package net.bblfish.triples.test; import com.hp.hpl.jena.rdf.model.*; import com.hp.hpl.jena.vocabulary.RDF; import com.hp.hpl.jena.datatypes.xsd.XSDDatatype; import java.io.*; import java.util.*; import java.text.SimpleDateFormat; /** * Date: May 6, 2004 * Time: 10:33:01 PM * author: hjs */ public class Blog3Example { Model worldModel = ModelFactory.createDefaultModel(); static SimpleDateFormat df, tagf, filef; Model entryDB = ModelFactory.createDefaultModel(); ArrayList entries = new ArrayList(); String base = "http://bblfish.net/work/atom-owl/2004-08-12/"; static { df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ"); //ISO 8601 format df.getTimeZone().setID("+00:00"); tagf = new SimpleDateFormat("yyyyMMdd/HHmm"); filef = new SimpleDateFormat("yyyy-MM-dd-HHmm"); } void publish() { File name = new File("AllInOneDatabase.n3"); entryDB.setNsPrefix("", Atom.NS); entryDB.setNsPrefix("xsd", XSDDatatype.XSD + "#"); entryDB.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); try { entryDB.write(new FileOutputStream(name), "N3-PP", name.toString()); } catch (FileNotFoundException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } } class Feed { File dir; String fileprefix; int numEntries; Resource id; private String lang; /** * A feed will contain a certain number of entries. * * @param fileprefix the file prefix, which will be followed by .n3 for the changing part of the feed and * a time stamp for the archived version * @param numEntries the number of entries in each feed file */ public Feed(String fileprefix, int numEntries) { this.fileprefix = fileprefix; this.numEntries = numEntries; } void init() { } Resource about; void setAbout(Resource about) { this.about = about; } void setLanguage(String lang) { this.lang = lang; } /* void addFeedEntry(Entry entry) { entries.add(entry); feedRes.addProperty(Atom.feedEntry, entry.entryRes); } */ /* void addNextLink(Entry e) { } */ void writeAsHtml() { try { Writer html = new FileWriter(new File("blogexample.html")); html.write("\n" + "\n" + "\n" + ""); html.write(""); header.writeEntryAsHtml(html); html.write("
"); List topentries = new ArrayList(getTopLevelEntries()); topentries.remove(header); Collections.sort(topentries); Collections.reverse(topentries); for (Iterator i = topentries.iterator(); i.hasNext();){ Entry e = (Entry)i.next(); e.writeAsHtml(html); } html.write(""); html.flush(); } catch (IOException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } } /** * * @return all entries that are not in reply to something else */ private Set getTopLevelEntries() { Set result = new HashSet(); for (Iterator i = entries.iterator(); i.hasNext();) { Entry e = (Entry)i.next(); if (!e.model.listSubjectsWithProperty(Atom.in_reply_to).hasNext()) result.add(e); } return result; } void publish(Resource dynamicRes, File file, List entries, File next) throws FileNotFoundException { Model model = ModelFactory.createDefaultModel(); Resource feedRes = model.createResource(base+file.toString(), Atom.Feed); feedRes.addProperty(Atom.header,header.entryRes); feedRes.addProperty(Atom.about,about); feedRes.addProperty(Atom.dynamic,dynamicRes); Statement stmt; for (Iterator it = entries.iterator(); it.hasNext();) { Entry e = (Entry) it.next(); feedRes.addProperty(Atom.entry, e.entryRes); stmt = model.createStatement(e.entryRes,Atom.id,e.id); model.add(stmt); stmt = model.createStatement(e.entryRes,Atom.entry_version,e.entryVersion); model.add(stmt); } if (next != null) { Resource linkRes = model.createResource(Atom.Link); linkRes.addProperty(Atom.mime_type, model.createTypedLiteral("application/rdf+n3")); linkRes.addProperty(Atom.text, model.createTypedLiteral("previous " + numEntries + " entries")); Resource lnk = model.createResource(base+next.toString()); linkRes.addProperty(Atom.href, lnk); feedRes.addProperty(Atom.previous, linkRes); } model.setNsPrefix("", Atom.NS); model.setNsPrefix("xsd", XSDDatatype.XSD + "#"); model.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); model.write(new FileOutputStream(file), "N3-PP", file.toString()); } void publish() throws FileNotFoundException { Resource feed = entryDB.createResource(base+fileprefix + ".n3"); feed.addProperty(RDF.type, Atom.Feed); System.out.println("num entries:" + entries.size()); for (int i = 0; i < entries.size(); i++) { Entry e = (Entry) entries.get(i); if (e == null) System.out.println(i + "=null"); else System.out.println(e.nameN3); } Collections.sort(entries); Collections.reverse(entries); File oldfile = null; for (int i = 0; i+numEntries < entries.size(); i += numEntries) { List todo = entries.subList(i, i+numEntries); File file = new File(fileprefix + "-entries_" + i +"_to_"+ (i+numEntries-1) + ".n3"); publish(feed, file, todo, oldfile); oldfile = file; } List todo = entries.subList(Math.max(0, entries.size() - numEntries), entries.size()); publish(feed, new File(fileprefix + ".n3"), todo, oldfile); } Entry header; public void setHeaderEntry(Entry entry) { this.header = entry; } class