Data Migration Model and Algorithm between Heterogeneous Databases based on Web Service

Transcription

1 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER Daa Migraion Model and Algorihm beween Heerogeneous Daabases based on Web Service Guowei Wang and Zongpu Jia School of Compuer Science and Technology, Henan Polyechnic Universiy, Jiaozuo, China Manjun Xue School of Archiecural and Arisic Design, Henan Polyechnic Universiy, Jiaozuo, China Absrac To solve he problems of daa conversion beween heerogeneous daabases ha arising from he progress of daa migraion, he paper presens an improved model of daa migraion and a daa conversion algorihm based on he research on daa synchronizaion via web service. The daa migraion model is divided ino legacy daa ier, middle ier and arge daa ier, which respecively provides daa exracing, daa convering and daa loading funcions. By esablishing he corresponding relaionships of differen daa fields beween heerogeneous legacy daabase and arge daabase, he daa conversion algorihm convers daa formas of legacy daabase ino required daa formas of arge daabase according o he relaionships, hen wries he convered XML documen o arge daabase o achieve daa migraion. Experimens show ha he model and algorihm can effecively realize daa migraion. Index Terms Daa Migraion; Heerogeneous Daabases; Daa Conversion; XML; Web Service; Daa Synchronizaion I. INTRODUCTION Wih he consanly growing of business scale and rapidly developing of compuer echnology, informaion applicaion sysems in enerprise need o be modified frequenly o more easily adap o new business requiremens. Due o he difference of operaing sysem, developing plaform and programming language and oher facors beween legacy sysem and arge sysem, here emerging a key problem ha daa from legacy daa sources of a legacy sysem need o be moved ino new daa sources of a arge sysem in heerogeneous environmen where legacy and new sysems have differen daa srucures [1]. Generally, we call his process of daa moving he daa migraion. The key poin of daa migraion is daa conversion. In a compuer environmen, daa is encoded in a variey of ways. For example, he operaing sysem is predicaed on cerain sandards for daa and file handling, each This work was suppored by sof science research program of Henan province ( ) and informaion echnology in educaion research program of Henan province (ITE12103). Corresponding auhor Zongpu Jia. compuer program handles daa in a differen manner. Whenever any one of hese variable is changed, daa mus be convered in some way before i can be used by a differen operaing sysem, daabase managemen sysem (DBMS) or program. Even differen versions of hese elemens usually involve differen daa srucures. For example, he changing of bis from one forma o anoher, usually for he purpose of applicaion ineroperabiliy or of capabiliy of using new feaures. Daa migraion is similar o daa inegraion and daa synchronizaion. Daa inegraion involves combining daa residing in differen sources and providing users wih a unified view of hese daa. Daa synchronizaion is he process of esablishing consisency among daa from a source o a arge daa sorage and vice versa and he coninuous harmonizaion of he daa over ime. The common feaures of hem is ha hey all need o ranspor daa from one daabase o anoher. Despie heir similariies, daa migraion, inegraion and synchronizaion differ in wo areas: Firs, number of daa sources and arges. The flow of daa from is sources o is arges can be described as many-o-one (inegraion), one-o-one (migraion), and many-o-many (synchronizaion). This enables us o differeniae hese similar daa-movemen echniques. Second, diversiy of legacy and arge daa models. Much of he ime spen in daa-movemen developmen concerns mappings and ransforms beween source and arge daa models. The more divergen hey are (or he greaer he number of daa models involved), he more ime developmen will ake. So i requires a horough undersanding of daa sources from various aspecs, such as daa ype, daa forma, idenifier naming, daabase objecs and applicaion when we achieve an effecive daa migraion procedure [2]. Daa of he legacy sysem is mapped o he arge sysem providing a design for daa exracion and daa loading. The design relaes legacy daa formas o he arge sysem's formas and requiremens. Daa migraion is usually performed programmaically o achieve an auomaed migraion. Programmaic daa migraion may involve many phases bu i minimally includes daa doi: /jnw

