Achieving Software Flexibility via Intelligent Workflow Techniques

Transcription

1 Proceedings of the 35th Hwii Interntionl Conference on System Sciences Achieving Softwre Flexibility vi Intelligent Workflow Techniques Dniel D. Zeng J. Leon Zho Deprtment of MIS Deprtment of MIS University of Arizon, Tucson, AZ University of Arizon, Tucson, AZ zeng@bp.rizon.edu lzho@bp.rizon.edu Abstrct In this pper, we investigte innovtive techniques of chieving softwre flexibility in workflow environment. We believe tht by incorporting workflow technology nd intelligent gent techniques into modern informtion systems, softwre cn be mde more robust, more cost effective to mintin, nd esier to chnge. In this pper, we present (1) n in-depth investigtion of softwre flexibility issues, (2) n integrted system rchitecture tht combines the workflow coordintion mechnisms nd the gent-bsed decision mking cpbilities, nd (3) frmework to evlute softwre rchitectures with emphsis on the cost implictions of system flexibility. A prototype system illustrting the implementtion of intelligent workflow concepts is lso reported. 1. Introduction The pst fifty yers of softwre engineering cn be seen s continuous quest of developing softwre systems tht re esier to design, cheper to mintin, nd more robust (Knoll nd Jrvenp, 1994; Hle et l., 2000). Severl milestones hve been chieved in this endevor, including dt-oriented softwre rchitecture, object-oriented lnguge, component-bsed softwre development, nd document-bsed interoperbility. Among these chievements, two importnt concepts re dt independence nd process independence. Dt independence is mesure of the robustness of business pplictions when the dt structures re modified. Reltionl dtbse becme dominnt in the dtbse mrket, minly becuse it chieved significnt dt independence. Process independence is mesure of the robustness of business pplictions when the process model is redesigned. The drive towrds more process independence hs led to the prolifertion of workflow systems in the softwre industry in the lst few yers. Very recently, most mjor softwre compnies hve either cquired or developed workflow components for integrtion into their existing softwre pltforms. Workflow mngement helps chieve softwre flexibility by modeling business processes explicitly nd mnging business processes s dt tht re much esier to modify thn conventionl progrm modules. Workflow mngement systems enble reuse of process templtes, robust integrtion of enterprise pplictions, nd flexible coordintion of humn gents nd tems. Despite recent significnt developments in workflow technology nd its prevlent cceptnce in prctice, current workflow mngement systems still demnd significnt costs in system design nd implementtion. Furthermore, these systems re still lcking in their bility of hndling exceptions nd deling with chnges. In this pper, we study dditionl techniques bsed on intelligent gents to incorporte more flexibility in conventionl workflow mngement systems. Our reserch gol is to further improve softwre flexibility by chieving more process independence. In the reminder of the pper, we first review relevnt literture in softwre flexibility, flexible workflow systems, nd intelligent gents in Section 2. We then propose conceptul frmework on softwre flexibility bsed on process independence in Section 3. In Section 4, we demonstrte how intelligent gent techniques cn be incorported into the workflow rchitecture to chieve high degree of softwre flexibility. In Section 5, we develop cost model to evlute three softwre rchitectures including conventionl informtion systems, workflowbsed informtion systems, nd intelligent workflow systems. Section 6 summrizes our reserch contributions nd outlines future reserch directions. 2. Literture Review 2.1. Softwre Flexibility Reserchers hve studied issues in the mngement of chnging business processes from strtegic, opertionl, nd system perspectives (Bowers, Button, nd Shrrock, 1995; Erl, 1994; Ellis nd Rozenberg, 1995). Process chnges cn occur often. Mny business processes re not well understood nd difficult to formlize, leding to mismtches between the system specifictions nd rel needs of the business. In ddition, there re often exceptions to the bsic routines of the business, requiring the system to be robust in order to hndle process devition from the norm. Nelson, et l. (1997) defines technology flexibility s the chrcteristics of technology tht llow or enble djustments or other chnges to the business process. They proposed mesurement frmework for technology flexibility tht include such fctors s modulrity, chnge cceptnce, nd consistency in the structurl flexibility /02 $17.00 (c) 2002 IEEE 1

2 Proceedings of the 35th Hwii Interntionl Conference on System Sciences dimension, nd rte of response, expertise, nd coordintion of ctions in the process flexibility dimension. Zho (1998) proposed two relted softwre flexibility concepts: system dptbility nd system verstility. System dptbility is the cpbility to modify the system to cope with mjor chnges in business processes with little or no interruption to business opertions. System verstility (or system robustness) is the cpbility of the system to llow flexible procedures to del with exceptions in processes nd procedures. Most recently, Deiters, Goesmnn, nd Löffeler (2000) delt with the issue of flexibility in technicl, orgniztionl, nd humn perspectives. They clssify flexibility into four dimensions: process flexibility, interorgniztionl flexibility, flexible mngement nd knowledge, nd flexible tsk lloction. They further proposed conceptul solutions for chieving flexible workflow support. In this pper, we extend nd unify those concepts of softwre flexibility nd pply the results to the development of flexible process technology by mens of intelligent workflow techniques Flexible