You are viewing a plain text version of this content. The canonical link for it is here.
Posted to docs@cocoon.apache.org by st...@outerthought.org on 2003/01/28 20:01:04 UTC
[WIKI-UPDATE] XMLFormXindice XMLFormXindiceOldVersion Tue Jan 28 20:01:04 2003
Page: http://wiki.cocoondev.org/Wiki.jsp?page=XMLFormXindice, version: 10 on Tue Jan 28 19:00:30 2003 by JosemaAlonso
+ We had to use an ugly casting mechanism in the {{addDocument}} method but that's what we have by now. In future JXPath versions this will be easier to accomplish.
Page: http://wiki.cocoondev.org/Wiki.jsp?page=XMLFormXindiceOldVersion, version: 1 on Tue Jan 28 18:57:06 2003 by JosemaAlonso
New page created:
+ !!!Overview
+ This How-To shows you how to use Xindice as the repository for XML resources from the XMLForm Framework. It requires prior knowledge of Cocoon XMLForm, XSLT, Schematron, Xindice and the XMLDB API.
+
+ !!!Purpose
+ You will learn how to build a simple wizard type XMLForm that stores XML data into a Xindice collection.
+
+ !!!Intended Audience
+ Cocoon users who want to learn how to store data obtained from XMLForms into Xindice.
+
+ !!!Prerequisites
+ Cocoon must be running on your system. The steps below have been tested with Cocoon 2.1-dev.
+ You will need the following:
+ *A servlet engine such as Tomcat.
+ *JDK 1.2 or later
+ *Xindice 1.0 installed (create a collection named {{Artist}})
+ *Cocoon 2.1 CVS to be installed with the command:
+ {{{build -Dinclude.webapp.libs=true webapp}}}
+ You will need to understand and be familiar with XSL, XForms, XPath, Schematron and Xindice. Some knowledge about the XMLDB API would be helpful, too. If you are unfamiliar with these technologies, it is advised that you learn these related concepts first. If you are unfamiliar with XMLForm, check out the [XMLForm Wizard How-To|http://xml.apache.org/cocoon/howto/xmlform-wizard/howto-xmlform-wizard.html] first.
+
+ !!!Steps
+ We will follow the needed steps in order to add a document like this:
+ {{{<Artist id="pearljam">
+ <Name>Pearl Jam</Name>
+ </Artist>}}}
+ to the Xindice root collection. We will get the identifier and name data using a XMLForm and store them in Xindice. We will build this XMLForm very similar to the one in the XMLForm Wizard How-To.
+ !!Building the XMLForm files
+ Create the files and name them as specified below.
+ !start.xform
+ {{{<?xml version="1.0"?>
+ <document>
+ <h1>This is the New Artist Wizard!</h1>
+ <info>Steps from here on, will let you insert a new
+ Artist in the database.
+ </info>
+ <h3>
+ <a href="Artist.xform?cocoon-action-start=true">
+ Start!
+ </a>
+ </h3>
+ </document>}}}
+ !artist.xform
+ {{{<?xml version="1.0"?>
+ <document
+ xmlns:xf="http://xml.apache.org/cocoon/xmlform/2002">
+ <xf:form id="form-insert" view="artist"
+ action="Artist.xform" method="post">
+ <xf:caption>New Artist</xf:caption>
+ <error>
+ <xf:violations class="error"/>
+ </error>
+ <xf:textbox ref="/artistDocument/@id">
+ <xf:caption>Artist identifier:</xf:caption>
+ </xf:textbox>
+ <xf:textbox ref="/artistDocument/Name">
+ <xf:caption>Artist Name:</xf:caption>
+ </xf:textbox>
+ <xf:submit id="prev" class="button">
+ <xf:caption>Prev</xf:caption>
+ <xf:hint>Go to previous page</xf:hint>
+ </xf:submit>
+ <xf:submit id="next" class="button">
+ <xf:caption>Next</xf:caption>
+ <xf:hint>Go to next page</xf:hint>
+ </xf:submit>
+ </xf:form>
+ </document>}}}
+ !end.xform
+ {{{<?xml version="1.0"?>
+ <document>
+ <h1>You have reached the last page!</h1>
+ <info>
+ You have inserted a New Artist successfully.
+ </info>
+ <h3>
+ <a href="Artist.xform">Go to home page.</a>
+ </h3>
+ </document>}}}
+ !error.xform
+ {{{<?xml version="1.0"?>
+ <document>
+ <h1>
+ You have reached the last page of the New Artist Wizard!