Link { Resource linkRes; Link(String rel, String mime, String href) { } Resource getResource() { return linkRes; } } } class Blog { Model model = ModelFactory.createDefaultModel(); Resource blogRes; File file = new File("blog.n3"); Blog() { blogRes = model.createResource(base+file.toString()); blogRes.addProperty(RDF.type,Atom.Blog); blogRes.addProperty(Atom.post_service,model.createResource(base+"Blog3Example.java")); blogRes.addProperty(Atom.version, "Atom 0.6");//does this make sense to have a version at this level? Why is that not at the top level of the xml? blogRes.addProperty(Atom.generator, "TripledBlog version 0.6"); blogRes.addProperty(Atom.lang, "en"); //would it be possible to add xml:lang here (instead of Atom.lang)? blogRes.addProperty(Atom.info, "This blog is an example blog to test out how one could create a blogging " + "standard using the very powerful Semantic Web tools. Note that the post-service for this blog is" + " currently the java file that generated all these files. This is a joke of course. In an easy to use" + " blogging tool, one would not have to edit a java file, compile it, then run it in order to add a new entry."); } void publish() throws FileNotFoundException { model.setNsPrefix("", Atom.NS); model.setNsPrefix("xsd", XSDDatatype.XSD + "#"); model.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); model.write(new FileOutputStream(file), "N3-PP", file.toString()); } } class Entry implements Comparable { File nameN3; File nameRDF; File simpleRDF; Model model = ModelFactory.createDefaultModel(); Resource entryRes; Resource id; Resource entryVersion; Set responses = new HashSet(); /* String rules = "[r1: (?e "+Atom.id + " ?id) -> (?id "+ RDF.type + " " + Atom.EntryID + ")] "+ "[r2: (?e "+ Atom.author +" ?author), (?e "+Atom.id + " ?id) -> (?id "+ Atom.author +" ?author)]" + "[r2: (?e "+ Atom. +" ?author), (?e "+Atom.id + " ?id) -> (?id "+ Atom.author +" ?author)]" + */ Entry(Date created) { this.nameN3 = new File("entry." + filef.format(created) + ".n3"); nameRDF = new File("entry." + filef.format(created) + ".rdf"); simpleRDF = new File("atom." + filef.format(created) + ".rdf"); entryRes = model.createResource(base+nameN3.toString()); id = model.createResource("tag:bblfish.net/" + tagf.format(created) + "/blog1"); entryVersion = model.createResource(id + "#version1"); entryRes.addProperty(RDF.type, Atom.Entry); entryRes.addProperty(Atom.id, id); entryRes.addProperty(Atom.entry_version, entryVersion); Resource linkRes = model.createResource(Atom.Link); linkRes.addProperty(Atom.mime_type, model.createTypedLiteral("text/html")); linkRes.addProperty(Atom.text, model.createTypedLiteral("html blog entry")); Resource lnk = model.createResource(base+"blogexample.html#"+nameN3.toString()); linkRes.addProperty(Atom.href, lnk); entryRes.addProperty(Atom.alternate,linkRes); Statement stmt = entryDB.createStatement(id, RDF.type, Atom.EntryID); entryDB.add(stmt); stmt = entryDB.createStatement(entryVersion, RDF.type, Atom.EntryVersion); entryDB.add(stmt); stmt = entryDB.createStatement(id, Atom.state, entryVersion); entryDB.add(stmt); stmt = entryDB.createStatement(entryVersion, Atom.entry_location, entryRes); entryDB.add(stmt); StmtIterator i = linkRes.listProperties(); entryDB.add(i); stmt = entryDB.createStatement(entryVersion, Atom.alternate, linkRes); entryDB.add(stmt); entries.add(this); setCreated(created); } void addResponse(Entry other) { Statement stmt = entryDB.createStatement(other.id, Atom.in_reply_to, entryVersion); entryDB.add(stmt); stmt = other.model.createStatement(other.entryRes, Atom.in_reply_to, entryVersion); other.model.add(stmt); // we need to state where the id can be found to which this is a response stmt = other.model.createStatement(entryVersion, Atom.entry_location, entryRes); other.model.add(stmt); responses.add(other); } Person author; void setAuthor(Person author) { this.author = author; model.add(author.statements()); entryRes.addProperty(Atom.author, author.getResource()); entryDB.add(author.statements()); Statement stmt = entryDB.createStatement(id, Atom.author, author.getResource()); entryDB.add(stmt); } void addContributor(Person contr) { model.add(contr.statements()); entryRes.addProperty(Atom.contributor, contr.getResource()); entryDB.add(contr.statements()); Statement stmt = entryDB.createStatement(entryRes, Atom.contributor, contr.getResource()); entryDB.add(stmt); } void addCopyright() { entryRes.addProperty(Atom.copyright, entryDB.createResource("http://creativecommons.org/licenses/by-sa/2.0/")); } Resource getResource() { return entryRes; } public int compareTo(Object o) { Entry e = (Entry) o; return e.creationDate.compareTo(creationDate); } String title; void setTitle(String title) { this.title = title; Content titleCnt = new Content(title, "text/simple"); entryRes.addProperty(Atom.title, titleCnt.getResource()); Statement stmt = entryDB.createStatement(entryVersion, Atom.title, titleCnt.getResource()); entryDB.add(stmt); } Date