DEV-15: XML in OpenEdge® Past, Present and Future Robin Brown Principal Software Engineer

DEV-15: XML in OpenEdge®Past, Present and Future

Robin BrownPrincipal Software Engineer

© 2006 Progress Software Corporation2DEV-15: XML in OpenEdge – Past, Present and Future

Why XML is Important

XML.Gov home page, http://xml.gov/index.asp

“Extensible Markup Language (XML) embodies the potential to alleviate many of the interoperability problems associated with the sharing of documents and data.”


Why XML?• Industry standard format for data exchange

Use Cases• Sending structured data over the Internet

– Back bone of Web Services/SOAP

• Sharing data with 3rd party applications– Crystal Reports

• Persistent storage between 4GL sessions– Context Management

Why XML is Important


OpenEdge Support for XML

1999 2000 2001 2002 2003 2004 2005 2006

We’re making XML easier to use

X-Document Load/Save

9.1A Sax-Reader

9.1D

Sax-Writer

10.1A

ProDataSet™ to/from XML

XML Schema ValidationWeb Services

Client

10.0A

Web Services Provider

SOA-12


Agenda

DOM and SAX Review SAX-WRITER Object XML Schema Validation ProDataSet and Temp-Table to/from XML What’s Next


XML – DOM vs. SAX

Document Object Model (DOM)• W3C standard

• DOM Tree in Memory

• Application logic - Tree traversal & tree building

Simple API for XML (SAX)• De facto standard

• Stream – forward only

• Application logic – Callbacks


DOM – X-Document:LOAD( )

(Element)Item ID=“1”

(Element)Music

(Text)Mozart’s Requiem

<?xml version=“1.0”?><Music> <Item ID="1">Mozart's Requiem</Item> <Item ID="2">Big Hits</Item></Music>

(Text)Big Hits

(Element)Item ID=“2”

CREATE X-DOCUMENT hDoc.hDoc:LOAD("file", “Music.xml", FALSE).


DOM – Parsing the Tree and Extracting

CREATE X-DOCUMENT hDoc.CREATE X-NODEREF hRoot.CREATE X-NODEREF hChild.CREATE X-NODEREF hText.

hDoc:LOAD("file", “Music.xml", FALSE).

hDoc:GET-DOCUMENT-ELEMENT(hRoot). /* <Music> */

REPEAT i = 1 TO hRoot:NUM-CHILDREN: hRoot:GET-CHILD(hChild, i). /* <Item> */

IF hChild:NUM-CHILDREN < 1 THEN NEXT.

cID = hChild:GET-ATTRIBUTE(“ID”).

hChild:GET-CHILD(hText, 1). /* Item Text */ CValue = hText:NODE-VALUE. END.

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DOM – Building the Tree and Saving

CREATE X-DOCUMENT hDoc.CREATE X-NODEREF hRoot.CREATE X-NODEREF hChild.CREATE X-NODEREF hText.

hDoc:CREATE-NODE(hRoot,"Music","ELEMENT").hDoc:APPEND-CHILD(hRoot).

hDoc:CREATE-NODE(hChild, "Item", "ELEMENT").hRoot:APPEND-CHILD(hChild).

hChild:SET-ATTRIBUTE("ID", "1").

hDoc:CREATE-NODE(hText, "", "TEXT").hChild:APPEND-CHILD(hText).hText:NODE-VALUE = "Mozart's Requiem".

hDoc:SAVE("file","Music2.xml").

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SAX-Reader:PARSE( )

<?xml version=“1.0”?><Music> <Item ID="1"> Mozart's Requiem </Item> </Music>

/* Handler.p */

PROC StartElement: END.

PROC Characters: END.

PROC EndElement: END.

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CREATE SAX-READER hSax.hSax:SET-INPUT-SOURCE("FILE",

"Music.xml").

RUN Handler.p Persistent SET h. hSax:HANDLER = h.

hSax:PARSE().


DOM vs. SAX

Advantages Disadvantages

DOM • All data always available

• In-place updates

• Memory Intensive

- Cannot handle large docs

SAX • Much less memory than DOM

• Can stop the parse early

• Can access data from a “bad” document (Partial Load)

• Forward Only

• Requires Context Management

- Callbacks / global variables


Agenda



SAX-Writer Functionality

Coding easier than DOM• Fewer objects

SAX-Writer object

CREATE SAX-WRITER

handle [IN WIDGET-POOL pool-name][NO‑ERROR].

Syntax

DEFINE VARIABLE hSAXWriter AS HANDLE NO-UNDO.CREATE SAX-WRITER hSAXWriter NO-ERROR.

Example


SAX-Writer Object

START-DOCUMENT START-ELEMENT SET-OUTPUT-DESTINATION WRITE-CHARACTERS DECLARE-NAMESPACE

END-DOCUMENT END-ELEMENT INSERT-ATTRIBUTE WRITE-DATA-ELEMENT

Methods (partial list)

ENCODING FRAGMENT STRICT WRITE-STATUS (Read-

Only)

FORMATTED STANDALONE VERSION

Attributes


SET-OUTPUT-DESTINATION ( )

handle:SET-OUTPUT-DESTINATION (mode,{file|stream|memptr|longchar}).