2 3128 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER 2014 exracion where daa is read from he legacy sysem and daa loading where daa is wrien o he arge sysem. Daa migraion is a messy, ime-consuming and difficul underaking. The srucuring of daa elemens ranslaion makes he daa migraion process very difficul o auomae because he daa migraion projec address he areas of reverse engineering, business reengineering, schema mapping and ranslaion, daa ransformaion, applicaion developmen, human compuer-ineracion and oher complicaed works. A survey of services firms found ha 72% of organizaions deferred moving applicaions because daa migraion is oo risky. Thus here is an urgen need o provide daa migraion model and migraion algorihm no only for accessing he daa which is sored in legacy sysems, bu also o provide sraegy which formas he migraed daa o adap o he plaforms and archiecures of arge sysem. Alhough here are many commercial ools claim o realize daa migraion auomaically, mos are specific o paricular DBMS and require a paricular daa srucure. A. Our Conribuions In his paper we invesigae daa migraion based on he research on daa inegraion and daa synchronizaion beween heerogeneous daabases via service oriened archiecure (SOA) and XML. In paricular, we developed a general daa migraion model ha can be used o achieve an effecive daa migraion procedure. Secondly, we presened a corresponding relaionship library ha can be applied in popular DBMS. Finally, we designed a daa conversion algorihm based on he migraion model and relaionships library o achieve daa migraion beween heerogeneous daabases hrough he mehods of XML documen processing and web service calling. B. Ouline The paper is divided ino 6 secions. The nex secion discusses he background and relaed work involved in daa migraion and daa synchronizaion projecs. Secion III deails he archiecure and funcion of he daa migraion model. Secion IV oulines he workflow of he migraion model. Secion V illusraes he proposed daa convering algorihm. The experimenal resuls and analysis are presened in Secion VI. Finally, he concluding secion presens a summary of he paper. II. BACKGROUND AND RELATED WORK Exising proposals for daa migraion beween heerogeneous daabases can be classified ino hree differen classes: manual daa inpu, using Exrac Transform Load ools (ETL), and programming mehods based on daabase echnology. We briefly ouline he programming mehod based on daabase echnology, which is he mos relevan effors in he hree classes. Mos programming mehods based on daabase echnology using middleware o achieve daa migraion. David I. Spivak in reference [3] provides new daa migraion funcors based on a sraighforward caegoryheoreic model of daabase o ranslae insances from one schema o he oher in canonical ways. These funcors parameerize projecions, unions, and joins over all ables simulaneously and can be used in place of conjuncive and disjuncive queries. Li Xiaohang e al. in reference [4] propose a mehod of SQL language reproducion o achieve daabase duplicaion. By building a racks able in source daabase, he mehod ranslaes he operaion of daa able ino corresponding SQL language sequences, hen execues hese SQL sequence in arge daabase according o ime order o generae required daa. The mehod can copies daa from legacy daabase o arge daabase bu heir approach is consrained o paricular daabases, if one of he fields in a daa able changes in daa ype, lengh or naming, he business may grind o a hal. By using ETL ool, reference [5] proposes a generalized daa migraion ool based on meadaa-driven echnology, bu ETL is complex design srucure ha runs under sric performance requiremens and is opimizaion is crucial for saisfying business objecives because of he operaions and he ypical srucural complexiy [6], meanwhile, due o he complexiy of componens exensibiliy, ETL componens are ighlycoupled o each ohers in he curren ETL framework [7]. ETL is mosly adap o hose informaion sysems whose version is upgraded from an old one, so he proposal does no working well when differences occurred in business processes or daabase. XML-based web service and SOA echnologies have been widely applied in digial campus of insiues and informaizaion of enerprises because of he plaformindependen characerisics [8]. Reference [9-12] respecively researched on web service and SOA for daa exchanging, inegraing, synchronizing and sharing o solve he problems abou informaion isolaed island ha arising from he procedure of informaion ransmiing beween disribued heerogeneous sysems. In order o realize daa synchronizaion and avoid daa inconsisency caused by one applicaion sysem, he key poins of hese works are focused on he consrucion of daa inerconnecion channel and plaform, declaraion of rules and oher aspecs, in he procedure of daa synchronizaion, only relevan daa in business legacy sysems is updaed according o he changes of he basic daa ha ransferred in he channel. In conras o numerous indusry and informaion ineress abou SOA and web service, a few research aenion has been given o he heoreical foundaions of daa migraion. Our works mainly aim o he daa formaing and whole daa moving from one daabase o anoher by improving he mehods of XML-based web service and SOA echnologies and daa synchronizaion ha sudied in heerogeneous informaion sysems. III. ARCHITECTURE OF THE DATA MIGRATION MODEL As shown in figure 1, he daa migraion model consiss of legacy daa ier, middle ier and arge daa ier, which respecively provides daa exracing, daa convering and daa loading funcions.