creationDate; private void setCreated(Date date) { this.creationDate = date; entryRes.addProperty(Atom.created, getDateLiteral(date)); Statement stmt = entryDB.createStatement(id, Atom.created, getDateLiteral(date)); entryDB.add(stmt); } Literal getDateLiteral(Date date) { String formattedDate = df.format(date); Literal d = model.createTypedLiteral(formattedDate, XSDDatatype.XSDdateTime); return d; } String body; void setBody(String body) { this.body = body; Content bodyCnt = new Content(body, "text/html"); entryRes.addProperty(Atom.content, bodyCnt.getResource()); Statement stmt = entryDB.createStatement(entryVersion, Atom.content, bodyCnt.getResource()); entryDB.add(stmt); } void writeAsHtml(Writer out) throws IOException { System.out.println("Number of responses for " + entryRes + ": " + responses.size()); out.write(""); writeEntryAsHtml(out); if (responses.size() > 0) { List resLst = new ArrayList(responses); out.write(""); out.write(""); out.write(""); out.write(""); out.write(""); out.write(""); out.write(""); out.write(""); } class Content { Resource content; String text; Content(String text, String mime) { this.text = text; content = model.createResource(Atom.Content); Literal val = model.createTypedLiteral(text); Statement stmt = entryDB.createStatement(content, Atom.mime_type, model.createTypedLiteral(mime)); entryDB.add(stmt); model.add(stmt); stmt = entryDB.createStatement(content, Atom.data, val); entryDB.add(stmt); model.add(stmt); } Resource getResource() { return content; } } void publish() throws FileNotFoundException { model.setNsPrefix("", Atom.NS); model.setNsPrefix("xsd", XSDDatatype.XSD + "#"); model.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); model.setNsPrefix("foaf","http://xmlns.com/foaf/0.1/"); model.write(new FileOutputStream(nameN3), "N3-PP", base); model.write(new FileOutputStream(nameRDF), "RDF/XML-ABBREV", base); Model simple = ModelFactory.createDefaultModel(); simple.setNsPrefix("", Atom.NS); simple.setNsPrefix("xsd", XSDDatatype.XSD + "#"); simple.setNsPrefix("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); simple.setNsPrefix("foaf","http://xmlns.com/foaf/0.1/"); simple.add(model); StmtIterator it = simple.listStatements(new SimpleSelector() { public boolean selects(Statement statement) { try { statement.getLiteral(); return true; } catch (Exception e) { return false; //pretty ugly way of coding } } }); ArrayList todelete = new ArrayList(); ArrayList toAdd = new ArrayList(); while (it.hasNext()) { Statement st = it.nextStatement(); Literal l = st.getLiteral(); if (l.getDatatype() != null) { Literal nl = simple.createLiteral(l.getString()); Statement result = model.createStatement( st.getSubject(),st.getPredicate(),(RDFNode)nl); todelete.add(st); toAdd.add(result); } } simple.remove(todelete); simple.add(toAdd); // NodeIt it = model.listObjectsOfProperty(); simple.write(new FileOutputStream(simpleRDF),"RDF/XML-ABBREV", base); } } class Person { Statement[] statements = new Statement[4]; Resource personRes; String name; Person(String name, String email, String url) { this.name = name; personRes = worldModel.createResource(FOAF.Agent); Resource webPage = worldModel.createResource(url); statements[3] = worldModel.createStatement(personRes, RDF.type, FOAF.Person); Literal nameLit = worldModel.createTypedLiteral(name); statements[0] = worldModel.createStatement(personRes, FOAF.name, nameLit); Resource emailRes = worldModel.createResource("mailto:" + email); statements[1] = worldModel.createStatement(personRes, FOAF.mbox, emailRes); statements[2] = worldModel.createStatement(personRes, FOAF.homepage, webPage); } Resource getResource() { return personRes; } public Statement[] statements() { return statements; } } public static void main(String[] args) throws FileNotFoundException { Blog3Example b2 = new Blog3Example(); Person henry = b2.new Person("Henry Story", "henry.story@bblfish.net", "http://bblfish.net/"); Person hjs = b2.new Person("H. Story", "hjs@bblfish.net", "http://bblfish.net/"); Person danny = b2.new Person("Danny Ayers", "danny666@virgilio.it", "http://dannyayers.com/"); Person asbjorn = b2.new Person("Asbjorn Ulsberg", "asbjorn@tigerstaden.no", "http://asbjorn.no/"); Person bob = b2.new Person("bob wyman", "bob@wyman.us", "http://wyman.us"); Person ken = b2.new Person("Ken McLeod", "ken@bitsko.slc.ut.us", "http://bitsko.slc.ut.us/blog"); Blog blog = b2.new Blog(); blog.publish(); Entry headEntry = b2.new Entry(new Date(104, 5, 29, 10, 10, 0)); headEntry.addCopyright(); headEntry.setAuthor(henry); headEntry.setTitle("A Blog on combining Atom and FOAF"); headEntry.setBody(" This is an example blog to illustrate what a fully semantic weblog could look like. Instead of using RSS" + " or Atom content for the feed, I show here how one can create a very powerful, flexible and easy to understand system" + " based on Semantic Web Triples, presented for clarity in N3 format" + " and backed up by an OWL ontology.