Defines the target for XML document

CREATE SAX-WRITER hSAXWriter.

ret = hSAXWriter:SET-OUTPUT-DESTINATION

(“FILE”,“C:\OpenEdge\WRK\swMusic.xml”).

Syntax

Example


Invoke Methods in Typical Order

CREATE SAX-WRITER SET-OUTPUT-DESTINATION START-DOCUMENT START-ELEMENT START-ELEMENT INSERT-ATTRIBUTE WRITE-DATA-ELEMENT

END-ELEMENT WRITE-CHARACTERS END-ELEMENT

END-DOCUMENT


SAX–WRITER Example

CREATE SAX-WRITER hSaxW.

hSaxW:SET-OUTPUT-DESTINATION("file", "swMusic.xml").

hSaxW:START-DOCUMENT().

hSaxW:START-ELEMENT("Music").

hSaxW:START-ELEMENT("Item").

hSaxW:INSERT-ATTRIBUTE("ID", "1").

hSaxW:WRITE-CHARACTERS("Mozart's Requiem").

hSaxW:END-ELEMENT("Item").

hSaxW:END-ELEMENT("Music").

hSaxW:END-DOCUMENT().

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/* STRICT = TRUE. */ START-DOCUMENT START-ELEMENT START-ELEMENT WRITE-DATA-ELEMENT

END-ELEMENT WRITE-CHARACTERSEND-DOCUMENT

STRICT Attribute

Forces XML to be well-formed

END-DOCUMENTFAILS!


Agenda



XML Schema Validation

Verify that data adheres to an agreed upon format

Validation occurs at runtime • X-Document Object

– LOAD( )

• Sax-Reader Object– PARSE( )– PARSE-FIRST( )– PARSE-NEXT( )


Schema Validation

Pre-10.1A - DTD• Document Type Definition• Older technology• XML Document MUST contain or specify DTD

10.1A - XSD• XML Schema Definition• Emerging standard (W3C)• XSD can be external to XML

Both DTD and XSD supported in 10.1A


New Method / Attributes

Method• ADD-SCHEMA-LOCATION

Attributes• SCHEMA-LOCATION

• NONAMESPACE-SCHEMA-LOCATION

Applies to X-Document and Sax-Reader objects


DOM Example

CREATE X-DOCUMENT hDoc.

hDoc:ADD-SCHEMA-LOCATION ("urn:music", "Music.xsd").

hDoc:LOAD("file", "Music.xml", TRUE /* validate */).


SAX Example

CREATE SAX-READER hSax.

hSax:SET-INPUT-SOURCE (“file”, “Music.xml”).

hSax:SCHEMA-LOCATION = “urn:music Music.xsd”.

hSax:VALIDATION-ENABLED = TRUE. /* validate */

hSax:PARSE( ).


Agenda



ProDataSet Functionality Continues to Mature

DataSet

ttOrder

ttOline

Query

hSource

defaultQuery

order query

oline query

Query Buffer

hSource

defaultQuery

Query Buffer

OpenEdge 10.1A simplifies and adds options for working with ProDataSets


New Methods Added

WRITE-XML WRITE-XMLSCHEMA READ-XML READ-XMLSCHEMA

Methods apply to• ProDataSet• Temp-Table• Temp-Table Buffer

.xsd.xsd

DataSet

ttOrder

ttOline

.xml.xml

ttItem


WRITE-XML (target-type,

{file | stream | memptr | handle | longchar}

[, formatted [, encoding

[, schema-location, [, write-schema

[, min-schema, write-before-image]]]]]])

WRITE-XML ( )

Syntax

DataSet

ttOrder

ttOline

.xml .xmlttItem

(*write-before-image for ProDataSets only)


TEMP-TABLE ttItem:WRITE-XML

("FILE", /*target-type*/

"ttItemXML.xml", /* file name */

TRUE, /* formatted */

?, /* encoding */

?, /* schema location */

?, /* write schema */

?). /* min XML Schema */

Temp-table Example

Format the output


Data ONLY - Temp-Table ttItem


ProDataSet Example – XML with Schema

DATASET dsOrder:WRITE-XML ("FILE",

"DSWriteXMLAndSchema.xml",


?, /* encoding */


TRUE, /* write schema */

TRUE, /* min XML Schema */

?). /* writebeforeimage */

Write XML Schema with the

data


ProDataSet Example – writeschema=TRUE

XML data

XML Schema


ProDataSet Example – writeschema=TRUE

XML data


ProDataSet Example – XML with Before-Tables

DATASET myds:WRITE-XML("FILE", /* target-type */

“custOrdBefore.xml", /*file*/


?, /* encoding */


?, /* write schema */

?, /* min XML schema */

TRUE)./* write beforeimage */

Write the Before Table data


ProDataSet – writebeforeImage = TRUE

Record marked as “created”

Record marked as “modified”

