Events between components?

[blevinson]

Hi, we're really liking SmartGWT and we're finding it a great product. We are currently evaluating SmartGWT EE 1.2.1 and are working on a couple different modules in a single page. The list on the right side fills up with a number of Employees and has a button to create a work item for that Employee. That work item needs to show up in a list on the left side when it's clicked. Currently, I am able to click on the button and the logic tells the server to create that work item. I currently have to refresh the page to get the "fetch" to pull the data into the left side. I would like to have it so I can have that other modules be notified that something has changed and update that list. I am using the DMI mechanism and have a hashmap holding the data (before persisting it) and am putting the objects in the session. I have tried to grab the instance object from the session and populate that hashmap with no change in the GUI. Is there a listener I can use to communicate between the modules?

Warm Regards,
Brant

[strawman]

few options

Cant comment on your exact situation. However, look at the eventbus component in SmartGWT extensions. It is a clean and easy way to do publish / subscribe events. I use it whenever I need multiple components to be messaged on the success of something.

Another option for refresh automatically is using a Timer component from GWT. However, you wil incur some cycles though. I use that in dashboard-style pages where status is refreshed every 5 minutes or so...

Good luck

Strawman

[blevinson]

RE: Events between components?

Thank you for the info strawman! I have been attempting to use this for a while now (about 3 hrs) but can't get the EventBus to work. It would be great if you or somebody could help me out a bit. Here is the relevant code (my alerts are custom functions). I get an alert for both Subscribing (1st) and after I click the button and I get Publishing (2nd). I never get the "Event!" which should happen if it works properly:

EffortList:

 
public class EffortList implements EntryPoint {
...
public void onModuleLoad() {
alert("Subscribing...");
Subscription subscription = EventBus.subscribe("addReviewEvent", new TopicSubscriber<DataSource>() {
public void onEvent(Subscription subscription, DataSource event) {
alert("Event!");
boundList.fetchData();
EventBus.unsubscribe(subscription); 
				}
			});
	 }
}

SearchEmployee:

 
public class SearchEmployee implements EntryPoint {
public void onModuleLoad() {
IButton createReviewBtn = new IButton("Create Effort");
...
createReviewBtn.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
		    alert("Published...");
		    EventBus.publish("addReviewEvent", event);
		}
}

Regards,
Brant

[mhulsman]

Why are you trying to load multiple different gwt modules in one page? Just have one module with only one onModuleLoad function that creates a smartgwt layout that has multiple widgets in it.

[strawman]

events

Yeah, I am not sure why you have multiple Entrypoints..


However, the subscribing class must implement "TopicSubscriber" interface.

Strawman

[trainer2009]

Hi ,
I am new to gwt and also to the eventbus.
I am trying to implement the eventbus and i am not sure how to get the implement event subscriber.So this is what i am doing.

I want the login displayed on the lower part of the panel when user clicks on "GO" link.
So in HeaderMenu class, onClick method , i fire the event
In SearchResultPanel, i want to listen to that event and display the name as "Welcome: blah blah blah"

2 things here which i am having questions
Question 1. When i implement TopicSubscriber<AppUser>, i have to implement the following method

public void onEvent(Subscription subscription, AppUser event) {
// TODO Auto-generated method stub
userName = event.getUserName();
SC.say("This event is not getting fired :"+event.getUserName());
}

This event doesnot get fired.Why is that?

