EXPERT SYSTEMS WITH APPLICATIONS IEEE 陳郁婷 A formal modeling platform for composing web services
Outline Introduction Petri Nets SCMP Example Conclusion
Introduction Service requesters regard most Web services as outsourced applications 不保證 connectivity and reliability 整合困難 The Web services technology stack still lacks a composition standard 互不相容 a composition must consider non-functional QoS issues more than functional QoS issues such as workflow reliability Petri Nets-based Composing SCMP (Service Composition Modeling Platform)
Petri Nets PN = (P, T, F, M, W) P : a set of places. T : a set of transitions that represents the set for tasks, processes, activities, or events. F : a set of arcs used to represents flow paths M : an initial marking (M0, ……,Mn) W : a set of arc weights denoting how many tokens are consumed from a place by a transition
Web Service Petri Net WSPN(Web Service Petri Net) WSPN = (P,T, F, Y, A) P : a set of places → P = {p1,p2,...,pn} T : a set of transitions → T = {t1,t2,...,tn} F : a set of arcs → Y : a set of types → Y = {y1,y2,...,yn} BP : base place SIP : service input place SOP : service output place A: P → Y : association of places to types
WfMC
SCMP (Service Composition Modeling Platform) A visual editing module defining a conceptual service composition model using the Petri Nets-based mechanism. A script language translation module translate a conceptual model into a preferred composition script language. A workflow measurable module employs evaluation algorithms to validate nonfunctional workflow properties of Web services compositions.
service finder Universal Description, Discovery and Integration (UDDI) business registry (namely, the UBR) description document loader mechanisms
WSFL and BPEL4WS language transformation translator employs XSLT and XPath specify elements and their relationships 可 link 到 workflow engines load the composition scripts Test the execution results
translate : conceptual services composition ↓ PNML (in XML) Safeness : if it has no more then one token of a Petri Nets Coverability tree algorithm Deadlocked : if no transitions are enabled transitive matrix algorithm Reachable : if it can be generated by a sequence of transition firings beginning at the initial marking
SCMP 截圖 BaseWSflow
Example 1 使用者要求英文文章 找尋中文文章 翻譯成英文文章 回傳結果給使用者
2.Factor building 1. visual editing
PNML code document newsRequest newsResponse englishNews translatedNews ProcessSRL BabelFish Sequence1...
Example 2 Lin 想借貸 50 萬
loanSerC
Conclusion SCMP 不需要很多時間及技巧就能建構一個健全的 service composition GUI 介面加快建構速度 未來 讓 SCMP 能連線到適當的 workflow engines 加入更多的 Petri Nets mathematical algorithms 或 formal analysis methods 來確認各種的 QoS properties.
Coverability tree
JARP Peri Net Analyzer
Web service binding layer
WSCSs translation layer