1. CIS5930 Internet Computing
XML Web Services Basics
Prof. Robert van Engelen

2. Web Services Basics Interoperability has highest priority
XML over HTTP
Web services can be created regardless of the programming language
Reusable application components
Software can be reused as service components in a service-oriented architecture, i.e. to support the requirements of software users
Compositionality is realized with open standards
Connect existing software
Publish the application as a service
Applications connect and interact by encoding and decoding data in XML
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3. XML Web Services Protocols
SOAP
“Simple Object Access Protocol” is an XML messaging protocol
Typically remote procedure call (RPC) request-response messages
Or XML-based messages (document/literal style)
WSDL
“Web Service Description Language” is an XML document that defines the service interface, protocol bindings, and service endpoint addresses
Uses XML schema to define XML types
Typically uses SOAP to bind the messaging protocol
UDDI
“Universal Description, Discovery and Integration” is a repository/database of services (e.g. defined by WSDLs)
Not very popular, won’t discuss
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COP4020 Fall 2006

4. WSDL
WSDL represents a contract between the service requestor and the service provider
WSDL is an XML specification that defines four critical pieces of information of an XML Web service:
Interface information describing all publicly available functions
Data type information for all message requests and message responses
Binding information about the transport protocol to be used
Address information for locating the specified service
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5. WSDL Specification
The definitions root element defines the name and namespace of the web service
The types element contains a set of XML schemas with all the data types (XML elements and types) used between the client and server
One or more message elements define the names of the messages, each contains zero or more message part elements, which can refer to message parameters or message return values
The portType element combines multiple message elements to form a complete one-way or round-trip operation
The binding element describes how the service will be implemented on the wire
The service element defines the endpoint address for invoking the service
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6. Example WSDL
The HelloService service provides a single publicly available function sayHello
The function expects a single string parameter, and returns a single string greeting
Request-response message pattern over HTTP using HTTP POST
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7. WSDL definition Root Element
Defines the name and targetNamespace: <definitions name="HelloService” targetNamespace=" xmlns=" xmlns:soap=" xmlns:tns=" xmlns:xsd="
Typically the xmlns namespace bindings are included in the root element and are used in the remainder of the WSDL
Note that the WSDL namespace is declared as the default namespace for all of the other WSDL elements ( so these elements are not explicitly namespace qualified
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8. The WSDL message Elements
Two message elements are defined
The first represents a request message, SayHelloRequest, and the second represents a response message, SayHelloResponse: <message name="SayHelloRequest"> <part name="firstName" type="xsd:string"/> </message> <message name="SayHelloResponse"> <part name="greeting" type="xsd:string"/> </message>
For the request, the part specifies the function parameters
For the response, the part specifies the function return values
The type is a QName value, indicating the schema type of the part
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9. Built-in XSD SimpleTypes
Simple type Example Value(s)
string Web Services
boolean true, false, 1, 0
float -INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN
double -INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN
decimal , 0, 123.4,
integer , -1, 0, 1,
nonPositiveInteger , -1, 0
negativeInteger , -1
long -1,
int -1,
short -1, 12678
byte -1, 126
nonNegativeInteger 0, 1,
unsignedLong 0,
unsignedInt 0,
unsignedShort 0, 12678
unsignedByte 0, 126
positiveInteger 1,
date
time 13:20:00.000, 13:20: :00
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10. The WSDL portType Element
The portType element defines a single operation, sayHello
