| There are many information systems designed for special purpose in companies. They can't intercommunicate and become a set of information islands. But the communications among the different departments are becoming a necessity as long as BPR is growing rapidly. Companies need to connect all the islands and make the knowledge in each system can be fetched by other systems. Enterprise Application Integration (EAI) is just the way to solve this problem. In the past 20 years, EAI has evolved from data integration to function integration, and the to business integration. Using business integration, companies can automate their business process and improve their performance.The Changchun Ideal Information Technology Ltd. has developed an integration platform called Ideal Enterprise Application Integration System (iEAI) to achieve business integration. A workflow mechanism and an open activity model related to this mechanism are put forward in this article to implement the solution of iEAI.Workflow is the core of iEAI. And all the applications related to the business are organized in a workflow, which is used to coordinate their interactions. The definition workflow and execution of workflow in this mechanism is distinguished in order to divide the work of integration more properly. Users can define workflows in an integration development environment called iEAI Studio, and then upload it to an integration server called iEAI Server. When clients call the workflow remotely, it will be executed in iEAI Server. Thus the corresponding business process is performed. An open activity model is also provided. It's the protocol between outer applications and iEAI. Vendors can provide their own activities, and they can also use their implementation to overwrite the attached activities.A flow chart is used to describe a workflow in iEAI, vertexes for activities and edges for execution sequence An activity can be connected to several activities. They can be executed sequentially or be executed conditionally. When conditions are encountered, the following activity should be selected in corresponding to the output of the activity running currently. There will be some activities should be executed parallel and iEAI organized them in a parallel structure to maintain the routes among them. There would also be some loops in the chart and iEAI would characterize them in a loop structure. The inputs of an activity maybe influenced by its former activities, so users should set the rules for data transfer. iEAI Studio is the tool for workflow definition. We draw flow chart in it and a description file is also generated automatically. All the information related to the workflows is stored in this file, including the activities, the control flows and the data flows between this activities.Workflow engine can parse this file and execute the workflows in it. It should provide the environment for the execution, too. When a client call a workflow, the engine will open the file, create an instance of the workflow and then execute it. Workflow engine should load the implementation of involved activities and create their instances. Workflow engine calculate the inputs by defined rules, call the activity and then receive the result. And then the succeed activity will be found according to the flow chart and the outputs. Multi-users can call one workflow simultaneously. Workflow engine will start one thread to a request from the client. All these thread are independent and won't influent other executions.All steps in the business process are performed by activities. Through activities, iEAI can interact with outer application systems and data sources. All activities should follow the activity model. The activity model provides the rules that all activities should follow. Studio can get the configuration,parameters of an activity. It can also connect related activities by the business process and establish the data transfer rules. Server should be able to provide inputs for an activity, call the activity and get the output of the a...
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