| Along with the development of medical information,digital hospital is becoming a new trend of modern medical development.The "three in one" integrated digital hospital information system consists of hospital business software,digital medical equipment and computer network.This system makes great contribution to integration of hospital resources and improving the service.In the past,the connection of information systems of different hospitals mainly relied on open databases,which can not adapt to large numbers of newly emerged digital medical equipment.The United States first proposed the HL7 standard to let down the bars between various equipments,which have already been widely used.In fact,HL7 is becoming a Prevailing standard of medical and health information delivery.HL7 standard is located in the seventh layer of OSI model,which is also known as the application layer.The original intention of HL7 is integration of the medical information scattered in devices at the semantic level.The latest proposed HL7 V3 is an application of unified process combined with object-oriented modeling.First,the message development framework has been built based on unified process to guide and standardize the direction of the system.The definition of the message model structuralized the messages of medical services system.Message development framework is divided into three categories according to the different content,range of application and intention of messages,which are reference information model,domain message information model, refined message information model.Finally,according to the data type of the programming language,the data type has been built which meets the needs of data representation of special medical environments.XML was recommended as the cartier of messages.HL7 V3 is not only of great significance to build medical message models but also irreplaceable golden rules in other fields.HL7 V3 is too superior to straight fit into existing medical systems.We need a message platform to reuse the existing functions without redesign the whole system.This paper developed a message platform to integrate heterogeneous system.This platform remains the existing system,adds a middleware to handle message processing and business processing.The message platform response the message in two different ways which are original confirm mode and enhanced confirm mode.In case of the former,when the server receives a message it requests the immediate processing and response.As to the enhanced confirm mode,when the server receives a message,it will send back a confirm message first.After the delayed processing of the original message,the server will package the result and send it back to the client.The core model of message platform including message configure model,message transmit model,message construct model,database operation model and HL7 message configuration model.It receives all the messages from the systems and analysis these messages before the database operation model visiting relevant databases or routing for the transmitting messages.Message configure model communicates with systems which do not meet HL7 standard.HL7 message configuration model communicates with those who meet the Standard.It creates relevant HL7 messages.Or it creates HL7 message according to the update message and then sends them.It also processes HL7 message and sends out instructions and data.During the implementation of message platform,we face two main problems:1.when the services provided by the platform can not satisfy clients,we need to add new services dynamically.Yet,we have to fit this new service into the original flow.2.Hypothetically,certain device had a temporal breakdown and we need a new device to take its place.In order to solve these problems,we proposed a way to minimize the cost of system transfer based on dynamic configuration.There are formal methods and non-formal methods in researching dynamic configuration.Formal dynamic configuration mainly starts at analyzing phase to introduce mathematical instruments to reassure correctness of the program.In this way,consistency of the system can be assured.Unfortunately,the formal methods are just an ideal suggestion in theory.The non-formal methods use XML to describe application system and its configuration changes.It is becoming a widely used practical application.The non-formal dynamic configuration methods include recovery methods;avoid methods and universal dynamic configuration frame.It is easier to realize the avoid methods.It has already been widely used,such as Jeff,Goudarzi and XRMI.But,these methods are all lack of certification model to evaluate the changes of the system caused by transferring components.Based on the theory of soaking and the relationship between activation transform function and threshold function,We have built a evaluation model to evaluate the changes that are made to the system by changing components.This model contains more state information,thus it can describe the changing system more precisely.We apply the original Blondel method to evaluate the influence caused by transferring components during dynamic configuration.This combined with Jeff is applied to the dynamic configuration of message platform.The message platform decides the set of influenced devices when it needs dynamic configuration.It provides the route to send an update message to those influenced devices according to configuration files defined in advance.Clients will response to this update,if they agree to receive the message;the client will be added into the update queue and compute the influence using Evolution Score algorithm.Eventually the message platform loads a configuration file.Based on the UID code find the device that needs dynamic configuration,and add it to the unified scheduling.Then send out the update to finish the dynamic configuration. We have built a message platform to integrate existing systems.Using application of dynamic configuration we can deal with request changing during running time.Evolutions Score has been used to evaluate the influence caused by the system changes.It should be paid attention to that HL7 V3 is just like.NET and JSR.They are all application protocols applying using in different fields.What has accomplished in this paper is part of the implementations of HL7.In the future,we will concentrate on combined with the latest technology to develop a better message platform which conforming to the HL7 standard. |
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