Web Services: SOAP

1
Web Services SOAP
2
SOAP

• SOAP ir standarts Web servisu sazinošanas
  protokols
• Originali SOAP nozimeja
• Simple Object Access Protocol
• velak ari
• Service Oriented Architecture Protocol
• bet sakot ar versiju 1.2 tas ir vienkarši SOAP

3
Vesture un versijas

• SOAP 1998. gada izstradaja Dave Winer, Don Box,
  Bob Atkinson un Mohsen Al-Ghosein
• SOAP 1.1 W3C ierosinajums 2000.gada maija
• J2EE 1.4 standarts
• SOAP 1.2 W3C rekomendacija sakot ar
  2003.gada juniju
• Java EE 5 standarts

4
Kas ir SOAP?

• SOAP is a communication protocol
• SOAP is for communication between applications
• SOAP is a format for sending messages
• SOAP is designed to communicate via Internet
• SOAP is platform independent
• SOAP is language independent
• SOAP is based on XML
• SOAP is simple and extensible
• SOAP allows you to get around firewalls
• SOAP is developed as a W3C standard

5
Kas SOAP nav?

• SOAP nav komponentu modelis
• Tas neaizvietos objektus un komponentus, piemeram
  EJB, JavaBeans
• SOAP nav programmešanas valoda
• Tas neaizvietos Java valodu
• SOAP nav risinajums visiem uzdevumiem
• Tas neaizvietos citas dalitas apstrades
  tehnologijas, tadas ka, piemeram, RMI

6
Kapec SOAP?

• Izstradajot lietojumprogrammas ir svarigi dot
  iespeju programmam sazinaties pa Internetu
• Viens sazinašanas veids ir RPC (Remote Procedure
  Call), bet HTTP nav isti piemerots šim variantam
• SOAP bija izveidots, lai nodrošinat iespeju
  sazinaties pa HTTP (kaut gan var tikt izmantots
  ari cits protokols, piemeram SMTP)

7
SOAP over HTTP, SMTP, and Raw TCP/IP
A SOAP XML document instance, which is called a
SOAP message, is usually carried as the payload
of some other network protocol
8
One-Way versus Request/Response

• Web services can use
• One-Way messaging or
• Request/Response messaging

9
Ko SOAP define?

• Message Envelope
• Encoding Rules
• RPC Convention
• Binding with underlying protocols

10
SOAP Message

• SOAP message is made of
• SOAP Envelope (in XML)
• Zero or more attachments
• Zero or more "underlying protocol" header fields
• SOAP Envelope is composed of
• SOAP body
• Main content of the message
• Zero or more SOAP header blocks
• Metadata
• Data aimed at intermediaries
• Can also contain application data for ultimate
  receiver

11
SOAP Message Format
12
SOAP in HTTP Request
Sender
Receiver
13
SOAP Message Structure

• A SOAP message is analogous to an envelope used
  in traditional postal service
• A SOAP message is a kind of XML document
• SOAP has its own XML schema, namespaces, and
  processing rules

lt?xml version"1.0" encoding"UTF-8"?gt ltsoapEnvel
ope xmlnssoap"http//schemas.xmlsoap.org/soap/en
velope/"gt ltsoapHeadergt lt!-- Header blocks
go here --gt lt/soapHeadergt ltsoapBodygt
lt!-- Application data goes here --gt
lt/soapBodygt lt/soapEnvelopegt
14
SOAP Message Structure

• A SOAP message may have a single Body element
  preceded, optionally, by one Header element
• The Envelope element cannot contain any other
  children!
• The Header element contains information about the
  message
• security credentials
• transaction IDs
• routing instructions
• debugging information
• payment tokens

15
Example SOAP Header

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltsoapEnvelope
• xmlnssoap"http//schemas.xmlsoap.org/soap/env
  elope/"
• xmlnsmi"http//www.Monson-Haefel.com/message-
  id"gt
• ltsoapHeadergt
• ltmimessage-idgt
• 11d1def534eab1c5faf3bfb4dcd7-8000
• lt/mimessage-idgt
• lt/soapHeadergt
• ltsoapBodygt
• lt!-- Application-specific data goes here --gt
  lt/soapBodygt
• lt/soapEnvelopegt

