partner webcast – oracle adf mobile - implementing data caching and syncing for working off line

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Implementing Data Caching Strategies for ADF Mobile

Steven Davelaar

ADF/Webcenter A-Team

Oracle Corporation

@stevendavelaar


Disclaimer

The following is intended to outline our general product direction. It is

intended for information purposes only, and may not be incorporated into

any contract.

It is not a commitment to deliver any material, code, or functionality, and

should not be relied upon in making purchasing decisions. The

development, release, and timing of any features or functionality

described for Oracle’s products remains at the sole discretion of Oracle.


Agenda

Data Caching and Data Sync Strategies

Implementing Data Caching and Synching Using A-

Team Mobile Persistence Extension


ADF Mobile Architecture

Device

Services

PhoneGap/

Cordova

Device Native Container

Web

View

Server

HTML

ADF Mobile

AMX View

Third Party

Web Sites

Server or Cloud

backend

Oracle IDM

Oracle IAM

Mobile

Device

Local

HTML

HTML5 & JavaScript Presentation

Configuration

Server

ADF Controller

Cre

de

ntia

l Ma

na

ge

me

nt,

SS

O &

Ac

ce

ss

Co

ntro

l

Ap

p

Co

nfig

Server

SOAP & REST

Web Services

Java VM

Business

Logic

ADF Model

Encrypted

SQLite DB

JD

BC

SQLite


Data Sources for ADF Mobile Applications

The data within an ADF Mobile application comes from 1 of 3 places

– Remote web services (SOAP, REST)

– Simple Java POJOs

– Local SQLite database

Typically all 3 are used in combination to allow your application to

– Web services: Retrieve and update data from/with remote servers

– Java POJOs: Cache that data locally for live access when disconnected

– Database: Persist & restore data when the application is stopped & restarted


Data Caching and Synching Challenges

Mobile devices can lose/turn off connectivity

Offline access to data is a common requirement

But it will increase the complexity of your application

If you cache data locally you must consider

– When to cache the data

– How much data to cache

– When to synchronize updates

– Recording the order of updates

– How to deal with synchronization conflicts

– Security of the data if the device is lost

Security


1. Online Read/Write

• Needs to be continuously

connected

• Does not cache any data locally

• No synchronization required

• No risk of data theft if the device is

stolen

Data Caching Strategies

2. Cached Reads, Online Write

• Caches data as it is accessed

or on startup

• Updates are via web service

calls


• Small risk of data theft

3. Cached Reads, Offline Writes


• Edits to cached data are saved

locally

• Edits to the local data are

periodically flushed to the server

• Greater risk of data theft

4. Full Synchronization

• All data is synchronized to the

device on startup


locally




ADF Mobile – Model Layer

Data Object

– Java class to hold attributes of an object

– Represents a single “row” of a collection

– Can contain sub-collections of other Data Objects to form complex object

hierarchies

Service Object

– Java class that provides CRUD operations

– Returns arrays of Data Objects in the get methods

– Exposed as Data Control to create UI using drag and drop


Java VM

ADF Model

Model Layer – Caching Data

Service

Object

Da

ta C

on

tro

l

Data Object

JDBC code

Encrypted

SQLite DB


Using the SQLite Database in ADF Mobile

Typically used by a single user

SQLite libraries and JDBC drivers are embedded in ADF Mobile

container

Encryption for the SQLite Database File is provided with ADF Mobile

Zero configuration

No Object-Relational Mapping (ORM) layer provided

– Access using plain JDBC statements


Initialize the Database

Start()

1. Creates the DB

2. Creates Connection

3. Connects

4. Populates DB

call Start()

LifeCycleListenerImpl.java

Application starts up

Note:

Need to add LifeCycleListenerImpl.java to the LifeCycleEvent

Listener Field of the adfmf-application.xml file.