Question 2.
If i add this as a part of the constructor, it does get called but the userName on th searchPanel still remains null
public SearchResultPanel(){

Subscription subscription = EventBus.subscribe("authenticateUser", new TopicSubscriber<AppUser>() {

public void onEvent(Subscription subscription, AppUser user) {
// TODO Auto-generated method stub
userName = user.getUserName();
SC.say("event called at the time of constructor:"+user.getUserName());
}

});



}


********************
This is my Subscriber class
********************
package com.myapp.web.gwt.client.search;

import com.myapp.web.gwt.client.eventbus.EventBus;
import com.myapp.web.gwt.client.eventbus.Subscription;
import com.myapp.web.gwt.client.eventbus.TopicSubscriber;
import com.myapp.web.gwt.shared.vo.authentication.AppUser;
import com.smartgwt.client.util.SC;
import com.smartgwt.client.widgets.Canvas;
import com.smartgwt.client.widgets.Label;
import com.smartgwt.client.widgets.layout.VLayout;
import com.smartgwt.client.widgets.tab.Tab;
import com.smartgwt.client.widgets.tab.TabSet;

public class SearchResultPanel implements TopicSubscriber<AppUser>{

static String userName ;
public SearchResultPanel(){

Subscription subscription = EventBus.subscribe("authenticateUser", new TopicSubscriber<AppUser>() {

public void onEvent(Subscription subscription, AppUser user) {
// TODO Auto-generated method stub
userName = user.getUserName();
SC.say("event called at the time of constructor:"+user.getUserName());
}

});



}

public Canvas getBasicSearchResults() {

VLayout testLayout = new VLayout();
Label welcome =null;
welcome =new Label("Welcome "+userName);
TabSet tabs = new TabSet();
Tab tab = new Tab("Current Status " );
tab.setCanClose(false);
tabs.addTab(tab);
tabs.setWidth("100%");
tabs.setHeight("100%");
testLayout .addMember(welcome);
testLayout .addMember(tabs);
return testLayout ;
}

public void onEvent(Subscription subscription, AppUser event) {
// TODO Auto-generated method stub
userName = event.getUserName();
SC.say("This event is not getting fired :"+event.getUserName());
}

}


**********************************
This is the MainClass
**********************************
package com.myapp.web.gwt.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.myapp.web.gwt.client.header.HeaderMenu;
import com.myapp.web.gwt.client.search.SearchResultPanel;
import com.smartgwt.client.widgets.layout.VLayout;

/**
* Entry point classes define <code>onModuleLoad()</code>.
*/
public class MyappMain implements EntryPoint {
/**
* The message displayed to the user when the server cannot be reached or
* returns an error.
*/
private static final String SERVER_ERROR = "An error occurred while "
+ "attempting to contact the server. Please check your network "
+ "connection and try again.";

/**
* Create a remote service proxy to talk to the server-side Myapp service.
*/
private final MyappServiceGWTWrapperAsync myappService = GWT.create(MyappServiceGWTWrapper.class);

/**
* This is the entry point method.
*/
public void onModuleLoad() {
VLayout fullPage= new VLayout();
fullPage.setBackgroundColor("#D8D8D8");
fullPage.setWidth("100%");
fullPage.setHeight("100%");
fullPage.addChild(HeaderMenu.getHeaderMenuPage());
SearchResultPanel searchResultPanel = new SearchResultPanel();
fullPage.addChild(searchResultPanel.getBasicSearchResults());
fullPage.draw();
}

// Create a handler for the sendButton and nameField
}

**********************************
This is the Class who is publishing the event
**********************************
package com.myapp.web.gwt.client.header;

import com.myapp.web.gwt.client.eventbus.EventBus;
import com.myapp.web.gwt.shared.vo.authentication.AppUser;
import com.smartgwt.client.types.Alignment;
import com.smartgwt.client.util.SC;
import com.smartgwt.client.widgets.Canvas;
import com.smartgwt.client.widgets.Img;
import com.smartgwt.client.widgets.form.DynamicForm;
import com.smartgwt.client.widgets.form.fields.LinkItem;
import com.smartgwt.client.widgets.form.fields.PasswordItem;
import com.smartgwt.client.widgets.form.fields.SpacerItem;
import com.smartgwt.client.widgets.form.fields.TextItem;
import com.smartgwt.client.widgets.form.fields.events.ClickEvent;
import com.smartgwt.client.widgets.form.fields.events.ClickHandler;
import com.smartgwt.client.widgets.layout.HLayout;
import com.smartgwt.client.widgets.layout.LayoutSpacer;

public class HeaderMenu {

public static HLayout getHeaderMenuPage(){
HLayout headerMenu = new HLayout();
headerMenu.setWidth("100%");
headerMenu.setHeight("5%");

headerMenu.setBackgroundColor("white");
Img myLogo = new Img();
myLogo .setSrc("http://www.abc.com/img/LOGO.JPG");
myLogo .setHeight("100%");


