copyright © 2002 sean c. sullivan xml case study: syncml sean c. sullivan at

Copyright © 2002 Sean C. Sullivan

XML case study: XML case study: SyncMLSyncML

Sean C. Sullivan

<sean> at <seansullivan> <.com>


Agenda

XML and SyncML Sync4j project Q & A


XML basics

“well-formed” documents DTD

– Document Type Definition “valid” documents


Simple XML document

<?xml version="1.0"?><!DOCTYPE Weather SYSTEM “weather.dtd”><Weather><Forecast><City>Portland, Oregon</City><Description>Rainy</Description><Temperature>47</Temperature></Forecast></Weather>


How are XML and SyncML related?

XML is a language for defining application-specific markup languages

SyncML is an XML-based markup language


Simple SyncML document<SyncML><SyncHdr><VerDTD>1.0</VerDTD><VerProto>SyncML/1.0</VerProto>…</SyncHdr><SyncBody><Add>…</Add></SyncBody></SyncML>


SyncML defined…“SyncML is a new industry initiative to develop and

promote a single, common data synchronization protocol that can be used industry-wide.” (syncml.org)

“SyncML is a specification for a common data synchronization framework and XML-based format […] for synchronizing data on networked devices.” (syncml.org)

“SyncML is a […] protocol for conveying data synchronization operations.” (syncml.org)


SyncML sponsors


What is data synchronization?

Data synchronization “is the process of making two sets of data look identical” (syncml.org whitepaper)


Data Synchronization

Resolve conflicts

Datastore1

Exchange data modifications

Datastore2

A CB C A BA CB


What is a “data synchronization protocol”?

Method of communication for a data synchronization session

Protocol includes:– naming and identification of records– common protocol commands– identification and resolution of

synchronization conflicts


SyncML features

Synchronize any type of data Multiple transport protocol bindings

– HTTP, WSP, OBEX Security Interoperability


SyncML: clients & servers

SyncMLserver

server modifications

client modifications


SyncML & XML

Abbreviated naming convention– Ex: ”protocol version” is <VerProto>

XML prolog is not required WBXML

– WAP Binary XML


SyncML documents

<SyncML> DTD Meta info DTD Device info DTD


<SyncML> document<?xml version="1.0"?><!DOCTYPE … ><SyncML><SyncHdr>…</SyncHdr><SyncBody><Add>…</Add></SyncBody></SyncML>

“A SyncML Message is a well-formed, but not necessarily valid, XML document.” (syncml.org)

Contains data synchronization commands (operations)


<SyncHdr> element<SyncHdr>

<VerDTD>1.0</VerDTD>

<VerProto>SyncML/1.0</VerProto>

<SessionID>session41</SessionID>

<MsgID>msg80386</MsgID>

…

</SyncHdr>


<SyncBody> element<SyncBody>

<Add>

<CmdID>cmd80486</CmdID>

…

<Item>…</Item>

</Add>

</SyncBody>


SyncML commands <Add> <Alert> <Atomic> <Copy> <Delete> <Exec> <Get> <Map>

<Put> <Replace> <Results> <Search> <Sequence> <Status> <Sync>


Meta Info document

Contains sync session parameters

<MetInf><Format>…</Format><Type>…</Type>…<MaxMsgSize>586</MaxMsgSize>…</MetInf>


Device Info document

Describes device capabilities

For both client and server

<DevInf>

…

<SwV>0.99</SwV>

<HwV>3.14</HwV>

…

<DevTyp>pda</DevTyp>

…

</DevInf>


Sync4j project

Java implementation of SyncML protocol

sync4j client & sync4j server open source http://sync4j.sourceforge.net/


XML parsing SAX

– “Simple API for XML” DOM

– document object model


Choosing an XML parser support for SAX 1.0? SAX 2.0? support for DOM? support for XML Namespaces? validating or non-validating parser? validation with DTD’s? validation with XML Schema?


XML parsers for Java Apache Xerces-J Apache Crimson Sun JAXP

– “Java API for XML Parsing” JDOM Also:

– DOM4J, Oracle XML Parser for Java, ElectricXML, kxml, …


sync4j key classes

Message DeviceInfo MetaInfo Command classes:

– AddCommand– DeleteCommand– ReplaceCommand


Sync4j Message example 1String strXML = “<SyncML> … </SyncML>”;Message msg;try{ msg = new Message(strXML);}catch (InvalidMarkupException ex){}catch (XMLSyntaxException ex){}


Sync4j Message example 2SyncHeader header = new SyncHeader(...);SyncBody body = new SyncBody(...);Message msg;msg = new Message(header, body);String strXML = msg.toXML();


XML data binding tools

Castor– http://www.castor.org/

Zeus– http://zeus.enhydra.org/

Sun JAXB– http://java.sun.com/xml/


Summary SyncML is an XML-based data

synchronization protocol Choose your XML parser carefully Consider using an XML data-binding

tool http://www.syncml.org/ http://sync4j.sourceforge.net/


XML case study: XML case study: SyncMLSyncML

Sean C. Sullivan

<sean> at <seansullivan> <.com>

copyright © 2002 sean c. sullivan xml case study: syncml sean c. sullivan at

Documents

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