+ </h1>
+ <info>
+ There have been problems and the Artist could not be added to the database.
+ Please try again.
+ </info>
+ <h3>
+ <a href="Artist.xform">Please, start again.</a>
+ </h3>
+ </document>}}}
+ !!Validation
+ For the sake of simplicity we just validate one property against one condition. We require the identifier to be at least two characters in length; the validation file, {{artist-validator.xml}} is as follows:
+ {{{<?xml version="1.0"?>
+ <schema ns="http://xml.apache.cocoon/xmlform"
+ xmlns="http://www.ascc.net/xml/schematron">
+ <phase id="artist">
+ <active pattern="artval"/>
+ </phase>
+ <pattern name="Artist Identifier Validation"
+ id="artval">
+ <rule context="/artistDocument/@id">
+ <assert test="string-length(.) > 1">
+ Artist Name should be at least 2 characters.
+ </assert>
+ </rule>
+ </pattern>
+ </schema>}}}
+ !Extended Validation
+ There could be more complicated rules in Schematron but we could also require the identifier to be unique in the database. In this case we should query the database and see if it already exists. If so, a new violation can be added to the form. Since these kinds of violations are out of the scope of Schematron, these operations should be accomplished in the Action using Java code.
+ !!Model Bean
+ Persistence for the data will be accomplished by this bean. In order to store the mentioned XML structure we will use a DOM Node. You can also try JXPath Containers as suggested by Ivelin. The model bean {{ArtistBean.java}} is as follows:
+ {{{package com.simbiosystems.cocoon.xmlform.xindice.howto;
+
+ import java.util.ArrayList;
+ import java.util.List;
+
+ import org.w3c.dom.*;
+ import javax.xml.parsers.*;
+ import javax.xml.transform.*;
+
+ /**
+ *
+ * A sample domain object used as a Form model.
+ * DOM Nodes, are handled correctly by the
+ * framework when referenced via JXPath.
+ *
+ */
+ public class ArtistBean {
+
+ //Holds the DOM Node that will be filled by the form and
+ //added later to Xindice
+ private Node artistDocument;
+
+ public ArtistBean () {
+ //create the document model
+ initModel();
+ }
+
+ /**
+ * Creates an empty DOM Node which holds an empty copy
+ * of an Artist document like this:
+ * <Artist id="">
+ * <Name></Name>
+ * </Artist>
+ * The data from the form is stored in it.
+ */
+ public void initModel() {
+
+ DOMImplementation impl;
+ try {
+ // Find the implementation
+ DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+ factory.setNamespaceAware(true);
+ factory.setValidating ( false );
+ DocumentBuilder builder = factory.newDocumentBuilder();
+ impl = builder.getDOMImplementation();
+ }
+ catch (Exception ex) {
+ throw new RuntimeException("Failed to initialize DOM factory. Root cause: \n" + ex);
+ }
+ //You can choose any altenative method for this...
+ //Create the node for the root, 'Artist'
+ Document doc = impl.createDocument( null, "Artist", null);
+ Node artistRoot = doc.getDocumentElement();
+
+ //add a 'id' attribute
+ Attr id = doc.createAttribute ( "id" );
+ id.setValue ( "" );
+ NamedNodeMap nmap = artistRoot.getAttributes();
+ nmap.setNamedItem ( id );
+
+ //add a 'Name' child
+ Node artistName = doc.createElement ( "Name" );
+ Text text = doc.createTextNode( "" );
+ description.appendChild(text);
+ artistRoot.appendChild( artistName );
+
+ artistDocument = artistRoot;
+ }
+
+ /**
+ * Gets the artistDocument
+ * @return Returns a Node
+ */
+ public Node getArtistDocument() {
+ return artistDocument;
+ }
+
+ /**
+ * Sets the artistDocument
+ * @param artistDocument The artistDocument to set
+ */
+ public void setArtistDocument(Node artistDocument) {
+ this.artistDocument = artistDocument;
+ }
+ }
+ }}}
+ !!The Action
+ In this Action we have integrated the Xindice handling code, getting the data from the model (from the DOM Node property) and storing it in Xindice. The Action that controls this form is {{ArtistAction.java}}:
+ {{{package com.simbiosystems.cocoon.xmlform.xindice.howto;
+
+ import java.util.Arrays;
+ import java.util.Enumeration;
+ import java.util.Map;
+
+ import javax.xml.parsers.DocumentBuilder;
+ import javax.xml.parsers.DocumentBuilderFactory;
+ import org.apache.avalon.framework.parameters.Parameters;
+ import org.apache.cocoon.Constants;
