- Email: [email protected]
server architecture
Computers ind. Engng, Vol.31, No, 3/4,pp. 603 - 607,1996
Pergamon
Copynght© 1995~ MadunePress Publishedby ElsevierScience~ Printedin GreatBritain S0360.8352(96)00290-2 0360-8352~96 $15.00+ 0.00
HIT-lIP: AN INFORMATION INTEGRATING PLATFORM FOR CIM SYSTEM BASED ON CLIENT/SERVER ARCHITECTURE WangGang X u X i a ~ GaoGumn Hafoin Institute of Technology P,P,. China Abstract: This paper prescmO a plan of an informmion integrating platform based on the client/server ~ , named HIT-lIP which developed in Harbin lnsUtme of T e c l ~ 01IT). The function structure, the system architecture and the dma0ed implemcmmion plan ~ the Hrr-HP are proposed. Keyword: Computer Integrated Manufacturing, CIM Integrating Infrastructure, CIM Open Architecture, Iuformmion lmegrming Plmform, ClienVServer. 0. INTRODUCTION Computer intqrated ~
(CIM) technology is a philosophy for manufacturing to enlmncc the product/~'ty,
the eomomical bemflt and thc market comlmi~ ability of entmprim by memm~imeoming infmmmion, resources, human and oqpm/zatiom of an ~ . Thc information intesrmion is tbc kcy to:hnology in a CIM systmn which is compmed o( wplicmi~ sysunns, devices and human. T h ~ arc many typm of informati~ in an ~ ~ m
t~
dam, mb~, s m p ~ and ~
dam, modeJ, mmhod, pmc~b~ and knowkxlse with ~ ~
~
mchnology. Add/tionally, information is processed in a d/strib.__,~__mndronmcnt which is built om the h e ~ o o m ~ networks. So the i m ~ i o n i n , grating plalformmwhich iMovides a ~ ~ m ~ stemSc, manasem~t, p r o c ~ communication mid service interface of the informmlon plays an important role in a C I ~ symem. Many integrating platforms have been presented in resmut years [1], such as CIM-OSA-HS (CIM Opea Systmn A~hitecture Integrating ~ [2], SAP. [3], CIM-BIOSYS [4] and UNITY [~]. In these platforms, CIM-OSAHS which developed by European ESPRIT project is a l i f e , , c y ~ r i ~ ~ plalfonn which provides the computer smvices for the d e v e ~ implcmentmiou and operation of a CIM sTmem. With its complete, open, slandardized and fommlized represeala~n, CIM-OSA-IIS becomes one ef the best CIM integrating platform in the world [6]. CIM-OSA-HS represents an enterprise by means of four views: function view, information view, resource view and or£ani~ation view. CIM systmu is built and rims on the basis of the cntea~rise model which is consists o/"these views.
The buiklins and the nmning of the CO~/sysu~ arc suppona/by the CHvi.OSA.HSat each phnmc ~ ~ ~ through a set odr common serviccs. However, thc information service provided by CIM-OSA-IIS and all oth~ intcgrMing platform is not sufficient and elr~icnt. Their system au~hitcctu~ function mrucu~ should be improv~ and dmaikd, so that 8m informat/on integrating platform can process more types o~ information and can provide manS~ information scrvicc. On the basis ~ the CIM..OSA-HS standard framewo~ we defined a ~ type of information integrating platform based on the clien~serve~ technology, the HIT-HP. This paper _~&,~cri_ "bes the key points on the plan of the HIT-IIP. 1. FUNCTION STRUCTURE OF THE HIT-lIP
AS a symem-wide,dimribuu~ inteoating pimfonn, the HIT-I~ have two envinmmmm: the applimtiou mvirmunem (AE) and the s u p p ~ mndromnem (SE). The AE is the CIM modeJ_in=s and opmmion environmcm in which distributed function entities (such as application so,rares, b,,nmn and machines) are nvming and access the integnuing services through the HIT-UP service inter~ce. The SE includes the distributed computing platform, the dam processing system, computer networks and operating system to support the implementation of the integrating platform. 1.1 Function Structure o~ the HIT-lIP In order to support the information integration, the HIT-lIP should provide the following functions. The first is the processing functions. The HIT-lIP should havc the abilities of processing and controlling all the types of modeling and olm'atJon procedure in each phase of the system life-cycle. The second is the representation functions. The HIT-IIP should represent the four views and the information in these views in the HIT-lIP seavice system. The third is the information functions. The HIT-lIP should provide information processing services, e.g. system-wide distributed data 603
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18th International Conference on Computers and Industrial Engineering
and exchanging. ~ dam dictiommy/dirmory maintenance, schema convmin~ controlling of the permimion and controlling of the information integrity and consisting. The forth is the communicUion functions. The HIT-I~ should provide o ~ n ~ i c a t i o n services for the ~ o n among the distrik_._~ function entities in a CIM system and among thc distributed smvice entities in the HIT-rIP ~ e.g. transparent a ~ e u to the remote fiugtiem emtities, Iranspment data ~ in the IgtemSenams netwmk, communication protocols in/out ~ the Hrr-m,. The fif,h is the controlling functions. As an ~ w i d e operating system, the H1T-IIP should plrovide lhe fBciliti~ about CODllil~Dt globltl ~ _ t t t y l _ oontroifil~ m u i f i - p ~ ~ conlLrollin~ ~ ' ~ COGLrollin~.~ ~ call c o n U o ] ] ~ ~ so OIL The sixth is the intel"faGcflmcfioM. The I'][]TlIP shoukl pmid~ tl~ m~-friendly, unified and comist~t ima'facc at wh/ch funct/on ent/tics in ~ ~ ~ ~