3 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER Legacy daa ier Middle ier Targe daa ier Legacy applicaion Daa convering module Corresponding relaionship Daa convering Excepion Excepion processing Convered daa Targe applicaion Legacy daabase Daa exracing module DB o XML Daa loading module XML o DB Targe daabase DB connecion web service Query designer Daa wrier DB connecion web service Figure 1. Archiecure of he daa migraion model DBA Legacy DB Targe DB UDDI Daa exracing Daa convering Excepion processing Daa loading Visis he query designer Connecion reques WebService calling Connecion response Connecion reques Connecion response Calling response Query reques Query resuls Query reques Query resuls XML Calls daa convering module Calls he daa conversion Web Service Convered daa Response message Insrucions for daa migraion Excepion processing Resuls Calls daa loading module XML Convered daa Figure 2. Workflow of he migraion model A. Legacy Daa Tier Legacy daa ier includes legacy applicaion sysem and is daabase ha need o ransform is daa o arge heerogeneous daabases. Legacy daa ier is he daa source of he migraion model. B. Middle Tier Middle ier conains daa exracing module, daa convering module, excepion processing module and daa loading module.

4 3130 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER 2014 Daa exracing module mainly realizes original daa acquisiion. By designing a query designer, daa exracing module esablishes daabase connecions of legacy daabase and arge daabase by calling he daabase connecion web service ha regisered in universal descripion discovery and inegraion (UDDI) cener, hen ges he daa able srucures from legacy daabase and arge daabase, finally esablishes he relaionships beween specific fields ha seleced from daa ables. Afer execuing he query, he rerieved daa will be wrien o a XML documen o faciliae daa conversion based on he convering algorihm. Daa convering module includes he corresponding relaionship library of heerogeneous daa ype and he implemenaion of daa convering algorihm, which were encapsulaed ino web service for service calling. Excepion processing module responses he errors or inconverible daa or oher informaion o daabase adminisraor (DBA) for anoher process according o migraion sraegies. Daa loading module processes he response XML of daa convering web service, hen wries he resuls o arge daabase via daa wrier. C. Targe Daa Tier Targe daa ier is composed of he arge daabase and is applicaion sysem programs, migraed daa is evenually wrien o arge daabase. D. Web Service In our works, we esablish daabase connecion web service inerface of popular DBMS o enhance he flexibiliy and expansibiliy of he model. Adminisraors selec or ener he ype, name, accoun, password of daabase, as well as parameers such as IP address of daabase server o generae daabase connecion sring auomaically. Besides, we encapsulae daa convering algorihm ino web services and regiser hem in UDDI cenre. Service requesers call he web service and perform he corresponding operaion, he resuls were reurned by way of simple objec Access Proocol (SOAP) afer he compleion [13]. IV. WORKFLOW OF THE MIGRATION MODEL As shown in figure 2, he workflow of he migraion model consiss of daa exracing procedure, daa convering procedure and daa loading procedure. A. Procedure of Daa Exracing DBA visis he query designer of daa exracing module