Synnefo » Pithos Web Client

/*

 * Copyright 2011-2013 GRNET S.A. All rights reserved.

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 * Redistribution and use in source and binary forms, with or

 * without modification, are permitted provided that the following

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 *

 *   1. Redistributions of source code must retain the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer.

 *

 *   2. Redistributions in binary form must reproduce the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer in the documentation and/or other materials

 *      provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

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 * The views and conclusions contained in the software and

 * documentation are those of the authors and should not be

 * interpreted as representing official policies, either expressed

 * or implied, of GRNET S.A.

 */

package gr.grnet.pithos.web.client.rest;

import gr.grnet.pithos.web.client.Pithos;

import gr.grnet.pithos.web.client.Resource;

import java.util.HashMap;

import java.util.Map;

import com.google.gwt.core.client.GWT;

import com.google.gwt.core.client.Scheduler.ScheduledCommand;

import com.google.gwt.http.client.Request;

import com.google.gwt.http.client.RequestBuilder;

import com.google.gwt.http.client.RequestException;

import com.google.gwt.http.client.Response;

public abstract class HeadRequest<T extends Resource> implements ScheduledCommand {

        protected static final int MAX_RETRIES = 3; 

        protected int retries = 0; 

        protected Class<T> aClass;

    private String api;

    protected String owner;

    private String path;

    private int okCode;

    protected T cached;

    protected T result;

    private Map<String, String> headers = new HashMap<String, String>();

    public abstract void onSuccess(T _result);

    public abstract void onError(Throwable t);

    public HeadRequest(Class<T> aClass, String api, String owner, String path, int okCode, T result) {

        this.aClass = aClass;

        this.api = api;

        this.owner = owner;

        this.path = path;

        this.okCode = okCode;

        this.result = result;

    }

    public HeadRequest(Class<T> aClass, String api, String owner, String path) {

        this(aClass, api, owner, path, Response.SC_NO_CONTENT, null);

    }

    public HeadRequest(Class<T> aClass, String api, String owner, String path, T result) {

        this(aClass, api, owner, path, Response.SC_NO_CONTENT, result);

    }

    @Override

    public void execute() {

            if (path.contains("?"))

                    path += "&t=" + System.currentTimeMillis();

            else

                    path += "?t=" + System.currentTimeMillis();

        Pithos.LOG("HEAD api = ", api, ", owner = ", owner, ", path = ", path);

        Pithos.LOG("   ==> ", api + owner + path);

        RequestBuilder builder = new RequestBuilder(RequestBuilder.HEAD, api + owner + path);

        for (String header : headers.keySet()) {

            builder.setHeader(header, headers.get(header));

        }

        try {

            builder.sendRequest("", new RestRequestCallback<T>(api + owner + path, okCode) {

                @Override

                public void onSuccess(T object) {

                    HeadRequest.this.onSuccess(object);

                }

                @Override

                public T deserialize(Response response) {

                    return Resource.createFromResponse(aClass, owner, response, result);

                }

                @Override

                public void onError(Request request, Throwable throwable) {

                    if (throwable instanceof RestException) {

                        if (((RestException) throwable).getHttpStatusCode() == 304 && cached != null){

                            GWT.log("Using cache: " + cached.toString(), null);

                            onSuccess(cached);

                            return;

                        }

                    }

                    HeadRequest.this.onError(throwable);

                }

                                @Override

                                public void onUnauthorized(Response response) {

                                        HeadRequest.this.onUnauthorized(response);

                                }

            });

            retries++;

        }

        catch (RequestException e) {

            Pithos.LOG(e);

        }

    }

    protected abstract void onUnauthorized(Response response);

        public void setHeader(String header, String value) {

        headers.put(header, value);

    }

}