16
SOAP Namespaces

• XML namespaces play an important role in SOAP
  messages
• Examples of namespace prefixes

Prefix Namespace
soap "http//schemas.xmlsoap.org/soap/envelope/"
xsi "http//www.w3.org/2001/XMLSchema-instance"
xsd "http//www.w3.org/2001/XMLSchema"
soapenc "http//schemas.xmlsoap.org/soap/encoding/"
wsdl "http//schemas.xmlsoap.org/wsdl/"
soapbind "http//schemas.xmlsoap.org/wsdl/soap/"
wsi "http//ws-i.org/schemas/conformanceClaim/"
17
Example SOAP Namespaces

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltsoapEnvelope
• xmlnssoap"http//schemas.xmlsoap.org/soap/envel
  ope/"
• xmlnssec"http//schemas.xmlsoap.org/soap/securi
  ty/2000-12"
• xmlnsds"http//www.w3.org/2000/09/xmldsig"
• xmlnsmi"http//www.Monson-Haefel.com/jwsbook/me
  ssage-id"gt
• ltsoapHeadergt
• ltmimessage-idgt11d1def534eab1c5faf3bfb4dcd7
  -8000lt/mimessage-idgt
• ltsecSignaturegt ... lt/secSignaturegt
• lt/soapHeadergt
• ltsoapBody secid"Body"gt
• ltpopurchaseOrder orderDate"2003-09-22"
• xmlnspo"http//www.Monson-Haefel.com/jwsboo
  k/PO"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-i
  nstance"gt
• ...
• lt/popurchaseOrdergt
• lt/soapBodygt
• lt/soapEnvelopegt

18
SOAP Message Path

• Initial sender creates message
• Ultimate receiver executes main operation
• Intermediaries perform additional processing

19
SOAP Nodes

• The applications along the message path are also
  called SOAP nodes
• Example
• security node authenticates users and verifies
  message integrity
• SOAP message Header blocks are intended to be
  processed in general by intermediary nodes

20
Roles and Targeting

• Header blocks are targeted to node via "role"
  attribute (URI)
• Role is either address of a node or role name
• E.g. this security intermediary (address)
• E.g. any security intermediary (role name)
• Example
• ltnsmyHeaderBlock role"/logging" /gt
• The Body is always targeted to ultimate receiver

21
Roles and Targeting

• SOAP defines three special roles
• none
• next
• ultimateReceiver
• The "mustUnderstand" attribute
• If set to true, the node must know how to
  process the header
• If a node doesn't understand a mandatory header
  block, it must generate a SOAP fault

22
Example Headers with Roles
lt?xml version'1.0' ?gt ltenvEnvelope
xmlnsenv"http//www.w3.org/2003/05/soap-envelope
"gt ltenvHeadergt ltmreservation
xmlnsm"" envrole "http//www.w3.org/200
3/05/soap-envelope/role/next" envmustUnderstand
"true"gt ltmreferencegtuuid093a2da1-q345-73
9r-ba5d-pqff98fe8j7d lt/mreferencegt
ltmdateAndTimegt2001-11-29T132000.000-0500lt/mda
teAndTimegt lt/mreservationgt
ltnpassenger xmlnsn" envrole" http//ww
w.w3.org/2003/05/soap-envelope/role/next"
envmustUnderstand"true"gt ltnnamegtÅke Jógvan
Øyvindlt/nnamegt lt/npassengergt
lt/envHeadergt
23
Intermediary Node Algorithm

• Receive message
• Determine roles played
• Verify all mandatory blocks targeted to node are
  understood
• Process appropriate header blocks
• Processing possibly produces a fault
• Remove processed headers
• Add new headers if necessary
• Forward message to next node

24
Ultimate Receiver Algorithm

• Receive message
• Process appropriate header blocks
• Processing possibly produces a fault
• Process all body blocks
• Processing possibly produces a fault

25
SOAP Messaging Modes

• SOAP supports four modes of messaging
• RPC/Literal
• Document/Literal
• RPC/Encoded
• Document/Encoded
• However, RPC/Encoded and Document/Encoded modes
  are explicitly prohibited

26
Document/Literal Mode

• In the Document/Literal mode of messaging, a SOAP
  Body element contains an XML document fragment
• A well-formed XML element that contains arbitrary
  application data (text and other elements) that
  belongs to some XML schema and namespace