hen selecs legacy daabase and arge daabase ha need o migrae daa. Query designer visis UDDI cener hen rerievals and calls daabase connecion web service of legacy daabase and arge daabase o generae daabase connecion sring for daabase connecion. Afer conneced o daabase, daa ables of legacy daabase and arge daabase will be displayed in he query designer. DBA chooses he needed daa ables and daa fields. Query designer rerieves he desired daa from legacy daabase and arge daabase. Rerieved daa including srucured informaion of daa able such as name, aribue informaion of fields such as name, ype, lengh and consrain informaion such as names and values of primary key or foreign key, which were used for daa conversion process when middle ier creaes fields mapping rules and relaionships. Daa exracing module preprocesses he daa ha rerieved from daabase, hen ranslaes he daa ino XML documen for convenien daa processing of web services in daa convering module. B. Procedure of Daa Convering Daa convering module calls he daa conversion web service ha regisered in UDDI cener, hen ranslaes he response XML documen ino compaible daa for arge daabase formas according o he corresponding relaionship library and daa convering algorihm. During he process of daa conversion, wheher he operaion brings a successful resul or no, daa convering module will sends a response message o noify DBA, if he daa conversion is no well done, i will records he error daa in daabase. DBA issues insrucions for daa migraion based on he response message. If he received response is message abou error conversion, DBA will issues excepion processing insrucions according o daa migraion sraegies, oherwise issues normal insrucions. C. Procedure of Daa Loading Afer received daa migraion insrucions, daa loading module processes he response XML documen ha reurned by daa convering web service. Daa loading module wries he processed daa o arge daabase via daa wrier calling. V. DATA CONVERTING ALGORITHM There are several facors ha may considerably complicae he process of daa migraion in heerogeneous environmen, while problems of daa rerieving from legacy daabase, daa wriing o arge daabase, web service encapsulaing and calling, exchanging beween XML and relaional daabase have been widely sudied by many researchers, in his secion, we mainly realize he definiion and implemenaion of corresponding relaionship library and daa convering algorihm. A. Definiion of Corresponding Relaionship Library Heerogeneous daabases use differen daa ypes o sore same daa, besides, represenaions and semanics of he same daa ype are all differen from each oher,

5 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER which mainly refleced in he name of daa ype and lengh of sored daa. For example, ineger daa in Oracle daabase is represened by NUMBER, bu in Informix daabase is INTEGER, moreover, he lengh of he CHAR daa ype in Oracle daabase is 2000, while in Informix daabase is 255. Essenially, corresponding relaionship library can be considered as he collecions of correspondence beween heerogeneous daabase daa ype. Table I shows he commonly used daa ypes in Oracle daabase and SQLServer2000 daabase. Taking ino accoun convenien operaion and accurae daa correspondence when concree implemenaion, we designed drop-down lis boxes in query designer o load daa fields from legacy daabase and arge daabase. The corresponding