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<%@ page contentType="text/plain;charset=ISO-8859-1" import="java.io.*" %>
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<%
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/************************************************
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* This is an example implementation of a Kepler AuthNamespace web service.
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*
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* The output parameters are
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* error, namespace
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* The optional input parameters are
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* username, password, namespace
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*
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************************************
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* Kepler AuthNamespace Web Service *
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************************************
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*
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* The namespace that is returned shall always be unique for the given URL regardless of URI input parameters
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* The file type returned by the webservice shall be text/plain and shall contain the two output parameters
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* formatted in accordance with the java.util.Properties specification.
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*
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* Optionally a username and password parameter may be supplied to the webservice for authenticating users
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* or simply for disallowing robots from accessing the service.
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* Implementations of the AuthNamespace service may also optionally accept a namespace as an input,
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* check to see if that namespace is available, and return it if it is available or return an error if it is not.
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*
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************************************************/
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try {
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/*
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* The authority string should exactly match the URL this service is accessed by.
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* This prevents having multiple URLs accessing this same JSP page which would be bad
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* since the namespaces generated by an authority must be unique to that authority.
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*/
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String authority = "http://library.kepler-project.org/kepler/style/skins/kepler/keplerAuthNameSpace.jsp";
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String accessedAuthority = request.getRequestURL().toString();
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/*
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* Get username and password inputs.
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*/
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String user = request.getParameter( "username" );
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String pass = request.getParameter( "password" );
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/*
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* Make sure the URL used to access this service is the correct authority URL.
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*/
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if ( accessedAuthority != null && accessedAuthority.equals( authority )) {
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/*
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* Check to make sure the "kepler" username/password was given
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* This will prevent stray robots or users from incrementing namespaces arbitrarily.
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*/
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if ( user != null && user.equals("kepler") ) {
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if ( pass != null && pass.equals("kepler") ) {
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if ( request.getParameter( "namespace" ) != null ) {
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// TODO query a database for the requested namespace
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// print namespace if it is not already taken and insert it into the database
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// return an error if the namespace has already been reserved
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} else {
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/* Store an incrementing integer in a file.
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* This approach may fail due to collisions under high load conditions.
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* But works fine for this example implementation.
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*/
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ServletContext context = session.getServletContext();
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String fname = "/var/kepler/last_issued_namespace.txt";
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Integer inc = new Integer(0);
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File f = new File( fname );
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if (f.exists()) {
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// Read in the previous Integer
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InputStream is = new FileInputStream(fname);
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ObjectInput oi = new ObjectInputStream(is);
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inc = (Integer) oi.readObject();
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oi.close();
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int i = inc.intValue() + 1;
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inc = new Integer( i );
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}
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// Write out the incremented integer (or 0 if the file does not exist)
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OutputStream os = new FileOutputStream(fname);
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ObjectOutputStream oos = new ObjectOutputStream(os);
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oos.writeObject( inc );
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oos.flush();
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/*
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* Print out the incremented Integer as the namespace output
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* in java.util.Properties format.
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*/
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out.println( "namespace=" + inc + "\n" );
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}
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} else {
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throw new Exception("The specified password is incorrect");
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}
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} else {
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throw new Exception("The specified username is incorrect.");
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}
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} else {
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throw new Exception("The specified authority URL is incorrect.");
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}
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} catch (Exception e) {
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/*
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* Print out the error in java.util.Properties format.
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*/
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out.println( "error=" + e.getMessage() + "\n" );
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}
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%>
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