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COMP268

ABAP and XML

Stefan Bresch, NW F ABAPThomas Ritter, NW F ABAP

Christoph Wedler, NW F ABAP

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SAP 2008 / SAP TechEd 08 / COMP268 Page 2

Disclaimer

This presentation outlines our general product direction and should not be

relied on in making a purchase decision. This presentation is not subject to

your license agreement or any other agreement with SAP. SAP has no

obligation to pursue any course of business outlined in this presentation or to

develop or release any functionality mentioned in this presentation. This

presentation and SAP's strategy and possible future developments are

subject to change and may be changed by SAP at any time for any reasonwithout notice. This document is provided without a warranty of any kind,

either express or implied, including but not limited to, the implied warranties

of merchantability, fitness for a particular purpose, or non-infringement. SAP

assumes no responsibility for errors or omissions in this document, except if

such damages were caused by SAP intentionally or grossly negligent.

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1. XML Overview

2. XML Processing in ABAP

3. ABAP XML Data Serialization

4. ABAP XML Mapping with ST and XSLT

5. Summary

Agenda

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XML from a Programmers Perspective

From a programmers perspective, XMLis ...

a generic data model(XML Infoset) for trees

ordered, structured nodes (elements)

unordered, unstructured nodes (attributes)

a generic syntax(markup) for representation of trees

the basis for an open set of standards and toolsparsing: texttree; rendering: treetext

typing, validating: XML Schema

querying, transforming: XPath, XSLT

a generic data structure conceptfor programming languages

primitive: DOM, SAX

data binding: JAXB

For all kinds of processing

except input/output, XMLdocuments should be thought

of in terms of the data model,

not in terms of their textual

representation. I.e., trees of

nodes, not sequences of tags.

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Transforming XML with XSLT

XSLT(extensible stylesheet language / transformations)is ...

a high level tree transformation language with XML syntax

declarative: no "state"

rule-based: pattern matching against source tree

functional: source navigation by XPathexpressions

compositional: result tree construction by XSLT instructionsmixed with literalXML

"the SQL of the web"

XSLT

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1. XML Overview




5. Summary

Agenda

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iXML Package

The iXML packages (since 4.6D): features

general XML parser/renderer

implemented in kernel (C++)

encapsulated in ABAP proxy classes (package SIXML)

interfaces IF_IXML_PARSER, IF_IXML_NODE, etc.

main factory class CL_IXMLDOM (Document Object Model)

superset of DOM level 1 (incl. XML namespaces)

DTD validation (since 6.10)

event-based parser (~SAX)

codepage support; implemenation based on UCS2/UCS4

examples program in package SIXML_TEST(examples shown here:T_PARSING_DOM, T_DOM_ITERATOR, T_PARSING_EVENT)

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iXML Package: XML Parser Example

Example: Create an iXML parser instance

create an input stream for the XML document xmlusing the stream factory

create a document and a parser for the document and input stream

DATA ixml TYPE REF TO if_ixml.DATA streamfactory TYPE REF TO if_ixml_stream_factory.DATA istream TYPE REF TO if_ixml_istream.

DATA document TYPE REF TO if_ixml_document.DATA parser TYPE REF TO if_ixml_parser.

ixml = cl_ixml=>create( ).streamfactory = ixml->create_stream_factory( ).istream = streamfactory->create_istream_xstring( string = xml).

document = ixml->create_document( ).parser = ixml->create_parser( document = documentstream_factory = stream_factoryistream = istream ).

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iXML Package: DOM Iterator

DATA iterator TYPE REF TO if_ixml_node_iterator.DATA node TYPE REF TO if_ixml_node.DATA name TYPE STRING.

parser->parse( ).node = document.iterator = node->create_iterator( ).node = iterator->get_next( ).WHILE node IS NOT INITIAL.

node = iterator->get_next( ).CASE node->get_type( ).WHEN if_ixml_node=>co_node_element.

name = node->get_name( )....

ENDCASE.node = iterator->get_next( ).

ENDWHILE.

Example: Iterate over the DOM

invoke the iXML parser and create an iterator

get the next node from the iterator in a loop until there is no more node

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iXML Package: Event Parser

DATA event TYPE REF TO if_ixml_event.DATA node TYPE REF TO if_ixml_node.DATA name TYPE STRING.

parser->set_event_subscription( if_ixml_event=>co_event_element_pre ).event = parser->parse_event( ).WHILE event IS NOT INITIAL.

node ?= event->get_node( ).CASE event->get_type( ).WHEN if_ixml_event=>co_event_element_pre.

name = node->get_name( )....

ENDCASE.event =parser->parse_event( ).

ENDWHILE.