LayoutSpacer layoutSpacer = new LayoutSpacer();
layoutSpacer .setWidth("75%");
layoutSpacer.setBackgroundColor("black");
Canvas loginCanvas= getLogin();

headerMenu.addMember(myLogo);
headerMenu.addMember(layoutSpacer);
headerMenu.addMember(loginCanvas);
return headerMenu;

}


public static HLayout getLogin() {
HLayout loginLayout = new HLayout();
final DynamicForm loginForm = new DynamicForm();

final TextItem loginText = new TextItem("loginId");
loginText .setTitle("Login");
loginText.setValue("sdss");
final PasswordItem passwordItem = new PasswordItem ("password");
passwordItem .setTitle("Password");

LinkItem submitItem = new LinkItem ("");
//submitItem .setTitle("LinkItem");
submitItem .setName("");
submitItem .setLinkTitle("Go");
submitItem .setShouldSaveValue(false);
submitItem .addClickHandler(new ClickHandler(){

public void onClick(ClickEvent event) {
// TODO Auto-generated method stub
if (loginForm.getValue("loginId")!=null && loginForm.getValue("loginId").toString().length()>0 &&
loginForm.getValue("password")!=null && loginForm.getValue("password").toString().length()>0 ){

AppUser user = new AppUser ();
System.out.println("im here "+loginForm.getValue("loginId").toString());
user .setUserName(loginForm.getValue("loginId").toString());
user .setPassword(loginForm.getValue("password").toString());
EventBus.publish("authenticateUser", user);
} else if(loginForm.getValue("loginId")== null || loginForm.getValue("loginId").toString().trim().length() ==0){
SC.warn("Login Id is required");

}else if(loginForm.getValue("password")== null || loginForm.getValue("password").toString().trim().length() ==0){
SC.warn("Password is required");
}
}});

loginForm.setBackgroundColor("");
loginForm.setNumCols(8);


loginForm.setID("loginForm");
SpacerItem spItem = new SpacerItem();
spItem .setWidth(1);
loginForm.setItems(loginText,passwordItem,spItem ,submitItem);
loginForm.setAlign(Alignment.RIGHT);
loginLayout.addChild(loginForm);
loginLayout.setWidth("100%");
return loginLayout;
}
}

[mihai007]

Hello.
The code is too complex to use it as a test case.
Try to simplify things and start from that to find out what actually does not work.

[trainer2009]

i was able to fix my issue but on the pther hand i also saw that we subscribe method is allowing mutiple entries of the same class so i updated the subscribe method as follow

public static Subscription subscribe(String topic,
TopicSubscriber<?> listener) {
Subscription subscription = new Subscription(topic, listener);
List<Subscription> topicSubscribers = topicSubscribersMap.get(topic);
if (topicSubscribers == null) {
topicSubscribers = new ArrayList<Subscription>();
topicSubscribersMap.put(topic, topicSubscribers);
}
boolean subscriberExists= false;
for (int iLocal=0 ; iLocal<topicSubscribers.size();iLocal++) {
Subscription localSubscription = (Subscription) topicSubscribers.get(iLocal);
if (localSubscription.getListener().getClass().toString() .equals(subscription.getListener().getClass().toString())){
subscriberExists = true;
}
}
if (!subscriberExists ){
topicSubscribers.add(subscription);
}
return subscription;
}