1. Slides for Chapter 19 Web Services
From Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design
Edition 4, © Addison-Wesley 2005

2. Figure 19.1 Web services infrastructure and components
Applications
Directory service
Security
Choreography
Web Services
Service descriptions (in WSDL)
SOAP
URIs (URLs or URNs)
XML
HTTP, SMTP or other transport
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

3. Figure 19.2 The ‘travel agent service’ combines other web services
flight booking a
flight booking b
Travel Agent
Client
Service
hire car booking a
hire car booking b
hotel booking a
hotel booking b
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

4. Figure 19.3 SOAP message in an envelope
header
header element
header element
body
body element
body element
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

5. Figure 19.4 Example of a simple request without headers
env:envelope
xmlns:env =namespace URI for SOAP envelopes
env:body
m:exchange
xmlns:m = namespace URI of the service description
m:arg1
m:arg2
Hello
World
In this figure and the next, each XML element is represented by a shaded box with its name in italic followed by any attributes and its content
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

6. Figure 19.5 Example of a reply corresponding to the request in Figure 19.4
env:envelope
xmlns:env = namespace URI for SOAP envelope
env:body
m:exchangeResponse
xmlns:m = namespace URI for the service description
m:res1
m:res2
World
Hello
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

7. POST /examples/stringer endpoint address HTTP header
Figure 19.6 Use of HTTP POST Request in SOAP client-server communication
POST /examples/stringer
endpoint address
HTTP header
Host:
Content-Type: application/soap+xml
Action:
action
<env:envelope xmlns:env=
namespace URI for SOAP envelope
>
<env:header> </env:header>
Soap message
<env:body> </env:body>
</env:Envelope>
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

8. Figure 19.7 Java web service interface ShapeList
import java.rmi.*;
public interface ShapeList extends Remote {
int newShape(GraphicalObject g) throws RemoteException;
int numberOfShapes()throws RemoteException;
int getVersion() throws RemoteException;
int getGOVersion(int i)throws RemoteException;
GraphicalObject getAllState(int i) throws RemoteException; }
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

9. Figure 19.8 Java implementation of the ShapeList server
import java.util.Vector;
public class ShapeListImpl implements ShapeList {
private Vector theList = new Vector();
private int version = 0;
private Vector theVersions = new Vector();
public int newShape(GraphicalObject g) throws RemoteException{
version++;
theList.addElement(g);
theVersions.addElement(new Integer(version));
return theList.size(); }
public int numberOfShapes(){}
public int getVersion() {}
public int getGOVersion(int i){ }
public GraphicalObject getAllState(int i) {}
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

10. Figure 19.9 Java implementation of the ShapeList client
package staticstub;
import javax.xml.rpc.Stub;
public class ShapeListClient {
public static void main(String[] args) { /* pass URL of service */
try {
Stub proxy = createProxy();
proxy._setProperty
(javax.xml.rpc.Stub.ENDPOINT_ADDRESS_PROPERTY, args[0]);
ShapeList aShapeList = (ShapeList)proxy;
GraphicalObject g = aShapeList.getAllState(0);
} catch (Exception ex) { ex.printStackTrace(); } }
private static Stub createProxy() {
return
(Stub) (new MyShapeListService_Impl().getShapeListPort());
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

11. Figure 19.10 The main elements in a WSDL description
definitions
interface
bindings
services
types
message
target namespace
document style
request-reply style
how
where
abstract
concrete
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

12. Figure 19.11 WSDL request and reply messages for the newShape operation
name =
"
ShapeList_newShape
"
message
name =
"
ShapeList_newShapeResponse
"
part
name
="GraphicalObject_1"
part
name=
"
result
"
type =
"
ns:GraphicalObject
"
type =
"
xsd:int
"
tns ﾐ target namespace
xsd ﾐ XML schema definitions
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

13. Figure 19.12 Message exchange patterns for WSDL operations
Name
Messages sent by
Client
Server
Delivery
Fault message
Request
Reply
may replace
Reply
In-Out
Request
no fault message
In-Only
Request
guaranteed
Robust In-Only
may be sent
Reply
Request
Out-In
may replace
Reply
Out-Only
Request
no fault message
Robust Out-Only
Request
guaranteed
may send fault
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

14. Figure 19.13 WSDL operation newShape
name =
"
newShape
"
pattern = In-Out
input
message =
"
tns:ShapeList_newShape
"
output
message =
"tns:ShapeList_newShapeResponse"
tns – target namespace
xsd – XML schema definitions
The names
operation
, pattern,
input
and
output
are defined in the XML schema for WSDL
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