" + " This project is a continuation of the work by Danny Ayers on " + " Atom+OWL, but it does not feel the need to stay so close to the Atom " + " specification, and is more interested in using all the tools available to the Semantic Web developer to show how much" + " further one can go in this direction, than it is in convincing people in the Atom community that there is a simple mapping " + " from their work to this one. By integrating with the rest of the Semantic Web community one can also more clearly" + " describe the true contribution of Atom: by refactoring Danny's simple mapping, and extracting elements that are" + " better addressed by other OWL libraries (such as FOAF), we can locate the" + " core of Atom.

Another difference concerns the role of standards. Whereas Atom which is aiming to create a standard " + " format for blogging, this method is following in the spirit of the FOAF group, " + " an attempt to create something like a software library, " + " in the spirit of an Open Source project." ); Entry entry0_1 = b2.new Entry(new Date(104, 6, 12, 19, 35, 0)); entry0_1.addCopyright(); entry0_1.setAuthor(henry); entry0_1.setTitle("Copyrights"); entry0_1.setBody("All of the content here" + " is freely licenced under the gpl for the code, and the " + "Attribution-ShareAlike 2.0 Creative Commons license, for the text. "); Entry entry0_2 = b2.new Entry(new Date(104, 6, 12, 19, 45, 0)); entry0_2.addCopyright(); entry0_2.setAuthor(henry); entry0_2.setTitle("A Note on Format"); entry0_2.setBody("This research is presented in blog format, so that it can itself be a test case for the" + " format it is advocating. The html presentation of this blog does not" + " follow the usual blogging tradition of presenting the main entries in inverse chronological order, as " + " this would make following the flow of ideas presented here a little awkward. " + "

