AbstractClient.java

package de.zib.gndms.gndmc;

/*
 * Copyright 2008-2011 Zuse Institute Berlin (ZIB)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import de.zib.gndms.common.rest.GNDMSResponseHeader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.FileSystemResource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestOperations;

import javax.inject.Inject;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

/**
 * An abstract client which implements the HTTP requests.
 * 
 * @author Ulrike Golas
 * 
 */
public abstract class AbstractClient {

	/**
	 * The logger.
	 */
	protected final Logger logger = LoggerFactory.getLogger(this.getClass());

	/**
	 * A rest template for internal use.
	 */
	private RestOperations restTemplate;

	/**
	 * The service url like <code>http://www.barz.org/gndms/<gridname></code>.
	 */
	private String serviceURL;

	/**
	 * The constructor.
	 */
	protected AbstractClient() {
	}

	/**
	 * The constructor.
	 * 
	 * @param serviceURL
	 *            The base url of the grid.
	 */
	public AbstractClient(final String serviceURL) {
		this.serviceURL = serviceURL;
	}
    
	/**
	 * Executes a given HTTP method on a url.
	 * 
	 * The request header contains a given user name and workflow id, the body of the request contains 
	 * a given object of type P.
	 * 
	 * @param <T> The body type of the response.
	 * @param <P> The body type of the request.
	 * @param x The kind of HTTP method to be executed.
	 * @param clazz The type of the return value.
	 * @param parm The body of the request.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @param wid The workflow id.
	 * @return The response as entity.
	 */
	private <T, P> ResponseEntity<T> unifiedX(final HttpMethod x,
			final Class<T> clazz, final P parm, final String url,
			final String dn, final String wid) {
		GNDMSResponseHeader requestHeaders = new GNDMSResponseHeader();
		if (dn != null) {
			requestHeaders.setDN(dn);
		}
		if (wid != null) {
			requestHeaders.setWId(wid);
		}
		HttpEntity<P> requestEntity = new HttpEntity<P>(parm, requestHeaders);

        if( null == restTemplate )
            throw new NullPointerException( "Please set RestTemplate in Client!" );
		return restTemplate.exchange(url, x, requestEntity, clazz);
	}

	/**
	 * Executes a GET on a url, where the request header contains a given user name.
	 * 
	 * @param <T> The body type of the response.
	 * @param clazz The type of the return value.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @return The response as entity.
	 */
	protected final <T> ResponseEntity<T> unifiedGet(final Class<T> clazz,
			final String url, final String dn) {
		return unifiedX(HttpMethod.GET, clazz, null, url, dn, null);
	}

	/**
	 * Executes a GET on a url, where the request header contains a given user name and workflow id.
	 * 
	 * @param <T> The body type of the response.
	 * @param clazz The type of the return value.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @param wid The workflow id.
	 * @return The response as entity.
	 */
	protected final <T> ResponseEntity<T> unifiedGet(final Class<T> clazz,
			final String url, final String dn, final String wid) {
		return unifiedX(HttpMethod.GET, clazz, null, url, dn, wid);
	}

	/**
	 * Executes a POST on a url.
	 * 
	 * The request header contains a given user name, the body of the request contains 
	 * a given object of type P.
	 * 
	 * @param <T> The body type of the response.
	 * @param <P> The body type of the request.
	 * @param clazz The type of the return value.
	 * @param parm The body of the request.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @return The response as entity.
	 */
	protected final <T, P> ResponseEntity<T> unifiedPost(final Class<T> clazz,
			final P parm, final String url, final String dn) {
		return unifiedX(HttpMethod.POST, clazz, parm, url, dn, null);
	}

	/**
	 * Executes a POST on a url.
	 * 
	 * The request header contains a given user name and workflow id, the body of the request contains 
	 * a given object of type P.
	 * 
	 * @param <T> The body type of the response.
	 * @param <P> The body type of the request.
	 * @param clazz The type of the return value.
	 * @param parm The body of the request.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @param wid The workflow id.
	 * @return The response as entity.
	 */
	protected final <T, P> ResponseEntity<T> unifiedPost(final Class<T> clazz,
			final P parm, final String url, final String dn, final String wid) {
		return unifiedX(HttpMethod.POST, clazz, parm, url, dn, wid);
	}

	/**
	 * Executes a PUT on a url.
	 * 
	 * The request header contains a given user name, the body of the request contains 
	 * a given object of type P.
	 * 
	 * @param <T> The body type of the response.
	 * @param <P> The body type of the request.
	 * @param clazz The type of the return value.
	 * @param parm The body of the request.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @return The response as entity.
	 */
	protected final <T, P> ResponseEntity<T> unifiedPut(final Class<T> clazz,
			final P parm, final String url, final String dn) {
		return unifiedX(HttpMethod.PUT, clazz, parm, url, dn, null);
	}