Workflow Systems Reserchers in workflow technology nd mngement re concerned with developing flexible workflow systems. As stted by Klein, Dellrocs, nd Bernstein (2000), Workflow systems must be dptive in order to effectively support tody s dynmic, uncertin, nd errorprone collbortive work environments. Workflow systems currently provide little support for dptive processes. Most do not llow one to modify process model once it hs strted executing. Exceptions re hndled by ttempting to include the workflow predefined conditionl brnches for ll possible contingencies. Severl importnt directions re currently pursued by reserchers to chieve workflow flexibility: Exception hndling: Fult tolernce is key requirement in process support systems including workflow systems. Hgen nd Alonso (2000) present solution for implementing more relible processes by using n exception hndling technique s used in progrmming lnguges. Dynmic model evolution: Dynmic workflow chnge requires the mngement of chnging process models. For instnce, Ellis nd Keddr (2000) ddress the problem of unmbiguously specifying process model chnges, vi txonomy of chnge modlities nd lnguge for the unmbiguous specifiction of procedurl chnge. Emergent process modeling: Another generl pproch for deling with dynmic dpttion is bsed on prtilly specified process models nd depends on flexible enctment systems to refine nd execute them t the runtime (Kumr nd Zho, 1999; Fustmnn, 2000). In this pper, we build upon those bsic ides of dynmic workflow mngement nd propose intelligent workflow techniques Intelligent Agent Concepts Intelligent gent technology is one of the fstest growing res of reserch nd system development in IT (Jennings, Sycr, nd Wooldridge, 1998). Intelligent gents nd multi-gent systems represent new wy of modeling mny complex informtion mngement nd decision tsks. Agents lso represent new computing environment for designing nd implementing complex softwre systems (Joshi nd Singh, 1999). Intelligent gents refer to utonomous softwre entities tht cn nvigte heterogeneous computing environments nd cn, either lone or working with other gents, chieve user-delegted gols. There re cler contrsts between gents nd trditionl AI systems. Trditionl AI systems hve usully been designed to operte under user's immedite control, while gents ct utonomously, usully on their owners' behlf (Spector, 1997). Intelligent gents hve been built in reserch lbs (Mes, 1994) nd for commercil pplictions (Etzioni nd Weld, 1995), such s electronic mil hndling gents, meeting scheduling gents, nd Internet serching gents. However, most of the gents implemented re reltively simple nd do not hve ll the fetures suggested in the literture. Currently, there re mny open reserch topics deling with intelligent gents including: plnning with incomplete informtion (Etzioni nd Weld, 1995), multigent communiction nd coordintion techniques (Sycr nd Zeng, 1996), dptive intelligence gents (Hyes-Roth, 1995; Decker nd Sycr, 1997), nd utomtic genertion of intelligent gents (Spector, 1997) Intelligent Agents for Workflow Systems Intelligent gents hve been used to chieve more flexibility in the modeling nd enctment of workflows (Edmonds et l., 1994; Mhling, Crven, nd Croft, 1995). Edmonds et l. (1994) studied collbortive design problem involving prticipnts with heterogeneous skills nd suggested tht multigent systems cn be deployed to support design with rnge of functions when considered from number of perspectives. Mhling, Crven, nd Croft (1995) presented n overview of the evolution of their office work systems. Polyflow, the most recent genertion of their office work systems, ws designed s gol-bsed workflow system tht uses the power of gol-bsed knowledge representtion to ssist in plnning, monitoring, nd repiring workflows with emphsis on the users nd their workgroups /02 $17.00 (c) 2002 IEEE 2

3 Proceedings of the 35th Hwii Interntionl Conference on System Sciences Sull (1998) proposed distributed environment for mnging lightweight workflow bsed on intelligent gents. Three types of gents were used, tht is, the courier gent tht hndles the trnsition between two process sttes, the tsk gent tht is to ccomplish tsk in collbortion with other humn or intelligent gents, nd the process gent tht supervises process instnce on behlf of the process inititor. Singh nd Huhns (1994) proposed to hndle workflow exceptions bsed on n dptive rule-bsed formultion using nonmonotonic resoning. A multi-gent rchitecture ws developed in the ADEPT (Advnced Decision Environment for Process Tsks) project (Jennings et l., 1996). ADEPT ims to design gent-oriented business process mngement by mens of cooperting nd utonomous gents. 3. Modeling Softwre Flexibility In this study, we focus on developing methodology for chieving softwre flexibility by integrting workflow nd intelligent gent techniques. For simplicity, we refer to the workflow systems tht tke dvntge of intelligent gents to significnt extent s intelligent workflow systems. We conceptulize softwre flexibility in two levels, i.e., technology flexibility nd system flexibility. By softwre flexibility, we refer to the bility of softwre ppliction to del with exceptions to the process model t the runtime nd to cope with periodic chnges to the process model. By technology flexibility, we men tht softwre flexibility cn be chieved by dopting the right combintion of specific modeling prdigm, progrmming technique, softwre rchitecture, nd development methodology. This level of flexibility is nlogous to the combintion of the structurl nd process dimensions proposed by Nelson et l. (1997), but with less emphsis on the orgniztionl effects. By system flexibility, we include both system dptbility nd system verstility discussed by Zho (1998). The kinds of flexibility presented by Deiters et l. (2000) re clssified