Eben Hewitt

1
XML-Based Technologies in SOAXML, Schema, SOAP,
WSDL, BPEL

• Eben Hewitt

2
Presentation Goals

• Provide a quick introduction to the WS
  technologies used to do SOA
• XML, Schema, SOAP, WSDL, BPEL, and ESB
• Give users and participants head-start
• Foundation for next presentation

3
Service-Oriented Review

• Platform agnostic
• Not procedural or OO
• Business Documents
• Loose coupling
• Law of Demeter

4
XML
5
XML Overview

• eXtensible Markup Language
• Describes data
• Invent your own tags

6
Problem with Non-XML Data

• What is this?
• 1998070420071110hih053280142187
• A purchase order?
• We can make good guesses

7
XML

• ltinvoicegt
• ltidgt19980704lt/idgt
• ltdategt20071110ltdategt
• ltstoregthih05lt/storegt
• ltterminalgt3lt/terminalgt
• ltprod-codegt28014lt/prod-codegt
• ltqtygt2ltqtygt
• lttotal-amtgt187lttotal-amtgt
• lt/invoicegt
• Self-describing
• Typed

8
Working with XML

• XML does nothing
• So you have to write software to process it
• But you can do so in any language
• Thats why XML is used in our SOA to represent
  business documents

9
Doing Stuff With XML

• Can store it as plain text in a
• Flat file
• SQL Database database as text or XML type
• Native XML database
• Can transmit it over
• HTTP or SOAP
• FTP

10
Common Uses

• Standard Enterprise Data
• Traverse the tree of nodes
• CRUD
• Transform it into another XML document
• new version
• vendor-specific
• Create new custom languages
• WML
• MathML

11
XML Document Requirements

• Declaration
• lt?xml version"1.0" encodingUTF-8"?gt
• Attributes must be quoted
• Must include closing tag
• XML is case-sensitive
• Proper nesting. OK
• ltbgtltigtIts bold and italiclt/igtlt/bgt

12
XML Constructs

• Elements lttaggtvaluelt/taggt
• Attributes lttag attributeNamevalue /gt
• Comments lt!-- my comment --gt
• Documents are Trees

13
Use Attributes Sparingly

• attributes cannot contain multiple values
• child elements can
• attributes are not easily expandable
• consider future changes
• attributes cannot describe structures
• child elements can

14
Well-Formed and Valid

• Well-Formed
• this XML document conforms to all syntax rules
• Valid
• this XML document is Valid AND conforms to a
  Schema

15
Parsing XML

• SAX is event-based parsing
• Every time a tag, attribute, text, comment,
  whitespace or other XML item is encountered, a
  call-back is fired.
• Then your code can do something if its
  interested in that event
• Must implement certain interfaces
• DOM creates in-memory tree
• Not as fast as SAX, but makes sense when
• You need random access to your document
• You need access to sibling elements
• Not appropriate for huge documents
• New StAX pull-parser
• Like SAX, but you ask for the events youre
  interested in.
• Very fast
• Unlike SAX, can write

16
XPath and XQuery

• XPath
• Navigate the elements and attributes in the tree
• /person/name/_at_title
• Not own file type, used within BPEL, Xquery, Java
  APIs
• Must know Xpath!
• XQuery
• To XML what SQL is to database tables
• Shares datatypes with Schema
• Advanced constructs
• FLOWR"For, Let, Order by, Where, Return
• Save in separate .xqy file
• Requires Implementation like Saxon-B

17
XML Schema
18
XML Schemas

• Describe the structure of XML documents!
• Written in XML themselves
• Support Reuse
• Do nothing on their own.
• Get a validating parser (later slide)

19
Schemas Also...

• Dictate data constraints
• Default values
• Fixed values (enums)
• Regular Expressions
• Order of elements
• Define datatypes
• Built-in
• Custom
• Support namespaces

20
Schema Example Store.xsd

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltschema xmlns"http//www.w3.org/2001/XMLSchema"
• xmlnsdte"http//schemas.dte.com/dte/general"
• targetNamespace"http//schemas.dte.com/dte/gener
  al"gt
• ltannotationgt
• ltdocumentation xmllang"engtA standard DTC
  Store.lt/documentationgt
• lt/annotationgt
• ltinclude schemaLocation"Address.xsd"/gt
• ltelement name"store" type"dteStore"/gt
• ltcomplexType name"Store"gt
• ltsequencegt
• ltelement name"storeCode"gt
• ltsimpleTypegt
• ltrestriction base"string"gt
• ltpattern value"A-Z3A-Z_\s
  \d2"/gt
• lt/restrictiongt
• lt/simpleTypegt
• lt/elementgt
• ltelement name"address"
  type"dteAddress"/gt