JDBC Example – Get Departments public void retrieveDepartmentsFromDB() {

try {

Connection conn = DBConnectionFactory.getConnection();

s_departments.clear();

conn.setAutoCommit(false);

PreparedStatement stat = conn.prepareStatement("SELECT * from DEPARTMENTS");

ResultSet rs = stat.executeQuery();

while (rs.next()) {

int id = rs.getInt("DEPARTMENT_ID");

String deptName = rs.getString("DEPARTMENT_NAME");

int mgrId = rs.getInt("MANAGER_ID");

int locId = rs.getInt("LOCATION_ID");

Department d = new Department(id, deptName, mgrId, locId);

s_departments.add(d);

}

rs.close();…


SQLite More Info

Check out SQLite website : http://www.sqlite.org/

Check out ADF Insider Essentials video by Frederic Desbiens

– http://www.youtube.com/watch?v=-XzE1n_j5Nc

http://www.sqlite.org/

http://www.youtube.com/watch?v=-XzE1n_j5Nc




Java VM

ADF Model


Service

Object

Da

ta C

on

tro

l

Data Object

JDBC code

Encrypted

SQLite DB

RestServiceAdapter

REST(JSON/XML)

SOAP/REST-XML


What is JSON?

JavaScript Object Notation

– text-based open standard designed

for human-readable data

interchange. It is derived from the

JavaScript scripting language for

representing simple data structures

and associative arrays, called

objects. Despite its relationship to

JavaScript, it is language-

independent, with parsers available

for many languages.


Using JSON REST Service

Create a URL Connection that points to the JSON data host

This URL should be based on the root of all JSON services

– For example, for a JSON service that returns employees and departments

(http://server:port/service/employees and

http://server:port/service/departments), the URL Data Control should point

to http://server:port/service/.

Use RestServiceAdaptor to invoke service


RestServiceAdaptor Example


Java VM

ADF Model


Service

Object

Da

ta C

on

tro

l

Data Object

JDBC code

Encrypted

SQLite DB

restServiceAdapter

REST(JSON/XML)

SOAP/REST-XML

SOAP/REST-XML Web Services

Da

ta

Co

ntr

ol

AdfmfJavaUtilities

invokeDataControlMethod


Using SOAP XML Service – Run Web Service Data Control Wizard


Invoking SOAP Web Service Programmatically


Implementing Data Caching Strategies

ADF Mobile provides basic support to implement strategy 2: Cached

Reads – Online Writes

– Java coding required to convert web service payload to Java data objects

and vice versa

– Extensive JDBC coding required when caching should survive application

stop/start, and/or flexible data filtering is needed

Would be really nice to have an ORM mapping framework that auto

generates the JDBC code…

Implementing strategies 3 and 4 with offline writes is much more

complex…


Agenda

Data Caching and Data Sync Strategies

Implementing Data Caching and Synching Using A-

Team Mobile Persistence Extension


A-Team Mobile Persistence Extension

Sample code created by Oracle Fusion Middleware A-Team

Significantly speeds up implementation of data caching and data

synching

Provided “as-is”, no support, no updates

Installable as Free JDeveloper extension

Will be included in ADF Mobile later this year


Local and Remote Persistence

Extension runtime library contains generic Java code to perform CRUD

operations against SQLite database and against remote web services.

– Service objects extend EntiyCRUDService class

– Service objects use DBPersistenceManager for CRUD operations

against SQLite database

– Service object can use a remote persistence manager for CRUD

operations against web service

The generic code in EntiyCRUDService class and persistence

managers is driven by metadata stored in persistence mapping XML

file


Remote Persistence Managers

Classes that perform appropriate web service

calls based on the CRUD operation performed

by the user and the persistence mapping

information

Currently persistence managers are available

for REST web services in both JSON and XML

format, and SOAP (ADF BC) web services

You can easily create custom persistence

managers as needed

– Extend from abstract class that contains

convenience methods


ADF Model

Runtime Persistence Architecture

DepartmentService

Data Control

Department

DepartmentService EntityCRUDService extends

DBPersistence

Manager

Persistence

Mapping XML

DEPARTMENTS

table

SQLite

uses

JDBC

Statements

references

REST(JSON/XML)