minly for developing prticulr types of workflow support functions. For instnce, they seprte process flexibility from flexible tsk lloction. In process flexibility, they studied how workflow modeling nd enctment cn be done to llow chnge of workflow models even during process execution. In flexible tsk lloction, they explore wys of ssigning tsks to gents tht re more robust. We coin the term of hierrchicl process mngement. In lrge-scle informtion system such s B2B trnsction processing system, the overll business process consists of mny subprocesses, including interenterprise processes, intr-enterprise processes, interfunction processes, nd intr-function processes. We refer to the modeling nd execution of this process hierrchy s hierrchicl process mngement. In the next section, we show tht different informtion techniques such s workflow nd intelligent gents cn be pplied to improve the technology flexibility nd system flexibility t the vrious levels of the process hierrchy. 4. Intelligent Workflow Mngement 4.1. Workflow-Bsed Flexibility Workflow technology is becoming the cornerstone of the next genertion of enterprise ppliction systems becuse it enbles better flexibility of softwre systems in severl respects: Speciliztion of components into functionl nd process components: The workflow model essentilly cptures the inter-component processes, using component-bsed softwre development philosophy. In some wys, regulr component such s dtbse cn be seen s functionl component, while the workflow engine cn be considered s process component. This is the essence of hierrchicl process mngement. The seprtion of process design nd process execution: The workflow prdigm enbles the seprtion of process design from process execution by mnging process model s templte tht cn be instncited t the runtime. This mkes it possible to isolte the chnge of processes to different levels of the process hierrchy, resulting in reduced process interdependence. As result, chnges to processes cn be mde fster nd cheper. Interoperbility between process components: Given two workflow-coordinted enterprise systems, the interoperbility between the two enterprise systems is turned into the interoperbility between two workflow engines. This helps improve the speed of estblishing, redesigning, nd executing the interenterprise processes, thus mking the overll system more flexible when the business reltionship between two enterprises undergoing chnges Intelligent Agent -Bsed Flexibility Intelligent gent techniques cn be pplied to improve the flexibility of informtion systems becuse of its severl inherent fetures, s is summrized below bsed on the literture discussed in Section 2: Speciliztion: Intelligent gents cn be progrmmed to follow specil instructions with specific gol from generic rchitecture. This enbles fst building of softwre components /02 $17.00 (c) 2002 IEEE 3

4 Proceedings of the 35th Hwii Interntionl Conference on System Sciences Negotition: Intelligent gents cn negotite with one nother to exhibit verstile behviors in the system tht would not be possible through rigid procedures. Coordintion: Intelligent gents cn be used to build collbortive community of gents (including both humn nd softwre gents) tht is more flexible thn the typicl workflow model Flexibility vi Intelligent Workflow We propose to combine the workflow-bsed flexibility nd the gent-bsed flexibility to chieve significntly improved overll softwre flexibility. We refer to this endevor s flexibility vi intelligent workflow. This pproch hs the following properties. Inter-enterprise flexibility cn be chieved by interoperting workflow engines tht ech coordintes n intr-enterprise business process. Intr-enterprise flexibility cn be relized by mens of the workflow mngement prdigm s forementioned. Inter-component flexibility is mde possible by mens of both workflow mngement nd gentbsed components. The next subsection illustrtes how these three types of flexibility re chieved under the hierrchicl process mngement prdigm we propose in this pper Hierrchicl Process Mngement Workflow Engine A Enterprise A Workflow Engine B Enterprise B Figure 1. Inter-enterprise process mngement. Figure 1 illustrtes how workflow engines re used to link business processes between two enterprises. The interopertion between two enterprises requires collection of such ctivities s dvertisement of services, negotition of contrcts, nd outsourcing of processes, which hs been referred to s cross-flow (Ludwig nd Hoffner, 1999). Dept. X Dept. Y Dept. Z Figure 2. Inter-deprtment process mngement. Figure 2 shows how to mnge inter-deprtment processes by modeling them under one or more workflow systems. An inter-deprtment process is more stble thn n inter-enterprise process becuse the reltive stbility of reltionships nd the close coordintion nd plnning bility within the sme enterprise. Component P Tsk Agent 1 Component Q Coordinting Agent C Component T Tsk Tsk... Agent 2 Agent N Figure 3. Inter-component process mngement. Inter-component process cn be mnged by integrting workflow components with intelligent gent components. As shown in Figure 3, the coordintion process mong community of intelligent gents is more flexible thn regulr workflow coordintion process becuse the interctions between the coordinting gent nd the tsk gents re chieved through flexible negotition in distributed mnner bsed on common gent lnguge nd progrm interfce A Prototype Intelligent Workflow System We hve developed prototype system to demonstrte the technologicl fesibility of integrting softwre gent technology with off-the-shelf workflow pckges. Our objectives re to identify potentil system integrtion chllenges nd to gin insights on the implictions of flexible workflow system in the mngement of chnging business processes. This system provides detiled illustrtion of how