The operation consists of a single input message (SayHelloRequest) and a single output message (SayHelloResponse): <portType name="Hello_PortType"> <operation name="sayHello"> <input message="tns:SayHelloRequest"/> <output message="tns:SayHelloResponse"/> </operation> </portType>
The input/output elements specify a message attribute of tns:SayHelloRequest or tns:SayHelloResponse
The tns prefix references the targetNamespace defined within the definitions element
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11. Message Exchange Patterns
The operation in portType uses input and/or output to define the message exchange pattern
WSDL supports four basic patterns of operation
One-way
Request-response
Solicit-response
Notification
The one-way and request-response are most often used
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12. The WSDL binding Element
The binding element provides specific details on how a portType operation will actually be transmitted over the wire
Bindings can be made available via multiple transports
Multiple bindings for a single portType can be specified
The binding element itself specifies name and type attributes: <binding name="Hello_Binding" type="tns:Hello_PortType">
The type attribute references the portType
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13. WSDL SOAP Bindings
WSDL 1.1 includes built-in extensions for SOAP 1.1 <binding name="Hello_Binding" type="tns:Hello_PortType">
<soap:binding style="rpc" transport=" <operation name="sayHello"> <soap:operation soapAction="sayHello"/> <input> <soap:body encodingStyle=“ namespace="urn:examples:helloservice” use="encoded"/> </input> <output> <soap:body encodingStyle=“ namespace="urn:examples:helloservice” use="encoded"/> </output> </operation> </binding>
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14. WSDL SOAP Bindings (cont’d)
The soap:binding element indicates a SOAP binding over HTTP transport
The style attribute indicates rpc for an RPC format or document for a document-oriented message format
The transport attribute defines the transport mechanism
The soap:operation element indicates the binding of a specific operation to a SOAP implementation
The soapAction attribute specifies that the SOAPAction HTTP header should be used for identifying the service (SOAP 1.1 only)
The soap:body element specifies the details of the input and output messages
The encodingStyle attribute defines the encoding format when the use attribute is encoded (RPC encoded) and the namespace attribute defines the RPC message namespace
For document/literal messaging, the use attribute is literal
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15. SOAP Request Message
An RPC request message uses the encodingStyle and namespace: <?xml version='1.0' encoding='UTF-8'?> <soap:Envelope xmlns:xsi=' xmlns:xsd=' xmlns:soap=' xmlns:soapenc=' soap:encodingStyle=' <soap:Body> <n:sayHello xmlns:n='urn:examples:helloservice'> <firstName xsi:type='xsd:string'>World</firstName> </n:sayHello> </soap:Body> </soap:Envelope>
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16. SOAP Response Message
An RPC request message: <?xml version='1.0' encoding='UTF-8'?> <SOAP-ENV:Envelope xmlns:SOAP-ENV=' xmlns:xsi=' xmlns:xsd=' <SOAP-ENV:Body> <ns1:sayHelloResponse xmlns:ns1='urn:examples:helloservice' SOAP-ENV:encodingStyle= ' <greeting xsi:type='xsd:string'>Hello, World!</greeting> </ns1:sayHelloResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
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17. Using WSDL Most Web service development toolkits support WSDL
Generate WSDL from server (interface) code
Translate WSDL to server objects and client proxies
Dynamic invocation obtains the WSDL, select an operation, populate the parameters and send the request message
Generic SOAP client:
Find more WSDLs and code at
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18. Generating WSDL and Server Code with gSOAP
Suppose we implement a HelloService with one operation sayHello that takes a string parameter s and returns the string “Hello s”
To bind XML namespaces to C (and C++) code, gSOAP uses a prefix convention for function names and type names: prefix_ _name
The service interface is defined in a header file containing the line: int ns__sayHello(char *firstName, char **greeting);
To generate WSDL and server code (-S) or client code (-C) in C (-c) for SOAP RPC encoding (-e): $ soapcpp2 -S -c -e hello.h
input
output
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19. Implementing a Web Service with gSOAP