Example: Listen to the event parser

subscribe to the events you are interested in

get the next event in a loop until there is no more event

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SXML Package

The SXML packages (since 7.0): features

streaming XML reader(parser) and writer(renderer)

implemented in kernel (C)

encapsulated in ABAP proxy classes

interfaces IF_SXML_READER, IF_SXML_WRITER, etc.

factories CL_SXML_STRING_READER, CL_SXML_STRING_WRITER, etc. token-based reader (pull principle)

additional high level interface (based on IF_SXML_NODEinterface)

codepage support; optimized for utf-8 (default codepage for XML)

optimized binary XML protocol (automatic detection in reader, writer can be

configured by factory method parameter TYPE = IF_SXML=>CO_XT_BINARY) streaming from/to dataset with CL_SXML_DATASET_READER,

CL_SXML_DATASET_WRITER(since 7.1)

reader and writer interoperable by reader method SKIP_NODE and writer methodWRITE_NODE

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SXML Package: XML Reader (token-based)

DATA reader TYPE REF TO if_sxml_reader.

DATA name TYPE STRING.

reader = cl_sxml_string_reader=>create( input = xml).

reader->next_node( ).

WHILE reader->node_type if_sxml_node=>co_nt_final.

CASE reader->node_type.

WHEN if_sxml_node=>co_nt_element_open.

name = reader->name....

ENDCASE.

reader->next_node( ).

ENDWHILE.

Example: Parse an XML document using the token-based interface

create a reader instance for the XML document xml loop until the final state is reached

the current node type, name and/or value are stored in the reader interface attributes

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SXML Package: XML Reader (node-based)

DATA reader TYPE REF TO if_sxml_reader.

DATA node TYPE REF TO if_sxml_node.

DATA open_element TYPE REF TO if_sxml_open_element.

DATA name TYPE STRING.

reader = cl_sxml_string_reader=>create( input = xml ).

node = reader->read_next_node( ).

WHILE node->type if_sxml_node=>co_nt_final.

CASE node->type.

WHEN if_sxml_node=>co_nt_element_open.open_element ?= node.

name = open_element->qname-name.

...

ENDCASE.

node = reader->read_next_node( ).

ENDWHILE.

Example: Parse an XML document using the node-based interface

create an reader instance for the XML document xml read next node until the final state is reached

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EXERCISE 1

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XSLT Processor

The SAP XSLT processor (since 6.10): features

performance, implemented in kernel (C++)

interoperable with iXML package

standard conformance (XSLT 1.0)

virtual machine: compilation to byte code, storage in database, and interpretation in

kernel integrated in ABAP language and ABAP Workbench

ABAP method call

XML result: (X)STRINGor tableor REF TO IF_IXML_OSTREAM

or

REF TO IF_IXML_DOCUMENT

XML source: (X)STRING or tableor REF TO IF_IXML_ISTREAMor REF TO IF_IXML_NODE

CALL TRANSFORMATION my_xsltPARAMETERS p1 = my1 ... pn = myn

SOURCE XML my_sourceRESULT XML my_result.

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1. XML Overview




5. Summary

Agenda

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ABAP XML Data Serialization

Serializing ABAP data to XML ...

... for XML-based communication

example: basXML

... for XML-based persistence

example: TREX

The canonical representation of ABAP data in XML is called asXML (ABAP

serialized XML)

ABAP data structure canonical representation /

asXML

serialization

de-serialization

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DEMO

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ABAP XML Data Serialization

The asXML representation is generated with the identity transformation ID.

CALL TRANSFORMATION ID

SOURCEp1= my_p1 ...pn= my_pn

RESULT XML xml.

Serialization: Type of ABAP sourcevariables determines generated asXML

representation.


SOURCE XML xml

RESULTp1= my_p1 ...pn= my_pn.

De-serialization: Type of ABAP result

variables determines required asXML

representation.

...

...

...

XML source: (X)STRING or tableor REF TO IF_SXML_READERor REF TO CL_FX_READER

XML result: (X)STRINGor tableor REF TO IF_SXML_WRITERor REF TO CL_FX_WRITER

uppercase!

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asXML: Values

DATA my_time type T.

my_time = '151659'.


SOURCE time= my_time

RESULT xml xml.

15:16:59

ABAP type/domain XML schema type Format/can. rep.

C,STRING xsd:string Hello

N xsd:string([0-9]+)

0123

I xsd:int -123

P xsd:decimal -1.23

F xsd:double -1.23E-2

D xsd:date* 2008-09-10

T xsd:time* 08:59:17

X,XSTRING xsd:base64Binary RWeJwq==

DECFLOAT16,DECFLOAT34

xsd:precisionDecimal

-1.2300

XSDBOOLEAN** xsd:boolean true,false

XSDLANGUAGE** xsd:language enXSDDATETIME_Z** xsd:dateTime 2008-09-10T08:59:17Z

XSDUUID_RAW**XSDUUID_CHAR**

001a4b50-534a-1ddc-95f8-7f56747c4990

XSDDATE_D** xsd:date 2008-09-10

XSDTIME_T** xsd:time 08:59:17

XSDANY** xsd:any ...mixed content ...*without consistency check, all content allowed ** since 7.0

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asXML: Structures

DATA my_time TYPE ty_time.

my_time-tzone = 'CET'.

my_time-time = '151659'.