n intelligent workflow system bsed on inter-component process mngement (see Figure 3) cn be engineered. In this section, we first briefly describe the ppliction scenrio in which the prototype system is situted. We then present the system rchitecture nd relted implementtion issues. Although the underlying implementtion frmework bsed on which our prototype system ws developed is generic, the implementtion context is rel-world ppliction tht fcilittes softwre doption in university setting. Working with the stff members of the instructionl support group (ISG) of lrge university nd group of students, we ctloged the current prctice, elicited user requirements, nd cquired necessry domin-specific knowledge. One of the primry roles of the ISG is to ssist fculty in deciding which instructionl softwre tool(s) best suits their needs. This recommendtion process cn be complex, due to the specilized needs of mny fculty members nd the wide rnge of vilble instructionl softwre pckges. A mjor source of the decision complexity stems from the fct tht mny of the tools hve overlpping cpbilities. For exmple, mny of the tools provide communiction cpbilities (e.g., student-to-student, student-to-instructor, student-group), but the cpbilities differ from tool to tool (e.g., whether the fculty cn set up filtering nd pprovl /02 $17.00 (c) 2002 IEEE 4

5 Proceedings of the 35th Hwii Interntionl Conference on System Sciences mechnism for student postings). The chrcteristics nd ttributes of one tool my work well in some situtions, nd my not work well in others. Similr situtions exist for other types of desired instructionl support such s Web-bsed ccess to course-relted mterils, online prctice nd self-tests, online quizzes nd exms, etc. In the current prctice, Web-bsed system collects fculty requests. One or more members of the technicl stff of the ISG nlyze these requests, come up with recommendtions, nd then discuss these recommendtions with the requesting fculty members. The whole process is typiclly itertive since request refinements nd dditions re common when the ISG stff members present their recommendtions with the requesters. It is highly desirble tht this time-consuming, error-prone, nd potentilly expensive (with respect to resources tht the ISG hs devoted to this softwre recommendtion tsk) cn be utomted or t lest fcilitted by n intelligent softwre system. From user s perspective, the gol of our prototyping effort is to develop virtul recommendtion gent tht understnds the cpbilities of the vilble softwre pckges, proctively communictes with the user to elicit their requirements, nd mkes sensible suggestions bsed on the user requests. As discussed in Section 4, different softwre system rchitectures re possible to develop this virtul recommendtion gent. It could be built s hrd-wired conventionl softwre system using ny of the common progrmming environments such s Jv. It could be developed s stndlone workflow ppliction bsed on commercil workflow engines such s Orcle Workflow. It could be developed s stndrd knowledge-bsed system using some knowledge-bsed system shells. In our implementtion, insted of relying on ny of the bovementioned reltively well-studied rchitectures, we choose hybrid, novel rchitecture combining workflow nd intelligent gent technologies to chieve high degrees of system flexibility nd extensibility. Web-bsed Front End MySQL Repository JAVA Servlets Coordinting Agent Recommending Agents Orcle Workflow Orcle 8i Dtbse Figure 4. Mjor Components of the Prototype Figure 4 shows the mjor components of the prototype system nd the high-level system rchitecture design. In our system, Orcle Workflow is used to model nd implement the business logic behind the tsk of recommending instructionl softwre. This logic reflects the rel work process used by the ISG. Using commercil workflow system simplifies system development nd mintennce significntly becuse tht it provides built-in grphicl CASE environment nd tht it helps eliminte lots of low-level trnsction-oriented coding tsks. To chieve higher levels of dt nd process independence mong vrious system components nd to enble high degrees of extensibility (e.g., when dditionl softwre pckges become vilble), we seprte the domin knowledge on vilble instructionl softwre nd mtching rules used to intelligently mtching user requests with vilble softwre cpbilities nd encpsulte them in n gent-bsed system implementtion frmework, which runs independently of the workflow module. The workflow module nd the gent module communicte with ech other using KQML, widely-used gent communiction protocol (Petrie, 1996), nd they work collbortively to serve the user needs. The min processing logic of the prototype system is cptured by the following sequence of steps: User requirements re gthered vi Web pge. The workflow process is initited upon the receipt of the request submission. The recommendtion tsk is forwrded to the coordinting gent. The coordinting gent works with recommending gents to process user requests. The results re returned by the coordinting gent to the workflow module. The workflow module routes the results bck to the Web interfce. Motivted by developing system tht cn scle nd cn hndle chnges nd future updtes esily, the gent module of our prototype is implemented s distributed, multi-gent bsed system. As illustrted in Figure 4, Collborting Agent functions s getwy between the gent module nd the workflow module. It receives recommendtion requests from the workflow module, coordintes with collbortive collection of gents ech of them specilizing in prticulr softwre product, resolves conflicts, nd then sends bck recommended solutions to the workflow module in the form of KQML messges. Figure 5 illustrtes the high-level design of multi-gent coordintion in our implemented prototype. A blckbord rchitecture is used to record ll user requests. When user request is posted to the blckbord in the order received, it becomes job, ssocited with time stmp nd n ID number for trcking nd evlution purposes. When job is tking too long to process, the Coordinting Agent will investigte nd re-ssign the job, if necessry /02 $17.00 (c) 2002 IEEE 5