27
Example Document/Literal Body

• ltsoapBodygt
• ltpopurchaseOrder orderDate"2003-09-22"
• xmlnspohttp//www.Monson-Haefel.com/jwsbook/P
  O"gt
• ltpoaccountNamegtAmazon.comlt/poaccountNamegt
• ltpoaccountNumbergt923lt/poaccountNumbergt
• ...
• ltpobookgt
• ltpotitlegtJ2EE Web Serviceslt/potitlegt
• ltpoquantitygt300lt/poquantitygt
• ltpowholesale-pricegt24.99lt/powholesale-pri
  cegt
• lt/pobookgt
• lt/popurchaseOrdergt
• lt/soapBodygt

28
RPC/Literal Mode

• The RPC/Literal mode of messaging enables SOAP
  messages to model calls to procedures or method
  calls with parameters and return values
• The contents of the Body are always formatted as
  a struct
• In many cases is used to expose traditional
  components (servlet, EJB, RMI) as Web services

29
Example RPC/Literal

• public interface BookQuote extends
  java.rmi.Remote
• public float getBookPrice(String ISBN)
• throws RemoteException, InvalidISBNException

ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
org/soap/envelope/" xmlnsmh"http//www.Monson-H
aefel.com/jwsbook/BookQuote"gt ltsoapBodygt
ltmhgetBookPricegtltisbngt0321146182lt/isbngtlt/mhgetB
ookPricegt lt/soapBodygt lt/soapEnvelopegt
ltsoapEnvelope xmlnssoap"http//schemas.xmlsoap.
org/soap/envelope/" xmlnsmh"http//www.Monson-H
aefel.com/jwsbook/BookQuote" gt ltsoapBodygt
ltmhgetBookPriceResponsegtltresultgt24.99lt/resultgt
lt/mhgetBookPriceResponsegt
lt/soapBodygt lt/soapEnvelopegt
30
SOAP Faults

• SOAP fault messages are the mechanism by which
  SOAP applications report errors to nodes earlier
  in the message path
• SOAP faults are returned to the receiver's
  immediate sender only
• Fault element information items
• faultcode
• Client, Server, VersionMismatch, MustUnderstand
• faultstring
• faultactor
• detail

31
Example SOAP Fault

• ltsoapFaultgt
• ltfaultcodegtsoapClientlt/faultcodegt
• ltfaultstringgt
• The ISBN value contains invalid characters
• lt/faultstringgt
• ltfaultactorgthttp//www.xyzcorp.comlt/faultactorgt
  
• ltdetailgt
• ltmhInvalidIsbnFaultDetailgt
• ltoffending-valuegt19318224-Dlt/offending-value
  gt
• ltconformance-rulesgt
• The first nine characters must be
  digits. The last
• character may be a digit or the letter
  'X'. Case is
• not important.
• lt/conformance-rulesgt
• lt/mhInvalidIsbnFaultDetailgt
• lt/detailgt
• lt/soapFaultgt

32
SOAP over HTTP

• SOAP messages sent over HTTP are placed in the
  payload of an HTTP request or response

POST /jwsbook/BookQuote HTTP/1.1 Host
www.Monson-Haefel.com Content-Type text/xml
charset"utf-8" Content-Length
295 SOAPAction"" lt?xml version"1.0"
encoding"UTF-8"?gt ltsoapEnvelope
xmlnssoap"http//schemas.xmlsoap.org/soap/envelo
pe/" xmlnsmh"http//www.Monson-Haefel.com/jwsbo
ok/BookQuote"gt ltsoapBodygt
ltmhgetBookPricegt ltisbngt0321146182lt/isbn
gt lt/mhgetBookPricegt lt/soapBodygt lt/soap
Envelopegt
33
References

• SOAP Tutorial (W3C Schools) http//www.w3schools.c
  om/soap/default.asp
• SOAP-1.2 Primer http//www.w3.org/TR/soap12-p
  art0/
• SOAP Version 1.2 W3C Specification
  http//www.w3.org/TR/soap12-part1/
• Book J2EE Web Services by Richard
  Monson-Haefel
• http//www.amazon.ca/J2EE-Web-Services-Richard-Mo
  nson-Haefel/dp/0321146182