Java development with XML services

In this chapter are shown some examples to access GeoNetwork XML services in Java. Apache http commons library is used to send the requests and retrieve the results.

Retrieve groups list

This example shows a simple request, without requiring authentication, to retrieve the GeoNetwork groups.

Source

package org.geonetwork.xmlservices.client;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.jdom.Document;
import org.jdom.Element;

public class GetGroupsClient {

  public static void main(String args[]) {
    **// Create request xml**
    Element request = new Element("request");
    **// Create PostMethod specifying service url**
    String serviceUrl = "http://localhost:8080/geonetwork/srv/en/xml.group.list";
    PostMethod post = new PostMethod(serviceUrl);

    try {
      String postData = Xml.getString(new Document(request));

      **// Set post data, mime-type and encoding**
      post.setRequestEntity(new StringRequestEntity(postData, "application/xml", "UTF8"));

      **// Send request**
      HttpClient httpclient = new HttpClient();
      int result = httpclient.executeMethod(post);

      **// Display status code**
      System.out.println("Response status code: " + result);

      **// Display response**
      System.out.println("Response body: ");
      System.out.println(post.getResponseBodyAsString());

    } catch (Exception ex) {
      ex.printStackTrace();

    } finally {
      **// Release current connection to the connection pool
      // once you are done**
      post.releaseConnection();
    }
  }
}

Output

Response status code: 200

Response body:
<?xml version="1.0" encoding="UTF-8"?>
  <response>
  <record>
    <id>2</id>
    <name>sample</name>
    <description>Demo group</description>
    <email>group@mail.net</email>
    <referrer />
    <label>
      <en>Sample group</en>
      <fr>Sample group</fr>
      <es>Sample group</es>
      <de>Beispielgruppe</de>
      <nl>Voorbeeldgroep</nl>
    </label>
  </record>
</response>

Create a new user (exception management)

This example show a request to create a new user, that requires authentication to complete succesfully. The request is executed without authentication to capture the exception returned by GeoNetwork.

Source

package org.geonetwork.xmlservices.client;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.jdom.Document;
import org.jdom.Element;

public class CreateUserClient {
  public static void main(String args[]) {

  **// Create request** xml
  Element request = new Element("request")
  .addContent(new Element("operation").setText("newuser"))
  .addContent(new Element("username").setText("samantha"))
  .addContent(new Element("password").setText("editor2"))
  .addContent(new Element("profile").setText("Editor"))
  .addContent(new Element("name").setText("Samantha"))
  .addContent(new Element("city").setText("Amsterdam"))
  .addContent(new Element("country").setText("Netherlands"))
  .addContent(new Element("email").setText("samantha@mail.net"));

  **// Create PostMethod specifying service url**
  String serviceUrl = "http://localhost:8080/geonetwork/srv/en/user.update";
  PostMethod post = new PostMethod(serviceUrl);

  try {
    String postData = Xml.getString(new Document(request));

    **// Set post data, mime-type and encoding**
    post.setRequestEntity(new StringRequestEntity(postData, "application/xml", "UTF8"));

    **// Send request**
    HttpClient httpclient = new HttpClient();
    int result = httpclient.executeMethod(post);

    **// Display status code**
    System.out.println("Response status code: " + result);

    **// Display response**
    System.out.println("Response body: ");
    String responseBody = post.getResponseBodyAsString();
    System.out.println(responseBody);

    if (result != HttpStatus.SC_OK) {
      **// Process exception**
      Element response = Xml.loadString(responseBody, false);
      System.out.println("Error code: " +
      response.getAttribute("id").getValue());
      System.out.println("Error message: " +
      response.getChildText("message"));
    }

    } catch (Exception ex) {
      ex.printStackTrace();

    } finally {
      // Release current connection to the connection pool
      // once you are done
      post.releaseConnection();
    }
  }
}

Output

Response status code: 401

Response body:
<?xml version="1.0" encoding="UTF-8"?>
<error id="service-not-allowed">
  <message>Service not allowed</message>
  <class>ServiceNotAllowedEx</class>
  <stack>
    <at class="jeeves.server.dispatchers.ServiceManager" file="ServiceManager.java" line="374" method="dispatch" />
    <at class="jeeves.server.JeevesEngine" file="JeevesEngine.java" line="621" method="dispatch" />
    <at class="jeeves.server.sources.http.JeevesServlet" file="JeevesServlet.java" line="174" method="execute" />
    <at class="jeeves.server.sources.http.JeevesServlet" file="JeevesServlet.java" line="99" method="doPost" />
    <at class="javax.servlet.http.HttpServlet" file="HttpServlet.java" line="727" method="service" />
    <at class="javax.servlet.http.HttpServlet" file="HttpServlet.java" line="820" method="service" />
    <at class="org.mortbay.jetty.servlet.ServletHolder" file="ServletHolder.java" line="502" method="handle" />
    <at class="org.mortbay.jetty.servlet.ServletHandler" file="ServletHandler.java" line="363" method="handle" />
    <at class="org.mortbay.jetty.security.SecurityHandler" file="SecurityHandler.java" line="216" method="handle" />
    <at class="org.mortbay.jetty.servlet.SessionHandler" file="SessionHandler.java" line="181" method="handle" />
  </stack>
  <object>user.update</object>
  <request>
    <language>en</language>
    <service>user.update</service>
  </request>
</error>

Error code: service-not-allowed Error message: Service not allowed

Create a new user (sending credentials)

This example show a request to create a new user, that requires authentication to complete succesfully.

In this example httpClient it's used first to send a login request to GeoNetwork, getting with JSESSIONID cookie. Nexts requests send to GeoNetwork using httpClient send the JSESSIONID cookie, and are managed as authenticated requests.

