Adding support for authenticated PID minter services, extracting iden…

…tifier from XML responses using XPath
fcrepo · May 13, 2014 · d25af3c · d25af3c
1 parent 8788457
commit d25af3c
Showing 1 changed file with 99 additions and 12 deletions.
diff --git a/fcrepo-kernel/src/main/java/org/fcrepo/kernel/identifiers/HttpPidMinter.java b/fcrepo-kernel/src/main/java/org/fcrepo/kernel/identifiers/HttpPidMinter.java
@@ -16,20 +16,37 @@
 package org.fcrepo.kernel.identifiers;
 
 import static org.slf4j.LoggerFactory.getLogger;
+import static org.apache.commons.lang.StringUtils.isBlank;
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import org.slf4j.Logger;
 import com.codahale.metrics.annotation.Timed;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.net.URI;
+
+import org.w3c.dom.Document;
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.xpath.XPathException;
+import javax.xml.xpath.XPathExpression;
+import javax.xml.xpath.XPathFactory;
 
 import org.apache.http.HttpResponse;
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.client.methods.HttpPut;
 import org.apache.http.client.methods.HttpUriRequest;
-import org.apache.http.impl.client.HttpClients;
+import org.apache.http.impl.client.HttpClientBuilder;
 import org.apache.http.util.EntityUtils;
 
+import org.apache.http.auth.AuthScope;
+import org.apache.http.auth.UsernamePasswordCredentials;
+import org.apache.http.client.CredentialsProvider;
+import org.apache.http.impl.client.BasicCredentialsProvider;
+
 
 /**
  * PidMinter that uses an external HTTP API to mint PIDs.
@@ -40,34 +57,85 @@
 public class HttpPidMinter extends BasePidMinter {
 
     private static final Logger log = getLogger(HttpPidMinter.class);
-    protected static HttpClient client = HttpClients.createSystem();
+    protected HttpClient client;
     protected String minterURL;
     protected String minterMethod;
+    protected String username;
+    protected String password;
     private String trimExpression;
+    private XPathExpression xpathExpression;
 
     /**
      * Set the URL for the minter service.
     **/
     public void setMinterURL( final String url ) {
-        minterURL = url;
+        log.debug("setMinterURL({})",url);
+        this.minterURL = url;
     }
 
     /**
      * Set the HTTP method (POST, PUT or GET) used to generate a new PID.  If no method
      * is specified, POST will be used by default.
     **/
     public void setMinterMethod( final String method ) {
-        minterMethod = method;
+        log.debug("setMinterMethod({})",method);
+        this.minterMethod = method;
     }
 
     /**
      * Set the regular expression used to remove unwanted text from the minter service
      * response.  For example, if the response text is "/foo/bar:baz" and the desired
-     * identifier is "baz", then the trimExpression would be ".*:".  If no expression is
-     * specified, the minter service response will be used unmodified.
+     * identifier is "baz", then the trimExpression would be ".*:".
     **/
     public void setTrimExpression( final String expr ) {
-        trimExpression = expr;
+        log.debug("setTrimExpression({})",expr);
+        this.trimExpression = expr;
+    }
+
+    /**
+     * Set the XPath expression used to extract the desired identifier from an XML minter
+     * response.
+    **/
+    public void setXpathExpression( final String xpath ) {
+        log.debug("setXpathExpression({})",xpath);
+        try {
+            this.xpathExpression = XPathFactory.newInstance().newXPath().compile(xpath);
+        } catch ( XPathException ex ) {
+            log.warn("Error parsing xpath ({}): {}", xpath, ex );
+        }
+    }
+
+    /**
+     * Set the username used to connect to the minter service.  Unless both username and password
+     * are set, no authentication will be used.
+    **/
+    public void setUsername( final String username ) {
+        log.debug("setUsername({})",username);
+        this.username = username;
+    }
+
+    /**
+     * Set the password used to connect to the minter service.  Unless both username and password
+     * are set, no authentication will be used.
+    **/
+    public void setPassword( final String password ) {
+        log.debug("setPassword({})",password);
+        this.password = password;
+    }
+
+    /**
+     * Setup authentication in httpclient.
+    **/
+    private HttpClient buildClient() {
+        HttpClientBuilder builder = HttpClientBuilder.create().useSystemProperties();
+        if (!isBlank(username) && !isBlank(password)) {
+            final URI uri = URI.create(minterURL);
+            final CredentialsProvider credsProvider = new BasicCredentialsProvider();
+            credsProvider.setCredentials(new AuthScope(uri.getHost(), uri.getPort()),
+                new UsernamePasswordCredentials(username, password));
+            builder = builder.setDefaultCredentialsProvider(credsProvider);
+        }
+        return builder.build();
     }
 
     /**
@@ -87,26 +155,45 @@ protected HttpUriRequest minterRequest() {
      * Remove unwanted text from the minter service response to produce the desired identifer.
      * Override this method for processing more complex than a simple regex replacement.
     **/
-    public String responseToPid( final String responseText ) {
-        if ( trimExpression == null ) {
-            return responseText;
-        } else {
+    public String responseToPid( final String responseText ) throws Exception {
+        log.debug("responseToPid({})", responseText);
+        if ( trimExpression != null ) {
             return responseText.replaceFirst(trimExpression,"");
+        } else if ( xpathExpression != null ) {
+            return xpath( responseText, xpathExpression );
+        } else {
+            return responseText;
         }
     }
 
+    /**
+     * Extract the desired identifier value from an XML response using XPath
+    **/
+    private static String xpath( String xml, XPathExpression xpath ) throws Exception {
+        final DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
+        final Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes()));
+        return xpath.evaluate(doc);
+    }
+
     /**
      * Mint a unique identifier using an external HTTP API.
      * @return
      */
     @Timed
     @Override
     public String mintPid() {
+        checkNotNull( minterURL, "Minter URL must be specified!" );
         try {
+            log.debug("mintPid()");
+            if ( client == null ) {
+                client = buildClient();
+            }
             final HttpResponse resp = client.execute( minterRequest() );
             return responseToPid( EntityUtils.toString(resp.getEntity()) );
         } catch ( IOException ex ) {
-            log.error("Error minting pid from {}: {}", minterURL, ex);
+            log.warn("Error minting pid from {}: {}", minterURL, ex);
+        } catch ( Exception ex ) {
+            log.warn("Error processing minter response", ex);
         }
         return null;
     }