relaionship will be auomaically compleed by programs afer he selec operaion of DBA, hen encapsulaed ino web service and regisered ino UDDI cener. TABLE I. DATA TYPES IN ORACLE AND SQLSERVER2000 SQL Server 2000 bigin, bi, decimal, in, money, numeric, smallin, smallmoney, inyin char, nchar, nvarchar daeime, smalldaeime floa, real image, sql_varian, ex, nex sysname Oracle NUMBER VARCHAR2 DATE FLOAT LONG RAW CHAR Definiion 1. Corresponding relaionship library Suppose ha funcion f ( c, v) convers he daa ype of fields c from legacy daabase o desired daa ype v of arge daabase. Suppose he corresponding relaionship library F is he collecion of f. Suppose ha legacy daabase D is he collecion of daa able T and consrains, C is a se of fields of daa able. Suppose daa conens of daa able is a se of n dimensional vecor, ( a1, a2,, a n ), each componen of is ai [ ci], ai D( ci). Suppose daa acquisiion funcion is DATA _ ACQ : (, F) { }, is he name of daa able from T. B. Implemenaion of Daa Convering Algorihm 1) Basic knowledge Definiion 2. Relaional schema A relaional schema is denoed by a 5-uple R ( T, C, F, PK, FK ) [14], where T is a finie se of able names. C is a funcion from a able name o a se of column names. F is a funcion from a column name c o is column ype definiion. Fc (), (,,,, n), where is meadaa daa ype, means ha wheher he value of c is unique or no, means ha wheher he value of c is null or no, is he defaul value of c, if c does no has a defaul value, is, n is a finie se of valid domain values of c. PK is a finie se of relaional inegriy primary key consrains ha can be eiher rerieved from daabases direcly or provided by human expers. FK is a finie se of relaional inegriy foreign key consrains ha can be eiher rerieved from daabases direcly or provided by human expers. Definiion 3. XML schema An XML schema is denoed by a 5-uple S ( E, A, ST, CT, r) [15], he meaning of each enry as follows: E is a finie se of elemen names. A is a funcion from an elemen name o a se of aribue names. ST is a funcion from an elemen name o is elemen ype definiion. CT is a funcion from an aribue name o is aribue ype definiion. r is a finie se of roo elemens. 2) Daa Convering Algorihm Suppose ha he relaional schema of source daabase D is R ( T, C, F, PK, FK), XML schema is S ( E, A, ST, CT, r) and daa convering rule is M ( R, S, Ma, Mc, M, Mk ). Inpus of daa convering algorihm are R, S, M, oupu of daa convering algorihm is XML e. The daa convering algorihm as follows: 1. Iniialize XML e m.. e n. 2. Assign m.. e. c 3. For each a in. A : c 3.1 If here exis a mapping rule ma. a a in M a hen iniialize p, and respecively assign an. and { ma. c} o is name and value, finally add p ino e. 3.2 If here is no exis a mapping rule ma. a a in M a hen do nohing bu coninues nex For each e ' in c. E : 4.1. If e'. ST hen a. If here exis a mapping rule mc. e e' in M c hen iniialize simple conen se and assign se { mc. c}, finally add se ino e. b. If here is no exis a mapping rule mc. e e' in M c hen do nohing bu coninues nex If e'. CTS hen a. If here exis a mapping rule m ' e' in M hen iniialize F. For each source consrain sc ( m ',{ ck Dk }) of m ' in M k, add fc ( ck, Dk ) ino F. For each relaional consrain rc ( m, m ',{ ci c j }) from m o m ' in M k, assign f ( c,{ [ c ]}) and add i ino F. c j i b. If here is no exis mapping rules m ' e' in M hen do nohing bu coninues nex 4.