Blog entries are written by Henry Story, as well as the replies which were added to illustrate" + " threading. All of html and N3 files contained in this directory " + " were generated by a little java program available in the same directory. " + " Some of the noteworthy files are:

" + "

This model is the second attempt and tries to incorporate all the lessons learned from the" + " first one"); Entry entry1 = b2.new Entry(new Date(104, 7, 12, 20, 35, 0)); entry1.addCopyright(); entry1.setAuthor(henry); entry1.setTitle("An overview UML diagram"); entry1.setBody("Here is a partially simplified UML diagram of Atom-FOAF.

" + "

The reality is a little" + " more complicated because there are in fact two ways to represent an Entry:" + "

" + " There is a simple logical relation between the two views, which I will get into in a later blog" + " entry.

" + " Two important things to notice here are the yellow and green background zones.
" + " The classes on the green background come from the FOAF " + " namespace. Those on the yellow background have until recently been thought to belong to the Atom " + " namespace. It is my contention here (arrived at after a long conversation with Ken McLeod) that these Feed" + " classes are in fact much more general, and don't in any particular way belong to Atom. We can find " + " similar structures in many places we look on the web - pretty much anywhere we need to " + " chunk a potentially large list of results into smaller sections - such as for example" + " search engine results, WebDav search results(?)... So this is a first attempt at " + " simplification. By pushing out everything Atom related into the Blog class located on the white background" + " reserved for Atom concepts, we end up with a little 'Feed'" + " structure that could be nicely useful elsewhere (after due renaming perhaps) and with a Blog class " + " where we can place a lot of the 'introspection' information.