6 Proceedings of the 35th Hwii Interntionl Conference on System Sciences Event Monitoring Tsk Alloction Tsk Announcement Request Interception Dtbse Connectivity Knowledge Repository Recommending Agents Figure 5. Design of Agent Coordintion Mechnisms. We ssume n open operting environment where recommending gents re distributed over the network nd cn pper nd dispper dynmiclly. To del with these openness issues, gent registrtion nd monitoring re necessry. All Recommending Agents tht re redy to serve the user requests will register their presence nd cpbilities before they cn be ssigned request by the Coordinting Agent. When Recommending Agent known to the system goes off-line for ny reson, the Coordinting Agent will nullify its registrtion so subsequent jobs re not ssigned. In ddition, the Coordinting Agent checks the worklod of ll registered Recommending Agents nd ssigns the job to the gent with the lest mount of work. All softwre recommendtions mde by the Recommending Agents re posted to the blckbord. This llows the Coordinting Agent to review nd merge the responses before returning them to the Workflow module. Also, should the Coordinting Agent itself go off-line for ny reson, ll outstnding jobs cn still be recovered from the blckbord. As of the writing of this pper, the prototype system hs been fully functionl. We re in the process of evluting its usefulness nd effectiveness, prticulrly in light of the ese of expnding the system functionlity nd exception hndling, in rel operting environment. We hypothesize tht the built-in softwre flexibility enbled by the workflow nd gent modules described bove will result in significnt reduction in softwre mintennce. A cse study is being plnned for future reserch. In the next section, we present generl frmework to evlution softwre system rchitectures, focusing on the potentil cost impcts of softwre flexibility. 5. A Generl Frmework for Evluting Softwre Architectures Softwre mintennce cost often constitutes significnt prt of the totl cost ssocited with developing nd operting softwre system during its life spn. Softwre flexibility hs mjor impct on softwre mintennce cost becuse more flexible softwre system helps reduce mintennce cost in severl wys. First, softwre system developed with the intent of being flexible is cpble of hndling certin exceptions in n utomted mnner, which in turn cuts bck the effort nd resources tht hve to be invested to del with these exceptions by both the softwre users nd the system development nd mintennce personnel. Second, in tody s competitive mrketplce, n enterprise typiclly goes through frequent chnges in its wys of deling with their customers nd suppliers. Also, its internl business processes often experience incrementl improvements nd occsionlly drstic modifictions. Mny of these business process chnges, both internl nd externl, entil chnges in softwre specifiction nd requests for dded functionlity, which re mong the mjor sources of softwre mintennce cost. A flexible softwre system provides vible lterntive in deling with these types of softwre mintennce costs since it is esier nd more cost-effective to reconfigure nd ressemble softwre components to meet chnges in user requirements. Different softwre technologies nd system rchitectures deliver different levels of softwre flexibility. In this section, we present some preliminry results of our reserch imed t developing generl cost-bsed frmework to help orgniztions mke decisions on which softwre technology or system rchitecture should be dopted given the chrcteristics of their business operting environments. In this frmework, we concentrte on softwre flexibility s the min point of reference when compring severl mjor softwre rchitectures tht re redily vilble or on the horizon for the orgniztions to enble their business process utomtion. In our nlysis, we focus on the totl cost of softwre development nd mintennce over the softwre life cycles. Three possible system rchitectures re considered in our study: ) conventionl informtion system in which no workflow or intelligent gent techniques will be used, b) workflow-bsed informtion system, nd c) n intelligent workflow system tht combines workflow nd intelligent gent techniques. In this section, we first present generl cost-bsed frmework developed to fcilitte optiml choice of softwre system rchitecture. We then discuss the three rchitectures under investigtion nd offer some descriptive insights regrding the vlue of built-in softwre flexibility, enbled by workflow nd softwre gent technologies. Severl importnt fctors tht re not cptured in our current frmework will be discussed in Section An Evlution Frmework The generl frmework consists of three prts. The first prt is concerned with the modeling of user requests nd mintennce needs. The second prt discusses vrious types /02 $17.00 (c) 2002 IEEE 6

