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Communications in Control Science and Engineering (CCSE) Volume 2, 2014
Research on Data Distribution Service for Aircraft Collaborative Design System Huaxing Bian*1, Yi Zhuang2, Dan Chen3 School of Comput er Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China *1
2
3
nuaa_bhx@sina.com; zy16@n uaa.edu.cn; chendan@n uaa.edu.cn
Abstract Aircraft designing is a complex, multi-disciplinary process, while the applications are separated from each other due to their particular design and analysis tools. The separated applications are unable to meet the collaborative designing requirements. One of the fundamental problems in Aircraft Collaborative Design System is that how to ma ke each subsystem collaborate. The known solutions, using Existing middlewares to unify data formats, are not reliable due to the tightly coupled architecture, poor portability and reusability, large update latency, etc. To solve this problem, the paper propose that apply DDS into Aircraft Collaborative Design System, and give the solution that how to use open source projects OpenDDS in Aircraft Collaborative Design System. Keywords Aircraft Collaborative Design System; Data Distribution Service; DDS; Data Integration
Introduction Computer and information technology has been incessantly i mproved and widel y deployed in the field of aviation. Applications of pri mary disci plines tow ards aircraft designing, such as dynamic an alysis and design, flight mech anics analysis and design, etc., have already achieved great development. However, aircraft designing is a complex, multidisciplinary process, while the applications are separated from each other due to their particular design and analysi s tools. The separated applications are unabl e to meet the collaborative designing requirements. As a result, we need to combine the multi-disciplinary applications by using unified data stan dard and manag ement methods. How ever, the applications are usually built on different platforms, implemented in various operating conditions, and programmed using different languag es, which all results in the “information islan d� phenomenon. Therefore,we need to est ablish an effective information sharing an d interaction mechanism among applications of the heterogeneous systems, an d to offer a designing environment that handles heterogeneous data in a consistent an d uniform way, so that we can eliminate the information islands fundamentally. To build such designing environment, a lot of integration platforms for heterogen eous systems have been developed. Most of the previously known platforms perform the information sharing by middleware technology. Messag es are converted to a certain format by the middleware using a special adapter, sent to the message bus, an d then recei ved by other applications by their adapters. The special adapters det ermine whether or not to receive these messages an d [1] conform them to their own format s . In these kinds of het erogeneous systems, the adapters an d messag e transformation rules in mi ddl ewares are tightly coupled an d lack of extensi bility and generality. Furthermore, each department needs to exchange information between departments and other relevant when there is new data i s generated and transmitted to the need for timely follow-up department, which helps short en the design period. In [2-4] to solve this problem. recent years, man y scholars have proposed many sol utions [5, 6]
The Data Distribution Service (DDS) is a high performance middl eware for predictable distribution of data with minimal overhead. DDS has been stan dardized by the Object Management Group (OMG) to expedite publish /subscribe communications in real-time and embedded systems. OMG DDS specification is increasingly being used to integrate real-world systems. Examples include Air-traffic Control Systems, Navy Combat Management Systems,etc. To solve this problem, the paper propose that apply DDS into Aircraft Collaborative Design System, and give the solution that how to use open source projects OpenDDS in Aircraft Collaborative Design System. Data Distribution Service(DDS) The specification for DDS is divi ded into two distinctsections
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. The first section covers data-centric publish/
Communications in Control Science and Engineering (CCSE) Volume 2, 2014
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subscribe (DCPS) level, and the second section covers the data local reconstruction layer (DLRL). DCPS is the lower layer API that applications can use to communicate with other DDS-enabled applications. DLRL is the upper l ayer of the specification that outlines how an application can interact with the DCPS data fi elds through their own objectoriented programming classes. DLRL i s an optional layer in the DDS specification. For better understanding, the following DDS concepts are briefly stated, some of them are depicted in Fig. 1. Domain
Topic A
Subscriber S1
Publisher P1
DataWriter
DataWriter
DataReader
DataReader
W1
W2
R1
R2
Data transmission channel
DataReader
DataReader
DataWriter
R3
DataWriter
R4
W3
W4
Publisher P2
Subscriber S2
Topic B Associated with the subject：
Affiliation：
Data flow：
FIG. 1 DDS ARCHITECTURE DIAGRAM
Domain, It is a virtual network concept which helps to isol ateand optimize communications among distributed applications that sh are common interests. Th e DDS applications are able to publish and subscribe data if they belong to the same Domain. Domain Participant, It represents the application involvement in the communication plane in a given Domain. It isolates applications running on the same set of physical computers. A Participant operates as a service entry-point and behaves as a container for other entity objects as well. Topic, It materializes the interaction between the GDS and the applications. A Topic can be defined as the logical channel that associates Participants. It is identified by its unique name in the whole Domain. Publisher, It is the object responsible for the act ual data dissemination.It may publish data objects of different types by using different DataWriters (see below). Subscri ber, A Subscriber is an entity responsibl e for receiving published data. It provides the recei ved data to the application. A Subscriber reads Topics in the GDS for which a matching subscription exi sts an d informs the DataReaders (defined below) that data has been received. DataWriter, Applications use DataWriters to write data in the GDS of a Domain through a P ublisher. A DataWriter acts as a typed accessor to a Publisher. Typed means that each Dat aWriter object is dedicated to one application dat a type (i.e. GPS data). DataReader, It notifies an application that data from the GDS is available. For accessing received dat a, the application must use a typed Dat aReader attached to the Subscriber. Quality of Service (QoS), The DDS QoS is a set of data transmission policies that not only controls the use of resources such as network bandwidth, memory, processor usage, etc. but also defines Topic properties such as dat a persi stence, reliability, timeliness, etc. QoS politics customize the DDS service provi ded for application requirements.
