web services

04/10/23 Distributed Computing, M. L. Liu 1

Web Services

M. L. Liu

04/10/23 Distributed Computing, M. L. Liu 2

Sources of InformationProgramming Web Services with SOAP, by Snell et al, O’ReillySOAP Tutorial, http://www.w3schools.com/soap/default.aspSoapRPC.com: Tutorials, (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1DaveNet : XML-RPC for Newbies, http://davenet.userland.com/1998/07/14/xmlRpcForNewbiesSoapRPC.com: Other resources, http://www.soaprpc.com/resources/

04/10/23 Distributed Computing, M. L. Liu 3

Web ServicesNetwork services provided over HTTP – “wired services”It is promoted as a new way to build network applications from distributed components that are language- and platform-independentThe technologies are still evolvingWe are more interested in the concept and principles, but we will look into one API (Apache SOAP).

04/10/23 Distributed Computing, M. L. Liu 4

Web Services

Th e we b(H TTP-ba s e d

n e two rk )

we b s e rv ice

we b s e rv ice

we b s e rv ice

clie n t

04/10/23 Distributed Computing, M. L. Liu 5

Web Service Software Components

A web service is a message-based network service.

A server which provides a web service must be capable of “sending and receiving messages using some combination of standard Internet protocols”

a pplica t io nlo g ic

s e rv icepro x y

s e rv icelis t e n e r

s e rv icere qu e s t

04/10/23 Distributed Computing, M. L. Liu 6

Just-in-time integration

Network services can be integrated dynamically, on an as-needed basis.

SunMicro’s jini is a framework that supports the idea.

Network services are registered with a service registry; a service consumer/client looks up the registry to fulfill its needs.

The binding of a client to the service can occur at runtime.

04/10/23 Distributed Computing, M. L. Liu 7

Web service protocol stack

t ra n s po rt

n e two rk

m e s s a g in g

s e rv ice de s cript io n

s e rv ice dis co v e ry

tra n s po rt

n e two rk

m e s s a g in g

s e rv ice de s cript io n

s e rv ice dis co v e ry

a pplica t io n a pplica t io n

04/10/23 Distributed Computing, M. L. Liu 8

Web service protocols

t ra n s po rt

n e two rk

m e s s a g in g

s e rv ice de s cript io n

s e rv ice dis co v e ry

a pplica t io n

UD D I (Un iv e rs a l D e s cript io n , D is co v e ry , a n d I n te g ra t io n )

W S D L (W e b S e rv ice D e s cript io n L a n g u a g e )

X M L , S O A P (S im ple O bje ct A cce s s Pro to co l)

TC P, H TTP, S M TP, J a bbe r

I P

04/10/23 Distributed Computing, M. L. Liu 9

SOAP

SOAP is a protocol which applies XML for message exchange in support of remote method calls over the Internet.

Compared to remote method invocation or CORBA-based facilities: – SOAP is web-based or “wired” and hence is not

subject to firewall restrictions– Language-independent– Can provide just-in-time service integration

04/10/23 Distributed Computing, M. L. Liu 10

Remote Procedure Call using HTTP

we bs e rv e r

we bclie n t

s e rvi ceobje ct

H TTP re qu e s t

H TTP re s po n s e

m e t h o d n a m e ,p a r a m e t e r l i s t

r e t u r n va l u e

04/10/23 Distributed Computing, M. L. Liu 11

SOAP Messages

m e s s a g e bo dy

S O A P bo dy

h e a de r blo ck

h e a de r blo ck

S O A P h e a de r

S O A P e n v e lo pe

opti

onal

req

uir

ed

04/10/23 Distributed Computing, M. L. Liu 12

An XML-encoded SOAP RPC

< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '> < s o a p:H e a de r>

< - - H e a de rs g o h e re - ->

< /s o a p:H e a de r> < s o a p:B o dy >

< - - R e qu e s t g o e s h e re - ->

< /s o a p:B o dy >< /s o a p:En v e lo pe >

S o u rce : h t tp: //www.x m l.co m /

04/10/23 Distributed Computing, M. L. Liu 13

Example of a SOAP message

< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '>< s o a p:H e a de r>

< h :L o g x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /lo g g in g '> < tra ce > 4 < /tra ce > < /h :L o g > < h : PS e rv e r x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /ps e rv e r' s o a p: m u s tUn de rs ta n d= 'tru e ' > < u s e rn a m e > a n o n cv s @ e x a m ple .o rg < /u s e rn a m e > < pa s s wo rd> a n o n cv s < /pa s s wo rd> < /h : PS e rv e r> < /s o a p:H e a de r>