+ import org.apache.cocoon.acting.AbstractXMLFormAction;
+ import org.apache.cocoon.components.validation.Violation;
+ import org.apache.cocoon.components.xmlform.Form;
+ import org.apache.cocoon.components.xmlform.FormListener;
+ import org.apache.cocoon.environment.Redirector;
+ import org.apache.cocoon.environment.Request;
+ import org.apache.cocoon.environment.Session;
+ import org.apache.cocoon.environment.SourceResolver;
+ import org.w3c.dom.DOMImplementation;
+ import org.w3c.dom.Node;
+
+ import com.simbiosystems.cocoon.xmlform.xindice.howto.XindiceManager;
+
+ /**
+ * This action handles XMLForms for the Artist data
+ */
+ public class ArtistAction extends AbstractXMLFormAction implements FormListener {
+ // different form views participating in the form
+ final String VIEW_START = "start";
+ final String VIEW_ARTIST = "artist";
+ final String VIEW_END = "end";
+ final String VIEW_ERROR = "error";
+ // action commands used in the wizard
+ final String CMD_START = "start";
+ final String CMD_NEXT = "next";
+ final String CMD_PREV = "prev";
+ //constants for the XML manipulation, it holds the full name of the collection
+ //to be used for storing the data
+ final String xindiceSubCol = "/Artist";
+ /**
+ * The first callback method which is called
+ * when an action is invoked.
+ *
+ * It is called before population.
+ * @return null if the Action is ready to continue.
+ * an objectModel map which will be returned
+ */
+ protected Map prepare() {
+ if ( getCommand() == null ) {
+ return page(VIEW_START);
+ }
+ else if ( getCommand().equals(CMD_START)) {
+ // reset state by removing old form if one exists
+ Form.remove( getObjectModel(), getFormId() );
+ getForm().addFormListener( this );
+ return page(VIEW_ARTIST);
+ }
+ // get ready for action
+ // if not ready return page("whereNext");
+ return null;
+ }
+ /**
+ * Invoked after form population
+ * Take appropriate action based on the command
+ *
+ */
+ public Map perform () {
+ // get the model which this Form encapsulates
+ // and apply logic to the model
+ ArtistBean jBean=(ArtistBean)getForm().getModel();
+ // set the page control flow parameter
+ // according to the validation result
+ if ( getCommand().equals(CMD_NEXT) &&
+ getForm().getViolations () != null ) {
+ // errors, back to the same page
+ return page( getFormView() );
+ }
+ else {
+ // validation passed
+ // continue with control flow
+ // clear validation left overs in case the user
+ // did not press the Next button
+ getForm().clearViolations();
+ // get the user submitted command
+ String command = getCommand();
+ // get the form view which was submitted
+ String formView = getFormView();
+ // apply control flow rules
+ if (formView.equals (VIEW_ARTIST)) {
+ if (command.equals(CMD_NEXT)) {
+ //extended validation
+ //test if the ID already exists in the DB
+ Node artistName = jBean.getArtistDocument().getAttributes().getNamedItem("id");
+ try {
+ XindiceManager xi = new XindiceManager();
+ Node result = xi.find(xindiceSubCol, "//Artist[@id='"+ artistName.getNodeValue() +"']", "Artists");
+ //if we do not get a null the element with that ID
+ //already existed we add the violation
+ if (result!=null) {
+ Violation v = new Violation();
+ v.setMessage("already exists in the database, please choose another one");
+ v.setPath("/artistName");
+ Violation[] va = { v };
+ getForm().addViolations(Arrays.asList((Object[])va));
+ //the ID already exists, back to the same
+ //page to correct the error
+ return page(VIEW_ARTIST);
+ }
+ }
+ catch (Exception e) {
+ getLogger().error("Cannot establish a connection to the DB", e);
+ }
+ //everything went fine, add the document to the database
+ try {
+ createDocument(jBean);
+ }
+ catch(Exception e) {
+ //there were errors, send it to the error page
+ getLogger().error("Cannot add DOM document to the database");
+ return page(VIEW_ERROR);
+ }
+ return page( VIEW_END);
+
+ }
+ if (command.equals(CMD_PREV)) {
+ return page(VIEW_START);
+ }
+ }
+ }
+ }
+
+ /**
+ * FormListener callback
+ * called in the beginning Form.populate()
+ * before population starts.
+ *
+ * This is the place to handle unchecked checkboxes.
+ *
+ */
+ public void reset( Form form ) {
+ // based on the current form view
+ // make some decisions regarding checkboxes, etc.