REST-JSON

PersistenceManager

HTTP

Requests


Other Runtime Persistence Features

Encryption of database

Auto-cleaning of unused database segments

Lazy loading of child collections (a.k.a “Indirection”)

Entity caching to minimize object creation

FindEntityByKey

– Checks cache first, then database

Designed for customization

– Easy to override and extend default behavior


Mobile Persistence Extension - JDeveloper Wizards

Three wizard are provided to create the artefacts needed for this

runtime persistence architecture:

– Mobile Business Objects From Web Service Data Control Wizard

– Mobile Business Objects From REST Web Service Wizard

– Mobile Business Objects From Database Tables (Local persistence only)

Another wizard is provided to generate a default CRUD user interface

on top of the business layer created by one of the above wizards.


Rest Wizard Demo - Toplink Data Services http://192.168.1.112:7101/ToplinkRest/persistence/v1.0/Model1/query

/Department.findAll


Wizards for Creating Runtime Persistence Artefacts


Business Objects From REST Web Service


SOAP Demo – ADF BC SDO Services


Run SOAP Web Service Data Control Wizard


Mobile Business Objects from WS Data Control


Generated Data Object Classes


Generated Service Object Classes


Generated SQL DDL Script


Generated Persistence Mapping File


Generated Persistence Mapping File RESTful resource calls


Generated Persistence Mapping File SOAP method calls


Generated Config File


Configured InitDBLifecycleListener


Create Data Control For Service Classes


Creating the Mobile User Interface

Build Using Drag and Drop

from DataControl Palette

Generate Using ADF

Mobile User Interface

Generator Wizard

Two Options


Building the User Interface


Using the Mobile User Interface Generator


Generated User Interface Artefacts


1. Online Read/Write

• Needs to be continuously

connected

• Does not cache any data locally


• No risk of data theft if the device is

stolen

Data Caching Strategies

2. Cached Reads, Online Write


• Updates are via web service

calls


• Small risk of data theft

3. Cached Reads, Offline Writes



locally



• Greater risk of data theft

4. Full Synchronization

• All data is synchronized to the

device on startup


locally




A-Team Mobile Persistence Extension- Offline Writes and Data Syncing

If a remote persistence manager is configured, and CUD service call

fails, the service call is registered as “pending” data synch action

– Failure reason registered (device offline, service not available, etc)

On next service call, the pending synch actions are processed first in

order of creation

– When failing again, the still pending synch action is updated with date of

last synch attempt and last error message

Out-of-the-box feature: NO Java coding required


Viewing Pending Data Sync Actions

A reusable “DataSync” feature is provided that can be added to your

mobile application

Register the feature in adfmf-application.xml


Viewing Pending Data Sync Actions

Add a button that navigates to the data sync feature


Viewing Pending Data Synch Actions


Notes on Data Sync Functionality

Pending changes can become obsolete because of updates in server

data by other clients

– The server–side code should identify this and throw an error when the data

sync action sends stale data

– Stale data detection can be done by including a data revision number or

‘last-modified” timestamp in payload. This number or timestamp should

match with server-side data record

Data sync actions that keep failing need to be removed manually

– Local database might be out-of-sync, app needs to offer reconcile action


More Info

A-Team Chronicles: http://www.ateam-oracle.com/?p=22331

Includes download links to

– A-Team Mobile Persistence Extension - JDeveloper Install File

– A-Team Mobile Persistence Videos

– A-Team Mobile Persistence Demo applications

http://www.ateam-oracle.com/?p=22331




Summary

Using the A-Team Mobile Persistence Extension significantly speeds

up and eases implemention of data caching and syncing using the on-

device SQLite database

Using the A-Team Mobile Persistence Extension significantly speeds

up and eases the use of RESTful web services

You need to think about how your end users should handle failed data

sync actions, and how to prevent updates based on stale data

Essential parts of A-Team Mobile Persistence Extension will be

included in future version of core product


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partner webcast – oracle adf mobile - implementing data caching and syncing for working off line

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