SOURCE time= my-time

RESULT XML xml.

CET

15:16:59

TYPES: BEGIN OF ty_time,

tzoneTYPE c LENGTH 3,timeTYPE T,

END OF ty_time.

Component names determine XML

sub element names

All types are allowed in

components, including structures

and internal tables

Additional sub elements are

ignored in XML input, components

without a corresponding XMLelement keep their value

Components are serialized in the

order in which they are defined in

the structure. Order in input is

insignificant; components are

addressed by name.

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asXML: Tables

DATA my_times TYPE ty_times.

my_time-tzone = 'CET'. INSERT my_time INTO TABLE my_times.

my_time-tzone = 'PST'. INSERT my_time INTO TABLE my_times.


SOURCE times= my_times

RESULT XML xml.

CET15:16:59

PST15:16:59

TYPES ty_times TYPE STANDARD TABLE

OF ty_time WITH DEFAULT KEY.

In serialization, the table line name is itemor the ABAP dictionary type

name if defined there. In de-serilization, the table line name is irrelevant.

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asXML: References

References and Referenced Objects

Separate section for referenced objects (heap section) anonymous data objects (created with CREATE DATA)

instances of ABAP classes (created with CREATE OBJECT)

Objects on the heap section (heap objects) have an identity represented by the id

attribute

References to heap objects refer to this identity and are therefore represented by anhrefattribute

Heap objects provide type information for deserialization (potential polymorphism)

Objects (instances of ABAP classes)

ABAP class must implement the interface IF_SERIALIZABLE_OBJECT

All attributes (including private attributes) are serialized and grouped into class parts

to avoid naming conflicts

Customized serialization by providing the private methods SERIALIZE_HELPERand

DESERIALIZE_HELPER: For each class part, only the parameters of the respecting

method are serialized / de-serialized.

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asXML: Objects

DATA incl_info TYPE REF TO cl_abap_source_info.

CREATE OBJECT incl_info EXPORTING p_name = 'MY_INCLUDE' p_kind = 'I'.


SOURCE src_info= incl_info

RESULT XML xml.

MY_INCLUDE

I

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asXML: Anonymous Data Objects

DATA iref TYPE REF TO I.

DATA dref TYPE REF TO DATA.

CREATE DATAdref.

iref->* = 42.

dref = iref.

CALL TRANSFORMATION IDSOURCE i= iref d= dref

RESULT XML xml.

42

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EXERCISE 2

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1. XML Overview




5. Summary

Agenda

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ABAP XML Mapping

The structure mapping

problem.

Which side is driving?

Inside-out approach: XMLXML mapping

Outside-in approach:

generation of proxy

classes

Symmetric approach:

mapping engine

XSLT with asXML

Simple Transformations

external XML format

ABAP data structure

external application

ABAP application

XML-based communicationoutside

inside

Mapping Engine

... for XML-based communication with external applications

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ABAP XML Mapping with XSLT and the asXML

format (1)

external XML format

ABAP data structure

canonical DOM

inboundoutbound

external XML format

1. build canonicalDOM

2. transform DOM to

outbound XML

1. parse inbound

XML to DOM

ABAP data structure

2a. transform inbound

DOM to canonical DOM

2b. bind data

2. transform inbound

DOM to data

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DEMO

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ABAP XML Mapping with XSLT and the asXML

format (2)

15:16:59

Rule for writing XSLT transformations for ABAP XML Mapping: Treat the

ABAP values (on the source or result side) in the XSLT program as if theywere given in their canonical representation.

Example

(outbound):

XML:

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ABAP XML Mapping with XSLT: Weaknesses

Learning XSLT

overkill for trivial transformation task

no integrated tool support

Asymetric programs

one program for ABAP to XML, one for XML to ABAP

Processing model

source tree node can be accessed in a random order using XPath

result tree can only be produced in a strictly linear fashion (document order)

Resource consumptionDOM construction (the DOM consumes 10 times as much memory as the textual

XML)

(Superflous codepage conversions)

XSLT Engine overhead

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ABAP XML Mapping with ST: Key Features

Simple Transformation programs are XML templates

literal XMLwith interspersed instructions

declarative, straightforward semantics

Data tree access by node references

instructions access data by simple reference expression

named childs of a data node are accessible by name

ST programs are reversible

serialization: write tokens to an xml stream

deserialization: match/consume token from an xml stream

Virtual machine (VM) compilation to byte code and storage in database

interpretation of byte code in kernel (lean engine)

In ST programs (as

opposed to XSLT),

the XML source is

accessed in a strictly

linear fashion.