.av/ca pmv/d~ by ~h~m'r-~. 1.20rsuizafion of the H r r - I ~ To provide the above functions, the HIT-lIP contains four classes of services. Business process services provide the function M"the system-w/de represent!ion, execution, processing and controlling of business proccsscs, and systemwide service-thread controlling service for the system-wide service distribution. Information services provide the system-wide oontrollin£ fulgtions of the representation, storage, access, management, integrity, cotlsistelgy and security of various data/information including engineering data, knowledge, procedure, method and model. Front-end services perform the interact/on between the HIT-I~ and various function entities in the cnterprise, n m m ~ the enteqpt~ resources for the enteq~rise belmviors and processes, and provide system-wide m ~ t interface between the HIT-HP and function entities in AE. Communiclion scrvices provide the function of the system-wide data exchange and process commum~cationinteraction with mmputer networks. The organization of the H1T-HP involves the service contained in each class of services and a set of communication protocols for the inte~ction between them. Business process services consist of the business process control semce (BC) which controls the execution and distribution of business p ~ (BPs) in order to comol the behavior of cntmprism and controls the system-wide grvice-thrmd in order to manage the distribution of the smvices for function maitim, m t e q a ~ activity control service (AC) which controls the execution ~f entmlnise activitim (EAs) in ord~ to organize and control the function operafimm of en!enprism, resource management service (RM) which manages the resources of a CIM system for the s~hfd,,tin~ alld ~ o n of BPs and EAs. From-end services consist ~ human frontend service (HF) which provides a ommistent user-machine interfa~ nughine front-end service (MF) which handles all ¢ffthe machines in a CIM system, and appliam'on front-end servi~ (AF) which handlcs all of thc application function enfit/es in a CIM symem. Commun/cat/on services consist of system-wide exclumge seavice (SE) which suppom system-wide d.,~, exchanging and local cquipmeat at~em, and omnmunication management service (CM) which provides trmmixuent access to CIM networks. Information services consists of symem-wide information service (SI) which is in charge of global data management (includin£ all types of information), data acceuing, schema ceaverting and ~t~ integrity controlling, data management service (DM) which is used for local data accemng and mamsenma by supponi~ af database managengnt systmm, knowloige ~ t servic~ ( K ~ which is used for the reprmmmion and p_roce~___'ngof knowkdgc information in CIM system and maps the Imowl~lgc processing request to the knowledge-base system or other knowledge management system, method nmnagement segvioe (MeM) which is used for the storage, management and usage of all types ~f mmhod (including math algorithm, system procedure, common program, etc.) in CIM systems based on the method database management system, model ~mn%g¢~nt service (MoM) which is umi for the storage, representation and management of models in the CIM systems based on the _mode__~! database m n a m:mmt system. The or£aniTJttionof the Hrg-IIP is shown in figure 1. The intem:tions bctwcgn these sendces and between the HIT.lIP service systenm running in different network nedes are perfomed by means of communication protocols. There are four types of protocols: server protocol, access protocol, agent protocol and external protocol. The different services in the different nodes interact with each other through smve~ protocol. The same tylgs of service in diffment nodes co-operate through the agent protocol. The different tyix= of services in the same node interact with each other through the access protocol. The interaction between function entities and the H1T-IIP services is achieved by the external protocol. The external protocols are the object-oriented, progratnmahle segvice interface at which function entities access the HIT-lIP services. 2. CLIENT/SERVER ARCHITECTURE In CIM-OSA-IIS system, the configuration in each computer network node must conta/n a whole services system evcn if the hardware confisurafion of these nodes is ~ n t . That means all nodes must have the ability to install and execute the CIM-OSA-IIS. The HIT-11P adopts client/server technology as its system architecture to provide flexibility c~the system configuration and more powerful information processing mcchanism which can bc shown in figurc 2.