	/**
	 * Executes a PUT on a url.
	 * 
	 * The request header contains a given user name and workflow id, the body of the request contains 
	 * a given object of type P.
	 * 
	 * @param <T> The body type of the response.
	 * @param <P> The body type of the request.
	 * @param clazz The type of the return value.
	 * @param parm The body of the request.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @param wid The workflow id.
	 * @return The response as entity.
	 */
	protected final <T, P> ResponseEntity<T> unifiedPut(final Class<T> clazz,
			final P parm, final String url, final String dn, final String wid) {
		return unifiedX(HttpMethod.PUT, clazz, parm, url, dn, wid);
	}

	/**
	 * Executes a DELETE on a url, where the request header contains a given user name.
	 * 
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @return The response as entity with Void body.
	 */
	protected final ResponseEntity<Integer> unifiedDelete(final String url,
			final String dn) {
		return unifiedX(HttpMethod.DELETE, Integer.class, null, url, dn, null);
	}

	/**
	 * Executes a DELETE on a url, where the request header contains a given user name.
	 * 
	 * @param <T> The body type of the response.
	 * @param clazz The type of the return value.
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @return The response as entity.
	 */
	protected final <T> ResponseEntity<T> unifiedDelete(final Class<T> clazz,
			final String url, final String dn) {
		return unifiedX(HttpMethod.DELETE, clazz, null, url, dn, null);
	}

	/**
	 * Executes a DELETE on a url, where the request header contains a given user name and workflow id.
	 * 
	 * @param url The url of the request.
	 * @param dn The user name.
	 * @param wid The workflow id.
	 * @return The response as entity with Void body.
	 */
	protected final ResponseEntity<Integer> unifiedDelete(final String url,
			final String dn, final String wid) {
		return unifiedX(HttpMethod.DELETE, Integer.class, 42, url, dn, wid);
	}


    /**
     * Upload (POST) a file on a url.
     *
     * The request header contains a given user name, the body of the request contains
     * a given object of type P.
     *
     * @param <T> The body type of the response.
     * @param clazz The type of the return value.
     * @param fileName Remote filename.
     * @param originalFileName Path to local file.
     * @param url The url of the request.
     * @param dn The user name.
     * @return The response as entity.
     */
    protected final <T> ResponseEntity<T> postFile( final Class<T> clazz,
                                                    final String fileName,
                                                    final String originalFileName,
                                                    final String url,
                                                    final String dn ) {

        GNDMSResponseHeader requestHeaders = new GNDMSResponseHeader();
        MultiValueMap< String, Object > form = new LinkedMultiValueMap< String, Object >();
        final HttpEntity requestEntity;

        if (dn != null) {
            requestHeaders.setDN( dn );
        }

        form.add( "file", new FileSystemResource( originalFileName ) );
        requestEntity = new HttpEntity( form, requestHeaders );

        if( null == restTemplate )
            throw new NullPointerException( "Please set RestTemplate in Client!" );

        return restTemplate.postForEntity( url, requestEntity, clazz );
    }


    /**
     * Upload (POST) multiple files on a url.
     *
     * The request header contains a given user name, the body of the request contains
     * a given object of type P.
     *
     * @param <T> The body type of the response.
     * @param clazz The type of the return value.
     * @param fileNames A collection of all files to upload
     * @param url The url of the request.
     * @param dn The user name.
     * @return The response as entity.
     */
    protected final <T> ResponseEntity<T> postFile( final Class<T> clazz,
                                                    final Collection< String > fileNames,
                                                    final String url,
                                                    final String dn ) {

        GNDMSResponseHeader requestHeaders = new GNDMSResponseHeader();
        MultiValueMap< String, Object > form = new LinkedMultiValueMap< String, Object >();
        final HttpEntity requestEntity;

        if (dn != null) {
            requestHeaders.setDN( dn );
        }
        
        List< FileSystemResource > files = new LinkedList< FileSystemResource >();
        for( String f: fileNames ) {
            files.add( new FileSystemResource( f ) );
        }
        form.add( "files", files );
        requestEntity = new HttpEntity( form, requestHeaders );

        if( null == restTemplate )
            throw new NullPointerException( "Please set RestTemplate in Client!" );

        return restTemplate.postForEntity( url, requestEntity, clazz );
    }


    /**
	 * Gets the rest template.
	 * 
	 * @return The rest template.
	 */
	public final RestOperations getRestTemplate() {
		return restTemplate;
	}

	/**
	 * Sets the rest template.
	 * 
	 * @param restTemplate The rest template.
	 */
	@Inject
	public final void setRestTemplate(final RestOperations restTemplate) {
		this.restTemplate = restTemplate;
	}

	/**
	 * Gets the service url.
	 * 
	 * @return The service url.
	 */
	public final String getServiceURL() {
		return serviceURL;
	}

	/**
	 * Sets the service url.
	 * 
	 * @param serviceURL The service url.
	 */
	public void setServiceURL(final String serviceURL) {
		this.serviceURL = serviceURL;
	}

}