7 Proceedings of the 35th Hwii Interntionl Conference on System Sciences of costs ssocited with initil system development nd on-going mintennce ctivities driven by chnging user requirements, dded functionlity, nd softwre bugs. The third prt of the model cptures the mintennce decisions tht the orgniztion hs to mke Mintennce Requests In the literture, two types of mintennce genertion processes hve been proposed (Mookerjee nd Tn, 1999; Chn et l., 1996). One is bsed on continuous mintennce, where softwre mintennce is performed on continuous bsis. The other is bsed on periodic mintennce due to considertions such s economies of scle, nd system degrdtion. To the best of our knowledge, ll existing models tret these two types of request genertion mutully exclusively. In rel-world pplictions, however, both mintennce types co-exist. For significnt new feture dditions due to chnges in business logic criticl system filures, or mjor devitions from design specifictions, softwre mintennce is typiclly performed on reltime bsis. Other minor feture requests nd bug fixings do not wrrnt immedite ttention nd therefore re being hndled periodiclly. In our model, these two types of requests re being explicitly hndled by different mechnisms. Note tht the genertion of these mintennce requests is independent of the underlying softwre infrstructure. Also, the modeling of these requests is independent from how they re being hndled. Whenever pproprite, we use the stndrd request genertion schemes, which hve been proposed in the literture (e.g., Boehm, 1981; Bnker et l., 1993; Mookerjee nd Tn, 1999). We ssume tht the criticl requests, referred to s Type I requests therefter, occur ccording to n Poisson process with time-dependent rrivl rte λ 1( t ), where t is the time elpsed since the initil production use of the system. The second type of noncriticl requests, clled Type II requests, follows similr rndom process with the following rrivl rte: α + 1 β α λ2( t) = M K t exp( βt) Γ( α + 1) where M mesures the newly dded complexities in the system, bsed on function points. α nd β re lerning fctors ssocited with the user. A lower vlue of α nd high vlue of β indicte fst lerning user. K denotes the verge number of requests generted for ech function point Softwre Development nd Mintennce Costs under Different System Architectures We decompose the totl softwre cost into three min ctegories: initil development cost, softwre mintennce cost, nd opportunity cost of witing times while the system is being mintined. Initil development cost includes ll the costs incurred during the initil system development nd testing phse. Exmples of such costs re: generl hrdwre nd softwre infrstructure investment, softwre development trining, costs ssocited with initil system nlysis nd design, system implementtion, debugging, nd testing. We use C to denote ll the cost ssocited with the 0 initil system development using the softwre rchitecture. Softwre mintennce cost is lso closely correlted with the underlying softwre rchitecture nd relted implementtion pltform. We dpt the stndrd cost models in the softwre engineering literture regrding softwre mintennce in our evlution frmework. Specificlly, we consider ll the mintennce costs incurred over the plnning horizon T. A period is defined s the time between two djcent type II mintennce ctivities. We use N to denote the number of type I requests tht i tke plce during the i th period. Then, the cost incurred during period i in connection with developing importnt new fetures nd fixing criticl bugs cn be modeled s: C i, I = c i, I,1 N i + i 1 1 i, I,2 2 i, I,3 γ Ni + γ Ni 2 j= 0 At the right-hnd side of the eqution, the first term cptures costs ssocited with the development of the requested new fetures, the second term reflects the cost of tuning the interctions mong these newly developed components, nd the third term represents the cost of integrting the new fetures into the existing system s i, I,1 whole (Mookerjee nd Tn 1999). c denotes the verge cost of nlyzing nd implementing new feture request. is the cost prmeter relted to integrtion γ i,i,2 i,i,3 mong the newly developed fetures. γ is the cost prmeter cpturing the ctivity mintining the whole system. To cpture the lerning effect on system development, minly s the result of productivity improvement when the system developers nd mintennce personnel re becoming more fmilir with the overll progrmming environment nd the implementtion pltform, we further model: c i, I,1 i = γ, I,1 exp( θ i 1 j= 0 where θ is the lerning rte when the softwre rchitecture is being used. The witing cost for mintennce request is the opportunity cost of witing between the time when the N j ) N j /02 $17.00 (c) 2002 IEEE 7

8 Proceedings of the 35th Hwii Interntionl Conference on System Sciences requests re mde by the user nd the time when the requests re being successfully delt with. We tret witing costs for the two types of requests seprtely. Bsed on the fct tht type I requests re being processed on continuous bsis, we clculte Type I request witing cost over the plnning horizon T s follows. w I ( P T ) λ ( x) I dx where P is the men coding time for hndling one criticl mintennce request nd w 1( t ) is the cost (in the form of lost businesses or reduced productivity) of witing t time units when type I request is issued. Similrly, we clculte the men Type II request witing cost per period s follows: τ II w2 ( P + τ x) λ2( x) dx 0 II where P is the verge time needed to complete requested tsk of type II under softwre rchitecture, nd τ is the time t which the next type II mintennce will strt Softwre Mintennce Decisions Different types of softwre mintennce requests require different rections from the softwre mintennce tem. Due to the nture of Type I requests, immedite mintennce effort will tke plce fter the requests re being mde. On the other hnd, in deling with Type II requests, the softwre mintennce personnel hs choice with respect to the frequency of mintennce effort nd the btch size. Timing nd scheduling of type II mintennce ctivities cn hve significnt cost impct on the totl system mintennce cost, s being demonstrted in pst reserch (Chn et l., 1996). For brevity, we will skip the discussions regrding how the softwre mintennce tem mkes optiml decisions on their mintennce schedules for type II requests. In the following discussions, we will ssume tht for given softwre rchitecture, the softwre mintennce tem will dopt the optiml mintennce policy given its knowledge bout the business