A Structural Model Of G Language & Its Platform Implementation

As one direction of the future instruments, virtual instrument (VI) is the infiltrativeresult of the computer and measuring instrument technology. User defined and software istwo main features of VI, whose purpose is to reduce development time to increase uservalue. Graphic Language (G Language) is one of visual languages for building VI systemrapidly and stably. Its implemental platform has been applied over 10 years. However,the graphic theory of the data structure model and operation mechanism is still in aprimary phase, and the researches on G language override and distributed framework aremuch fewer, which even lacks of a suit of mature and authoritative theory. It is veryimportant to do the research and develop advanced and achievable G language and itsdevelopment platform.We study the structure and operation mechanisms for G language on thebackground of science instruments project of the national science fund, science leadingproject of Jilin Province and innovation fund of Jilin University. This thesis presents aset of achievable data structure model for G language, and on this basis we expand Glanguage functions. We implemented that node function override and distributedframework. As a basis, we researched and developed a graphical development platformfor virtual instrument called LabScene, and we validated its functions in teaching andengineering applications. Because of its simple visual operation, the students andresearchers can create VI systems rapidly based on this platform to meet theirrequirements.Compared with the other international implements of G language, this model hassome new design concepts and functions in theory, structural running and functionalexpansion:1. On the basis of the simulated hardware and the advanced language functionswhich are to be achieved, the author makes a summary of the hardware virtual model. Theprogramming environment accords with user's habits after we get the basic elements ofthe G language. Using orthogonal trifurcate tree to describe the entire connection-wireflow as ordinary circuit diagram links, we discover it is true that the direction of data flowhas a good description mode. These have helped to get its essence for the structural designof the G language.2. The syntax of G language can be described by two kinds of relations: datadirectional relation based on dataflow and controllable relation of procedural control.Single AOV network and existing tree model can not express these double relations of theG language well. This thesis educes a new concept of brother AOV network from layergraph and brother graph, which is a subset of the former, then we can solve the problemand realize the right control as data flow interpret, for loop, case control, sequence andsub VI. G language running model is realized by combining sorting brother AOV networkwith rules of node relation transmit.3. Aimed at the graphic language specific data requirements, a kind of newmemory allocation and management algorithm based on two-dimensional link-table ispresented in this paper. Based on allocation and management for basic data type andcomplicated data structure as array and cluster, it realizes the data generation and lifecycle management, completeness of data information and independent character. On thepremise of not sacrificing operational efficiency, the algorithm can run firmly for a longtime, and avoid producing the memory fragments effectively. This algorithm plays a keyrole in the G language interpreter and running model.4. The general graphic language is run and driven by a dynamic pure dataflowwhich ties up systematic resource, limits the real time performance and is unable tointegrated message-driven operating system well. This thesis presents a message drivesrunning model, combining the message execution mechanism and running rule, which canrealize analysis and run graphic program. So it can be guaranteed from functioncompleteness and has good real time performance. The user can request to be respondedtimely, and to be provided a new model for graphical debugging and operation.5. Solution to functional override of G language and third-party nodes joined:Users can describe their own creation nodes dynamically in a standard XML way and theexisting nodes can be replaced by what you want to achieve. The solutions of thefunctional override for G language are realized which are absent in other realization.6. Technology applications with XML data description: XML is used to describethe information for persistence and dynamic creation of class architecture, standardizationand third-party nodes, and both local and distributed nodes exchange data, sub-VImodular. This thesis offers a new class libratory and information described solution, toensure the system's openness and expansion.7. Network framework based on multi-layer: The intermediate server, a netresource management, is added to LabScene system which can receive passively andsearch net resource in network actively. It needs to be satisfied with standard and will beused in LabScene graphics environment without difference. To improve communicationwithin many developers and managers, LabScene integrates the text, files, audio, videoand stream to exchange information.Practice has proved that: on one hand, this structure model of G language and itsplatform, LabScene, can realize to develop VI with G language and have a flexibledevelopment capacity as advanced language. On the other hand, G language can be usedto realize function and position transparency in G language override and distributedapplications.The theoretical research work for G language in the international fields is a new topic.These theories have been explored and made some preliminary achievements in this field,which can be used as academic foundation for VI platform development in structuremodels, running and expansion framework. In fact, these achievements not only can beused in VI, but also provide reference in other basic platform and distributed system.