Push to the limit - rich and pro-active user interfaces with ADF (Oracle Open World 2011)

Push to the limit – rich and pro-active user interfaces with ADF
Lucas Jellema – AMIS (Nieuwegein, The Netherlands)
Oracle Open World 2011

Overview
Real time architecture
Push – ADF middle tier to browser
Active Data Service
Custom Push
Push triggering pull
Push – Database to middle tier
Push all the way across the tiers
Client to Client Push

Asynchronous communication in the real world
“I’ll get back to you”
“Don’t call us,…”
Low fuel warning in car
“Please let me know”
“Return to sender – address unknown”
Newspaper delivery
Next instruction from car navigation system
Telephone ringing
Alarm clock buzzing
Parking sensors beeping
Fire alarm screaming

Asynchronous interactions and push in the IT landscape
More timely information
Notification as soon as possible
Proactive offering
Do not ask and you shall be given
Lower load on back end – don’t call us (all the time) …
Stop hitting the F5 button!
Multi-channel information manipulation and dissemination
Changes and events come in from everywhere
Decouple system components through generic infrastructure for handling events and push
Yet integrate

Pushing it … into the user interface
Automatically refreshing (part of) a page
Update table
Redrawing chart
Displaying popup to alert user to an event
Arrival of message (email or chat)
Signing in or out of contact (presence)
Lock or release of some resource
Notification
Changing status of items on the page
Highlight change indicator
Show icon
Change text to italic
Play a sound

3rd party
Mobile Device
Mobile Device
Web Browser
Web Browser
JEE Application Server
Complex Event Processor
Non
Java
Server
RDBMS
Email Server
Chat Server
RDBMS

The ‘Only tell when asked’ game

Introducing ADF Active Data Service
Built in mechanism in ADF to push updates from the middle tier to the browser
active UI components that refresh upon reception of the push (table, image, output text, DVT graphs)
client side infrastructure to process received push messages
a multiplexed (multi-event) channel to push to client – leveraging WebLogic Server push capabilities
Long poll today, WebSockets or SPDY tomorrow
server side infrastructure to manage active beans and turn events into pushed messages
Active data control:
BAM Data Control for push from BAM’s Active Data Cache all the way to data bound UI components

Overview of ADS infrastructure

Using ADF active Data Service to embed chat client in web application
Instant Messaging should be instant
Requirement to push incoming messages to client
Common IM protocol is XMPP (over TCP)
Extensible Messaging and Presence Protocol
XMPP Java Libraries help to connect to and communicate with XMPP servers
For example Smack
To embed chat in in ADF application we need to
consume messages over XMPP
and push them to the Web Client
The ADS approach:
Use ‘active’ UI Components
Bind them to bean that implements ActiveDataModel
Turning the IM messages into entries in ActiveDataModel

Example of ADS: Google Talk
Web Browser

Push trough Active Data Service
Web Browser
ADS
MessageReceiver

Introducing Business Activity Monitoring
Operational Business Intelligence
Data fed in from many sources:
RFID sensors, BPEL, Database Triggers, RSS, ODI
Real Time insight
Dashboard
Live updates
Looking for threshold crossing, exceptions, trends, missing events
Display visually and turn into alerts & notifications

Introducing Business Activity Monitoring
ADF Application

Embedding real time displays in ADF based on BAM Data Control
Configure connection to BAM Server
Create BAM Data Control
Based on Data Objects inActive Data Cache
Drag & Drop Data Control’scollections & attributes toADF Faces pages
Just like ADF BC Data Control
However: BAM Data Control is active

Live volleyball reporting
Web Browser
JMS Queue
BAM
Data Object

Create BAM Data control

Programmatic cross tier interaction
Web Browser

Client
JavaScript
Components
manipulate
component
user action
JavaScript Function
component
clientListener
component
userorprogrammaticaction
partialSubmitautoSubmit
Load JSON, CSS, Image, XML, JS
property change
Requestdata orPush message
poll
setPropertyListener
partial triggers, added targets
Queue Custom Event
serverListener
activeOutputText
ERKS ‘ppr script’
partial page refresh
Full pagereload
push
add JS toexecute (ERKS)
Server (middle tier)
component
activeOutputText
component
add componentsas partial target
actionListener, valueChangeListener, …Listener
Bean
serverListener
Active DataModel
Object
Components
Beans & Objects
push (DB QRCN)
Database
Client Server interactions vv.

The push-to-nudge trick(Matthias Wessendorf)
Client Listener Function
Show popup
Update field value
Modify style property
Call Server (PPR)
activeOutputText
clientListener
type=propertyChange
Servlet
Active Bean
Active data
register
Event Handler
JMS Listener
Scheduled Job
&
Event Listener

Simple nudge to client

Client to client push – slide synchronization

activeImageBean
activeImageBean

Cross tier push – architecture pattern
listener
listener
listener
register
event handler
Payload Retriever
Scheduled Poll Job
Push Receptor
‘Events collector’

Cross gap push mechanisms
Many channels are available to push messages from one entity to another,
across application, technology and location boundaries
JMS
(one way) WebService (SOAP or REST)
“HTTP Channel”
WebSockets
Http Call to Servlet
XMPP

Client to Client pusH
Usually really a combination of
Client-to-Server
and Server-to-the-other-Client push
Exception: Blue Tooth, Near-Field Communication