18th lnternalional Conference on Computers and Industrial Engineering ...°". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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One mvef4ode and some ~nt-nodes attached to the sea~er-node d~Cdy form a s e ~ . One server-node can pmvkk servk:es for many client-nodes and one c~ent-node can obUun ser~ces from many server-nodes. Clieat-node
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18th International Conference on Computers and Industrial Engineering
access services from server-nodes in other service-cells through the set,r-node in its own service-cell. Server-nodes in the different service-cells interact with each other in the same way. The HIT-liP service system nnming on the stayernode can be also a client if it calls other server-nodes to provide services for it. So a client-node is always a client, but a server-node may be both server and client. The client receives service requests which come from function entities. However, it is -n~_le to process them because of the lacking of the business process services and the information services. It must pass the request to its server-node in the same service-cell and then passes the results returned by the server-node back to the function entities which commit the request. The server also can subcontract the service task to other servers called sub-servers in order to distribute the service in the system-wide and this forms a service-thread for the request. The selection of the server and sub-servers is made by the server itself accordinE to the condition of the dynamic system load, system configuration and system resource constraints, and this is ~nsimrent to function entities. The interaction between the client and its sem~r or the server and its sub-servers is performedby the server protocols. Function entities do not know where the scarer is even if the node on which the client is running is a server-node. The fimction entity interacts transparently with a logical server on its node. This can be illustrated by figure 3. Client Client-node I FuaceeaEnety [
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F: Fmnt-e~l Services B: B - . ~ i ~ Process Services I: Information Services C: Communication s e r v i ~ Fig.3. The structure of the logicalserver 3. SERVICE THREAD For the implementation of the client/server architecture, we define the service-thread as the system-wide service and scheduling unit which links the client and its servers together. The service-thread is a logical server to the function entities, and is created and controlled by the server in the same service-cell. The controlling strategy of the servicethread can be described as the following. When a server receives a service request from a client, the server cry_t_~ a global service-thread which points to its client for the request. When some sub-servers are selected by the server, these sub-servers create a local service-thread which points to the server and the server links these sun-servers to the global service-thread. So the server controls a service-thread tree illustrated by the figure 4. A server can processes multiple service-threads and a server can be tied to multiple clients at the same time so that onc client can assess multi setwrs for its multiple requests and one server can serve for multiple clients at the same time too. The controllinE of the service-thread is the key technology for the client/server architecture. As the system-wide operation and distribution controller, the BC, actually its service-thread controlling functional unit(BC-TC-FU), is responsible for the controlling of the service-thread. To provide the function of the system-wide service-thread controllinf~ BC-TC-FU should provide the following functions, Request registration functions which register the service requests from function entities into a request table in order to process them. Server selection functions which select servers or rob-servers for the client by means of some optimiTs,ion algorithm. Thread management functions which create and operate the service-thread end/or a sub-service-thread, copy and/or transmit them to other server to distribute the service in system-wide. Thread controlling fimctions which control the integrity and consistency of the service-thread in client and its servers as the system-wide controlling object. Thread removing functions which pass the result back to the function entity, untie all servers, remove the service-thread and the service request. The processing workflow of service-thread is described briefly as follow. When a function entity issues a service request by means of external protocol, the front-end services of the client receives the request and pass it to the BC in its server-