operting environment nd relted estimted cost prmeters, which re system rchitecture-dependent A Descriptive Comprison of the Three Architectures Following the generl frmework presented in Section 5.1, we compre the three system rchitectures, nmely, no-workflow, workflow, nd workflow plus gent in light of vrying degrees of softwre flexibility nd potentil cost impcts. In our frmework, certin softwre rchitecture is chrcterized by set of cost prmeters representing how much resource is required to develop the system under the given rchitecture, nd how quickly nd cost-effective new feture requests nd exceptions nd bug-fixing cn be hndled during system mintennce. Due to the emerging nd dynmic nture of workflow nd softwre gent technologies, empiricl dt needed to perform meningful vlidtion of the cross-rchitecture comprison is virtully nonexistent. While we re working on collecting such empiricl evidence, we first present high-level descriptive comprison of the three rchitectures by drwing experience from our development effort presented in Section 4.5 nd from our knowledge on softwre engineering. The results of our nlysis re summrized in Tble 1. Although we believe tht this tble reflects the bsic cost trde-offs of existing nd emerging softwre technologies nd corresponding implementtion prctice, we cution tht it is highly specultive. The min point of our discussion is to demonstrte the process of using the frmework developed in Section 5.1 to nlyze softwre rchitecture lterntives nd to provide point of deprture for follow-up studies. Noworkflow Workflow C Medium Low High 0 i,i,1 r High Medium Low θ Medium Medium High, r, r, High Medium Low i I,2 P, P I II i, I,3 Workflow/ Agent Tble 1: Compring Three Softwre Architectures. We briefly discuss Tble 1 nd explin the rtionle behind the given cost estimtions. Consider the initil system development cost (the 2 nd row of the tble). Becuse of the built-in process utomtion nd trnsctionl support in workflow systems, combined with the strong CASE support, it tkes reltively smll mount of effort to implement business pplictions with processes tht re reltively strightforwrd. When no workflow systems re being dopted, developing the needed functionlity would tke significntly more efforts under the conventionl IS development prdigm. From our experience, developing system tht uses both workflow nd softwre gent technology turns out to incur the highest fixed set-up cost in the initil system development phse. This is prtilly due to the reltive immturity of gent technology nd the lck of commonly-ccepted gent development environment. In ddition, designing nd implementing flexible, generic communiction protocol to integrte workflow system nd relted softwre gents cn be time-consuming nd expensive. On the other hnd, when the bsic integrtion nd collbortion infrstructure re completed, coding productivity will improve. Coupled with the incresing fmilirity with gent-bsed system development ( reltively new set of system design nd progrmming skills /02 $17.00 (c) 2002 IEEE 8

9 Proceedings of the 35th Hwii Interntionl Conference on System Sciences to most system developers) through hnding mintennce requests, we expect higher gins on productivity over time (see the fourth row of Tble 1). Becuse of the built-in system flexibility nd intelligence enbled by softwre gents, it is conceivble tht ll the cost prmeters relted to cost effectiveness nd timeliness of hndling both types of user requests during the system mintennce phse, re lower for the workflow/gent lterntive. Cost svings cn be enbled in severl wys. First, during the execution, some process devitions my be viewed under the workflow nd gent rchitecture s operble, wheres rigid conventionl system hs to tret them s exceptions nd progrmmer intervention is required. Second, the workflow/gent rchitecture enbles higher-level dt seprtion nd better system modulrity, which in turn decrese the dependence mong system components (see the row i, I,2 i, I,3 corresponding to r, r ). Third, gent technology cn esily extend the cpbilities of workflow system while tking the full dvntge of commercilly vilble workflow systems in terms of dt mngement, messge hndling, nd trnsction processing. Bsed on this nlysis, we hypothesize tht it mkes most economic nd technologicl sense to dopt the workflow/gent rchitecture when the business environments re voltile nd constnt chnges hve to be mde to the softwre system. In more stble environments, workflow system lone rchitecture might be preferred. In our ongoing reserch, we re developing simultion-bsed method to vlidte this hypothesis. 6. Conclusions In this pper, we investigted severl innovtive techniques of chieving softwre flexibility in workflow environment. Next, we first summrize the reserch contributions of our work presented in this pper nd then point out severl future reserch directions. We motivted the study of softwre flexibility in the context of workflow mngement systems nd discuss relted modeling issues. We rgue tht workflow system enhnced by intelligent gent technology under the generl umbrell of inter-component process mngement provides vible system implementtion rchitecture to chieve high-level softwre flexibility. A proof-of-concept prototype system is presented, emboding the proposed system rchitecture design. We lso presented generl evlution frmework which cn be used to nlyze the economic impcts of vrious types of softwre rchitectures with respect to totl softwre cost. We offer some generl technologicl nd mngeril insights s to the vrying degrees of softwre flexibility nd cost implictions for conventionl softwre, workflow systems, nd the proposed intelligent workflow systems. This frmework cn serve s theoreticl bsis for mking potentilly criticl softwre rchitecture decisions fcing virtully ll IT dopters. In our future