Integration of heterogeneous systems based on object-oriented technology

Author: Wu shanrong

Abstract: This paper studies the core concepts of XMI technology, puts forward the XMI integration model of the integrated system, and studies its expression and processing, the information exchange mode between heterogeneous systems based on the XMI model is provided. Workflow technology has produced a wealth of research results in the integration of heterogeneous systems. In this paper, XMI/XML is combined with workflow technology, and a Workflow Model Based on XMI/XML technology is proposed for the integration of heterogeneous systems.
Keywords: System Integration XMI workflow technology

As information technology is applied in the operation and management of enterprises, a large amount of information exchange between different information systems makes system interfaces more complex and difficult to maintain, and becomes the bottleneck of information construction, system integration has become a top priority for Enterprise Informatization Construction. This article describes how to use object-oriented technology to build information exchange standards for enterprises and integrate heterogeneous systems with workflow technology.
It is advantageous to use an object-oriented perspective to examine the resources, information, and business processes in system integration and design the system. The international standard for exchanging metadata between heterogeneous applications is the XMI proposed by OMG, which is the result of the combination of UML and XML technologies. This paper studies the expression and processing of the XMI model of the integrated system, and proposes an application information exchange mode based on the XMI model.
Internal system integration and restructuring can also be seen as a process of Business Process Reconstruction (BPR. Its core is the re-organization of the entire enterprise's internal operation and management chain information process. If the integration of external enterprises and organizational application systems is taken into account, it can also be considered as a combination of the entire industrial chain information process. Workflow technology has rich research achievements in this aspect, and there are still deficiencies. This article combines XMI/XML technology with workflow management technology, and proposes a Workflow Model Based on XMI/XML technology to integrate heterogeneous systems.
1. XMI-based object-oriented information exchange technology
In the process of system integration, application systems are generally heterogeneous on different platforms. Therefore, to exchange information between them, there must be a unified industrial standard for exchanging objects and information in the development environment. In this regard, the Object Management Organization (OMG) has developed relevant standards. The operational standard XMI was initially proposed to use XML to solve the problem of developers exchanging resources between different tools. It became the OMG Recommendation Standard and the basis for Open Information Model Exchange. [1]
XMI declares a developed information exchange model. Technical-oriented developers can exchange program data on the Internet in a standard manner, which brings consistency and compatibility to applications in a collaborative environment. By establishing industrial standards for storing and sharing object information, development teams using different tools can collaborate at the application level, allowing developers to exchange applications, tools, and stored data on the web, create a secure and distributed application for the development environment of the team.
XMI implements integration of UML and MOF (Meta Object Facility) based on XML technology. The XMI standard covers the transformation of UML models and the metadata model of MOF. Defines a standard xml dtd to exchange UML and MOF information. It will also include other fields such as data warehouses, Component-Based openness, and Web Metadata. XMI allows automatic generation of xml dtd for the metadata model. Allow developers of object technologies using different tools to share information on the Internet. XMI plays a major role in application system interoperability. XMI enables XML to transmit important model information between different application environments. XMI is a "stream" standard that can be stored in a file system or extract streams transmitted over the Internet from a database or storage.
XMI has great application value in reality. These technologies are integrated on the Internet to simplify the interoperability between different development tools. For example, XMI enables the model created by Rational Rose to be converted to an XMI file, which can be accepted by Oracle databases, ibm va for Java, IBM DB2, Unisys, and other software. XMI is supported by the knowledge base and database to reduce the time and cost of interoperability in heterogeneous software environments. XMI enables unprecedented knowledge base integration. Storage, exchange, and data extraction allow you to share metadata in a wide range of development scenarios, such as code, data architecture, and data management.

At the beginning of system integration, each participant needs to build XMI and build a unified XMI expression. The application software models used by members of the integrated system are different, and their expressions for their own classes, objects, and other models are also different. Therefore, when exchanging model information, we need a proper way to express it. When integrating the model information exchange of system members, the advantages of XMI in expressing the meta-model are shown through the expression of XMI on the meta-model, various Applications of the integrated system can unify model information at the same level to build the final enterprise XMI model.
Is an instance of the integrated system. Generate an XMI model expression based on the motorcycle model of the integrated system member. Then check the consistency of the model. In this step, models from different applications are unified and XMI models are generated. Then, the XMI model that has passed the consistency check is passed to the next application. The application can generate a schema for information exchange accordingly. Information exchange between applications is performed through XML documents or messages based on these schemas.

Figure 1 expression and processing of the XMI model of the Integrated System

The following is the XMI Expression Code of the motorcycle model.
<? XML version = "1.0" encoding = "UTF-8"?>
<! Doctype XMI System "motor. DTD">
<XMI x mi. Version = "1.0">
<XMI. header>
<Xmi.doc umentation>
Motor model by XMI.
</Xmi.doc umentation>
</XMI. header>
<XMI. content>
<Motor>
<Motor. Make> Jincheng </motor. Make>
<Motor. type> jc125 </motor. type>
<Motor. Year> 99 </motor. Year>
<Motor. Color> Red </motor. Color>
<Motor. Price> 5000 </motor. Price>
</Motor>
</XMI. content>
</XMI>
After XMI is integrated, the information exchange of the integrated system is further optimized. We have added XMI as a metadata expression tool for information exchange to perform certain conversions and ing, thus gaining more flexibility and compatibility between tools ..