18th International Conference on Computers and Industrial Engineering rode within the s i n e ~vice-ceil. The BC ~ the ~
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The information integrating platform is a basic ~ environment to the CIM system of an enterprise and provides the basic infommfion pnxzssin& bes/ness pmceu coatmU/ag and mmmunicat/on servi~s for the ~ af an e n t e r p ~ throesh a set of common servioes tyste~ Ceesidm~ the development ~ relevant tecimolollYsuch as intenisent m n u f a c t e r ~ k n o w k ~ e n S i , e e r ~ ctieat/suver ~ , etc., we det~ and improve the CIM-OSAHS framewo~ aud propose the plan e/'the I-IIT-HPwhich is a plan of an opea integrating p l a t f ~ ~ on ~ ~ . OSA standard framework and the implementation approach based on the clieat/serve~technology. REI~I~NCE:
1 T. L Williams et. al. ArchqecUlre for In~gr~in~ Manufacturing Activities and Enterprise. Proceeding ~ 12th WoHd C c q F ~ ]FAC, Sydney: 1993. 2 ESPRIT ~ u m AMICE. CIM-OSA Arc,hitecture Dw~l~ion. AD 1.0. Belgium: Springer-Verlag, 1991 3 E.F. Wheel~ & A. G. G a n ~ Introduction to Sy~___em~ Architec~-e. IBM System J., 1988,27(3). 4 A. Ryan, eL al. ModeilinS and Implementati~ c/" lafonnafion Driven Manufacturing Control System. Prec. of ICCIM ~ . , Siasalmre: 1991. 5 C. G. Park. Trend Towards Open Architecture Control System for Developing Countr/es. Proc¢~_i-~. of 12th World WAC, Sydney: 1993. 6 Xu Xiaofei, eL al. Architecture and System Design for a CIM Integratin~ ]nflastnicU~. J. of Harbin IItitut¢ of Teclmoiogy, 1995, 1(2).
Pergamon
Copynght© 1995~ MadunePress Publishedby ElsevierScience~ Printedin GreatBritain S0360.8352(96)00290-2 0360-8352~96 $15.00+ 0.00
HIT-lIP: AN INFORMATION INTEGRATING PLATFORM FOR CIM SYSTEM BASED ON CLIENT/SERVER ARCHITECTURE WangGang X u X i a ~ GaoGumn Hafoin Institute of Technology P,P,. China Abstract: This paper prescmO a plan of an informmion integrating platform based on the client/server ~ , named HIT-lIP which developed in Harbin lnsUtme of T e c l ~ 01IT). The function structure, the system architecture and the dma0ed implemcmmion plan ~ the Hrr-HP are proposed. Keyword: Computer Integrated Manufacturing, CIM Integrating Infrastructure, CIM Open Architecture, Iuformmion lmegrming Plmform, ClienVServer. 0. INTRODUCTION Computer intqrated ~
(CIM) technology is a philosophy for manufacturing to enlmncc the product/~'ty,
the eomomical bemflt and thc market comlmi~ ability of entmprim by memm~imeoming infmmmion, resources, human and oqpm/zatiom of an ~ . Thc information intesrmion is tbc kcy to:hnology in a CIM systmn which is compmed o( wplicmi~ sysunns, devices and human. T h ~ arc many typm of informati~ in an ~ ~ m
t~
dam, mb~, s m p ~ and ~
dam, modeJ, mmhod, pmc~b~ and knowkxlse with ~ ~
~
mchnology. Add/tionally, information is processed in a d/strib.__,~__mndronmcnt which is built om the h e ~ o o m ~ networks. So the i m ~ i o n i n , grating plalformmwhich iMovides a ~ ~ m ~ stemSc, manasem~t, p r o c ~ communication mid service interface of the informmlon plays an important role in a C I ~ symem. Many integrating platforms have been presented in resmut years [1], such as CIM-OSA-HS (CIM Opea Systmn A~hitecture Integrating ~ [2], SAP. [3], CIM-BIOSYS [4] and UNITY [~]. In these platforms, CIM-OSAHS which developed by European ESPRIT project is a l i f e , , c y ~ r i ~ ~ plalfonn which provides the computer smvices for the d e v e ~ implcmentmiou and operation of a CIM sTmem. With its complete, open, slandardized and fommlized represeala~n, CIM-OSA-IIS becomes one ef the best CIM integrating platform in the world [6]. CIM-OSA-HS represents an enterprise by means of four views: function view, information view, resource view and or£ani~ation view. CIM systmu is built and rims on the basis of the cntea~rise model which is consists o/"these views.