Add directives to the header file specification to define the service name, namespace, and endpoint: //gsoap ns service name: hello //gsoap ns service namespace: urn:hello //gsoap ns service location: int ns__sayHello(char *firstName, char **greeting);
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20. Implementing a Web Service with gSOAP (cont’d)
The following files are generated: soapStub.h annotated copy of the header file soapH.h XML serializer declarations soapC.c XML serializers for C/C++ types soapServer.c SOAP server skeleton and dispatcher hello.nsmap XML namespace mapping table hello.wsdl the service WSDL hello.sayHello.req.xml sample request message hello.sayHello.res.xml sample response message
To complete the service, we create a C implementation of the sayHello function with the following parameters: int ns__sayHello(struct soap *soap, char *firstName, char **greeting);
The first arg is the gSOAP engine context (runtime environment)
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21. Implementing a Web Service with gSOAP (cont’d)
Implementation of the sayHello function in hello.c: int ns__sayHello(struct soap *soap, char *firstName, char **greeting) { if (!firstName) return soap_sender_fault(soap, “No name!”, NULL); *greeting = (char*)soap_malloc(soap, strlen(firstName)+8); strcpy(*greeting, “Hello ”); strcat(*greeting, firstName); strcat(*greeting, “!”); return SOAP_OK; }
For a simple CGI-based service, add the service dispatcher: #include “hello.nsmap” int main() { return soap_serve(soap_new()); }
Compile with gcc -o hello.cgi hello.c stdsoap2.c soapC.c soapServer.c
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22. Implementing a Web Service with gSOAP (cont’d)
Deploy hello.cgi as a service in Apache (e.g. cgi-bin dir) and publish hello.wsdl on the Web site
To test the service over stdin/stdout, modify hello.sayHello.req.xml to include a name string and run hello.cgi from the command line: $ ./hello.cgi < hello.sayHello.req.xml
To deploy as an iterative stand-alone service, use the following: #include “hello.nsmap” int main() { struct soap *soap = soap_new(); soap_bind(soap, NULL, 8080, 100); for (;;) { if (soap_accept(soap) < 0) break; soap_serve(soap); soap_destroy(soap); soap_end(soap); } soap_print_fault(soap, stderr); soap_done(soap); free(soap); return 0; }
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23. Implementing a Concurrent Web Service with gSOAP
#include “hello.nsmap” int main() { pthread_t tid; struct soap *soap = soap_new(); soap_bind(soap, NULL, 8080, 100); for (;;) { if (soap_accept(soap) < 0) break; pthread_create(&tid,NULL,(void*(*)(void*))serve,(void*)soap_copy(soap)); } soap_print_fault(soap, stderr); soap_done(soap); free(soap); return 0; } void *serve(void *soap) { pthread_detach(pthread_self()); soap_serve((struct soap*)soap); soap_destroy((struct soap*)soap); soap_end((struct soap*)soap); soap_done((struct soap*)soap); free(soap); return NULL; } int ns__sayHello(struct soap *soap, char *firstName, char **greeting) { … }
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24. Implementing a Client with gSOAP
Since we already have a gSOAP header file with the service definitions, we can also create a client from it: $ soapcpp2 -C -c -e hello.h
The client uses the stub call defined in soapClient.c: #include “hello.nsmap” int main() { struct soap *soap = soap_new(); char *s; if (soap_call_ns__sayHello(soap, NULL, NULL, “Robert”, &s)) soap_print_fault(soap, stderr); else printf(“The response is %s\n”, s); soap_destroy(soap); soap_end(soap); soap_done(soap); free(soap); return 0; }
Compile with gcc -o client client.c stdsoap2.c soapC.c soapClient.c
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25. Implementing a Service with ASP.NET in VB
WebService Language="VB" Class="TempConvert" %> Imports System Imports System.Web.Services Public Class TempConvert :Inherits WebService <WebMethod()> Public Function FahrenheitToCelsius (ByVal Fahrenheit As Int16) As Int Dim celsius As Int celsius = ((((Fahrenheit) - 32) / 9) * 5) Return celsius End Function <WebMethod()> Public Function CelsiusToFahrenheit (ByVal Celsius As Int16) As Int Dim fahrenheit As Int fahrenheit = ((((Celsius) * 9) / 5) + 32) Return fahrenheit End Function End Class
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26. Implementing a Client with SOAP::Lite for Perl
Example in Perl using the SOAP::Lite package: use SOAP::Lite;   print "Connecting to Hello Service...\n"; print SOAP::Lite -> service(' -> sayHello ('World');
The program generates the following output: Connecting to Hello Service... Hello World!
