ER2004, Shanghai, China Enterprise Modeling with Conceptual XML Stephen W. Liddle Rollins Center for eBusiness and School of Accountancy & Information Systems David W. Embley & Reema Al-Kamha Department of Computer Science Brigham Young University, Provo, Utah, USA

11 Nov 2004 ER2004, Shanghai, China 2 XML for Fun and Profit The benefits of XML are clear:  Great for hierarchical, mostly human-readable, textual data  Meta-data travels with the data  Standardized, “commoditized” data interchange XML enjoys a significant “network effect”  Value of XML = O(n 2 ), where n is number of users

11 Nov 2004 ER2004, Shanghai, China 3 Death by a Thousand Paper Cuts But XML also has disadvantages:  (Aside from minor issues like query-processing and storage efficiency concerns)  Schema definitions are complex and numerous Details can be laborious, tedious Allows arbitrary amounts of heterogeneity The number of schemata increases geometrically  Thanks to the network effect, XML is ubiquitous  Rigid tree structure influences XML data modeling

11 Nov 2004 ER2004, Shanghai, China 4 The Modern Enterprise Remote Divisions & Employees Customers Employees Suppliers Distributors & Channel Partners Strategic Partners ERP Supply Chain Management CRM and Support Employee Systems Partner & Channel Management FIREWALL From Carey, Enterprise Information Integration – XML to the Rescue!, ER2003 Wide variety of data sources Increasing heterogeneity Increasing need for integration

11 Nov 2004 ER2004, Shanghai, China 5 Model-Driven Nirvana OMG’s Model-Driven Architecture (MDA) hopes to lead us to the Promised Land Vision: integrate all assets into one enterprise-wide, global information appliance by separating business logic from platform technology Reverse-engineer legacy components  Semi-automated (at best) Platform- Independent Model Translate Platform- Specific Model Executable System Abstract Model Automated Mapping

11 Nov 2004 ER2004, Shanghai, China 6 Mike Carey’s ER2003 Challenge to the Conceptual Modeling Community Produce a simple conceptual model that:  Works well with XML and XML Schema  Abstracts well for conceptual entities and relationships  Scales to handle large data sets and complex object interrelationships  Allows for queries and defined views via XQuery  Accommodates heterogeneity

11 Nov 2004 ER2004, Shanghai, China 7 Our Vision: Conceptual XML We have an answer to the challenge!  Collectively we’ve been developing it for 30 years Conceptual XML (C-XML) is a conceptual model:  High-level object and relationship sets  Seamless abstraction  “Model-equivalent” with XML Schema

11 Nov 2004 ER2004, Shanghai, China 8 How C-XML Helps the Enterprise Enterprise Application Infrastructure  Standards-based  XML-compliant C-XML Model Management Layer  Supports conceptual abstractions  Integrates XML Schema, XQuery views into enterprise view DataSource XML View DataSource DataSource DataSource

11 Nov 2004 ER2004, Shanghai, China 9 C-XML Example Data frame annotations are not shown

11 Nov 2004 ER2004, Shanghai, China 10 C-XML  XML Schema Translations We need information- and constraint- preserving translations in both directions Translations need not be inverses  It is sufficient that they create equivalence classes Our community has created numerous XML generation algorithms  But there hasn’t been much work on the reverse  We can guarantee certain good design properties with respect to generated XML Schema

11 Nov 2004 ER2004, Shanghai, China 11 C-XML Example 44: 45: 46: 47: 48:... 49: 50: 51: 52: 53: 54: 55:

11 Nov 2004 ER2004, Shanghai, China 12 C-XML Example 56: 57: 58: 59: 60:... 79: 80:

11 Nov 2004 ER2004, Shanghai, China 13 C-XML Example 11:

11 Nov 2004 ER2004, Shanghai, China 14 C-XML Example 35: 36: 37: 38:... 60: 61: 62:... 74: 75:... 77: 78:

11 Nov 2004 ER2004, Shanghai, China 15 Converting XML Schema back to C-XML We separate structural from non-structural concepts  Structural: elements, attributes, …  Non-structural: attribute types, order constraints, … Algorithm overview:  Generate object sets for each element, attribute  Connected by relationship sets  Nested according to XML hierarchy  Re-code all constraints in C-XML

11 Nov 2004 ER2004, Shanghai, China 16 Initial Result of Reverse Conversion

11 Nov 2004 ER2004, Shanghai, China 17 Strikingly Different?

11 Nov 2004 ER2004, Shanghai, China 18 Or Not? Artifact of XML Schema Artifact of XML nesting n-ary relationship decomposition

11 Nov 2004 ER2004, Shanghai, China 19 Preserving Information and Constraints We formalize C-XML using predicate calculus See the paper for definitions, lemmas, theorems We claim that our translations between C- XML and XML Schema preserve information and constraints

11 Nov 2004 ER2004, Shanghai, China 20 View Mechanisms in C-XML High-level abstractions  For model management, reducing cognitive load C-XML XQuery views  Generate XQuery from conceptual description XQuery integration mappings  For bringing together disparate chunks of XML

11 Nov 2004 ER2004, Shanghai, China 21 C-XML XQuery Views Need to generate XQuery views from C-XML views  XQuery can be cumbersome  Must follow hierarchical XML layout C-XQuery borrows syntax from XQuery  FLWOR expressions  Path expressions are conceptual “A//B” designates path from A to B regardless of hierarchy or intervening steps  Attribute/element distinction is not necessary Execution is by view unfolding and translation to standard XQuery

11 Nov 2004 ER2004, Shanghai, China 22 XQuery vs. C-XQuery Consider conceptual path “Item//OrderID” “OrderID” or

11 Nov 2004 ER2004, Shanghai, China 23 Our Contributions A vision for applying conceptual modeling to the task of enterprise-wide XML support A framework to support the vision:  Information- and constraint-preserving mappings between C-XML and XML Schema  Defined mechanisms for producing and using first- class, high-level, conceptual abstractions  XQuery view definitions over both standard and federated conceptual-model instances

11 Nov 2004 ER2004, Shanghai, China 24 C-XQuery Example define view CustomersByItemsOrdered {for $item in Item return {$item/ItemNr, $item/Description} {for $customer in $item/Order/Customer return {$customer/CustomerName, $customer/CustomerAddr} {for $order in $customer/Order, $item2 in $order/Item where $item2 = $item return {$order/OrderDate, $item2/Qty, $item2/SalePrice} } } }

11 Nov 2004 ER2004, Shanghai, China 25 Views within Views define view RecentNitrogenFertilizerCustomers {for $i in CustomersByItemsOrdered where $i/Description = “Nitrogen Fertilizer” return {for $c in $i/Customer let $total := sum( for $o in $c/Order where $o/OrderDate > add-days(current-date(), -90) return $o/Qty * $o/SalePrice ) return {$c/CustomerName, Total=$total} } } for $c in RecentNitrogenFertilizerCustomers/Customer where $c/Total > 300 return {$c/CustomerName, $c/Total}

11 Nov 2004 ER2004, Shanghai, China 26 C-XQuery Mapping define view CatalogItemToItem {for $cItem in CatalogItem let $itemNr := CatalogNr-to-ItemNr($cItem) let $price := $cItem/MSRP * (1 + $cItem/MarkupPercent) return {$itemNr} {$cItem/ShortName} {$price} }

11 Nov 2004 ER2004, Shanghai, China 27 C-XML Workflow Diagram