ADF Mobile: Implementing Data Caching and Synching

Implementing Data Caching Strategies for ADF Mobile

Copyright © 2013, Oracle and/or its affiliates. All rights reserved.1

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


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 ArchitectureDevice Native Container

Web

View

Server

HTML

ADF Mobile

AMX View

Third Party

Web Sites

Third Party

Web Sites

Oracle IDM

Oracle IAM

Oracle IDM

Oracle IAMLocal

HTML

HTML5 & JavaScript Presentation

Configuration

Server

Configuration

Server

ADF Controller

Credential Management,

SSO & Access Control



App

Config

App

Config


Device

Services

PhoneGap/

Cordova

Server or Cloud

backend

Server or Cloud

backend

Mobile

Device





Server

SOAP & REST

Web Services

SOAP & REST

Web Services

Java VM

Business

Logic

ADF Model

Encrypted

SQLite DB

JDBC

SQLite

ADF Mobile ArchitectureDevice Native Container

Web

View

Server

HTML

ADF Mobile

AMX View

Third Party

Web Sites

Third Party

Web Sites

Oracle IDM

Oracle IAM

Oracle IDM

Oracle IAMLocal

HTML

HTML5 & JavaScript Presentation

Configuration

Server

Configuration

Server

ADF Controller





App

Config

App

Config


Device

Services

PhoneGap/

Cordova

Server or Cloud

backend

Server or Cloud

backend

Mobile

Device





Server

SOAP & REST

Web Services

SOAP & REST

Web Services

Java VM

Business

Logic

ADF Model

Encrypted

SQLite DB

JDBC

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

Se

cu

rity


– 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

Se

cu

rity

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

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


Data Caching Strategies

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

Data Control

Data Object

JDBC code

Encrypted

SQLite DB


Data Control

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

call Start()

LifeCycleListenerImpl.java


Start()

1. Creates the DB

2. Creates Connection

3. Connects

4. Populates DB

Application starts up

Note:

Need to add LifeCycleListenerImpl.java to the LifeCycleEvent

Listener Field of the adfmf-application.xml file.

JDBC Example – Get Departmentspublic 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()) {


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


Java VM

ADF Model


Service

Object

Data Control

Data Object

JDBC code

Encrypted

SQLite DB

RestServiceAdapter


Data Control

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


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

Data Control

Data Object

JDBC code

Encrypted

SQLite DB

restServiceAdapter


Data Control

restServiceAdapter

REST(JSON/XML)

SOAP/REST-XML

SOAP/REST-XML Web Services

Data

Control

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 codeO

� Implementing strategies 3 and 4 with offline writes is much more

complexO

Agenda

� Data Caching and Data Sync Strategies




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


� 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


– 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


� 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

DepartmentServiceEntityCRUDServiceextends

DBPersistence

Manager

uses

REST-JSON

PersistenceManager


Persistence

Mapping XML

DEPARTMENTS

table

SQLite

JDBC

Statements

references

REST(JSON/XML)

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


� 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 - JDeveloperWizards

� 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 ServicesO/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 FileRESTful resource calls


Generated Persistence Mapping FileSOAP 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

Two Options


Mobile User Interface

Generator Wizard

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

2. Cached Reads, Online Write


• Updates are via web service

calls


• Small risk of data theft


Data Caching Strategies

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


– 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


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


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

ADF Mobile: Implementing Data Caching and Synching

Technology

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