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Communications in Control Science and Engineering (CCSE) Volume 2, 2014
DDS can be described as an overlay peer-to-peer structure where the Publishers of a given Topic are linked to all Subscri bers for the same Topic through the GDS. Hereaft er, DataReaders and DataWriters will be jointly referred to as Endpoints. Aircraft Co llaborative Design System(ACDS) The ACDS is the design system for aircraft. Aircraft design is a very complex t ask, which contains a lot of branches. And each branch is quite complicat ed. Therefore, the need for multiple departments or companies collaborat e together to complete.Departmental collaboration model is depicted in Fig. 2. Department A, Depart ment B, Depart ment C need exch ange information timely.For example, department B need the result data of department A, department C need the result data of department B,etc. How timely manner will result dat a to the appropriat e department, is the issue in this article requires Dynast y.
Deaprtment A
Dapartment B
Data
Data Data Data
Data
Data
Department C
FIG. 2 DEPARTMENTAL COLLABORATION MODEL
Aircraft Co llaborative Design System Data Distribution Services and Processes Aircraft Collaborative Design System Data Distribution Services Aircraft collaborative design system aimes at the individual aircraft design process effective converg ence, thus shortening the duration of aircraft design. Aircraft design process design to many branches, making it impossi ble can be done by a single department, which requires cooperation between depart ments. When a department has produced new research than how to effectively and timely follow-up department, is one of the issues to be resolved. An d aircraft design will continue to develop, there will be a new branch of production, so these depart ments must adopt a loosely coupled way integration between software of each department. System architecture is depicted in Fig. 3. Dynamic analysis and design system
DDS middleware Publisher
Subscriber
Aircraft construction analysis and design system
flight mechanics analysis and design system
DDS middleware Publisher
Subscriber
DDS middleware
‌‌
Subscriber
OS
OS
OS
Hardware platform
Hardware platform
Hardware platform
Data distribution platform
FIG. 3 SYSTEM ARCHITECTURE DIAGRAM
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[7]
Considered with demand for aircraft collaborative design system, the paper put OpenDDS in the form of middl eware into the aircraft collaborative design system. Aircraft collaborative design system builds the appropriate topic for the different result of data from different departments. P ublisher sends data to the global data space(GDS) through the datawriter. If S ubscriber needs the related data, it coul d subscribe rel ated topics from the global dat a space. In this way, various depart ments could publish and subscribe of data through the data distri bution platform. In order to ensure quality of service, each entity can configure the QoS provided by DDS. It takes full advantage of application-level quality of service support DDS provides, but also increases the flexibility of the system. Aircraft Collaborative Design System Data Distribution Processes This section gives the system data distribution process: (1)Subscriber create Dat aReader; (2) Subscriber subscri be related topics from GDS; (3)Publisher create DataWriter; (4)Publisher publish data into GDS through DataWriter; (5) Data distribution platform distribute data through network; (6)Remote DDS application receive dat a, and deal with these data then insert into database; Conclusions DDS data-centric data transmission, reduces the degree of coupling between the various sub-system integration. To meet airplane collaborative design loosel y coupled,and timeliness requirements,the paper propose that apply dat a distribution service into the Aircraft Collaborative Design System.In real aircraft collaborative design system we use open source projects OpenDDS, and achieve good results. REFERENCES
[1]
Zhan P P. “Research and Implementation of a ServiceOriented Message Middleware.” Xi An Dian Zi University, 2010.
[2]
Heisey C W, Hendrickson A G, Chludzinski B J, et al. “A Reference Software Architecture to Support Unmanned Aircraft Integration in the National Airspace System.” Journal of Intelligent & Robotic Systems, 2013,69(1-4):pp. 41-55.
[3]
Deng W, Zhao H, Zou L, et al. “Research on Application Information Syste m Integration Platform in Medicine Manufacturing Enterprise.” Journal of medical systems, 2012, 36(4): pp.2289-2295.
[4]
Xie P, Rui Z. “Study on the Integration Framework and Reliable Information Transmission of Manufacturing Inte-grated Services Platform.” Journal of Computers,2013, 8(1): pp.146-154.
[5]
Object Management Group, OMG. Data Distribution Service for Real-time Systems specification, version 1.2, 2007.
[6]
Object Management Group, OMG. The Real-time Publish-Subscribe Wire Protocol DDS Interoperability Wire Protocol specification, version 2.1, 2009.
[7]
Object Computing, Inc. OpenDDS, 2010. http://www.opendds.org.
Huaxing Bian was born in 1989. He has received the B.S. degree in Computer Science and Technology. Now she is a Master candidate of Nanjing University of Aeronautics and Astronautics, Jiangsu, China. Her research interests include information security and network and Distributed Computing. Yi Zhuang was born in 1957. She is a professor and doctoral supervisor of Nanjing University of Aeronautics and Astronautics. Her research interests include network and Distributed Computation and Information Security. Dan Chen was born in 1957. She is an associate professor and doctoral supervisor of Nanjing University of Aeronautics and Astronautics. Her research interests include information hiding and watermarking.
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