15. Figure 19.14 SOAP binding and service definitions
name =
"
ShapeListBinding
"
name =
"
MyShapeListService
"
type =
"
tns:ShapeList
"
soap:binding
transport = URI
endpoint
for schemas for soap/http
style=
rpc
name =
"
ShapeListPort
"
"
"
binding =
"
tns:ShapeListBinding
"
operation
name=
"
newShape
"
soap:address
input
location = service URI
soap:body
encoding, namespace
output
soap:body
encoding, namespace
the service URI is:
soap:operation
soapAction “
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

16. Figure 19.15 The main UDDI data structures
businessEntity
businessServices
human readable
businessServices
information
businessServices
bindingTemplate
about the publisher
human readable
bindingTemplate
information
URL
bindingTemplate
about a
tModel
information
family of services
about the
tModel
URL
service interfaces
service interfaces
tModel
key
URL
service descriptions
key
key
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

17. Figure 19.16 Algorithms required for XML signature
Type of algorithm
Name of algorithm
Required
reference
Message digest
SHA-1
Section 7.4.3
Encoding
base64
[Freed and Borenstein 1996]
Signature
DSA with SHA-1
[NIST 1994]
(asymmetric)
RSA with SHA-1
Recommended
Section 7.3.2
MAC signature
(symmetric)
HMAC-SHA-1
Section and Krawczyk
et al.
[1997]
Canonicalization
Canonical XML
Page 810 
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

18. Figure 19.17 Algorithms required for encryption(the algorithms in Figure 19.16 are also required)
Type of algorithm
Name of algorithm
Required
reference
Block cipher
TRIPLEDES,
AES 128
required
Section 7.3.1
AES-256
AES-192
optional
Encoding
base64
required
[Freed and Borenstein 1996]
Key transport
RSA-v1.5,
RSA-OAEP
required
Section 7.3.2
[Kaliski and Staddon 1998]
Symmetric key
TRIPLEDES
required
[Housley 2002]
wrap (signature
KeyWrap,
by shared key)
AES-128 KeyWrap,
AES 256KeyWrap
AES-192 KeyWrap
optional
Key agreement
Diffie-Hellman
optional
[Rescorla, 1999]
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

19. Figure 19.18 Travel agent scenario
1. The client asks the travel agent service for information about a set of services; for example, flights, car hire and hotel bookings.
2. The travel agent service collects prices and availability information and sends it to the client, which chooses one of the following on behalf of the user:
(a) refine the query, possibly involving more providers to get more information, then repeat step 2;
(b) make reservations;
(c) quit.
3. The client requests a reservation and the travel agent service checks availability.
4. Either all are available;
or for services that are not available;
either alternatives are offered to the client who goes back to step 3;
or the client goes back to step 1.
5. Take deposit.
6. Give the client a reservation number as a confirmation.
7. During the period until the final payment, the client may modify or cancel reservations
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

20. Figure 19.19 Open grid services architecture
Application specfic grid services
application specific
e.g. astronomy, biomedical informatics, high-energy physics
interfaces
OGSA
services: directory, management, security
standard
grid service interfaces
OGSI
services: naming, service data (metadata)
service creation and deletion, fault model, service groups
e.g.
GridService
Factory
web services
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005

21. Figure 19.20 A selection of the grid projects presented in Foster & Kesselman[2004]
Description of the project
Reference
1. Aircraft engine maintenance using fault histories and
sensors for predictive diagnostics
2. Telepresence for predicting the effects of
earthquakes on buildings, using simulations and test sites
3. Bio-medical informatics network providing
nbcr.sdsc.edu
researchers with access to experiments and visualizations of results
4. Analysis of data from the CMS high energy particle
detector at CERN by physicists world-wide over 15 years
5. Testing the effects of candidate drug molecules for
[Taufer et al. 2003]
their effect on the activity of a protein, by performing parallel
[Chien 2004
computations using idle desktop computers
6. Use of the Sun Grid Engine to enhance aerial
photographs by using spare capacity on a cluster of web servers
7. The butterfly Grid supports multiplayer games for
very large numbers of players on the internet over the Globus toolkit
8. The Access Grid supports the needs of small group
collaboration, for example by providing shared workspaces
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn © Addison-Wesley Publishers 2005