Server to mobile push:multiplexed, semi-poll based

Push from Database to middle tier
Middle tier asks database – through JDBC, ODBC, SQL*Net, HTTP, …
The database is reactive only – not pushy at all
Some mechanisms allow the database to take the initiative and start to push
Database Query Result Change Notification
Http calls from utl_http or JSP
Table with Multiplexed Poll

The Hollywood Principle: Query ResultSet Change Notification
POJO / ADF BC

Cache Refresh triggered by DB
Oracle RDBMS invokes Java Listener with event details
POJO / ADF BC
Register DatabaseChangeNotification
SQL query
PL/SQL

Shared Application Modules
Regular Application Module instances are session level – i.e. not shared across (web) sessions
Shared Application Module instances are shared across sessions like an Application Scope Managed Bean
Used for Static Data Sets: Look Up Data and Reference Tables
Sessions can reuse the data from a shared Application Module without having to access the database
And without loading the data in session level memory scope
View Accessors can be used to access data in the Shared Application Module’s VOs
For example for use in LOVs or Validation Rules

Shared Application Module Instance

Auto Refresh for View Objects
ViewObjects in a Shared Application Module can be registered for auto refresh
Typically such application wide VOs are near-static
Whenever the underlying data set changes (in the database), the VO rowset should be refreshed
By setting Auto Refresh (to true) for the ViewObject, the VO will be refreshed whenever the database is changed
ADF registers the VO query with the Database (11g) Result Set Change Notification mechanism through JDBC
Note: the VO should not have an Order By clause nor select a Date column

Steps for auto refresh enabling
Create Shared Application Module
New application module that is added to list of Application Level instances in the Project properties
Create the ViewObject that queries the ‘static data’ and add to Shared Application Module
Set the Auto Refresh property to true for VO instance
Database must be 11g (and have parameter compatible set to 11.1.0 or above)
database user must have the Change Notification privilege
To piggy back changes to page, set changeEventPolicy to autoPPR on data binding

Set Auto Refresh for ViewObject
Set Auto Refresh for ViewObject
Grant Change Notification todatabase user

Demo: Database push to View Object in action
DBQRCN

Auto-PPR for immediate refresh of Data Bound components
To have ADF automatically refresh data bound components when underlying value binding has changed its value
Set changeEventPolicy=ppr on iterator
Refresh as piggy back on any request cycle
No partialTriggers attribute required!

Alternative Database to middle tier push implementation
Session scope bean
listener
listener
listener
register
Application scope bean
event handler
servlet
Payload Retriever
Scheduled Poll Job
Push Receptor
utl_http
RDBMS
‘Events collector’
trigger

Cross Tier Push
Web Browser
table
activeOT
Cache refresher
evtlsnr
servlet
RDBMS
job
trg

Initiate ‘normaL’ PPR cycle in which to refresh ui components
Client Listener Function
component
queue event
activeOutputText
someComponent
serverListener
clientListener
type=propertyChange
refresh page
PPR request
Bean
Iterator
Auto ppr
retrieve data
View
clear cache
Entity
RDBMS

Server Push challenges
How to push against the ‘one way direction’ and despite limitations
HTTP and JDBC are request/response – not response only
Browser limit of only two channels to one server
Server side ‘event handling’
Session has to have an active life beyond requests
Or requests have a life beyond response
Higher load on the server
How to handle the (potential) volume of ‘concurrent’ channels and the number of open threads
NIO, Servlet 3.0, Jetty Continuations, Tomcat Advanced I/O

Server Push challenges (2)
Where do events to push actually come from?
Who perceives/receives (real-time) events (on the server side)
How are they tied in to the appropriate sessions?
Client (consumer) side: how to asynchronously receive events and how to process them/turn them into action and UI updates
How to correlate an asynchronously received message with a previously sent request or a subscription
For example: mobile phone showing SMS or WhatsApp messages in a conversation thread style

Future Developments
The real time enterprise
The event driven enterprise
Further evolution of push notification at every tier
Mobile perhaps leading the way
Infrastructure and frameworks providing push mechanisms
Such as Active Data Service
Servlet 3.0, Java NIO, WebSockets,SPDY, XMPP and other lighter weight solutions for bi-directional communication over TCP
And broad support in browsers and application servers

Summary
Push
Pro active or at least real time user interface
Real time user to user interaction
Decrease load on infrastructure (refresh over and over)
Real push hardly exists
Smart poll/pull is often underlying implementation
Piggy backing, Multiplexing, decoupling etc. are required to scale
ADS is powerful
Especially with the ‘nudge now you do a fine grained fetch or refresh’ pattern
Database can push too – using DBQRCN, HTTP, ….
ADF can push to Android or iOS
Using Google and Apple Push Notification Services
ADF Mobile should support push notification as well

Session Plugging
Sunday – Gold Nuggets in ADF (S32502)3.15-4.15, Moscone West-2000
Tuesday – Reaching Out from PL/SQL (S08625 )10.15-11.15, Mariott Marquis, Salon 7
Tuesday – (JavaOne) Cross Tier Push Architecture (Don’t call us, we’ll push you) (S24722)4.30-5.15 PM, Hotel Nikko, Monterey I/II
Wednesday – Push to the Limit: Rich and Proactive User Interfaces with Oracle ADF (S08620)5-6 PM, Mariott Marquis, Golden Gate A
Thursday –Instant Agility in Oracle Fusion Middleware through Design Time @ Run Time (S08623)4-5 PM, Moscone West – 2020

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Push to the limit - rich and pro-active user interfaces with ADF (Oracle Open World 2011)

by Lucas Jellema

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