Si l T f ti E i P

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Simple Transformations: Expressive Power

Anything that can be done with ...

accessing each node in the data tree any number of times

accessing each node in the XML tree at most once, in document order (with

"lookahead 1" on XML source)

which includes (any combination of) ...

renamings(e.g.: structure-component / element names)

projections(omission of sub-trees)

permutations(changes in sub-tree order)

constants(e.g.: constant values, insertion of tree levels)

defaults(for initial / special values)

conditionals(e.g.: existence of sub-trees, value of nodes)

value maps

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DEMOD b I t t d XML B

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Debugger: Integrated XML Browser

ST D b

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ST Debugger

ST C t t T l t

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( )*

( )*

(

[ context declaration]

template content

)*

ST Constructs: Templates

Example:

ST C t t V l

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ST Constructs: Value

S: ABAP data (by ref-node-expression) to XML (apply asXML value conversion rules)

D: XML to ABAP data (by ref-node-expression) (apply asXML value conversion rules)

Example:

ST Constr cts Literal XML

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ST Constructs: Literal XML

S: write literal content

D: match literal content (if no match: CX_ST_MATCH exception)

template content

07:12:00

Example:

Short:

ST Constructs: Table Loop

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ST Constructs: Table Loop

S: Evaluate content for all lines of internal table

D: Evaluate content, insert lines into table until matching fails

template content

Example:

08:57:00

08:58:00

ST Constructs: Basic Conditional

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ST Constructs: Basic Conditional

S: [if check-clause and assertions are true:] evaluate template content

D: [if template content matches:] evaluate template content [establish assertions][evaluate check-clause]

template content

Example:

15:00:00

ST Constructs: Composite Conditional

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ST Constructs: Composite Conditional

S: evaluate first case with true data condition (case with no data condition: serialization default)

D: evaluate first case with matching pattern (case with no pattern content: deserialization default)

( template content )*

( template content )*

S: evaluate all cases with true data condition

D: evaluate all cases with matching pattern

ST Constructs: Modularization

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ST Constructs: Modularization

Apply template and pass roots and parameters(A sub-template without an explicit rootdeclaration has an implicit unnamed root bound to the current nodeat the point of invocation.)

( )*

( )*

( )*

( )*

Call main template in another ST program and pass roots and parameters

ST Constructs: Variables

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ST Constructs: Variables

Declare variable (part of the context declaration)

S: Write variable to XML

D: Read variable from XML

S: Assign ABAP data (by ref-node-expression) to variable

D: Assign variable or constant to ABAP data (by ref-node-expression)

type = C|STRING|D|T|F|I|N|P|X|XSTRING

ST Constructs: Skip and Copy

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ST Constructs: Skip and Copy

S: copy ABAP data (by ref-node-expression) to XML using asXML representation

D: copy XML (in asXML format) to ABAP data (by ref-node-expression)

D: match and skip [numberof] nodes [named element-name]

Example:

CET08:58:00

PST08:59:00

ST Constructs: ABAP call

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ST Constructs: ABAP call

( )*

Example:

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EXERCISE 3

Agenda

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1. XML Overview




5. Summary

Agenda

Summary: XML Transformations in ABAP

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Summary: XML Transformations in ABAP

XSLT (since release 6.20)

works on the canonical representation of ABAP data (asXML)

builds DOM for source side

arbitrary complex transformations

ST (since release 6.40)

only for ABAP to XML and XML to ABAP

only linear transformations

speedup of 10-30; unlimited size of data

reversible (one transformation for both directions)

ID (since release 6.20) fast, unlimited size of data

supports only asXML fromat; no external format

examples: basXML RFC, TREX, MemoryInspector

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Take advantage of the enhanced, expanded and multi tier certifications from SAP today!

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Further Information

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Further Information

SAP Professional JournalJul/Aug 2002: From XML to ABAP Data Structures and Back: Bridging the Gap with

XSLT

Nov/Dec 2002: Mastering the asXML Format to Leverage ABAP-XML Serialization

Jan/Feb 2005: Quickly and Easily Map Your ABAP and XML Data Using Simple

Transformations

SAP Public Web:

SAP Developer Network (SDN): www.sdn.sap.comForumsABAPDevelopement
http://www.sdn.sap.com/http://www.sdn.sap.com/

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Documents

sap teched

transforming xml

xml processing

xml overview2

comp268 page

abap xml mapping

abap xml data serialization4

general xml parserrenderer