21
aStore.xml

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltdtestore xmlnsdte"http//schemas.dte.com/dte/g
  eneral"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-in
  stance"
• xsischemaLocation"http//schemas.dte.com/dte
  /general
• 
  home/ehewitt/schemas/dte/general/Store.xsd"gt
• ltstoreCodegtAZP 23lt/storeCodegt
• ltaddressgt
• ltstreetgt555 Some Streetlt/streetgt
• ltcitygtPhoenixlt/citygt
• ltstategtAZlt/stategt
• ltzipgt86001lt/zipgt
• lt/addressgt
• lt/dtestoregt
• Note that Store.xsd reuses Address.xsd

22
The Importance of Built-in DataTypes

• Programs or locales can use data differently.
• When is 07-11-2007?
• The XML built-in data type "date" requires the
  format "YYYY-MM-DD".
• ltdate type"date"gt2007-07-11lt/dategt
• Important datatypes include
• String and Token
• Date and Time, Duration
• Signed and Unsigned Decimal, Integer, byte, short
• Boolean
• Binary data in hex and base64

23
Using XML on iSeries

• Built-in SAX Parser built into COBOL
• XML Toolkit for iSeries
• contains DOM and SAX parsers
• XMLPR400 for ILE COBOL
• See www.mowyourlawn.com and www.web400.com for
  easier wrappers
• XML Parser QSYS/QXML4PR310
• See API spec in library/file/memberQSYSINC/QCBLLE
  SRC/QXML4PR310
• The linkage file to facilitate your COBOL
  application code is library/file/member
• QSYSINC/QCBLLESRC/QXML4PRLNK
• For the COBOL ILE compiler, use the CL command
  Create COBOL Module (CRTCBLMOD.
• Use one of the following commands, specifying the
  parser service program on the bind
• CRTPGM PGM(ltyour_librarygt/ltyour_programgt)
  MODULE(ltyour_librarygt/ltyour_modulesgt)
• BNDSRVPGM(QSYS/QXML4PR310)
• See http//publib.boulder.ibm.com/iseries/v5r1/ic2
  924/index.htm?info/rzakl/rzakltools.htm

24
Schema Conclusion

• Schemas are very flexible, but very complex
• There are entire books written on schemas
• Schemas describe the valid structure of XML
  documents, which includes
• SOAP documents
• WSDLs
• BPELs
• Our custom business objects
• We use Schemas to perform validation at runtime
• You must understand schemas!

25
SOAP
26
SOAP

• Simple Object Access Protocol
• Reuses HTTP
• Stateless
• Request-Response
• One way
• Or other bindings (SMTP, RMI, JMS)
• Transfer XML documents between disparate apps
• Requires SOAP implementation

27
SOAP Basic Unit The Envelope

• ltsoapenvelopegt
• Header
• directives
• meta-data
• Body
• required
• contains payload
• Attachments
• just like in email, usually for binary data
• Fault

28
SOAP Message

• ltsoapenvEnvelope xsischemaLocation"http//schem
  as.xmlsoap.org/soap/envelope/ http//schemas.xmlso
  ap.org/soap/envelope/"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
  ce"
• xmlnsxsd"http//www.w3.org/2001/XMLSchema"
• xmlnssoapenv"http//schemas.xmlsoap.org/soap/env
  elope/"
• xmlnsqs"http//ns.dte.com/dtc/quickscreen"gt
• ltsoapenvBodygt
• ltqscc1PreApproveApplicationgt
• ltpersongt
• ltnamegt
• ltfirstNamegtEbenlt/firstName
  gt
• ltmiddleInitialgtMlt/middleIn
  itialgt
• ltlastNamegtHewittlt/lastName
  gt
• lt/namegt
• ltusAddressgt
• ltstreetgt20225 N
  SCOTTSDALElt/streetgt
• ltstreet2gtSTE
  305lt/street2gt
• ltcitygtSCOTTSDALElt/citygt
• ltstategtAZlt/stategt
• ltpostalCodegt85255lt/postalC
  odegt