The buiklins and the nmning of the CO~/sysu~ arc suppona/by the CHvi.OSA.HSat each phnmc ~ ~ ~ through a set odr common serviccs. However, thc information service provided by CIM-OSA-IIS and all oth~ intcgrMing platform is not sufficient and elr~icnt. Their system au~hitcctu~ function mrucu~ should be improv~ and dmaikd, so that 8m informat/on integrating platform can process more types o~ information and can provide manS~ information scrvicc. On the basis ~ the CIM..OSA-HS standard framewo~ we defined a ~ type of information integrating platform based on the clien~serve~ technology, the HIT-HP. This paper _~&,~cri_ "bes the key points on the plan of the HIT-IIP. 1. FUNCTION STRUCTURE OF THE HIT-lIP
AS a symem-wide,dimribuu~ inteoating pimfonn, the HIT-I~ have two envinmmmm: the applimtiou mvirmunem (AE) and the s u p p ~ mndromnem (SE). The AE is the CIM modeJ_in=s and opmmion environmcm in which distributed function entities (such as application so,rares, b,,nmn and machines) are nvming and access the integnuing services through the HIT-UP service inter~ce. The SE includes the distributed computing platform, the dam processing system, computer networks and operating system to support the implementation of the integrating platform. 1.1 Function Structure o~ the HIT-lIP In order to support the information integration, the HIT-lIP should provide the following functions. The first is the processing functions. The HIT-lIP should havc the abilities of processing and controlling all the types of modeling and olm'atJon procedure in each phase of the system life-cycle. The second is the representation functions. The HIT-IIP should represent the four views and the information in these views in the HIT-lIP seavice system. The third is the information functions. The HIT-lIP should provide information processing services, e.g. system-wide distributed data 603
604
18th International Conference on Computers and Industrial Engineering
and exchanging. ~ dam dictiommy/dirmory maintenance, schema convmin~ controlling of the permimion and controlling of the information integrity and consisting. The forth is the communicUion functions. The HIT-I~ should provide o ~ n ~ i c a t i o n services for the ~ o n among the distrik_._~ function entities in a CIM system and among thc distributed smvice entities in the HIT-rIP ~ e.g. transparent a ~ e u to the remote fiugtiem emtities, Iranspment data ~ in the IgtemSenams netwmk, communication protocols in/out ~ the Hrr-m,. The fif,h is the controlling functions. As an ~ w i d e operating system, the H1T-IIP should plrovide lhe fBciliti~ about CODllil~Dt globltl ~ _ t t t y l _ oontroifil~ m u i f i - p ~ ~ conlLrollin~ ~ ' ~ COGLrollin~.~ ~ call c o n U o ] ] ~ ~ so OIL The sixth is the intel"faGcflmcfioM. The I'][]TlIP shoukl pmid~ tl~ m~-friendly, unified and comist~t ima'facc at wh/ch funct/on ent/tics in ~ ~ ~ ~
.av/ca pmv/d~ by ~h~m'r-~. 1.20rsuizafion of the H r r - I ~ To provide the above functions, the HIT-lIP contains four classes of services. Business process services provide the function M"the system-w/de represent!ion, execution, processing and controlling of business proccsscs, and systemwide service-thread controlling service for the system-wide service distribution. Information services provide the system-wide oontrollin£ fulgtions of the representation, storage, access, management, integrity, cotlsistelgy and security of various data/information including engineering data, knowledge, procedure, method and model. Front-end services perform the interact/on between the HIT-I~ and various function entities in the cnterprise, n m m ~ the enteqpt~ resources for the enteq~rise belmviors and processes, and provide system-wide m ~ t interface between the