Thanks all ! Martynas : I take a look on your application/framework. It means the VUE is described in RDF as templates, isn'it? I will have to design by example Quizz etc in RDF ? I guess I need some more hours to decript how work Graphity, and I will do that when I get bored about sesame/jena JPA and other reasoners stuff !
Ashish : " what benefit do you get converting Javabeans to RDF? " - jbeans -> RDF : is a way to get data persistance. - RDF because I need SWRL rule or equivalent on the data (say propose learning support to student based on rules) - I need OWL reasonning inferencing too. => OOP, and javabeans (JPA), is a stable and ubiquitous way to manage the model of data. In a classical MVC architecture, with JSP and EL, it's a simple and eprouved way to design a website. Then thanks to JPA (PA4RDF or Alibaba with sesame), CURL actions will be OOP. I will work on complex jbeans : QUIZZ and various type of exercices and need complex object manipulations. By the way, this do not mean all fonctionnality will be done with JPA. By example, I will add a SWRL module (based on pellet?), that may retrieve data with SPARQL, and reason on that statements. Claude : Thanks for quick answer. I am comparing Alibaba (https://bitbucket.org/openrdf/alibaba/src/master/object-repository/ = ELMO's successor) VS your PA4RDF. 1)An interesting annotation in Alibaba is the @SPARQL annotation. I guess the only way doing that with PA4RDF is an abstract/concrete class with ARQ query inside ? Is there a way to get the URI of he instance inside it ? (alibaba has the $this used in @SPARQL annotation) 2)What about ordoned lists in PA4RDF ? Is Colllection<valueClass> getX() keeps order ? Alibaba do not use collection. 3)On this page http://pa4rdf.sourceforge.net/examples/concreteClassSubject.html, is this a mistake ? "Iterator<String> authors = book.getAuthors();" should be "Iterator<String> authors = book.getAuthor();" Right ? 4) " as setting the bean properties should be performed inside a transaction and the transaction committed when all the properties have been updated" : I guess you mean model.begin() / model.commit(). Then a last question. Alibaba give ability to manage connection and model. Is the only way to access the same model in the aplication is using a static model (by example initialized when web appli begin ?) 5) The last one : When you say in your introduction : " map a RDF triple (subject, predicate, object) to a Plain Old Java Object (POJO)", this do not say that PA4RDF javabeans can't extends other PA4RDF javabeans ? eg : JbeanUser <- JbeanStrudent Thanks for answers Nicolas PARIS 2015-01-07 12:02 GMT+01:00 Claude Warren <[email protected]>: > I was asked to comment on this thread and so as the developer for PA4RDF I > will. > > PA4RDF was originally an interface only mapping: Annotated Interface > directly mapping onto the RDF structure with the Subject of the triples > being the instance of the interface and various properties of the subject > mapped to methods. PA4RDF did all the mapping from RDF data types to Java > data types and back. It also had a nomenclature to distinguish between > properties that should be single instance and those that can be multiple > instance. > > The use of Interface only became to unwieldy so it has been extended to > handle abstract and concrete classes. It still handles all the conversions > and ensuring that the property is single instance when required. > > It was later extended again to handle triggers (of a sort) wherein specific > methods can be called after the getter, setter or remover methods. This is > to assist the developer in maintaining internal consistency. > > Now as to weather or not it works in the MVC environment. My experience is > that it does. That was primarily why I wrote it. I started out by looking > at using the standard JPA annotations to read/write the graph but found > that the impedance mismatch was to great. > > PA4RDF does not make copies of the data, it uses the Jena model interface > directly. Since the Resources in the Model always have access to the > current state of the model the PA4RDF annotated beans always have access to > the current state of the model. They are never disconnected. (Disconnected > operation is a planned feature). The lack of disconnection has some impact > on program design as setting the bean properties should be performed inside > a transaction and the transaction committed when all the properties have > been updated. > > The example cited above ( > http://pa4rdf.sourceforge.net/examples/concreteClassSubject.html) handles > the case where there is no interface to annotate and the developer may be > plugging PA4RDF into an existing class. > > For most projects with simple beans the annotated interface ( > http://pa4rdf.sourceforge.net/examples/interface.html) is a better example. > > If you have a requirement to process some of the properties before > returning them (in the PA4RDF examples returning a "cite" for a book, you > can annotate an abstract class. You could also have the abstract class > extend an annotated interface and that would work as well). > > Finally, the concrete example is also used in cases where you can not pass > an abstract class or an interface to some other class. I don't recall the > specific case but I do remember encountering the case where I needed the > ability to create a concrete class as the tool I was using would not allow > an Abstract class or Interface to be used). > > I think you will find that PA4RDF works well as a replacement for JPA and > has additional capabilities that exploit the underlying Model. If it > doesn't I am more than willing to accept code fixes and ideas. Also any > documentation would be gladly accepted. > > Claude Warren > > > > > > On Wed, Jan 7, 2015 at 6:29 AM, Ashish Nijhara <[email protected]> > wrote: > >> Nicolas: It is important to understand why would you like RDF into >> JavaBeans. I mean in that case, a regular java application with RDBMS would >> also do the job or? So, if you consider for a second, you would have >> Javabeans being the objects updated by the application, internally you want >> to convert them to RDF and store them in a triple store. The architecture, >> however correct, sounds clunky unless there is a deep reason to have such >> an architecture and not intuitive. >> >> I agree with Martynas, RDF opens a lot more possibilities. >> >> To answer the questions >> 1) Are there good practice or some DAO to design ? >> As mentioned above, what benefit do you get converting Javabeans to RDF? If >> no benefit, then stick to one paradigm and keep it simple!! >> 2) In term of performances, is it better to use ARQ (sparql) OR jena >> ontologie API ? >> For getting bulk information out, my experience has been SPARQL is better. >> (3) is it a good choice to store all in a triple store ? (versus >> traditional relational databases) ) >> Storing things in a triple store is better, in RDBMS you may end up using >> Jena SDB to store triples in RDBMS which gets clunky and slow. >> >> On Wed, Jan 7, 2015 at 5:53 AM, Martynas Jusevičius <[email protected] >> > >> wrote: >> >> > Nicolas: fair enough. However you should know that by simply replacing >> > the relational DB with a triplestore while using the same >> > object-oriented programming approach you're not getting even half of >> > the advantages of semantic technologies. RDF opens possibilities for >> > new software design patterns. >> > >> > On Tue, Jan 6, 2015 at 9:37 PM, Nicolas Paris <[email protected]> >> wrote: >> > > Martynas : Thanks for the link. Maybe your solution is excellent, but >> > > I don't want to lose me : classical MVC, is a security for me and the >> > > project. >> > > >> > > Olivier : The Elmo documentation is great. Do you think my application >> > > could be done with sesame ? I mean, sesame has a triple store, a >> > > reasoner, and looks like having a javabeans system much advanced than >> > > jena/PA4RDF have ? >> > > Anyway, jena/PA4RDF can actually do the job ; the documentation for >> > > PA4RDF is just really poor. >> > > Nicolas PARIS >> > > >> > > >> > > 2015-01-06 10:48 GMT+01:00 Olivier Rossel <[email protected]>: >> > >> Martynas, >> > >> >> > >> that is a bit off-topic but maybe you could organize a webinar so you >> > >> can show us some features of graphityhq. >> > >> >> > >> Nicolas: >> > >> >> > >> honestly, i know not very much about PA4RDF, >> > >> I use Elmo (rebranded as AliBaba) : >> > >> >> > >> http://sourceforge.net/projects/sesame/files/AliBabaElmo/1.5/openrdf-elmo-1.5.zip/download >> > >> >> > >> There is a nice user guide in the zip file, that gives a lot of >> details >> > >> about how to annotate beans so the persistence is transparent. >> > >> I think inheritance is explained too. >> > >> >> > >> On Tue, Jan 6, 2015 at 2:29 AM, Martynas Jusevičius >> > >> <[email protected]> wrote: >> > >>> Nicolas, >> > >>> >> > >>> I