" + " The UML diagram is of course backed up by the formally specified Atom OWL spec" + " that ships with this release."); Entry entry1_0 = b2.new Entry(new Date(104, 7, 13, 5, 30, 0)); entry1_0.addCopyright(); entry1_0.setAuthor(bob); entry1_0.setTitle("It's all about the Entries, stupid!"); entry1_0.setBody("This also very nicely illustrates what I was trying to get at with my " + "It's about the Entries, Stupid!" + " post I sent a few months back. By simplifying the model down to the core it becomes apparent that" + " it is indeed the Entry that is at the core of Atom. The person and the Feed concepts are not" + " central to Atom. They are generic concepts that can be found and used elsewhere."); entry1.addResponse(entry1_0); Entry entry1_1 = b2.new Entry(new Date(104, 7, 13, 10, 47, 0)); entry1_1.addCopyright(); entry1_1.setAuthor(hjs); entry1_1.setTitle("N3 illustration - The Feed"); entry1_1.setBody("To start off let us look at the feed files. There are two sets of these files:" + "

" + " Each of these files is a part of the whole result. I don't yet have a concept yet the union of all the " + " content in these files. This may be something that needs adding. Each file points to the previous " + " results with code such as 
  " +
                "  <>   :previous\n" +
                "              [ a       :Link ;\n" +
                "                :href   <feed-entries_0_to_3.n3> ;\n" +
                "                :mime-type \"application/rdf+n3\"^^xsd:string ;\n" +
                "                :text   \"previous 4 entries\"^^xsd:string \n" +
                "              ] .\n" +
                "

" + " which says that the previous entries can be found at the resource <feed-entries_0_to_3.n3>." + " <feed-entries_0_to_3.n3> itself points to the dynamic element of the feed thus 
" +
                "  <>   a       :Feed ;\n" +
                "      :about  <blog.n3> ;\n" +
                "      :dynamic <feed.n3> ;\n" +
                "

" + " which points to the dynamic part of the feed. It also points to the blog file that contains" + " the so called 'introspection' information about the blog: namely where the url for adding new entries" + " is located, and other things which I know are not yet fully thought through.

" + " Notice: The current feeds contain very little information. They point" + " to the entries themselves. feed.n3 for example points to four (only four for illustrative" + " purposes) entries as shown here:" + " 

" +
                "<>    a       :Feed ;\n" +
                "      :dynamic <> ;\n" +
                "      :entry  <entry.2004-08-13-1047.n3> , <entry.2004-08-13-1445.n3> ,\n " +
                "              <entry.2004-08-13-1752.n3> , <entry.2004-08-13-1632.n3> ;\n" +
                "

" + " To help clients tell which entries they have or have not downloaded we can add further information" + " such as the EntryID and the EntryVersion of each of these entries. That is done further down in the" + " feed.n3 file:" + " 
" +
                 "<entry.2004-08-13-1047.n3>\n" +
                "      :entry-version <tag:bblfish.net/20040813/1047/blog1#version1> ;\n" +
                "      :id     <tag:bblfish.net/20040813/1047/blog1> .\n" +
                "\n" +
                "<entry.2004-08-13-1445.n3>\n" +
                "      :entry-version <tag:bblfish.net/20040813/1445/blog1#version1> ;\n" +
                "      :id     <tag:bblfish.net/20040813/1445/blog1> ." +
                "

" + " Clearly a lot more could be added. One could add the title (an obvious addition), perhaps the publication date, " + " the last changed" + " date... One could of course add everything, as with the AllInOneDatabase.n3," + " but that would be extreemely wasteful in bandwidth and very un-" + "RESTful. What to add and not to add" + " is really an empirical research topic. Having very little information is not really a problem. As long as the" + " client can determine where the entries are and which entries it allready has fetched (hence the entry-version field) it will only" + " need to fetch the content once. With " + " HTTP 1.1 Persistent Connections, having to make multiple requests is not at all a problem. " ); entry1.addResponse(entry1_1); Entry entry2 = b2.new Entry(new Date(104, 7, 13, 14, 45, 0)); entry2.addCopyright(); entry2.setAuthor(henry); entry2.setTitle("Two perspectives on a blog entry"); entry2.setBody("The current model proposes two view on an entry: " + "This is illustrated by the following diagram:

" + "" + "

" + "Again I have tried to highlight the two areas by placing their classes on differently colored backgrounds." + " On the yellow background is the main class for the temporal Entry representation, and on the green background, we" + " have the atemporal Entry Representation. Given any one of these one can deduce the other. Ie, they are " + " logical consequences of one another.