Figure 3 XMI information expression and Processing Model

The object model created by applications that integrate system members is first converted to XMI expression by XMI generation tools. This local XMI model is used together with the XMI model applied by other members of the integrated system, and UML design tools such as Rose are used for consistent processing to generate a consistent integrated system XMI object model. At the same time, from the unified integrated system XMI object model using the UML activity design tool, we can generate an effective integrated system information flow model. Based on this model, the iterative development mode of UML can effectively develop XML Information Servers of the integrated system. XML Information Server is a unified interface for Integrating System members to exchange information with the outside world.

2. System-integrated workflow XML Solution
To cope with changes to external environments and internal members, the integrated system must maintain its own adjustment flexibility. Workflow technology studies the automation of enterprise business processing, which provides a good research method for the integration of enterprise application systems. This section combines XMI technology and object-oriented technology to propose a workflow model for an integrated system.
2.1 workflow technology Overview
A workflow is a part or whole of the Business Process (WfMC ). In other words, a workflow automates the process of transmitting text, information, and tasks between participants in a work process based on a set of defined rules for a certain business purpose. A workflow can also be described as a stream of information and control in a business process (or transaction processing process.
Workflow Management System (WMS) is a system environment that supports workflow operation. Typical business processes, such as loan approval, claim processing, and Bill issuance, are represented in workflows, namely, a computer-based business process model, which describes all the parameters involved in completing these processes. These parameters include defining each step (entering the customer information, accessing the database, and obtaining the signature), establishing the execution sequence of each step and the conditions including data flow between steps, etc, the owner of each step and the application software (databases, editors, workbooks) used for each action ). Therefore, the workflow management system (WMS) is a tool set used to define and design the workflow processes and processes to run the environment, as well as the user and application interfaces involved in the workflow process.

 

Figure 4 workflow metadata
WfMC recognizes that a general workflow definition model can bring two benefits: (1) workflow definitions generated by a workflow modeling tool can be executed in multiple workflow running systems (enact ); (2) You can implement collaboration between workflows by outputting a general workflow definition to other workflow systems. To this end, WfMC proposes a workflow meta model to describe the objects, object relationships, and attributes in the workflow definition, so as to form the basis of a Workflow Information exchange format set. Figure 4 is a workflow meta-model. This meta-model is an important reference for workflow management system design. It provides important object categories and relationships between object classes. The traditional workflow theory focuses on sharing and cooperation, but does not consider performance, scalability, and reliability. In addition, the current workflow research has done a lot of research on a single manufacturing enterprise, but there are still some deficiencies in the research on workflow of circulation enterprises and cross-enterprise workflow.
2.2 integrate the system Workflow Management System Model
To implement a flexible and effective workflow management system, a series of key technologies must be supported. This involves the following main aspects: A. XMI-based resource and object definition technology. B. Rules-based workflow engine and monitoring engine technologies. C. Information Exchange Technology Based on whiteboard (shared workstation. D. Rule definition and validation Technology Based on XML/XSL. E. XML server-based information processing technology. F. Web-based communication technology. And so on.
The key point of the combination of XMI/XML technology and workflow theory is that XMI is used to express various resources, organizations, and XML/XSL in a workflow to express process rules.
XMI's ability to express resources is achieved through its ability to express the metadata model. The XMI expression ensures that the resource model can be accurately described regardless of the application resources and provided to other applications with standard XML syntax.
The ability of XML/XSL to express rules is not obvious. Because XML is essentially a representation language rather than a processing language, it is not very advantageous in expressing the process. However, the development of standards such as XSL and XPath has brought about changes to XML. XSL is also a language that complies with XML specifications. XSL documents are also XML documents. It was initially designed to be a language for processing and transforming XML documents, that is, the XML syntax is used to process XML documents. However, in the process of processing and converting XML documents, it is inevitable to use the syntax structure of various programming languages, such as if and when. This gives XML the process description capability. We use this capability to express workflow rules in XML/XSL.
The following is an example of an XSL expression rule.
<XSL: Choose>
<XSL: When test = "Motor [@ price> 2000]">
<XSL: element name = "dispose_process">
<XSL: attribute name = "dispose_type"> special_approve </XSL: attribute>
<XSL: attribute name = "order_no">
<XSL: value-of select = "motor/@ order_no"/>
</XSL: attribute>
</XSL: Element>
</XSL: When>
<XSL: otherwise>
</XSL: otherwise>
</XSL: Choose>

<XSL: variable name = "disposer">/moter_store </XSL: Variable>
<XSL: template match = "Motor">
<XSL: element name = "order_dispatch">
<XSL: attribute name = "disposer">
<XSL: value-of select = "{$ disposer}/sales"/>
</XSL: attribute>
</XSL: Element>
</XSL: Template>

<Motor price = "2500" order_no = "011204"/>

In the preceding example, the XSL template parses the XML order document to generate a processing instruction document for this order and attaches relevant information. This processing instruction document can be sent to the corresponding processing party to complete the processing of the order. The following is a workflow model of an Integrated System Based on XMI/XML technology ..