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27. SOAP Fault messages
The gSOAP service may return a SOAP Fault: return soap_sender_fault(soap, “description”, detail);
If the problem is at the receiving side (SOAP-ENV:Server) use: return soap_receiver_fault(soap, “description”, detail);
Example SOAP Fault message: HTTP/ Internal Server Error Server: gSOAP/2.7 Content-Type: text/xml; charset=utf-8 Content-Length: 520 Connection: close <?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV=" xmlns:SOAP-ENC=" xmlns:xsi=" xmlns:xsd=" xmlns:ns="urn:hello"> <SOAP-ENV:Body SOAP-ENV:encodingStyle=" <SOAP-ENV:Fault> <faultcode>SOAP-ENV:Client</faultcode> <faultstring>No name!</faultstring> </SOAP-ENV:Fault> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
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28. SOAP 1.1 Faults The SOAP Fault element has the following sub elements:
<faultcode> A code for identifying the fault
<faultstring> A human readable explanation of the fault
<faultactor> Information about who caused the fault to happen (opt)
<detail> Holds application specific error information
The faultcode values defined below must be used in the faultcode element when describing faults:
VersionMismatch: Invalid namespace for the SOAP Envelope element
MustUnderstand: An immediate child element of the Header element, with the mustUnderstand attribute set to "1", was not understood
Client: Message was incorrectly formed or contained incorrect info
Server: There was a problem with the server and processing could not proceed
Note: SOAP 1.2 differs slightly (mostly element naming)
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29. WSDL and SOAP Faults
Faults in portType operations specify which faults may be returned: <message name="AuthenticationFault"> <part name="AuthenticationFault” element=”f:AuthenticationFault"/> </message> <portType name=“myPort”> <operation name=“getStatus”> <input message=“tns:getStatusRequest”/> <output message=“tns:getStatusResponse”/> <fault name=“fault” message=“tns:AthenticiationFault”/> </operation> </portType> <binding name=“myBinding” type=“myPort”> <operation name="getStatus"> <wsdl:input> <soap:body use="literal"/> </wsdl:input> <wsdl:output> <soap:body use="literal"/> </wsdl:output> <wsdl:fault name="AuthenticationFault"> <soap:fault name="AuthenticationFault" use="literal"/> </wsdl:fault> </operation> </binding>
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30. SOAP Headers
The optional SOAP Header element contains SOAP processing information in one or more subelements, such as addressing and authentication, for example: <SOAP-ENV:Envelope …> <SOAP-ENV:Header> <wsse:Security SOAP-ENV:mustUnderstand="1"> <wsse:UsernameToken wsu:Id="User"> <wsse:Username>engelen</wsse:Username> <wsse:Password Type=" <wsse:Nonce>NDU0MGE5YjljYTUzYzAzZjA2MTc=</wsse:Nonce> <wsu:Created> T12:27:37Z</wsu:Created> </wsse:UsernameToken> </wsse:Security> </SOAP-ENV:Header> <SOAP-ENV:Body> … </SOAP-ENV:Body> </SOAP-ENV:Envelope>
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31. SOAP Headers (cont’d)
The optional actor attribute may be used to address the Header element to a particular endpoint: <SOAP-ENV:Header> <m:Transaction SOAP-ENV:actor=”endpoint URL” SOAP-ENV:mustUnderstand=“1”> … </m:Transaction> <wsse:Security>…</wsse:Security> </SOAP-ENV:Header>
This allows the header information to be targeted at any intermediate SOAP processors for which this information is intended
The SOAP mustUnderstand attribute is used to indicate whether a header entry is mandatory or optional for the recipient to process
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32. SOAP Headers (cont’d)
The SOAP Header is a struct in gSOAP, defined in the header file: #import “wsse.h” // get WSSE Security elements struct SOAP_ENV__Header { mustUnderstand _m__Transaction *m__Transaction; mustUnderstand _wsse__Security *wsse__Security; }; and accessible in the soap context, for example: soap.header.m__Transaction = new _m__Transaction();
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33. SOAP RPC Encoding
SOAP RPC encoding defines rules on representing primitive types, xs:simpleTypes (e.g. enumerations), array, and records (structs) as xs:complexTypes in XML
Closer to the notion of programming language types
Full XML schema support is not possible
XML attributes not supported
No element repetitions with maxOccurs=“unbounded”
Only xs:sequence and xs:all, no xs:choice
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34. SOAP RPC Encoding (cont’d)
Primitive types
Built-in XSD types, such as xs:string (see Schema specification)
Schema xs:simpleTypes for elements, such as enumerations <xs:simpleType name=”switch"> <xs:restriction base="xsd:token"> <xs:enumeration value=”on"/> <xs:enumeration value=”off"/> </xs:restriction> </xs:simpleType>