" + " Some of the main points distinguishing them are:

" + ""); Entry entry2_0 = b2.new Entry(new Date(104, 7, 13, 16, 32, 0)); entry2_0.addCopyright(); entry2_0.setAuthor(hjs); entry2_0.setTitle("Graphical illustration of the two pespectives"); entry2_0.setBody("Let me illustrate two views on an Entry graphically, so as not to have to take any sides among" + " the many possible serialisations of semantic web triples: N3, N-Triples, RDF, ... Each of these serialisation formats can" + " be mapped onto a graph of triples, as explained in the w3c's RDF Semantics" + " paper. I here represent resources in rounded rectangles, blank nodes by circles, Literals by rectangles, and of course" + " predicates by named arrows.

" + " Let us start off with a simple graphical representation of an Entry written in a file " + " entry1.n3, written by Karl Dubost, where he asserts the" + " cryptic '2b v not2b'.

" + " The id of the entry is tag:e1, and it is the first version as hinted at by the " + " entry-version which is tag:e1#v1. The entry was created on 11 Jun 2002 at 5pm, and" + " was published (issued) shortly thereafter, at 10 minutes past 5. (Note that since we know that the entry is written" + " by Karl Dubost, we may be able to find who is friends are if we have access to some FOAF files that mention him.)

" + " Perhaps shortly later Karl finds that he wants to make a change to his entry. He prefers titles to start with" + " capitals, and changes his statement to a question. He is still thinking about this change, so this" + " change does not yet have a publication date. (how we got this file is of course a problem for my story now)." + " As a result the graph we have is as follows:
" + "
" + " Here I have highlighted in green the changes to the graph. Gone is the issued field, a modified date has" + " appeared, and the data fields of the title and entry fields have slightly changed. Of course we have a new" + " version id.

" + " Any person who fetches " + " entry1.n3 after the change (and after he issues it) will not be able to retrieve the original version, " + " as it will have been" + " completely replaced by the new one. They will know when the file was last modified though. But if someone were to keep track" + " of all these changes - either the editor that Karl is using in order to allow him to backtrack to previous versions" + " were he to think he had made a mistake, or some agregator that wanted to keep a fuller view of the changes made to the" + " posts on Karl's web site (perhaps in order to notify the aggregator's owner that a reply he wrote to Ken's post had changed) -" + " then he would presumably want to keep the changes stored in its local database by organising the entries by EntryID, in " + " a database similar to our AllInOneDatabase.n3. The graph for this entry would then" + " look like this:
" + "
" + " Here the root of the tree is the EntryID, which points to the two EntryVersions." + " Notice that in this case the EntryVersions have an entry-location, to help" + " find the original entry file. The location is" + " not attached to the EntryID as the location of an Entry could change over time. In this case " + " the entry has remained in the same position.

" + " It should be very easy to specify a logical relation allowing one to deduce one of the views from the other. " + " Since we are speaking in ontology, there is not concptual priority of one of these views over the other. They" + " both exist simultaneously."); entry2.addResponse(entry2_0); Entry entry2_1 = b2.new Entry(new Date(104, 7, 13, 17, 52, 0)); entry2_1.addCopyright(); entry2_1.setAuthor(hjs); entry2_1.setTitle("N3 illustration on the two pespectives"); entry2_1.setBody("The entry file using the Entry class is pretty easy to understand. As an example let us take the " + "file describing this entry, namely entry.2004-08-13-1752.n3." + "