HIT-HP and function entities in AE. Communiclion scrvices provide the function of the system-wide data exchange and process commum~cationinteraction with mmputer networks. The organization of the H1T-HP involves the service contained in each class of services and a set of communication protocols for the inte~ction between them. Business process services consist of the business process control semce (BC) which controls the execution and distribution of business p ~ (BPs) in order to comol the behavior of cntmprism and controls the system-wide grvice-thrmd in order to manage the distribution of the smvices for function maitim, m t e q a ~ activity control service (AC) which controls the execution ~f entmlnise activitim (EAs) in ord~ to organize and control the function operafimm of en!enprism, resource management service (RM) which manages the resources of a CIM system for the s~hfd,,tin~ alld ~ o n of BPs and EAs. From-end services consist ~ human frontend service (HF) which provides a ommistent user-machine interfa~ nughine front-end service (MF) which handles all ¢ffthe machines in a CIM system, and appliam'on front-end servi~ (AF) which handlcs all of thc application function enfit/es in a CIM symem. Commun/cat/on services consist of system-wide exclumge seavice (SE) which suppom system-wide d.,~, exchanging and local cquipmeat at~em, and omnmunication management service (CM) which provides trmmixuent access to CIM networks. Information services consists of symem-wide information service (SI) which is in charge of global data management (includin£ all types of information), data acceuing, schema ceaverting and ~t~ integrity controlling, data management service (DM) which is used for local data accemng and mamsenma by supponi~ af database managengnt systmm, knowloige ~ t servic~ ( K ~ which is used for the reprmmmion and p_roce~___'ngof knowkdgc information in CIM system and maps the Imowl~lgc processing request to the knowledge-base system or other knowledge management system, method nmnagement segvioe (MeM) which is used for the storage, management and usage of all types ~f mmhod (including math algorithm, system procedure, common program, etc.) in CIM systems based on the method database management system, model ~mn%g¢~nt service (MoM) which is umi for the storage, representation and management of models in the CIM systems based on the _mode__~! database m n a m:mmt system. The or£aniTJttionof the Hrg-IIP is shown in figure 1. The intem:tions bctwcgn these sendces and between the HIT.lIP service systenm running in different network nedes are perfomed by means of communication protocols. There are four types of protocols: server protocol, access protocol, agent protocol and external protocol. The different services in the different nodes interact with each other through smve~ protocol. The same tylgs of service in diffment nodes co-operate through the agent protocol. The different tyix= of services in the same node interact with each other through the access protocol. The interaction between function entities and the H1T-IIP services is achieved by the external protocol. The external protocols are the object-oriented, progratnmahle segvice interface at which function entities access the HIT-lIP services. 2. CLIENT/SERVER ARCHITECTURE In CIM-OSA-IIS system, the configuration in each computer network node must conta/n a whole services system evcn if the hardware confisurafion of these nodes is ~ n t . That means all nodes must have the ability to install and execute the CIM-OSA-IIS. The HIT-11P adopts client/server technology as its system architecture to provide flexibility c~the system configuration and more powerful information processing mcchanism which can bc shown in figurc 2.