29
SOAP Faults

• ltenvEnvelope xmlnsenv"http//www.w3.org/2003/05
  /soap-envelope"
• xmlnsm"http//www.example.org/time
  outs"
• xmlnsxml"http//www.w3.org/XML/199
  8/namespace"gt
• ltenvBodygt
• ltenvFaultgt
• ltenvCodegt
• ltenvValuegtenvSenderlt/envValuegt
• ltenvSubcodegt
• ltenvValuegtmMessageTimeoutlt/envValuegt
• lt/envSubcodegt
• lt/envCodegt
• ltenvReasongt
• ltenvText xmllang"en"gtSender
  Timeoutlt/envTextgt
• lt/envReasongt
• ltenvDetailgt
• ltmMaxTimegtP5Mlt/mMaxTimegt
• lt/envDetailgt
• lt/envFaultgt
• lt/envBodygt

30
Using SOAP

• Requires a host language API
• Java using GlassFish, WebLogic
• On mainframes IBM has SupportPac for CICS
• On iSeries COBOL, use Java wrappers and WebSphere
• Next presentation...

31
WSDL 2.0
32
WSDL 2.0

• Stands for Web Services Description Language
• Written in XML
• WSDLs define the interface or contract of a Web
  Service
• ContractWhat must be done, not how it must be
  done.
• Because no implementation is given, the client
  and the service can be written in any language.
• (Client in Python, Service in .NET, Client in
  COBOL, Service in Java, etc)
• Like an interface or an abstract class
• Tells you only what the services API is

33
Using WSDL

• A client program connecting to a web service can
  read the WSDL to determine what functions are
  available on the server.
• Any custom datatypes used ("DTC Store") are
  embedded in the WSDL file in the form of XML
  Schema.
• The client can then use SOAP to invoke one of the
  functions listed in the WSDL.
• That process can be automated with tools.

34
WSDL Document Overview
35
WSDL Elements (3 of 5)

• lttypesgt
• Describes all data types used by the web service,
  defined as Schemas (default).
• When a WSDL file specifies a targetNamespace of
  'X', all the things defined within that WSDL file
  are considered defined under the namespace 'X'.
• Not necessary if you only use built-in data types
  (string, integer, boolean, etc)
• ltmessagegt
• Defines the SOAP messages exchanged in using this
  Web Service.
• Each is a one-way SOAP message, either a request
  or response.
• Child element is ltpartgt.
• ltportTypegt
• Defines the operations performed by the web
  service.
• Like a class with a collection of methods.
• Combines multiple ltmessagegt elements.

36
WSDL Elements cont.

• ltservicegt
• What is the actual address (URL) of the service?
• Points to a ltportTypegt.
• Nothing at that URL if you merely pull it up in a
  browser.
• You can specify multiple ltservicegt types for the
  same binding (ie, for a mirror).
• ltbindinggt
• How will the physical transportation of the
  messages occur? What protocol details do we need
  to know?
• transport"http//schemas.xmlsoap.org/soap/http"
  means "use SOAP over HTTP"

37
WSDL SOAP Binding

• ltbinding name"CustomerManagementPortBinding"
  type"tnsCustomerManagement"gt
• ltsoapbinding transport"http//schemas.xmlsoap.or
  g/soap/http" style"document" /gt
• ltoperation name"lookupCustomer"gt
• ltsoapoperation soapAction"" /gt
• ltinputgtltsoapbody use"literal" /gtlt/inputgt
• ltoutputgtltsoapbody use"literal" /gtlt/outputgt
• lt/operationgt
• lt/bindinggt
• How many namespaces are going on here?
• Why are some names NS-qualified?
• Is the output required?

38
WSDL RPC and Document

• RPC
• The SOAP request will include a wrapper XML
  element indicating the function name.
• The name of the element taken from the operation
  name attribute and the namespace taken from the
  operation namespace attribute.
• Document
• Request and response messages will consist simply
  of XML documents, which is flatter.
• Client should use pass-through documents defined
  with XML schemas rather than RPC calling
  conventions.
• The message is placed directly into the body
  portion of the SOAP envelope, either as-is or
  encoded.

39
Debate RPC vs Document Style

• Document Style
• Allows full use of XML, described in an open
  format that is human readable, self-describing,
  and self-validating.
• does not require a rigid contract
• RPC Style
• requires that the structure of the SOAP request
  body contain both the operation name and the set
  of method parameters.
• Use document style for
• asynchronous processing
• maintaining application state
• publishing services for outside partners
• easier validation and use of complex documents
• minimize in-memory processing (can choose
  DOM/SAX/StAX)
• We use document

40
Encoding Use Models Literal or Encoded

• Dictates how to translate a WSDL binding to a
  SOAP message
• Literal
• The body contents should conform to a
  user-defined XML Schema structure.
• Advantages
• you can validate the message body with the
  user-defined XML Schema
• you can transform the message using a
  transformation language like XSLT.
• Encoded
• The message has to use Schema datatypes, BUT the
  message structure need not conform to any
  user-defined XML schema.
• This makes it difficult to validate the message
  body or use XSLT based transformations on the
  message body.
• We use literal.