Base64 (xs:base64Binary) and hex (xs:hexBinary) types
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35. SOAP RPC Encoding (cont’d)
Arrays are “SOAP encoded” arrays: <xs:complexType name="ArrayOfstring"> <xs:complexContent> <xs:restriction base="SOAP-ENC:Array"> <xs:sequence> <xs:element name="item" type="xsd:string” minOccurs="0" maxOccurs="unbounded”/> </xs:sequence> <xs:attribute ref="SOAP-ENC:arrayType” wsdl:arrayType="xsd:string[]"/> </xs:restriction> </xs:complexContent> </xs:complexType>
Arrays are encoded in SOAP messages follows: <inputStringArray SOAP-ENC:arrayType="xsd:string[2]"> <item xsi:type=“xsd:string”>hello</item> <item xsi:type=“xsd:string”>world!</item> </inputStringArray>
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36. SOAP RPC Encoding (cont’d)
Struct are just xs:complexTypes with xs:sequence (or xs:all): <xs:complexType name=”lightSwitch"> <xs:sequence> <xs:element name=“light” type=“tns:switch”/> <xs:element name=“level” type=“xs:int”/> <xs:element name=“image” type=“xs:base64Binary”/> </xs:sequence> </xs:complexType>
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37. RPC versus Doc/lit in WSDL
Document/literal SOAP messages don’t include encodingStyle and XML types for request/responses are not constraint by the SOAP RPC encoding rules
Document style and literal use are declared in the bindings: <binding type="glossaryTerms" name="b1"> <soap:binding style="document” transport=" <operation> <soap:operation soapAction=" <input> <soap:body use="literal"/> </input> <output> <soap:body use="literal"/> </output> </operation> </binding>
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38. RPC versus Doc/lit in WSDL (cont’d)
The parts in messages now refer to elements, which will be the request/response elements in the SOAP Body <definitions xmlns:m=“urn:examples:tempservice” …> <message name="getTermRequest"> <part name="term" element=”m:getTemp"/> </message> <message name="getTermResponse"> <part name="value" element=”m:getTempResult"/> </message> <portType name="glossaryTerms"> <operation name="getTerm"> <input message="getTermRequest"/> <output message="getTermResponse"/> </operation> </portType>
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39. RPC versus Doc/lit in WSDL (cont’d)
The parts in messages refer to elements that define the request and response elements in the SOAP Body of a message: <types> <xs:schema xmlns:xs=“ targetNamespace=“urn:examples:tempservice” … elementFormDefault=“qualified” attributeFormDefault=“unqualified”> <xs:element name=“getTemp”> <xs:complexType> <xs:sequence> <xs:element name=“zipCode” type=“xs:string”/> </xs:sequence> </xs:complexType> </xs:element> <xs:element name=“getTempResult”> <xs:complexType> <xs:sequence> <xs:element name=“temp” type=“xs:float”/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> </types>
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40. SOAP Request Message in Doc/Lit Style
Note the absence of SOAP-ENC:encodingStyle and xsi:type in the message: <?xml version='1.0' encoding='UTF-8'?> <soap:Envelope xmlns:xsi=' xmlns:xsd=' xmlns:soap=' <soap:Body> <n:getTemp xmlns:n='urn:examples:tempservice'> <n:zipCode>32306</n:zipCode> </n:getTemp> </soap:Body> </soap:Envelope>
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41. SOAP Multi-ref Encoding
SOAP operation (request/response)
The XSD type system to represent values of primitive types in XML, such as bool, integer, float, string, base64
A SOAP array type to encode sparse and partial arrays
Id-href XML attributes to implement graph edges to encode multi-ref objects
<env:Envelope> <env:Body env:encodingStyle=“…”> <ns:myRemoteOp> <arg1 xsi:type=“xsd:int”>123</arg1> <arg2 enc:arrayType=“xsd:string[5]”> <item>abc</item> <item href=“#_1”/> <item href=“#_1”/> <item href=“#_2”/> <item enc:position=“[5]”>xyz</item> </arg2> </ns:myRemoteOp> <mref id=“_1”>abc</mref> <mref id=“_2”>def</mref> </env:Body> </env:Envelope>
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42. Static Structure Analysis for SOAP RPC Encoding
XML Schema
<complexType name=“X”> <sequence> <element name=“y” type=“tns:Y”/> <element name=“z” type=“tns:Z”/> </sequence> … </complexType>
<complexType name=“X”> <sequence>…</sequence> </complexType> <complexType name=“Y”> <sequence>…</sequence> </complexType
<complexType name=“X”> <sequence>…</sequence> </complexType
Example XML Instance
<x> <y>…</y> <z>…</z> … </x>
<x> <y href=“#123”/> … <y href=“#123”/> … </x> … <mref id=“123”>…</mref>
<x> <x href=“#456”/> … <x href=“#456”/> … </x> … <mref id=“456”>…</mref> X Y Z X Y X
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43. gSOAP Constructs a Plausible Object Model for Serialization
typedef int SSN; struct Node { int val; int *ptr; float num; struct Node *next; };
val
ptr
num
next
Node
SSN
Source code type definitions
Data model graph (arcs denote all possible pointer references)