reserch, we re plnning to conduct cse study to evlute the implemented prototype in the context of recommending softwre pckges. The system rchitecture exmined in this pper represents n exmple of loose integrtion between the workflow nd the gentbsed system in tht the gent module opertes outside of the workflow system. We re currently conducting reserch towrds tight integrtion between these two technologies. For instnce, in tightly integrted rchitecture, gent cpbilities such s personliztion, resource modeling, nd conflict resolution will directly enhnce the core functionlity of workflow engine. In the evlution frmework presented in Section 5, we focused exclusively on softwre mintennce nd ssume tht during softwre system s life spn, the underlying softwre rchitecture will remin the sme. In tody s highly voltile softwre development environment, model tht tckles decisions concerning softwre replcement is desired. We pln to extend our model to del with these softwre replcement issues with n emphsis on flexibility in our future reserch. References 1. Bnker, R., Dt, S., Kemerer, C., nd Zweig, D., Softwre Complexity nd Mintennce Costs, Communictions of the ACM, Vol. 36, No. 11, Boehm, B. Softwre Engineering Economics, Pretice Hll, Bowers, John, Grhm Button, nd Wes Shrrock, "Workflow from within nd without", Proc. of the 4 th Europen Conf. on CSCW, Chn, T. Chung, S., nd Ho, T. An Economic Model to Estimte Softwre Rewriting nd Replcement Times, IEEE Trns. On Softwre Engineering, Vol. 22, No. 8, August Decker, K.S. nd Sycr, K. "Intelligent dptive informtion gents". Journl of Intelligent Info Systems: vol.9, no.3 (Nov.-Dec. 1997) p Deiters, W., T. Goesmnn, T. Löffeler, Flexibility in Workflow Mngement: Dimensions nd Solutions, Interntionl Journl of Computer Systems Science nd Engineering, Vol 15, No 5, September 2000, pp Erl, Michel J., The new nd the old of business process redesign, Journl of Strtegic Info. Systems, Vol 3, No. 1, 1994, pp /02 $17.00 (c) 2002 IEEE 9

10 Proceedings of the 35th Hwii Interntionl Conference on System Sciences Edmonds, E.A., et l., "Support for collbortive design: gents nd emergence", Communictions of the ACM, vol.37, no.7 (July 1994) p Ellis, C. nd G. Rozenberg, Dynmic chnge within workflow systems, Proceedings of the COOCS 95, Milpits, CA, USA, Ellis, C. nd K. Keddr, ML-DEWS: modeling lnguge to support dynmic evolution within workflow systems. Computer Supported Coopertive Work: The Journl of Collbortive Computing, Aug. 2000, vol.9, (no.3-4): Etzioni, O. nd D.S. Weld, "Intelligent gents on the Internet: Fct, fiction, nd forecst". IEEE Expert vol.10, no.4 (Aug. 1995) p Fustmnn, G. Configurtion for dpttion- humn-centered pproch to flexible workflow enctment. Computer Supported Coopertive Work: The Journl of Collbortive Computing, Aug. 2000, vol.9, (no.3-4): Hgen, C. nd G. Alonso, Exception hndling in workflow mngement systems. IEEE Trnsctions on Softwre Engineering, Oct. 2000, vol.26, (no.10): Hle, J., Prrish, A., Dixon, B., nd Smith, R. Enhncing the Cocomo estimtion models, IEEE Softwre, Volume: 17 Issue: 6, Nov.-Dec. 2000, Pge(s): Hyes-Roth, B. et l. "A domin-specific softwre rchitecture for dptive intelligent systems," IEEE TSE 21(4) (1995) p Jennings, N., Sycr, K., nd Wooldridge, W. A rodmp of gent reserch nd development, Autonomous Agents nd Multi Agent Systems, Vol 1, No 1, July Jennings, N.R. et l., "Agent-bsed business process mngement". Interntionl Journl of Coopertive Informtion Systems vol.5, no.2-3 (June-Sept. 1996) p Joshi, H. nd Singh, M. Multigent Systems on the net. Communictions of the ACM, Vol 42, No 3, Klein, M., C. Dellrocs, nd A. Bernstein, Introduction to the specil issue on dptive workflow systems. Computer Supported Coopertive Work: The Journl of Collbortive Computing, Aug. 2000, vol.9, (no.3-4): Knoll, K. nd S. L. Jrvenp, Informtion technology lignment or "fit" in highly turbulent environments: the concept of flexibility, Proceedings of the 1994 computer personnel reserch conference on Reinventing IS, Mrch 24-26, 1994, Alexndri, VA USA, Pges Kumr, A. nd Zho, J. L. Dynmic Routing nd Opertionl Controls in Workflow Mngement Systems, Mngement Science, Feb. 1999, vol.45, (no.2): Ludwig, Heiko nd Yigl Hoffner, Contrct-bsed Cross-Orgnistionl Workflows - The CrossFlow Project, Proceedings of the Workshop on Cross- Orgnistionl Workflow Mngement nd Coordintion, Sn Frncisco, USA, Februry 22, Mes, P, "Agents tht reduce work nd informtion overlod", CACM, vol.37, no.7 (July 1994), p30-40, Mhling, D.E., N. Crven, nd W.B. Croft, "From office utomtion to intelligent workflow systems", IEEE Expert, vol.10, no.3 (1995) p Mookerjee V. nd Tn, Y. Optiml Softwre Mintennce nd Replcement Policies, Proceedings of Ninth Workshop on Informtion Technologies nd Systems, 1999, December. 26. Nelson, K. M. et l., "Technology flexibility: conceptuliztion, vlidtion, nd mesurement", Proceedings of HICSS Petrie, C. Agent-Bsed Engineering, the Web, nd Intelligence, IEEE Expert, 1996, December. 28. Singh, M. nd Huhns, M. Automting workflows for service provisioning: Integrting AI nd dtbse technologies, IEEE Expert, Vol 9, No 5, 1994, p Spector, L. "Automtic genertion of intelligent gent progrms". IEEE Expert 12, 1 (1997) p Stohr, Edwrd A. nd J. Leon Zho, "A technology dpttion model for business process utomtion", Proceedings of HICSS Sull, W. A distributed environment for enbling lightweight flexible workflows. Proceedings of the Thirty-First Hwii Interntionl Conference on System Sciences, Jn. 6-9, 1998, p vol Sycr, K. nd D. Zeng. "Coordintion of multiple intelligent softwre gents". Intl. J. of Coop Info Systems vol.5, no.2-3 (1996) p Zho, J. Leon, Intelligent Agents for Flexible Workflow Systems, Proceedings of the AIS Americs Conference on Informtion Systems, Bltimore, Mrylnd, August 14-16, /02 $17.00 (c) 2002 IEEE 10