+ String formView = getFormView();
+ }
+
+ /**
+ * Inserts the document into the database
+ */
+ public void createDocument(ArtistBean jBean)
+ throws Exception {
+ try {
+ //add the document to the database
+ XindiceManager xi = new XindiceManager();
+ xi.add(xindiceSubCol, jBean.getArtistDocument(), null);
+ }
+ catch (Exception e) {
+ getLogger().error("DOM Document could not be created", e);
+ throw e;
+ }
+ }
+ }
+ }}}
+ !The helper class
+ In order to make this work we need to use a helper class. This class uses the XMLDB to connect to Xindice and make the operations available to the Action. You should extend it to add more operations. The helper class {{XindiceManager.java}} is as follows:
+ {{{/**
+ * Helper class for Xindice related operations
+ *
+ */
+ package com.simbiosystems.cocoon.xmlform.xindice.howto;
+
+ import javax.xml.parsers.DocumentBuilder;
+ import javax.xml.parsers.DocumentBuilderFactory;
+ import org.w3c.dom.DOMImplementation;
+ import org.w3c.dom.Document;
+ import org.w3c.dom.Element;
+ import org.w3c.dom.Node;
+ import org.xmldb.api.DatabaseManager;
+ import org.xmldb.api.base.Collection;
+ import org.xmldb.api.base.Database;
+ import org.xmldb.api.base.Resource;
+ import org.xmldb.api.base.ResourceIterator;
+ import org.xmldb.api.base.ResourceSet;
+ import org.xmldb.api.base.XMLDBException;
+ import org.xmldb.api.modules.XMLResource;
+ import org.xmldb.api.modules.XPathQueryService;
+
+ public class XindiceManager {
+
+ private static final String driver = "org.apache.xindice.client.xmldb.DatabaseImpl";
+ private static final String rootCollection = "xmldb:xindice:///db/";
+
+ /**
+ * Constructor
+ *
+ */
+ public XindiceManager() {
+
+ }
+
+ /**
+ * Search for a document in the DB. If not found, return null.
+ *
+ * @param subCol name of the subCollection to query if any. If blank or null,
+ * queries go against the rootCollection.
+ * @param xpath XPath expression for the query, if none, it returns the whole Collection
+ * @param resultRootelement name of the root element for the DOM document which will
+ * wrap the results
+ * @return a DOM Node with the matched documents
+ *
+ */
+ public Node find(String subCol, String xpath, String resultRootElement)
+ throws Exception {
+
+ //prepare DOM document
+ DOMImplementation impl;
+ DocumentBuilder builder;
+ try {
+ // Find the implementation
+ DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+ factory.setNamespaceAware( false );
+ factory.setValidating ( false );
+ builder = factory.newDocumentBuilder();
+ impl = builder.getDOMImplementation();
+ }
+ catch (Exception ex) {
+ throw new RuntimeException("[XindiceManager.find]: Failed to initialize DOM factory. Root cause: \n" + ex);
+ }
+ //create the Document which will hold the results
+ Document resultDoc = impl.createDocument(null, resultRootElement, null);
+ Node root = resultDoc.getDocumentElement();
+
+ //And now the Xindice part
+
+ Collection col = null;
+ String strData = null;
+
+ try {
+ Class c = Class.forName(driver);
+
+ Database database = (Database) c.newInstance();
+ DatabaseManager.registerDatabase(database);
+
+ String localCol = rootCollection + subCol;
+
+ col = DatabaseManager.getCollection(localCol);
+
+ //Make the XPath query and get the resources
+ XPathQueryService service =
+ (XPathQueryService) col.getService("XPathQueryService", "1.0");
+ ResourceSet resultSet = service.query(xpath);
+ // Iterate the xpath results and add each of them to the main Document
+ ResourceIterator iterator = resultSet.getIterator();
+
+ //if not resources are present, just return null
+ if(!iterator.hasMoreResources()) return null;
+
+ while(iterator.hasMoreResources()) {
+ Resource r = iterator.nextResource();
+
+ Element resElement = ((Document)((XMLResource)r).getContentAsDOM()).getDocumentElement();
+
+ // Remove unwanted attributes
+ resElement.removeAttribute("src:col");
+ resElement.removeAttribute("src:key");
+ resElement.removeAttribute("xmlns:src");
+
+ // Add this result to the root element
+ Element importedElement = (Element)resultDoc.importNode(resElement, true);
+ root.appendChild(importedElement);
+ }
+ //return the Document root
+ return root;
+ }
+ catch (Exception e) {
+ System.err.println("[XindiceManager.find]: Find Exception occured :" + e.getMessage());
+ throw e;
+ }
+ finally {
+ if (col != null) {
+ col.close();
+ }
+ }
+ }
+
+ /**
+ * Add a document to the DB. If a key is not passed, it generates a unique one.