Source

package org.geonetwork.xmlservices.client;

import org.apache.commons.httpclient.Credentials;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.auth.AuthScope;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.jdom.Document;
import org.jdom.Element;

public class CreateUserClientAuth {
  private HttpClient httpclient;

  CreateUserClientAuth() {
    httpclient = new HttpClient();
  }

  **/**
  * Authenticates the user in GeoNetwork and send a request
  * that needs authentication to create a new user
  *
  */**
  public void sendRequest() {
    **// Authenticate user**
    if (!login()) System.exit(-1);

    **// Create request XML**
    Element request = new Element("request")
    .addContent(new Element("operation").setText("newuser"))
    .addContent(new Element("username").setText("samantha"))
    .addContent(new Element("password").setText("editor2"))
    .addContent(new Element("profile").setText("Editor"))
    .addContent(new Element("name").setText("Samantha"))
    .addContent(new Element("city").setText("Amsterdam"))
    .addContent(new Element("country").setText("Netherlands"))
    .addContent(new Element("email").setText("samantha@mail.net"));

    **// Create PostMethod specifying service url**
    String serviceUrl = "http://localhost:8080/geonetwork/srv/en/user.update";
    PostMethod post = new PostMethod(serviceUrl);

    try {
      String postData = Xml.getString(new Document(request));

      **// Set post data, mime-type and encoding**
      post.setRequestEntity(new StringRequestEntity(postData, "application/xml", "UTF8"));

      **// Send request**
      **(httpClient has been set in
      // login request with JSESSIONID cookie)**
      int result = httpclient.executeMethod(post);

      **// Display status code**
      System.out.println("Create user response status code: " + result);

      if (result != HttpStatus.SC_OK) {
        **// Process exception**
        String responseBody = post.getResponseBodyAsString();
        Element response = Xml.loadString(responseBody, false);
        System.out.println("Error code: " +
        response.getAttribute("id").getValue());
        System.out.println("Error message: " +
        response.getChildText("message"));
      }

    } catch (Exception ex) {
      ex.printStackTrace();

    } finally {
      **// Release current connection to the connection pool
      // once you are done**
      post.releaseConnection();
    }
  }

  **/**
  * Logins a user in GeoNetwork
  *
  * After login **httpClient** gets with JSSESIONID cookie. Using it
  * for nexts requests, these are managed as "authenticated requests"
  *
  * @return  True if login it's ok, false otherwise
  */**
  private boolean login() {
    **// Create request XML**
    Element request = new Element("request")
    .addContent(new Element("username").setText("admin"))
    .addContent(new Element("password").setText("admin"));

    **// Create PostMethod specifying login service url**
    String loginUrl =
    "http://localhost:8080/geonetwork/srv/en/xml.user.login";
    PostMethod post = new PostMethod(loginUrl);

    try {
      String postData = Xml.getString(new Document(request));

      **// Set post data, mime-type and encoding**
      post.setRequestEntity(new StringRequestEntity(postData,
      "application/xml", "UTF8"));

      **// Send login request**
      int result = httpclient.executeMethod(post);

      **// Display status code and authentication session cookie**
      System.out.println("Login response status code: " + result);
      System.out.println("Authentication session cookie: " +
      httpclient.getState().getCookies()[0]);

      return (result == HttpStatus.SC_OK);

    } catch (Exception ex) {
      ex.printStackTrace();
      return false;

    } finally {
      // Release current connection to the connection pool
      // once you are done
      post.releaseConnection();
    }

  }

  public static void main(String args[]) {
    CreateUserClientAuth request = new CreateUserClientAuth();

    request.sendRequest();
  }
}

Output

Login response status code: 200
Authentication session cookie: JSESSIONID=ozj8iyva0agv
Create user response status code: 200

Trying to run again the program, as the user it's just created we get an exception:

Login response status code: 200
Authentication session cookie: JSESSIONID=1q09kwg0r6fqe
Create user response status code: 500

Error response:

<?xml version="1.0" encoding="UTF-8"?>
<error id="error">
  <message>ERROR: duplicate key violates unique constraint "users_username_key"</message>
  <class>PSQLException</class>
  <stack>
    <at class="org.postgresql.core.v3.QueryExecutorImpl" file="QueryExecutorImpl.java" line="1548" method="receiveErrorResponse" />
    <at class="org.postgresql.core.v3.QueryExecutorImpl" file="QueryExecutorImpl.java" line="1316" method="processResults" />
    <at class="org.postgresql.core.v3.QueryExecutorImpl" file="QueryExecutorImpl.java" line="191" method="execute" />
    <at class="org.postgresql.jdbc2.AbstractJdbc2Statement" file="AbstractJdbc2Statement.java" line="452" method="execute" />
    <at class="org.postgresql.jdbc2.AbstractJdbc2Statement" file="AbstractJdbc2Statement.java" line="351"
    method="executeWithFlags" />
    <at class="org.postgresql.jdbc2.AbstractJdbc2Statement" file="AbstractJdbc2Statement.java" line="305"
    method="executeUpdate" />
    <at class="jeeves.resources.dbms.Dbms" file="Dbms.java" line="261" method="execute" />
    <at class="org.fao.geonet.services.user.Update" file="Update.java" line="134" method="exec" />
    <at class="jeeves.server.dispatchers.ServiceInfo" file="ServiceInfo.java" line="238" method="execService" />
    <at class="jeeves.server.dispatchers.ServiceInfo" file="ServiceInfo.java" line="141" method="execServices" />
  </stack>
  <request>
    <language>en</language>
    <service>user.update</service>
  </request>
</error>

Error code: error Error message: ERROR: duplicate key violates unique constraint "users_username_key"