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Issue #469: Implementation of Event-based Asynchronous pattern

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WSSIA
2016-08-08 23:31:41 +01:00
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event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/App.java Normal file
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/**
* The MIT License Copyright (c) 2014 Ilkka Seppälä
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package com.iluwatar.event.asynchronous;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.Scanner;
/**
*
* This application demonstrates the <b>Event-based Asynchronous</b> pattern. Essentially, users (of the pattern) may
* choose to run events in an Asynchronous or Synchronous mode. There can be multiple Asynchronous events running at
* once but only one Synchronous event can run at a time. Asynchronous events are synonymous to multi-threads. The key
* point here is that the threads run in the background and the user is free to carry on with other processes. Once an
* event is complete, the appropriate listener/callback method will be called. The listener then proceeds to carry out
* further processing depending on the needs of the user.
*
* The {@link EventManager} manages the events/threads that the user creates. Currently, the supported event operations
* are: <code>start</code>, <code>stop</code>, <code>getStatus</code>. For Synchronous events, the user is unable to
* start another (Synchronous) event if one is already running at the time. The running event would have to either be
* stopped or completed before a new event can be started.
*
* The Event-based Asynchronous Pattern makes available the advantages of multithreaded applications while hiding many
* of the complex issues inherent in multithreaded design. Using a class that supports this pattern can allow you to:-
* (1) Perform time-consuming tasks, such as downloads and database operations, "in the background," without
* interrupting your application. (2) Execute multiple operations simultaneously, receiving notifications when each
* completes. (3) Wait for resources to become available without stopping ("hanging") your application. (4) Communicate
* with pending asynchronous operations using the familiar events-and-delegates model.
*
* @see EventManager
* @see Event
*
*/
public class App {
boolean interactiveMode = false;
public static void main(String[] args) {
App app = new App();
app.setUp();
app.run();
}
/**
* App can run in interactive mode or not. Interactive mode == Allow user interaction with command line.
* Non-interactive is a quick sequential run through the available {@link EventManager} operations.
*/
public void setUp() {
Properties prop = new Properties();
String propFileName = "config.properties";
InputStream inputStream = App.class.getClassLoader().getResourceAsStream(propFileName);
if (inputStream != null) {
try {
prop.load(inputStream);
} catch (IOException e) {
}
String property = prop.getProperty("INTERACTIVE_MODE");
if (property.equalsIgnoreCase("YES")) {
interactiveMode = true;
}
}
}
public void run() {
if (interactiveMode) {
runInteractiveMode();
} else {
quickRun();
}
}
public void quickRun() {
EventManager eventManager = new EventManager();
try {
// Create an Asynchronous event.
int aEventID = eventManager.createAsyncEvent(60);
System.out.println("Event [" + aEventID + "] has been created.");
eventManager.startEvent(aEventID);
System.out.println("Event [" + aEventID + "] has been started.");
// Create a Synchronous event.
int sEventID = eventManager.createSyncEvent(60);
System.out.println("Event [" + sEventID + "] has been created.");
eventManager.startEvent(sEventID);
System.out.println("Event [" + sEventID + "] has been started.");
eventManager.getStatus(aEventID);
eventManager.getStatus(sEventID);
eventManager.stopEvent(aEventID);
System.out.println("Event [" + aEventID + "] has been stopped.");
eventManager.stopEvent(sEventID);
System.out.println("Event [" + sEventID + "] has been stopped.");
} catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException
| InvalidOperationException e) {
System.out.println(e.getMessage());
}
}
public void runInteractiveMode() {
EventManager eventManager = new EventManager();
Scanner s = new Scanner(System.in);
int option = 0;
option = -1;
while (option != 5) {
System.out
.println("(1) START_EVENT \n(2) STOP_EVENT \n(3) STATUS_OF_EVENT \n(4) STATUS_OF_ALL_EVENTS \n(5) EXIT");
System.out.print("Choose [1,2,3,4,5]: ");
option = s.nextInt();
if (option == 1) {
s.nextLine();
System.out.print("(A)sync or (S)ync event?: ");
String eventType = s.nextLine();
System.out.print("How long should this event run for (in seconds)?: ");
int eventTime = s.nextInt();
if (eventType.equalsIgnoreCase("A")) {
try {
int eventID = eventManager.createAsyncEvent(eventTime);
System.out.println("Event [" + eventID + "] has been created.");
eventManager.startEvent(eventID);
System.out.println("Event [" + eventID + "] has been started.");
} catch (MaxNumOfEventsAllowedException | LongRunningEventException | EventDoesNotExistException e) {
System.out.println(e.getMessage());
}
} else if (eventType.equalsIgnoreCase("S")) {
try {
int eventID = eventManager.createSyncEvent(eventTime);
System.out.println("Event [" + eventID + "] has been created.");
eventManager.startEvent(eventID);
System.out.println("Event [" + eventID + "] has been started.");
} catch (MaxNumOfEventsAllowedException | InvalidOperationException | LongRunningEventException
| EventDoesNotExistException e) {
System.out.println(e.getMessage());
}
} else {
System.out.println("Unknown event type.");
}
} else if (option == 2) {
System.out.print("Event ID: ");
int eventID = s.nextInt();
try {
eventManager.stopEvent(eventID);
System.out.println("Event [" + eventID + "] has been stopped.");
} catch (EventDoesNotExistException e) {
System.out.println(e.getMessage());
}
} else if (option == 3) {
System.out.print("Event ID: ");
int eventID = s.nextInt();
try {
eventManager.getStatus(eventID);
} catch (EventDoesNotExistException e) {
System.out.println(e.getMessage());
}
} else if (option == 4) {
eventManager.getStatusOfAllEvents();
}
}
s.close();
}
}