  " +
                "<>    a       :Entry ;\n" +
                "      :author [ a       <http://xmlns.com/foaf/0.1/Person> ;\n" +
                "                <http://xmlns.com/foaf/0.1/homepage>\n" +
                "                        <http://bblfish.net/> ;\n" +
                "                <http://xmlns.com/foaf/0.1/mbox>\n" +
                "                        <mailto:hjs@bblfish.net> ;\n" +
                "                <http://xmlns.com/foaf/0.1/name>\n" +
                "                        \"H. Story\"^^xsd:string\n" +
                "              ] ;" +
                "

" + " The first line just specifies that this file ('<>' in N3) is an Entry. It then continues" + " by specifying the author of the Entry using the FOAF classes. Everything else in the file is" + " pretty self evident. Perhaps the following requires a little closer look at" + "
" +
                "      :id     <tag:bblfish.net/20040813/1752/blog1> ;\n" +
                "      :entry-version <tag:bblfish.net/20040813/1752/blog1#version1> ;\n" +
                "      :in-reply-to <tag:bblfish.net/20040813/1445/blog1#version1> ;\n" +
                "      :title  [ a       :Content ;\n" +
                "                :data   \"N3 illustration on the two pespectives\"^^rdf:string ;\n" +
                "                :mime-type \"text/simple\"^^xsd:string\n" +
                "              ] .\n" +
                "

" + " Here we specify the id and entry-version tags. Notice that with a well designed URI structure one" + " should be able to guess the id tag from the version tag. Here the version tag just consists of the" + " entry id with '#version1' appended.

" + " Notice the in-reply-to property. It relates the current Entry not to another Entry (with" + " a URL) but to antother EntryVersion. How do we retrieve the location of the EntryVersion to which this" + " Entry is a reply? Well further down in the file we have the following statement: " + "

  " +
                "<tag:bblfish.net/20040813/1445/blog1#version1>\n" +
                "      :entry-location <entry.2004-08-13-1445.n3> ." +
                "

" + " which associate that entry version with a Entry URL namely the above " + "entry.2004-08-13-1445.n3.

" + " How does this Entry appear in the AllInOneDatabase.n3? We just need to" + " search that file for the EntryID tag:bblfish.net/20040813/1752/blog1" + "

" +
                "<tag:bblfish.net/20040813/1752/blog1>\n" +
                "      a       :EntryID ;\n" +
                "      :author _:b2 ;\n" +
                "      :created \"2004-08-13T17:52:00+0200\"^^xsd:dateTime ;\n" +
                "      :in-reply-to <tag:bblfish.net/20040813/1445/blog1#version1> ;\n" +
                "      :state  <tag:bblfish.net/20040813/1752/blog1#version1> ."+
                "

" + " This just gives us the author _:b2 wich is an empty node that is specified" + " in more detail elsewhere in the file, the creation time, what this EntryId was in reply to," + " and the EntryState tag. The values for that tag are also to be found in the file, and its content should" + " correspond to the text you are now reading." + " "); entry2.addResponse(entry2_1); entry1.publish(); headEntry.publish(); entry0_1.publish(); entry0_2.publish(); entry1_0.publish(); entry1_1.publish(); entry2.publish(); entry2_0.publish(); entry2_1.publish(); Feed feed = b2.new Feed("feed", 4); feed.setLanguage("en"); feed.setHeaderEntry(headEntry); feed.setAbout(blog.blogRes); feed.publish(); feed.writeAsHtml(); b2.publish(); } }
responses"); Collections.sort(resLst); if (inverse) Collections.reverse(resLst); for (Iterator i = resLst.iterator(); i.hasNext();) { Entry e = (Entry) i.next(); e.writeAsHtml(out); } } out.write("
"); } boolean inverse = true; void invert() { inverse = !inverse; } void writeEntryAsHtml(Writer out) throws IOException { out.write("
title" + title + "
author" + author.name + "created" + creationDate.toGMTString() + "N3 file"+nameN3+"RDF file"+nameRDF+"Atom-like RDF file"+simpleRDF+"
" + body + "