Impedance Mismatch 2.0

Impedance mismatch 2.0,[object Object],BouvetOne 2010-01-28,[object Object],Lars Marius Garshol, <larsga@bouvet.no>,[object Object]

Impedance mismatch 1.0,[object Object],Java objects,[object Object],Tables,[object Object],?,[object Object],Objects and relations have different structures,[object Object],causes lots of extra development work,[object Object],a well-understood problem today,[object Object]

Impedance mismatch 2.0,[object Object],?,[object Object],Objects and semantic technologies have the same issue,[object Object],this is not well understood, however...,[object Object]

And the solution is...?,[object Object],I don’t suggest that I have it,[object Object],what I am suggesting is that we need to think more seriously about this problem,[object Object],This talk sketches some approaches,[object Object],I would be very interested in feedback on them,[object Object]

Some important concerns,[object Object],Whipuptitude,[object Object],how easy it is to get something up and running,[object Object],Manipulexity,[object Object],how complicated data/interface you can handle,[object Object],Knowledge of TMs,[object Object],is it possible to shield some developers from TMs?,[object Object],Testability,[object Object],how easy is it to do automated testing?,[object Object],Flexibility,[object Object],how hard is it to change the application?,[object Object]

The one-layer approach,[object Object],JSP,[object Object],JSP,[object Object],JSP,[object Object],Write lots of JSPs,[object Object],put your queries in the JSPs,[object Object],off you go,[object Object],Messy, but effective,[object Object],high whipuptitude, but brittle,[object Object],limited manipulexity,[object Object],usually lots of boilerplate code,[object Object],Difficult to test,[object Object]

Write a domain model,[object Object],JSP,[object Object],Domain model,[object Object],JSP,[object Object],JSP,[object Object],Write a domain model,[object Object],put as much business logic as possible inside,[object Object],hide all Topic Maps queries in it,[object Object],then build JSPs as a thin layer on top,[object Object],Scales to higher manipulexity,[object Object],much easier to test,[object Object],public class Person {,[object Object], public String getName();,[object Object], public String getEmail();,[object Object], public Date getDateOfBirth();,[object Object], // ...,[object Object],},[object Object]

But...,[object Object],Very low whipuptitude,[object Object],takes a while to figure out how to approach writing this code,[object Object],lots of scaffolding to do before you get started,[object Object],Wasn’t one of the benefits of TMs flexibility?,[object Object],now any ontology change has to be followed by an update to the domain model,[object Object],this is slow and a lot of work,[object Object],compared to an RDBMS and an OR-mapper, is this really any faster?,[object Object]

Generate a domain model,[object Object],JSP,[object Object],Generated domain model,[object Object],JSP,[object Object],Custom code,[object Object],JSP,[object Object],Use a tool that generates the model,[object Object],obviously, it must allow custom extensions,[object Object],saves effort by avoiding most of the routine work,[object Object],business logic still has to be written manually,[object Object],Scales to even higher manipulexity,[object Object],whipuptitude no longer quite so bad,[object Object],http://www.networkedplanet.com/ontopic/2007/07/topic_map_objects_research_pap.html,[object Object]

To make this work...,[object Object],Use schema + annotations as input,[object Object],also conventions instead of config, where possible,[object Object],allow ontology annotations to provide additional generated business logic, where possible,[object Object],(.NET allows partial classes, avoiding subclassing),[object Object],Generated code not to be edited,[object Object],all custom logic in separate subclasses,[object Object],Might be able to use tolog rules to implement some of the business logic without Java,[object Object]

A portlet approach,[object Object],JSP,[object Object],TreePortlet,[object Object],JSP,[object Object],RelatedTopics,[object Object],JSP,[object Object],TopicList,[object Object],Use generic components for display,[object Object],at least as far as possible,[object Object],these rely on configuration and ontology annotation,[object Object],note: components reflect interface, not the domain,[object Object],Enormous whipuptitude,[object Object],manipulexity probably limited,[object Object]

Ontology changes,[object Object],All applications have some ontology expectations,[object Object],however, using a generic approach these can be minimized,[object Object],sometimes to the point where no code changes are required for certain ontology changes,[object Object],However, this requires the use of generic components,[object Object],usually also requires some forethought,[object Object],with a traditional domain model this is not really possible,[object Object]

Evaluation,[object Object],whipuptitude,[object Object],Generic,[object Object],portlets,[object Object],One-layer,[object Object],approach,[object Object],Generated domain model,[object Object],Self-written domain model,[object Object],manipulexity,[object Object]

But what do you think?,[object Object],Would any of these approaches really solve the problem?,[object Object],Do we need more?,[object Object],Do we need something entirely different?,[object Object]

Impedance Mismatch 2.0

Impedance Mismatch 2.0

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