+ * This version uses a DOM Document.
+ * @param subCol name of the subCollection in which to add the resource if any. If blank or
+ * null, insertions go against the rootCollection.
+ * @param document DOM document to be inserted
+ * @param key unique key for the resource to be created, if none, one is created on the fly
+ */
+ public void add(String subCol, Node document, String key) throws Exception {
+ Collection col = null;
+ Node xmldoc = null;
+ try {
+ Class c = Class.forName(driver);
+
+ Database database = (Database) c.newInstance();
+ DatabaseManager.registerDatabase(database);
+
+ col = DatabaseManager.getCollection(rootCollection + subCol);
+
+ XMLResource document_ = (XMLResource) col.createResource(null, "XMLResource");
+ document_.setContentAsDOM(document);
+ col.storeResource(document_);
+ }
+ catch (XMLDBException e) {
+ System.err.println("XML:DB - Add Exception occured " + e.errorCode);
+ throw e;
+ }
+ finally {
+ if (col != null) {
+ col.close();
+ }
+ }
+ }
+ }
+ }}}
+ !!The Sitemap
+ Remember you should have the XMLFormTransformer defined like this:
+ {{{<map:transformer name="xmlform" src="org.apache.cocoon.transformation.XMLFormTransformer"
+ logger="xmlform"/>}}}
+ Then, you must declare the Action to be used in the correspondent section:
+ {{{<map:action logger="xmlform" name="ArtistAction" src="com.simbiosystems.cocoon.xmlform.xindice.howto.ArtistAction"/>}}}
+ !The Pipeline
+ {{{<!-- XMLForms pipeline -->
+ <map:pipeline>
+ <map:match pattern="**/*.xform">
+ <map:act type="ArtistAction">
+ <map:parameter name="actionName" value="{2}Action"/>
+ <!-- XMLForm parameters for the Action -->
+ <map:parameter name="xmlform-validator-schema-ns" value="http://www.ascc.net/xml/schematron"/>
+ <map:parameter name="xmlform-validator-schema" value="{1}/{2}/schematron/artist-validator.xml"/>
+ <map:parameter name="xmlform-id" value="form-insert"/>
+ <map:parameter name="xmlform-scope" value="session"/>
+ <map:parameter name="xmlform-model"
+ value="com.simbiosystems.cocoon.xmlform.xindice.howto.ArtistBean"/>
+ <!-- XMLForm document, {page} comes from Action -->
+ <map:generate src="{../1}/{../2}/{page}.xml"/>
+ </map:act>
+ <!-- populating the doc with model instance data -->
+ <map:transform type="xmlform"/>
+ <!-- look and feel of the form controls -->
+ <map:transform src="styles/wizard2html.xsl"/>
+ <!-- Transforming the XMLForm controls to HTML -->
+ <map:transform src="styles/xmlform2html.xsl"/>
+ <!-- sending the HTML back to the browser -->
+ <map:serialize type="html"/>
+ </map:match>
+ </map:pipeline>}}}
+ Depending on where you have Cocoon installed and where you have configured the files in this howto, you could make a request to a URL like {{http://localhost:8080/cocoon/Artist.xform}} and start using the Form.
+ !!Final Considerations
+ Making the operations from the Action using the helper class seems to be the easiest way. You can think of other ways or other operations using other Xindice tools available in Cocoon such as the pseudo protocol. For example, you could use it to query the DB for data that could be stored in a sitemap parameter. You could then get the data from the Action and use it to fill a selectbox in the form.\\
+ We did not mentioned other operations such as updates. This can be also accomplished this way. For example, if you want to edit the data we just stored, you could load it in the DOM Node at the beginning by using the {{find}} method of the helper class. This way you get a filled form in the next step ready for editing. Other ways or interacting with the repository include the XMLDB Transformer. Since it uses XUpdate alike syntax, you could format a XML String for it in the last step of the Action, making it available to the sitemap then, so the Transformer could get it and make the operations.\\
+ I'm sure you can think of more different ways. I encourage you to contribute them if you have tested it succesfully.
+ !!Summary
+ This How-To makes possible the use of Xindice from XMLForms in order to add data to the repository. You learned how to connect to the DB from the Action, and how to make complex validation using information stored in the DB. I hope it was helpful for you.
+