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44. Generating an XML Schema Definition for Serialized XML
<simpleType name=“SSN”> <restriction base=“int”/> </simpleType> <complexType name=“Node”> <sequence> <element name=“val” type=“int”/> <element name=“ptr” type=“int” minOccurs=“0”/> <element name=“num” type=“float”/> <element name=“next” type=“tns:Node” minOccurs=“0”/> </sequence> </complexType>
val
ptr
num
next
Node
SSN
Data model graph
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45. Generating Code for Runtime Points-To Analysis
serialize_pointerToint(int *p)
{ if (p != NULL) { // lookup and mark (p,TYPE_int) // as target in ptr hash table
} } serialize_Node(struct Node *p) { if (p != NULL) { // lookup and mark (p,TYPE_Node) // as target in ptr hash table mark_embedded(&p->val,TYPE_int); serialize_pointerToint(p->ptr); // skip p->num serialize_pointerToNode(p->next); } }
val
ptr
num
next
Node
SSN
Data model graph
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46. Generating Serialization Code
put_pointerToint(int *p)
{ if (p != NULL) { // lookup (p,TYPE_int) // if embedded, then output “ref” // if single, then output value // if multi, then output value // with “id” and mark embedded
} } put_Node(struct Node *p) { if (p != NULL) { // lookup (p,TYPE_Node) // if embedded, then output “ref” // if single, then output value // if multi, then output value // with “id” and mark embedded
put_int(&p->val); put_pointerToint(p->ptr); put_float(&p->num) put_pointerToNode(p->next); } }
val
ptr
num
next
Node
SSN
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47. Serialization Example
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
Node loc=A
Node loc=B
=789
Ptr hash table after runtime points-to analysis by the generated algorithm constructed from the data model
SSN loc=C ID
PtrLoc
PtrType
PtrSize
PtrCount
RefType 1 A
Node 16 2
multi B
int 4
embedded 3
single C
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48. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
SSN loc=C
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49. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> </Node>
SSN loc=C
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50. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> </Node>
SSN loc=C
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51. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> </Node>
SSN loc=C
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52. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> </Node>
SSN loc=C
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53. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> </next> </Node>
SSN loc=C
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54. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> </next>
</Node>
SSN loc=C
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55. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> </next> </Node>
SSN loc=C
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56. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> </next> </Node>
SSN loc=C
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57. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> <next ref=“#_1”/> </next> </Node>
SSN loc=C
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58. Serialization Example (cont’d)
multi, id=1
single
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
multi, id=1
Node loc=A
Node loc=B
single
embedded, id=2
=789
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> <next ref=“#_1”/> </next> </Node>
SSN loc=C
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59. Deserialization Example
<Node id=“_1”> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =?
ptr =?
num =?
next =?
id=1
Node
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60. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =?
num =?
next =?
id=1
Node
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61. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =?
num =?
next =?
id=1
Node
ref=2 (unresolved)
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62. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =?
num =1.4
next =?
id=1
Node
ref=2 (unresolved)
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63. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =?
num =1.4
next =B
val =?
ptr =?
num =?
next =?
id=1
Node
Node
ref=2 (unresolved)
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64. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =B
num =1.4
next =B
val =456
ptr =?
num =?
next =?
id=1
Node
id=2
Node
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65. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =?
next =?
id=1
Node
id=2
Node
=789
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66. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =?