< s o a p:B o dy > < m :C h e ck o u t x m ln s :m = 'h t tp: //e x a m ple .o rg /cv s '> < s o u rce > /x m l/s o a p/we bs e rv ice s /cv s < /s o u rce > < re v is io n > 1 .1 < /re v is io n > < de s t in a t io n > /e tc/u s r/m a rt in g /s o u rce /x m l< /de s t in a t io n > < /m :C h e ck o u t> < /s o a p:B o dy >< /s o a p:En v e lo pe >

s o u rce : h t tp: //www.x m l.co m

04/10/23 Distributed Computing, M. L. Liu 14

A SOAP Message that contains a remote procedure call

source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

<SOAP-ENV:Envelope SOAP-ENV:encodingStyle= "http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">

<SOAP-ENV:Body>       <m:getStateName xmlns:m="http://www.soapware.org/">         <statenum xsi:type="xsd:int">41</statenum>         </m:getStateName> </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

04/10/23 Distributed Computing, M. L. Liu 15

An Example SOAP Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P-ENV :En v e lo pe S O A P- ENV :e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < s ta te n u m x s i: ty pe = " x s d: in t" > 4 1 < /s ta te n u m > < /m :g e tS ta te Na m e > < /S O A P- ENV :B o dy > < /S O A P- ENV :En v e lo pe >

pa ra m e te r o f ty pe in t a n d v a lu e 4 1

pro ce du ren a m e

n a m e o f s e rv e r

04/10/23 Distributed Computing, M. L. Liu 16

Response example source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P- ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e R e s po n s e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < R e s u lt x s i: ty pe = " x s d:s trin g " > S o u th D a k o ta < /R e s u lt> < /m :g e tS ta te Na m e R e s po n s e > < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >

n a m e o f s e rv e r

r e tu r n ed v a lu e

pro ce du re n a m e

04/10/23 Distributed Computing, M. L. Liu 17

Example of a SOAP message for an error RPC response

source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1< ? x m l v e rs io n = " 1 .0 " ? >< S O A P-ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P-ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < S O A P- ENV :Fa u lt> < fa u lt co de > S O A P- ENV :C lie n t< /fa u lt co de > < fa u lt s t rin g > C a n 't ca ll g e tS ta te Na m e be ca u s e th e re a re t o o m a n y pa ra m e te rs . < /fa u lt s t rin g > < /S O A P- ENV :Fa u lt> < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >

04/10/23 Distributed Computing, M. L. Liu 18

HTTP and SOAP RPC Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

A SOAP message can be used to transport a SOAP remote procedure request/response, as follows: POST /examples HTTP/1.1

User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"<blank line>

<text for SOAP message>

04/10/23 Distributed Computing, M. L. Liu 19

An HTTP request that carries a SOAP RPC request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

POST /examples HTTP/1.1User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle=

"http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"><SOAP-ENV:Body>       <m:getStateName xmlns:m="http://www.soapware.org/">         <statenum xsi:type="xsd:int">41</statenum>         </m:getStateName> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

04/10/23 Distributed Computing, M. L. Liu 20

An HTTP request that carries a SOAP RPC responsesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

HTTP/1.1 200 OKConnection: closeContent-Length: 499Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:05:04 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">   <SOAP-ENV:Body>      <m:getStateNameResponse xmlns:m="http://www.soapware.org/">         <Result xsi:type="xsd:string">South Dakota</Result>         </m:getStateNameResponse>      </SOAP-ENV:Body>   </SOAP-ENV:Envelope>

04/10/23 Distributed Computing, M. L. Liu 21

Error Examplesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

HTTP/1.1 500 Server ErrorConnection: closeContent-Length: 511Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:06:32 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">   <SOAP-ENV:Body>      <SOAP-ENV:Fault>         <faultcode>SOAP-ENV:Client</faultcode>         <faultstring>Can't call getStateName because there are too many parameters.</faultstring>         </SOAP-ENV:Fault>      </SOAP-ENV:Body>   </SOAP-ENV:Envelope>