41
BPEL
42
BPEL 2.0 Overview

• Business Process Execution Language
• Standard that defines State Transitions
• Executable XML-based language for Business
  Process Modeling
• Requires a BPEL Engine to execute
• Allows "orchestration" of Web Services via WSDL
  ltportTypegts

43
Orchestration

• Individual Services are built to last a long
  time.
• Orchestrations composed of services are built for
  change.
• This is where you get agility.
• Just like WSDL defines the contract for a Web
  Service, BPEL defines the contract for service
  compositions.

44
Three BPEL Constructs

• Programming logic - BPEL
• Data types - XSD
• Input/Output (I/O) - WSDL
• The BPEL is responsible for invoking services as
  defined here

45
Using Compositions

• Four Individual Services
• CreateEmployee (HR)
• CreateAccount (Payroll)
• CreateEmailAccount
• ProvisionWorkstation
• One Service Composition
• NewHire
• CreateEmployee (HR)
• CreateAccount (Payroll)
• CreateEmailAccount
• ProvisionWorkstation

46
BPEL ltProcessgt
1.) Declare namespaces (reuse) ltprocess
xmlnsemesb"http//ns.dte.com/dtc/esb/email . .
. xmlnsemailws"http//ns.dte.com/dtc/ws/email"gt
ltimport namespace"http//ns.dte.com/dtc/general
" location"commonsvc/EmailService/Email.xs
d importType"http//www.w3.org/2001/XMLSchem
a"/gt 2.) Define inputs and outputs
(reuse) ltpartnerLinksgt ltpartnerLink
name"EmailPartner"
partnerLinkType"ns1EmailLinkType"
partnerRole"EmailRole"/gt ltpartnerLink
name"EmailEsb partnerLinkTypeemesbEmai
lPL" myRole"EmailEsbPortTypeRole"/gt lt/partnerLink
sgt Maps to a WSDL ltportTypegt 3.) Declare
variables (local and temporary) ltvariable
name"SendEmailIn" messageType"emailwssendEmail"
/gt Used to pass data to services and to BPEL
constructs 4.) Define the workflow using
ltsequencegt
47
Partner Links

• ltpartnerLinksgt
• ltpartnerLink name"EmailEsb
  partnerLinkTypeemesbEmailPL
• myRole"EmailEsbPortTypeRole"/gt
• ltpartnerLink name"EmailPartner
  partnerLinkType"ns1EmailLink"
• partnerRole"EmailRole"/gt
• lt/partnerLinksgt
• All services are Partners
• EmailEsb uses myRole because thats what the
  BPELs own clients invoke in the ESB
• EmailPartner uses partnerRole because that
  represents the invocation of the service
• The ESB is acting as the service

48
BPEL ltsequencegt

• ltsequencegt
• ltreceive name"ReceiveEmail" createInstance"yes"
  
• partnerLink"EmailEsb operation"EmailOperatio
  n
• portTypeemesbEmailPortType
• variable"EmailOpIn"/gt
• ltassign name"Assign1"gt
• ltcopygt
• ltfrom variable"EmailOpIn part"emailMsg"/gt
• ltto variable"SendMe" part"emailMsg/gt
• lt/copygt
• lt/assigngt
• ltinvoke name"InvokeEmailSendingService"
• partnerLink"EmailPartner"
• operation"sendEmail" portType"emailwsEmail"
  
• inputVariable"SendMe /gt
• lt/sequencegt

49
BPEL Design View
50
What Can You Do in BPEL?

• Invoke Services
• Variables
• Create local variables
• XML and WSDL typed variables
• Access with XPath
• Transform with XSLT
• Structured Programming Constructs
• If-then-elseif-else
• while, forEach
• Life Cycle
• sequences, processes
• repeatUntil
• Fault handlers
• Bindings for Given Protocol
• HTTP External support for SOAP over HTTP
• File Transport service to a file system
• FTP
• JMS

51
Next Presentation

• SOA III Working with Web Services Technologies
  in Java
• ESB JAX WS 2.0
• SOAP APIs including SAAJ, JAXB
• Ant tools
• GlassFish v2
• Common Dispatcher and client libraries
• ESB

52
Questions

• Thank you!