After table data


ProDataSet – writebeforeImage = TRUE

Before-image of modified record


.xsd

WRITE-XMLSCHEMA ( )

Write XML Schema Definition (XSD)

• For Temp-Tables contains – Table definition,

including indexes

• For ProDataSets contains– Table definitions,

including indexes– Data relation

definitions

DataSet

ttOrder

ttOlinettItem

.xsd


Using with Temp-Tables and ProDataSets

WRITE-XMLSCHEMA (target-type, {file |

stream | memptr | handle | longchar}

[, formatted [, encoding

[, min-xmlschema ]]])

min-xmlschema – • if TRUE only write standard XML Schema

structures• if FALSE, add XML Schema extensions from

‘prodata’ namespace– Allows round-trip of Progress definition

Syntax


Progress XML Schema Extensions

Standard XML Schema

Dataset DataSet / Table names

Table Table / Field names

Field Name

Data Type

Extent

Initial value

Index Unique Indexes

Relation Unique Data-Relations

XML Schema Extensions

None

Temp-Table UNDO status

Format

Label

Decimals

Case-sensitive

Read-only...

Non-unique Indexes

Non-Unique Data-Relations

+

MIN-SCHEMA = TRUE

MIN-SCHEMA = FALSE


TEMP-TABLE ttItem:WRITE-XMLSCHEMA

("FILE", /*target-type*/

"ttItem.xsd", /* file name */


?, /* encoding */

FALSE). /* min XML Schema */

Temp-table Example

Write XML Schema

Extensions


Progress XML Schema Extensions

non-unique index definition

field-level attributes

“prodata” namespace


XML Read Methods

READ-XML

READ-XMLSCHEMA .xsd

.xsdDataSet

ttOrder

ttOline

.xml

.xml

ttItem


READ-XML Method

READ-XML (source-type,

{file | memptr | handle | longchar}

, read-mode

, schema‑location

, override-default-mapping

[, field-type-mapping

[, verify-schema-mode ]])

Syntax

Populates ProDataSet or Temp-Table with:• XML data, XML Schema, or Both


Reads XML containing Before-Image information

–Progress “datasetChanges”

–Microsoft “Diffgram”

ProDataSet events DO NOT fire

Change tracking is turned OFF

Reading XML Into A ProDataSet

READ-XML( )


Using READ-XMLSCHEMA( )

Create a Progress definition from XML Schema

Verify XML Schema against Progress definition

READ-XMLSCHEMA (source-type,

{file | memptr | handle | longchar}

, override-default-mapping

[, field-type-mapping

[, verify-schema-mode ]])

Syntax


New XML Attributes

Attribute Applies to...

NAMESPACE-URI / NAMESPACE-PREFIX

ProDataSet, Temp-Table and Buffer

XML-NODE-TYPE Buffer-Field

XML-DATA-TYPE Buffer-Field

NESTED Data-Relation

Available on static definitions• DEFINE DATASET, TEMP-TABLE, BUFFER

Gives you Control over XML format


XML-NODE-TYPE = “Attribute”

BUFFER ttItem:BUFFER-FIELD(1):XML-NODE-TYPE = “Attribute”.


NESTED Attribute ProDataSet Data-Relation

Order Records NESTED within

Customer 1

DATASET CustOrder:GET-RELATION(“custOrd”):NESTED = TRUE.


ProDataSet and Temp-Table To/From XML

Easier than DOM and SAX • Productivity increase

Faster than DOM and SAX• Performance increase

Relational structure maps well to XML• XML data (.xml)

• XML Schema (.xsd)

The right features for the right job!


ProDataSet and Temp-Table To/From XML

Easier than SAX and DOM • Productivity increase

Faster than SAX and DOM• Performance increase

Relational structure maps well to XML• XML data (.xml)

• XML Schema (.xsd)

The right features for the right job!

DOM and SAX still have their

uses!


Demo


Agenda



D I S C L A I M E R

Under Development

This talk includes information about potential future products and/or product enhancements.

What I am going to say reflects our current thinking, but the information contained herein is preliminary and subject to change. Any future products we ultimately deliver may be materially different from what is described here.

D I S C L A I M E R


XML Futures

SAX-ATTRIBUTES XSLT XPath / XQuery Support for XML 1.1 / 2.0


In Summary

XML is Key Component in SOA Architectures

OpenEdge provides the ABL to work with XML

We’re continuing to make working with XML easier


For More Information...

Relevant Exchange Sessions• DEV-9: Using the ProDataSet in OpenEdge 10

• SOA-12: Integrate over the Web with OpenEdge Web Services

Other Resources• PSDN

• http://www.xml.com


Education / Documentation References

Course• XML Essentials • 4GL Development with XML• What's New in OpenEdge 10.1: SOA Support

Documentation• OpenEdge Development: Progress 4GL

Reference• OpenEdge Development: Programming

Interfaces


Questions?


Thank you foryour time


Documents

DEV-15: XML in OpenEdge® Past, Present and Future Robin Brown Principal Software Engineer