suggest you also take a look at Graphity Client: >> > >>> https://github.com/Graphity/graphity-client >> > >>> >> > >>> You don't really need an object layer representing your RDF classes >> > >>> above Jena, it is a bottleneck. You can express both the webapp >> > >>> structure and the instance data as RDF, and define a mapping from >> HTTP >> > >>> access to RDF state changes over SPARQL. >> > >>> >> > >>> Here's an example of how that structure (sitemap ontology) looks >> like: >> > >>> >> > >> http://lists.w3.org/Archives/Public/public-declarative-apps/2015Jan/0000.html >> > >>> >> > >>> Here's an example of an editing interface: >> > >>> >> > >> http://linkeddatahub.com/bibframe/instances?mode=http%3A%2F%2Fgraphity.org%2Fgc%23CreateMode >> > >>> >> > >>> Disclaimer: I'm the main developer. >> > >>> >> > >>> >> > >>> Martynas >> > >>> graphityhq.com >> > >>> >> > >>> On Mon, Jan 5, 2015 at 9:07 PM, Nicolas Paris <[email protected]> >> > wrote: >> > >>>> Thanks for answers ! >> > >>>> >> > >>>> - About http://callimachusproject.org/ : interesting but I have to >> > >>>> create application from scratch, because very specific >> > >>>> >> > >>>> - About PA4RDF : It seems very interessant. Any other tutorial, >> > >>>> related post or tip ? >> > >>>> Olivier, what do you exactly mean by "a bean <-> graph mapper" ? >> > >>>> I generate an OWL ontology, that is my structure of data. I will >> > >>>> modelise beans inspiring this structure. Say owl properties will be >> > >>>> java class properties. And RDF class's inheritance will be mapped to >> > >>>> java inheritance. Do you agree ? >> > >>>> However, it appears that the POJO class of PA4RDF limits the >> > inheritance. >> > >>>> The example here >> > >>>> http://pa4rdf.sourceforge.net/examples/concreteClassSubject.html >> > >>>> could feet with user <- student inheritance ? Or will I have to >> > >>>> duplicate code for Teacher & Student as they inherite from User ? >> > >>>> >> > >>>> Thanks again for this link Olivier ! >> > >>>> Nicolas PARIS >> > >>>> >> > >>>> >> > >>>> 2015-01-05 15:44 GMT+01:00 Olivier Rossel <[email protected] >> >: >> > >>>>> There was a discussion some weeks ago about PA4RDF. >> > >>>>> It might be a good starting point, in you think a bean <-> graph >> > mapper >> > >>>>> could be useful in your case. >> > >>>>> >> > >>>>> Also http://callimachusproject.org/ could be another interesting >> > >>>>> project to investigate in your case. >> > >>>>> >> > >>>>> On Mon, Jan 5, 2015 at 2:41 PM, Nicolas Paris <[email protected] >> > >> > wrote: >> > >>>>>> Hello, >> > >>>>>> >> > >>>>>> I am creating a web semantic application, were persistant data is >> > all >> > >>>>>> stored in triple store (TDB). >> > >>>>>> I mean, users(foaf), parameters etc. >> > >>>>>> This application is an e-learning application, with exercices >> > >>>>>> proposition based on reasonners. >> > >>>>>> >> > >>>>>> I want to use a classic MVC design pattern (jsp / servlets / >> > javabeans). >> > >>>>>> So a javabeans user, teacher, and student with heritage. >> > >>>>>> My naïve aproach would be to initialise jbeans from TDB, using >> jena >> > >>>>>> model getInstance etc. Or Sparql Querys with ARQ >> > >>>>>> and my setters will do both : >> > >>>>>> - set jbeans propertys >> > >>>>>> - modify triple (dataset jena setProperty ; dataset commit , OR >> > SPARQL querys) >> > >>>>>> >> > >>>>>> Example bad pseudo-code: >> > >>>>>> Class student extends user { >> > >>>>>> private Integer age; >> > >>>>>> private Ressource student = myModel.getIndividual( >> > >>>>>> "http://www.myexample.com/mySchema#student1"; ); >> > >>>>>> >> > >>>>>> public void setAge(Integer age){ >> > >>>>>> this.age = age; //modify jbeans property >> > >>>>>> student.setPropertyValue("http://www.myexample.com/mySchema#age >> > ","1^^integer") >> > >>>>>> # modify TDB valyue >> > >>>>>> } >> > >>>>>> >> > >>>>>> } >> > >>>>>> >> > >>>>>> >> > >>>>>> 1) Are there good practice or some DAO to design ? >> > >>>>>> 2) In term of performances, is it better to use ARQ (sparql) OR >> jena >> > >>>>>> ontologie API ? >> > >>>>>> (3) is it a good choice to store all in a triple store ? (versus >> > >>>>>> traditional relational databases) ) >> > >>>>>> >> > >>>>>> Thanks a lot >> > >>>>>> >> > >>>>>> >> > >>>>>> >> > >>>>>> Nicolas PARIS >> > >> > > > > -- > I like: Like Like - The likeliest place on the web > <http://like-like.xenei.com> > LinkedIn: http://www.linkedin.com/in/claudewarren
