layout planning to optimize the material flow, the logistic processes, and so forth. The hand icon in the top left corner of the task indicates that this task has to be performed manually by the user.

When the user finished the layout planning, the last task Store Resource Data in PPR-Hub is executed. This task generates a message to send the optimized planning data over the ESB back to the PPR-Hub, where they are stored and are now available for other systems in the production planning.

4 Review of the Approach and Related Work

The following section summarizes the benefits and discusses shortcoming of the presented approach. Finally, related work is given and compared with the service-based architecture.

4.1 Benefits of the Implemented Prototype

For the manageability of our IT infrastructure approach, this prototype demonstrates great advantages compared to the previously implemented point-to-point interfaces between the applications:

  • The ESB as central integration backbone eases the connection of the heterogeneous applications to this prototype.

  • The use of a common message format reduces the number of different transformations, which leads to a better extensibility and scalability of the infrastructure.

  • The content-based router enables the loose coupling of the applications to the ESB by introducing a central database for the registration of application endpoints.

  • The implementation of MQs boosts the loose coupling at the connectivity layer. Additionally, the robustness of the complete infrastructure is improved against temporary failures of networks or applications.

  • Changing from a synchronous to an asynchronous communication increases the performance by reducing unnecessary blocking of applications when waiting till a message is sent or is available to be received.

  • The platform-independent Web services technology enables unified interfaces to heterogeneous applications and databases as well as their loose coupling in workflows.

Proprietary applications can be integrated in various ways into an SOA. To access the functionality of a program, an available interface can be used or a new one can be implemented, provided that the source code is available. If neither is available, the functionality of a program cannot be easily integrated in a workflow, as in our case. Nevertheless, the data can be accessed by an interface over the program logic or directly over the database of a program. In the prototype the databases of the integrated programs were equipped with an Web service interface which lead to an enhances data exchange between the applications. To fully automate the planning processes, functionality has to be exposed as Web services to be able to execute them within a workflow activity.

Extending the prototype with a simulation tool like the logistic simulation tool would make sense. The optimized layout could be verified by simulating the production processes and the throughput can be measured. Therefore, the simulation tool has to be equipped with a Web service interface to receive the necessary data for the simulation.

The common message format has to be extended to include besides the resource data also product and process data. In the currently used common message format, this extension is already provided and can be easily performed. Additionally, the Web service interface of the PPR-Hub has to be extended to read and write the product and process data. On the other hand, the Web service interface of the Layout Planning Table remains unchanged. Two alternatives are possible, when integrating a simulation tool with a workflow. The presented layout planning workflow can be extended to include the simulation tool or a new simulation workflow can be implemented to control the data exchange between the PPR-Hub and the simulation tool. In the second case, the layout planning workflow and the new simulation workflow have to be executed consecutively.

4.2 Related Work

In the last few years, the main PLM vendors like Dassault Systèmes, PTC and Siemens PLM Software extended their PLM solutions with a service-based approach to get the desired continuous integration of the product life cycle [19]. However, they adopted their own proprietary integration middleware and thus created restricted interoperability properties: they lack possibilities to integrate systems of other vendors, miss flexibility in business process support and applications are not loosely coupled to the integration middleware. Furthermore, the interfaces are not open, so it is hard or even impossible for other software vendors to connect their applications to these middleware systems.

Rantzau et al. implemented a Data Change Propagation System called Champagne for heterogeneous information systems [20]. The Champagne platform manages dependencies between the schemas of different distributed applications. Compared to the presented prototype in this paper, Champagne implements a tight coupling to the participating applications. Hence, each change in a coupled system lead to changes in the source code of corresponding propagation scripts, which have to be performed manually by a software developer or an administrator.

5 Conclusions and Outlook

Highly volatile markets and growing competition force companies to continuously increase their effectiveness. The tough competition, growing customization of products and environmental regulations forces companies to continuously adapt their business processes. The flexibility of the company has to be improved to adapt to the constantly changing environment. This can be achieved by a more flexible support of business processes and the IT infrastructure. Additionally, the applications, which support a business process task, have to be better integrated to improve the data and information flow. The vision is a continuous integration of all applications used during the product life cycle to accelerate the data exchange.

The paper presents a service-based architecture to integrate the different phases of the product life cycle. The phase-overlapping integration is performed by the PLM-Bus, which allows exchanging data and coordinating processes between the phases. The benefits of this architecture are a clear separation between different levels of abstraction as well as the possibility to adapt each ESB to the requirements of its phase such as availability, data throughput and time requirements. Additionally, the integration of security issues in this architecture is discussed.

Furthermore, the developed prototype based on the Production Planning Service Bus performs a service-based integration of the production planning environment at the IFF. The benefits and problems of the prototype and the integration of proprietary applications are discussed, like a flexible composition of Web services in a BPEL process, and an outlook on useful extensions of the implementation in the production planning is given.

The next step in the service-based integration of PLM is the implementation of the PLM-Bus to efficiently couple the production planning and production phase. The goal is to establish a bidirectional communication between the digital and physical factory to automatically adopt the current production status for the planning and to accomplish an optimized planning in the production environment.