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18th International Conference on Computers and Industrial Engineering
access services from server-nodes in other service-cells through the set,r-node in its own service-cell. Server-nodes in the different service-cells interact with each other in the same way. The HIT-liP service system nnming on the stayernode can be also a client if it calls other server-nodes to provide services for it. So a client-node is always a client, but a server-node may be both server and client. The client receives service requests which come from function entities. However, it is -n~_le to process them because of the lacking of the business process services and the information services. It must pass the request to its server-node in the same service-cell and then passes the results returned by the server-node back to the function entities which commit the request. The server also can subcontract the service task to other servers called sub-servers in order to distribute the service in the system-wide and this forms a service-thread for the request. The selection of the server and sub-servers is made by the server itself accordinE to the condition of the dynamic system load, system configuration and system resource constraints, and this is ~nsimrent to function entities. The interaction between the client and its sem~r or the server and its sub-servers is performedby the server protocols. Function entities do not know where the scarer is even if the node on which the client is running is a server-node. The fimction entity interacts transparently with a logical server on its node. This can be illustrated by figure 3. Client Client-node I FuaceeaEnety [
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F: Fmnt-e~l Services B: B - . ~ i ~ Process Services I: Information Services C: Communication s e r v i ~ Fig.3. The structure of the logicalserver 3. SERVICE THREAD For the implementation of the client/server architecture, we define the service-thread as the system-wide service and scheduling unit which links the client and its servers together. The service-thread is a logical server to the function entities, and is created and controlled by the server in the same service-cell. The controlling strategy of the servicethread can be described as the following. When a server receives a service request from a client, the server cry_t_~ a global service-thread which points to its client for the request. When some sub-servers are selected by the server, these sub-servers create a local service-thread which points to the server and the server links these sun-servers to the global service-thread. So the server controls a service-thread tree illustrated by the figure 4. A server can processes multiple service-threads and a server can be tied to multiple clients at the same time so that onc client can assess multi setwrs for its multiple requests and one server can serve for multiple clients at the same time too. The controllinE of the service-thread is the key technology for the client/server architecture. As the system-wide operation and distribution controller, the BC, actually its service-thread controlling functional unit(BC-TC-FU), is responsible for the controlling of the service-thread. To provide the function of the system-wide service-thread controllinf~ BC-TC-FU should provide the following functions, Request registration functions which register the service requests from function entities into a request table in order to process them. Server selection functions which select servers or rob-servers for the client by means of some optimiTs,ion algorithm. Thread management functions which create and operate the service-thread end/or a sub-service-thread, copy and/or transmit them to other server to distribute the service in system-wide. Thread controlling fimctions which control the integrity and consistency of the service-thread in client and its servers as the system-wide controlling object. Thread removing functions which pass the result back to the function entity, untie all servers, remove the service-thread and the service request. The processing workflow of service-thread is described briefly as follow. When a function entity issues a service request by means of external protocol, the front-end services of the client receives the request and pass it to the BC in its server-
18th International Conference on Computers and Industrial Engineering rode within the s i n e ~vice-ceil. The BC ~ the ~
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The information integrating platform is a basic ~ environment to the CIM system of an enterprise and provides the basic infommfion pnxzssin& bes/ness pmceu coatmU/ag and mmmunicat/on servi~s for the ~ af an e n t e r p ~ throesh a set of common servioes tyste~ Ceesidm~ the development ~ relevant tecimolollYsuch as intenisent m n u f a c t e r ~ k n o w k ~ e n S i , e e r ~ ctieat/suver ~ , etc., we det~ and improve the CIM-OSAHS framewo~ aud propose the plan e/'the I-IIT-HPwhich is a plan of an opea integrating p l a t f ~ ~ on ~ ~ . OSA standard framework and the implementation approach based on the clieat/serve~technology. REI~I~NCE:
1 T. L Williams et. al. ArchqecUlre for In~gr~in~ Manufacturing Activities and Enterprise. Proceeding ~ 12th WoHd C c q F ~ ]FAC, Sydney: 1993. 2 ESPRIT ~ u m AMICE. CIM-OSA Arc,hitecture Dw~l~ion. AD 1.0. Belgium: Springer-Verlag, 1991 3 E.F. Wheel~ & A. G. G a n ~ Introduction to Sy~___em~ Architec~-e. IBM System J., 1988,27(3). 4 A. Ryan, eL al. ModeilinS and Implementati~ c/" lafonnafion Driven Manufacturing Control System. Prec. of ICCIM ~ . , Siasalmre: 1991. 5 C. G. Park. Trend Towards Open Architecture Control System for Developing Countr/es. Proc¢~_i-~. of 12th World WAC, Sydney: 1993. 6 Xu Xiaofei, eL al. Architecture and System Design for a CIM Integratin~ ]nflastnicU~. J. of Harbin IItitut¢ of Teclmoiogy, 1995, 1(2).