04/10/23 Distributed Computing, M. L. Liu 22

SOAP Packagessource: http://www.soapuser.com

Apache SOAP for Java

Apache Axis for Java

Idoox WASP for C++

Microsoft SOAP Toolkit (part of the .net framework)

SOAP::Lite for Perl

04/10/23 Distributed Computing, M. L. Liu 23

Apache SOAP

Allows clients and services to be written in Java

Part of the Apache-XML project (http://xml.apache.org/)

SOAP package downloadable: http://xml.apache.org/dist/soap/

Installation instruction:

http://www.xmethods.com/gettingstarted/apache.html

04/10/23 Distributed Computing, M. L. Liu 24

Apache SOAP installation

% T O M C AT _ HO M E %

w eb ap p s

s o ap

W E B- I N F

c las s es

o n jav a

C alc S er v ic e . jav aC alc S er v ic e . c las sD ep lo y m en tD es c r ip to r .x m l

s o ap .w ar

s o ap

C :

s o ap - 2 _ 2

lib

x er c es , ja r m ail. ja r s o ap . ja r ac tiv a tio n . ja r

04/10/23 Distributed Computing, M. L. Liu 25

Classpath setting

set CLASSPATH=C:\soap\soap-2_2\lib\xerces.jar;

C:\jdk1.3\bin;

C:\jdk1.3\lib\tools.jar;

C:\soap\soap-2_2\lib\mail.jar;

C:\soap\soap-2_2\lib\soap.jar;

C:\soap\soap-2_2\lib\activation.jar;

C:\tomcat\lib\servlet.jar;

.;

04/10/23 Distributed Computing, M. L. Liu 26

Writing a Client Application using Apache SOAPsource: http://www.xmethods.com/gettingstarted/apache.html

Classpath Your CLASSPATH environment variable should have both the "soap.jar" and "xerces.jar" JAR files included. Importing packages For basic SOAP method invocation, you should import the following at minimum:

// Required due to use of URL class , required by Call class import java.net.*;

// Required due to use of Vector class import java.util.*;

// Apache SOAP classes used by client import org.apache.soap.util.xml.*; import org.apache.soap.*; import org.apache.soap.rpc.*;

04/10/23 Distributed Computing, M. L. Liu 27

Ready-made SOAP ServicesA number of SOAP ready-made services are available at http://www.xmethods.com/

XMethods Service Weather Temperature

ID8

Service Owner:xmethods.net

Contact Email:support@xmethods.net

Service Description:Current temperature in a given U.S. zipcode region.

SOAP Implementation:Apache SOAP

04/10/23 Distributed Computing, M. L. Liu 28

Sample SOAP service

An aly ze W S D L | View R P C P r o f ile | h t tp :/ /w w w .x m eth o d s .n e t /s d /2 0 0 1 /T em p era tu r eS erv ic e .w s d lX M eth o d s I D 8S er v ic e O w n er : x m eth o d s .n e tC o n tac t Em ail: s u p p o r t@ x m eth o d s .n e tS er v ic e Ho m e P ag e:D es c r ip tio n : C u r r en t tem p era tu r e in a g iv en U.S . z ip c o d e r eg io n .S O AP Im p lem en ta tio n : Ap ac h e S O AP

W e a the r - T e m p e ra tu re

Found at http://www.xmethods.com

04/10/23 Distributed Computing, M. L. Liu 29

RPC Profile for Service

R PC Pro f ile fo r S e rv ice " W e a th e r - Te m pe ra tu re "

M e th o d Na m e g e tTe m pEn dpo in t UR L h t tp: //s e rv ice s .x m e th o ds .n e t :8 0 /s o a p/s e rv le t /rpcro u te rS O A PA ct io nM e th o d Na m e s pa ce UR I u rn :x m e th o ds -Te m pe ra tu reI n pu t Pa ra m e te rs z ip c o d e s t rin g

O u tpu t Pa ra m e te rs r e tu r n f lo a t

See sample: TempClient.java

04/10/23 Distributed Computing, M. L. Liu 30

Client program samples

See samples in client folder:– TempClient.java– StockQuoteClient.java– CurrencyClient.java