6 3132 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER Calculae se from m '. ha saisfied given condiion of F by calling DATA _ ACQ( m '., F ). 6. For each ' in, recursively call DATA _ CON and add he calculaing resul e'' DATA _ CON ( m ',, CR ( m ', )) ino XML e. 7. Reurn XML e. VI. EXPERIMENTAL RESULTS AND ANALYSIS A. Experimen Main fields of able ha named uiion in legacy daabase as follow: uiion( su _ no, su _ name, su _ school, su _ dep, erm, ui _ sd,...) Our work is o migrae he daa of uiion able from legacy daabase o wo ables of arge daabase ha respecively named su and su_uiion: su( su _ id, su _ name, su _ school, su _ class,...) su _ uiion( su _ id, erm _ name, uiion _ amoun,...). The relaional schema source able is ' ' ' ' ' ' R ( T, C, F, PK, FK ), he meaning of each enry as follows: ' T { uiion}. C ' ( uiion) { su _ no, su _ name, dep _ name, erm, ui _ sd} F ' ( su _ no) { sring, unique, no _ nullable,, } F ' ( ui _ sd) { number, no _ unique, no _ nullable,,0} PK ' ( uiion { su _ no}} ' FK The XML schema as follows: E { su_school(" su _ school ", TSCHOOL, ), su _ dep(" su _ dep ", TDEPT, ), su(" su", TSTU, ) } A { TSCHOOL. su _ school(" su _ school", sring," required "), TDEPT. su _ class(" su _ class", sring," required "), TDEPT. su _ name(" su _ name", sring," required "), TDEPT. su _ id(" su _ id ", sring," required "), TSTU. su _ id(" su _ id ", sring," required "), TSTU. erm _ name(" erm _ name", sring," required "), TSTU. uiion _ amoun(" uiion _ amoun", decimal," required ")} r uiion According o he daa convering algorihm, reurned XML conains deparmen informaion and uiion informaion of sudens, which can be easily wrie o arge daabase. B. Resuls and Analysis In his secion we analyze he resuls and show some graphs ha summarize he behavior of he algorihm by comparing our works wih mehod of daa synchronizaion and Daa Transformaion Services (DTS) of SQL Server2000 and a similar mehod ha presened in reference [16]. We evaluae our mehod in wo aspecs: he execuion ime and he memory uilizaion. 1) Comparison wih Daa Synchronizaion Principle of mos daa synchronizaion mehods beween heerogeneous daabase uses riggers [17] or agen [18] or oher way o monior he daa changes of local daabase, hen adds, updaes or delees corresponding daa in arge daabase via web service or XML, he daa operaion is occurred a random and only a few daa is modified. While he mehod of our works formas he fields of daa able in legacy sysems in a cerain periods of ime according o he daa forma of arge daabase hrough corresponding relaionship library and daa convering algorihm, hen moves he daa o arge daabase, i needs o migrae a large quaniies of daa. So i is an improved mehod based on daa synchronizaion. 2) Comparison wih Similar Daa Migraion Mehods Mehod in reference [16] ranslaes he daa ype of fields in able of legacy daabase ino arge daabase and generaes SQL sring o creae source daabase based on corresponding relaionship, which is similar o our works. Besides, boh mehods are exacly same in programming language, DBMS and daabase servers. We perform experimens on machines equipped wih 2.13 GHz Inel Core 2 processor and 1.99 GB RAM and windows server 2003 enerprise ediion OS, DBMS in server of legacy sysem is SQL server2000 while in arge server is oracle9i. Since reference [16] only gives he performances on migraing and rows of daa, we compare our works wih he mehod of reference [16] on execuion ime and memory uilizaion only in hese wo cases. As shown in able II, reference [16] akes a lile more ime consuming and a lile less memory uilizing han our works o process rows of daa. However, in he procedure of rows of daa migraion, reference [16] akes much more ime consuming and memory uilizing han our works. This is due o he following wo facs. Firs, reference [16] needs o connec boh daabase server of legacy sysem and arge sysem for differen fields relaing when he daa migraion occurs, if he quaniy of daa is oo large, i needs much more ime o rerieve required daa ype. Second, reference [16] only uses he calculaing abiliy of daabase servers o process migraed daa. While in our works, we consruc corresponding relaionship library and deploy i o a server in middle ier before he procedure of daa migraion, and also, we use his machine o run he daa convering algorihm. I needs o connec he server jus one ime, hen reads he whole corresponding relaionships ino memory, so he memory uilizaion of daabase server and execuion ime are only a bi variaions when migraes a few rows of daa, bu wih he increasing of daa quaniy, he percenage of memory uilizaion for corresponding relaionship library has declined o a low level, comparaively, he execuion ime superioriy of our works appeared. DTS is a se of objecs and uiliies used o auomaically perform exrac, ransform and load operaions o or from a daabase. The objecs are DTS packages and heir componens, and he uiliies are