id=1
Node
id=2
Node
=789
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SSN

67. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> <next ref=“#_1”/> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
id=1
Node
Node
=789
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SSN

68. Deserialization Example (cont’d)
<Node id=“_1”> <val>123</val> <ptr ref=“#_2”/> <num>1.4</num> <next> <val id=“_2”>456</val> <ptr>789</ptr> <num>2.3</num> <next ref=“#_1”/> </next> </Node>
Recursive descent parsing with object deserialization operations as semantic actions
val =123
ptr =B
num =1.4
next =B
val =456
ptr =C
num =2.3
next =A
id=1
Node
Node
=789
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SSN

69. Converting a WSDL to Code with gSOAP
The wsdl2h tool converts a (set of) WSDL files and schemas to a header file
The header file is then processed by soapcpp2 as before
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70. WS-* Protocols and Plugins
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71. SOAP With MTOM Attachments
Raw binary data can be transported in a SOAP message as base64
MTOM (Message Transmission Optimization Mechanism) using MIME attachments to carry binary data with a SOAP message
Supports embedding of type and other information
Allows streaming (attachments produced on demand)
Example HTTP header for SOAP with MTOM: POST / HTTP/1.1 Host: Content-Type: multipart/related; boundary=”mimeboundary"; type="application/xop+xml"; start="<soapmsg>"; start-info="application/soap+xml; charset=utf-8"
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72. SOAP With MTOM Attachments (cont’d)
Example HTTP body with SOAP message and MTOM attachment: --mimeboundary Content-Type: application/xop+xml;charset=utf-8;type=application/soap+xml Content-Transfer-Encoding: binary Content-ID: <soapmsg> <SOAP-ENV:Envelope xmlns:SOAP-ENV=”…” xmlns:xop=" xmlns:xmlmime=" <SOAP-ENV:Body> <m:PutImage xmlns:m=" <m:data xmlmime:contentType=”image/jpeg"> <xop:Include href="cid:image"/> </m:data> </m:PutImage> </SOAP-ENV:Body> </SOAP-ENV:Envelope> --mimeboundary Content-Type: image/jpeg Content-Transfer-Encoding: binary Content-ID: <image> … image data … --mimeboundary--
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73. WS-Addressing
WS-Addressing is a Web services protocol for routing messages (request, response, and faults)
Supports message transmission through networks with processing nodes such as endpoint managers, firewalls, and gateways <S:Envelope xmlns:S=" xmlns:wsa=" <S:Header> <wsa:MessageID> uuid:6B29FC40-CA B31D-00DD010662DA </wsa:MessageID> <wsa:ReplyTo> <wsa:Address> </wsa:ReplyTo> <wsa:To> <wsa:Action> </S:Header> <S:Body> </S:Body> </S:Envelope>
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74. WS-Addressing (cont’d)
WS-Addressing header elements within the SOAP Header:
<wsa:MessageID> xs:anyURI </wsa:MessageID> defines a unique message ID, e.g. UUID (optional)
<wsa:RelatesTo RelationshipType="..."?> xs:anyURI </wsa:RelatesTo> conveys the message ID of the related message, e.g. the request message ID when this is a reply message (required for responses)
<wsa:To> xs:anyURI </wsa:To> the destination address (required)
<wsa:Action> xs:anyURI </wsa:Action> conveys the SOAP action property (required)
<wsa:From> endpoint-reference </wsa:From> the source endpoint information (optional)
<wsa:ReplyTo> endpoint-reference </wsa:ReplyTo> the reply endpoint (required for request with an expected reply)
<wsa:FaultTo> endpoint-reference </wsa:FaultTo> the fault endpoint (optional)
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75. WS-Security WS-Security provides message-level security Authentication
HTTPS provides end-to-end transport-level security
Authentication
Username and (digest) password (with nonce, timestamps)
Digital signatures
XML DSig with DSA, HMAC, …
Can sign all or specific parts of the message
Embedding of security tokens such as certificates
Support for SAML
Encryption
XML Enc with RSA, …
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76. Username Token
The Username token security header in wsse:Security contains a username and password in plain text or a digest password: <SOAP-ENV:Envelope xmlns:SOAP-ENV=“…” xmlns:wsse=“…” xmlns:wsu=“…”> <SOAP-ENV:Header> <wsse:Security SOAP-ENV:mustUnderstand="1"> <wsse:UsernameToken wsu:Id="User"> <wsse:Username>engelen</wsse:Username> <wsse:Password Type=" <wsse:Nonce>NDU0MGE5YjljYTUzYzAzZjA2MTc=</wsse:Nonce> <wsu:Created> T12:27:37Z</wsu:Created> </wsse:UsernameToken> </wsse:Security> </SOAP-ENV:Header> <SOAP-ENV:Body> … </SOAP-ENV:Body> </SOAP-ENV:Envelope>