04/10/23 Distributed Computing, M. L. Liu 31

SOAP data typesSOAP Data Types,

http://www.sdc.iup.edu/outreach/spring2002/webservices/datatypes.htmlUses XML Schema data typesPrimitive Typesstring, boolean, decimal, float, double, duration, dateTime, time, date, gYearMonth, gYear, gMonthDay, gDay, gMonth, hexBinary, base64Binary, anyURI, QName, NOTATION

04/10/23 Distributed Computing, M. L. Liu 32

SOAP data typesDerived Types

Simple types (derived from a single primitive type)* integer is derived from decimal* int (-2147483648 <= int <= 2147483647) is derived from long which is derived from integer * 5-digit zip code can be derived from int* may use regular expressions to specify derived types, such as ([A-Z]){2,3}-\d{5}

04/10/23 Distributed Computing, M. L. Liu 33

Complex Type

Complex types (struct or array)Struct example

<instructor> <firstname xsi:type="xsd:string">Ed</firstname>

<lastname xsi:type="xsd:string">Donley</lastname> </instructor>

Array example <mathcourses xsi:type=

"SOAP-ENC:Array" SOAP ENC:arrayType="se:string[3]"> <se:string>10452C</se:string> <se:string>10454C</se:string> <se:string>11123T</se:string>

</mathcourses>

04/10/23 Distributed Computing, M. L. Liu 34

Creating Web Services (server-side SOAP)

O'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.htmApache SOAP allows you to create and deploy a SOAP web service.You must install some .jar files on your system and set the CLASSPATH to them:

Algorithm:1. Write a class for providing the service.2. Create a deployment descriptor in XML.3. Deploy the service with the service manager.

04/10/23 Distributed Computing, M. L. Liu 35

The Apache SOAP service manager

The service manager is itself implemented as a SOAP service.

To see what services are deployed on your system:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter list

To deploy a service:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter deploy foo.xml

04/10/23 Distributed Computing, M. L. Liu 36

Creating a SOAP ServiceO'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002]http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

A SOAP service can be just about any Java class that exposes public methods for invocation. The class does not need to know anything about SOAP, or even that it is being executed as a SOAP service. The method parameters of a SOAP service must be serializable. The available types that can be used as SOAP service parameters are shown in (Listing 2) (shown on next slide)

04/10/23 Distributed Computing, M. L. Liu 37

SOAP Service Parameter TypesAll Java primitive types and their corresponding wrapper classes

Java arrays

java.lang.String

java.util.Date

java.util.GregorianCalendar

java.util.Vector

java.util.Hashtable

java.util.Map

04/10/23 Distributed Computing, M. L. Liu 38

SOAP Service Parameter Typesjava.math.BigDecimal javax.mail.internet.MimeBodyPart

java.io.InputStream

javax.activation.DataSource

javax.activation.DataHandler

org.apache.soap.util.xml.QName

org.apache.soap.rpc.Parameter

java.lang.Object (must be a JavaBean)

04/10/23 Distributed Computing, M. L. Liu 39

Sample SOAP Service Implementations

See sample in SOAP folder:

TempService: A temperature service

Exchange: currency exchange service and client

04/10/23 Distributed Computing, M. L. Liu 40

Sample SOAP Service Class// A sample SOAP service class// source: http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

package onjava;public class CalcService { public int add(int p1, int p2) { return p1 + p2; }

public int subtract(int p1, int p2) {

return p1 - p2; }}

04/10/23 Distributed Computing, M. L. Liu 41

Deployment Descriptor<isd:service xmlns:isd="http://xml.apache.org/xml-

soap/deployment" id="urn:onjavaserver"> <isd:provider type="java" scope="Application" methods="add subtract"> <isd:java class="onjava.CalcService"/> </isd:provider>

<isd:faultListener>org.apache.soap.server.DOMFaultListener</isd:faultListener>

</isd:service>

04/10/23 Distributed Computing, M. L. Liu 42

SummarySOAP is a protocol that makes use of HTTP requests and responses to effect remote method calls to web services.

A SOAP method call is encoded in XML and is embedded in an HTTP request

The return value of a method call is likewise embedded and encoded in an HTTP response

A number of SOAP APIs are available for programming web services and client method calls. The Apache API was introduced.