7 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER called DTS ools. DTS is widely used wih Microsof SQL Server daabases, meanwhile i could be used independenly wih oher daabases. DTS allows daa o be ransformed and loaded from heerogeneous sources using OLE DB or ODBC ino any suppored daabase. TABLE II. COMPARISON OF OUR WORKS AND REFERENCE [16] Rows of daa execuion ime of our work 22s 24m execuion ime of reference [16] 21s 28m memory uilizaion of our work 38M 154M memory uilizaion of reference [16] 37M 192M In figure 3 and figure 4, we compare he performance of execuion ime and memory uilizaion beween DTS and our works under same environmen by migraing o rows of daa from daabase server of legacy sysem o arge sysem. As shown in he figures, wih he increasing of migraed daa, execuion ime of DTS becomes much more han ha of our works, i approximaely akes more 1200s o process daa records, meanwhile, memory uilizaion of our works reveals a general rend of seady rise bu flucuaes around 40M in DTS, i roughly uses 160M memory in our works while sill keeps 40M in DTS when daa quaniy is Figure 3. Comparison of execuion ime performance process daa and keeps a sable memory uilizaion. Mehod of our works fills all he needed daa ino daases by programming, hen loads he daases ino memory a one ime, finally updaes daabase o realize daa migraion, so i akes a few execuion ime bu needs more memory o sore he migraed daa along wih he growing of daa quaniy. Bu using DTS, he daa ables need o be preprocessed, which is a ime-consuming and complex work ha requires professionals who have horough undersanding of daabase principle, he mehod presened in his paper can auomaically migrae daa hrough correspondence and programming, alhough he memory uilizaion is high, daa migraion is processed before he running of arge sysem, so i has no impac on he performance of arge sysem. VII. CONCLUSIONS AND FUTURE WORK Principle of daa migraion mehods beween heerogeneous daabase can be considered as one way daa synchronizing from legacy sysems o arge sysems. We presened daa migraion model and daa convering algorihm based on daa synchronizaion and explained in deail he archiecure and realizaion for daa migraing beween heerogeneous relaional daabases. A comprehensive analysis of heir performance has shown desired resuls and allowed us o focus on furher developmens in specific aspecs. The daa migraion model and daa convering algorihm are able o migrae rows of daa from SQLServer2000 daabase o Oracle daabase by using 160M memory in 1500s. The execuion ime and memory uilizaion are mainly affeced by he quaniy of daa o be migraed, he daa convering algorihm allows us o cope wih daa ype differences in a fairly efficien way wihou any impac on he performance of arge sysem. However, in pracical applicaions, rule based daa migraion mehod is difficul o solve all he problems. The mehod of our works is insufficien o deal wih he maers when he conen represenaion of fields in daa able of legacy sysem is differen from ha of arge sysem, in cerain circumsances i needs manual operaions or SQL saemens o realize he whole daa migraion. Given hese resuls we idenified a few poins which will be par of fuure work. The mos imporan one is he inegraion of daa ype conversion and daa conen conversion, which is he key poins o realize auomaic daa migraion. Finally, for opimizing memory uilizaion, improvemens of he daa convering algorihm may be required. Figure 4. Comparison of memory uilizaion performance DTS keeps he daabase in a conneced sae and loads he daa ha o be processed ino memory in baches, for example, DTS loads 1000 rows of daa ino memory in a bach. I needs o rerieve required daa repeaedly according o he oal quaniy of daa and pars quaniy of each bach, which causes DTS spends more ime o REFERENCES [1] Bernhard Thalheim, Qing Wang, Daa migraion: A heoreical perspecive, Daa & Knowledge Engineering, vol. 87, pp , [2] Bo Li, Peng Wang, Yongfei Zhang, Classificaion-based Muli-clien Video Transmission over Heerogeneous Neworks, Journal Of Mulimedia, vol. 8, no. 4, pp , 2013.