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77. Security Timestamps
A timestamp can be included to define the lifetime of a message
The timestamp will only be tamper proof when digitally signed, hence the wsu:Id which is referenced by the signature info <SOAP-ENV:Envelope …> <SOAP-ENV:Header> <wsse:Security> <wsu:Timestamp wsu:Id="timestamp"> <wsu:Created> T08:42:00Z</wsu:Created> <wsu:Expires> T09:00:00Z</wsu:Expires> </wsu:Timestamp> </wsse:Security> </SOAP-ENV:Header> <SOAP-ENV:Body> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
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78. Signatures The wsse:BinarySecurityToken contains the public key
The ds:Signature element contains signature info with digest value for each signed message part and the signature value <wsse:Security> <wsse:BinarySecurityToken wsu:Id=“X509Token” …> public key </wsse:BinarySecurityToken> <ds:Signature> <ds:SignedInfo> what is signed: reference URI to signed part with digest of that XML message part how it is signed: digests algorithms and canonicalization of XML </ds:SignedInfo> <ds:SignatureValue> signature </ds:SignatureValue> <ds:KeyInfo> <wsse:SecurityTokenReference> <wsse:Reference URI="#X509Token"/> </wsse:SecurityTokenReference> </ds:KeyInfo> </ds:Signature> </wsse:Security>
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79. Signature Example
<wsse:Security> <wsse:BinarySecurityToken …> … </wsse:BinarySecurityToken> <ds:Signature> <ds:SignedInfo> <ds:CanonicalizationMethod Algorithm=" <ds:SignatureMethod Algorithm=" <ds:Reference URI="#myBody"> <ds:Transforms> <ds:Transform Algorithm=" </ds:Transforms> <ds:DigestMethod Algorithm=" <ds:DigestValue>EULddytSo1...</ds:DigestValue> </ds:Reference> </ds:SignedInfo> <ds:SignatureValue>BL8jdfToEb1l/vXcMZNNjPOV...</ds:SignatureValue> <ds:KeyInfo> <wsse:SecurityTokenReference> <wsse:Reference URI="#X509Token"/> </wsse:SecurityTokenReference> </ds:KeyInfo> </ds:Signature> </wsse:Security>
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80. List of WS-* Protocols Messaging Service description SOAP
SOAP with Attachments (SwA)
SOAP with MTOM (Message Transmission Optimization Mechanism)
XML-RPC: a simpler XML RPC format (no WSDL or schemas)
WS-Addressing: routing, endpoints, and addressing properties
Service description
WSDL
WS-MetadataExchange: how an endpoint can request the various types of metadata it may need to effectively communicate with the service
WS-Policy: describes the capabilities, requirements, and general characteristics of a service
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81. List of WS-* Protocols Directory access and discovery
UDDI (Universal Description, Discovery, and Integration) v2/v3
WS-Discovery: a multicast discovery protocol to locate services on a network
Managing services
WS-Management: for management of servers, devices, applications
Transaction-based services
WS-Transaction: describes the coordination types atomic transaction (TA) and business activity (BA)
Publish/subscribe
WS-Eventing
WS-Notification
Security and reliability
HTTPS (transport-level)
WS-Security (message-level)
WS-ReliableMessaging
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82. Other Notable WS-* Protocols
Managing resources: Web Services Resource Framework (WSRF)
WS-ResourceProperties: defines are resource’s properties
WS-ResourceLifetime: inspect and monitor the lifetime of a resource
WS-ServiceGroup: defines how resources are grouped together for a domain specific purpose (service classification and constraints)
WS-BaseFaults: defines faults related to resource management
Managing resources
WS-Transfer: operations for sending and receiving the representation of a given resource and operations for creating and deleting a resource
Best practices
Provide additional information to improve interoperability between vendor implementations
WS-I Basic profile (BP1.0a, BP1.1)
WS-I Basic security profile
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83. Other Notable WS-* Protocols
Device Profile for Web Services (DPWS)
Goals similar to universal plug and play (UPnP)
Seamless integration and discovery of devices over the Internet
Printing, scanning, etc. over Internet by discovering these services
Uploading images from camera to PC over the (wireless) Internet
Microsoft Vista natively integrates DPWS
Builds on
WS-Eventing (publish/subscribe)
WS-Discovery
WS-Addressing
WS-Security
WS-Policy
WS-MetaExchange
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84. To be continued…
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