Figure 6 XMI/XML-Based Integrated System Workflow Model
The model shown in is based on the XML technology and focuses on the workflow engine. Both the client and server use web technology for communication. The workflow engine is a key part of workflow scheduling. We use facilitator to implement it. The reasoning rules used by facilitator are provided by a rule generation tool based on XML/XSL. These reasoning rules are expressed in XML/XSL and stored in the behavior rule repository. The rule generation tool also allows you to edit monitoring rules. These monitoring rules are also expressed in XML and stored in the monitoring rule repository. XML/XSL is used to express rule editing. XML is a standard language for information exchange, and more tools are supported. Rules expressed in XML syntax can be understood and compatible with a large number of third-party verification tools, or accepted by a variety of other applications. [2]
The monitoring system is implemented using agent. Both the workflow engine and it can perceive the changes in the running environment (whiteboard) to determine their own behavior. The action that triggers the workflow engine can be the application action of the client, or the request of the client is triggered by the processing program of the server. [4]
We use an XMI resource generation tool to express enterprise resources. This generation tool can be directly implemented using the XML editor, or the user can set it on a graphical interface, and then generate the Resource Description in XMI format. The XMI resource library, XML/XSL behavior rule library, and XML/XSL monitoring rule library should all be stored in an Object-Oriented XML database.
The workflow engine processes events by calling the XMI resource library on the server. These resource libraries may come from the encapsulated legacy system. Through XMI encapsulation, we can form an XML server to accept engine scheduling. In addition, the resources and services we express using XMI are open, and through the Web, it can provide services for other legal clients outside the enterprise. Note that the resource expression of XMI can be understood and accepted by a large number of tools. [3]

The integrated system Workflow Model Based on XMI/XML technology has the following advantages.
1. Target driver. Ensuring task integrity, correctness, time constraints, robustness, and service quality is achieved by improving the intelligence of the monitoring system. The XML editing tool can be used to compile the rules that the monitoring system follows. These rules can be verified through tools such as Petri Net and automatic mechanism [18], so as to make a correct solution for various situations. It should be pointed out that, although the monitoring rules are described in XML, the XML editor can and should be visualized. You can also use tools such as rose to verify that the model is correct and effective. [5]
2. It is built on the Business Process processing model. The integrated system workflow management system uses XSL technology to implement business processing models. XML does not have sufficient workflow description capabilities. It cannot describe issues such as conditions, but the XSL language provides a good supplement to this. The workflow management system uses the XSL language to support business processing models of enterprises.
3. Integration with the organizational model. The structural characteristics of the XML language are very in line with the requirements for describing the organizational model of the enterprise, and the scalability of XML provides strong support for flexible restructuring of organizational models. Therefore, using XML/XSL technology to construct behavior rules/monitoring rule repository can comprehensively solve the aforementioned problems.
4. Reduce application complexity. XML/XSL rules are readable by machines and people at the same time. The increase in Rule understanding and structure simplifies the expression and processing of rules.
5. Open Standards ensure interoperability between systems. Interoperability can actually be achieved through standards. After there is an information exchange standard, the communication between systems is transformed from a two-to-two correspondence to a standard ing. Through the definition of Enterprise XMI/XML information exchange standards, the semantic and Structure Model of Information System exchange is defined to achieve high standardization and interoperability.
3. Conclusion
The combination of XMI/XML technology and workflow management technology brings great benefits to system agile integration and ensures system interoperability. In essence, the flexibility required by workflows is the strength of integrated system technologies such as XMI and XML. Therefore, their combination has a good effect, which is also natural and easy to implement.

References:
[1] J. e. robbins, D. f. redmiles. cognitive support, UML adherence, and XMI interchange in Argo/UML. 79-89. information and software technology 42 (2000 ).
[2] A. h.m. Ter hosftede, M. E. orlowsja, J. Rajapakse. verification problems in conceptual workflow specifications. Data & knodge DGE engineering 24 (1998): 235-256.
[3] defining the semantics of reactive components in event-driven workflow execution with event histories. Information System 1998, 23 (3): 235-252.
[4] Robert J. glushko, Jay M. tenenbaum, Bauer Meltzer. an XML framework for Agent-based e-commerce. communications of the ACM. 106-114. march 1999/vol42.no. 3.
[5] W. m.p. van der Aalst and. h.m. TER Hofstede. verification of workflow task structures: A Petri-net-based approach. information Systems, 2000, 25 (1): 43-69.

 

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