8 3134 JOURNAL OF NETWORKS, VOL. 9, NO. 11, NOVEMBER 2014 [3] Davi I Spivak, Funcorial daa migraion, Informaion and Compuaion, vol. 217, pp , [4] LI Xiaohang, HU Xiaopeng, LI Gang, Improvemen and Implemenaion of Heerogeneous Daabase Replicaion Approach, Compuer Engineering, vol. 35, no. 8, pp , [5] REN Qingdong, LI Tianyang, YUAN Man, e al., Generalized daa migraion ool based on meadaa driven, Journal Of Daqing Peroleum Insiue, vol. 35, no. 1, pp , [6] Anasasios Karagiannis, Panos Vassiliadis, Alkis Simisis, Scheduling sraegies for efficien ETL execuion, Informaion Sysems, vol. 38, pp , [7] Mohammed M I Awad, Mohd Syazwan Abdullah, Abdul Bashah Ma Ali, Exending ETL framework using service oriened archiecure, Procedia Compuer Science, vol. 3, pp , [8] Qing Li, Hon Chung Mak, Jianmin Zhao. e al., OXML: an Objec XML Daabase Supporing Rich Media Indexing and Rerieval, Journal Of Mulimedia, vol. 6, no. 2, pp , [9] Wang Xi Vincen, Xu Xun William, DIMP: an ineroperable soluion for sofware inegraion and produc daa exchange, Enerprise Informaion Sysems, vol. 6, no. 3, pp , [10] Xu Bin, A daa secure soluion for heerogeneous enerprise legacy sysems inegraion, Journal of Sofware, vol. 4, no. 6, pp , [11] Liao Guoqiong, Daa synchronizaion and resynchronizaion for heerogeneous daabases replicaion in Middleware-based archiecure, Journal of Neworks, vol. 7, no. 1, pp , [12] Shen Dayong, Deng Meixia, Di Liping, e al., Sudy on generaion and sharing of on-demand global seamless daa- Taking MODIS NDVI as an example, Compuers & Geosciences, vol. 54, pp , [13] Chien Cheng Lin, ChenLiang Fang, Deron Liang, A porable inercepor mechanism for SOAP frameworks, Compuer Sandards & Inerfaces, vol. 36, pp , [14] Chengsen Yang, Jinguang Sun, The exchange from relaional schemas o XML schemas based on semanic consrains, Wuhan Universiy Journal of Naural Sciences, vol. 13, no. 4, pp , [15] Dongwon Lee, Murali Mani, Frank Chiu, e al., NeT & CoT: ranslaing relaional schemas o XML schemas using semanic consrains, Proceedings of he elevenh inernaional conference on Informaion and knowledge managemen, McLean, Virginia, USA, [16] Yu qiuming, research on daa migraion beween Heerogeneous Daabases, Nanchang Universiy, [17] Cure. O, Squelbu. R, A daabase rigger sraegy o mainain knowledge bases developed via daa migraion, Progress In Arificial Inelligence, Proceedings, vol. 3808, pp , [18] Kerschberg. L, Chowdhury. M, Damiano. A, Jeong, e al., Knowledge Sifer: Agen-based onology-driven search over heerogeneous daabases using semanic web services, Semanics Of A Neworked World: Semanics For Grid Daabases, vol. 3226, pp , Guowei Wang is a Ph.D candidae in Henan Polyechnic Universiy. The major research fields include sysem archiecure of compuer, compuer securiy and daabase applicaions. Zongpu Jia received his Ph.D in sysem archiecure from Jilin Universiy, China, in He is a professor in school of compuer science and echnology, Henan Polyechnic Universiy. His research fields include compuer nework echnology, compuer conrol echnology, and informaion sysems. Manjun Xue earned her maser degree from Henan Normal Universiy, China, in Her research fields mainly include compuer-aided design and websie opimizaion.