org.eclipse.osbp.runtime.common/src/org/eclipse/osbp/runtime/common/session/ISession.java

/*
 *                                                                            
 *  Copyright (c) 2011 - 2017 - Loetz GmbH & Co KG, 69115 Heidelberg, Germany 
 *                                                                            
 *  All rights reserved. This program and the accompanying materials           
 *  are made available under the terms of the Eclipse Public License 2.0        
 *  which accompanies this distribution, and is available at                  
 *  https://www.eclipse.org/legal/epl-2.0/
 *
 *  SPDX-License-Identifier: EPL-2.0                                 
 *                                                                            
 *  Initial contribution:                                                      
 *     Loetz GmbH & Co. KG                              
 * 
 */
package org.eclipse.osbp.runtime.common.session;

import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.function.Function;
import java.util.function.Predicate;

import org.eclipse.e4.core.contexts.IEclipseContext;
import org.eclipse.osbp.runtime.common.session.ISessionManager.FutureResult;

/**
 * And abstraction above a state. Eg. Vaadin UI.
 */
public interface ISession {

	// do not access directly! Use #getCurrent()
	public static ThreadLocal<ISession> current = new ThreadLocal<>();

	public static ISession getCurrent() {
		return current.get();
	}

	public static void makeCurrent(IEclipseContext context) {
		ISession session = context.get(ISession.class);
		session.makeDefault();
	}

	String HOSTNAME = "hostname";
	String IS_SLAVE = "slave";

	/**
	 * Registers this session instance in a ThreadLocal variable.
	 */
	void makeDefault();

	/**
	 * Deregisters this session instance in a ThreadLocal variable.
	 */
	void unmakeDefault();

	/**
	 * Returns the eclispe context.
	 * 
	 * @return
	 */
	IEclipseContext getEclipseContext();

	/**
	 * Returns the host address of the session.
	 * 
	 * @return
	 */
	String getHost();

	/**
	 * Executes the function in the scope of the session.
	 * 
	 * @param function
	 * @return
	 */
	<T> T apply(Function<ISession, T> function);

	/**
	 * Creates a {@link CompletableFuture} for the given function. This method
	 * must NOT block.
	 * 
	 * @param function
	 * @param callback
	 * @return
	 */
	<T> CompletableFuture<FutureResult<T>> async(final Function<ISession, T> function, SessionCallback<T> callback);

	/**
	 * Creates a {@link CompletableFuture} for the given function. This method
	 * must NOT block.
	 * 
	 * @param function
	 * @param callback
	 * @return
	 */
	<T> CompletableFuture<FutureResult<T>> async(final Function<ISession, T> function, SessionCallback<T> callback,
			ExecutorService executor);

	/**
	 * Sends the given data to the session. Call must by synced.
	 * 
	 * @param data
	 */
	void sendData(Map<String, Object> data);

	/**
	 * Returns the property associated with the key.
	 * 
	 * @param key
	 * @return
	 */
	<T> T get(Class<T> key);

	/**
	 * Returns the property associated with the key.
	 * 
	 * @param key
	 * @return
	 */
	Object get(String key);

	void set(String key, Object object);

	/**
	 * Returns true, if the session has slave sessions. Otherwise false.
	 * 
	 * @return
	 */
	boolean isMasterSession();

	/**
	 * Returns true, if the session is a slave session and has a master session.
	 * Otherwise false.
	 * 
	 * @return
	 */
	boolean isSlaveSession();

	/**
	 * Returns the type {@link Type} of this session.
	 * 
	 * @return
	 */
	Type getType();

	/**
	 * Returns the master session, if the session is a slave session.
	 * <code>Null</code> otherwise.
	 * 
	 * @return
	 */
	ISession getMaster();

	/**
	 * Returns an unmodifiable list of all slave sessions connected to this
	 * master. Returns never <code>null</code>.
	 * 
	 * @return
	 */
	List<ISession> getSlaves();

	/**
	 * Returns a list of slaves filtered by given filter.
	 * 
	 * @param filter
	 * @return
	 */
	List<ISession> getSlaves(Predicate<ISession> filter);

	/**
	 * Adds a session which is a slave. Slaves are used to "paint" on web UIs
	 * controlled by the master session.
	 * 
	 * @param name
	 * @return
	 */
	void addSlave(ISession slave);

	/**
	 * See {@link #addSlaveSession(ISession)}
	 * 
	 * @param slave
	 */
	void removeSlave(ISession slave);

	/**
	 * In case of slave session, the session MUST provide a fragment following
	 * the pattern: {master-host}{UI-to-display}
	 * 
	 * @return
	 */
	String getFragment();

	enum Type {
		MASTER, SLAVE;
	}

	/**
	 * Sets the transaction handler.
	 *
	 * @param transaction the new transaction handler
	 */
	void setTransactionHandler(ITransactionHandler transaction);
	
	/**
	 * Gets the transaction handler.
	 *
	 * @return the transaction handler
	 */
	ITransactionHandler getTransactionHandler();
	
	/**
	 * Gets the vaadin  UI.
	 *
	 * @return the ui
	 */
	Object getUI();
}