devilish web services composition and orchestration engine students: flavio palandri antonelli...
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Devilish Web Services Composition and Orchestration Engine
Students: Flavio Palandri antonelli Alessandro Porfiri
“Seminars in Software Engineering” course’s project 2007/2008Professor Giuseppe De Giacomo
Web Services
Software modules designed to support interaction between heterogeneous systems in a network or in internet
public interface description of available operation Standard communication protocols Interaction via standard messages
Great diffusion of Web Services systems Many functionalities already implemented and available
ClientService request
Community
Service 1
Service n
mapping
Scenario – Web Services Composition
Service 2
mapping
mapping
A client requires a TARGET service to be implementedAll functionalities are already implemented in other AVAILABLE SERVICES
Idea: we could realize the TARGET service combining Availables
Objectives
Analyzing Services Composition Problem from a theoretical point of view
Studying Web Services technologies Understanding tools already implemented to build automatically the
composition WSCE TLV
Development of a tool able to manage the whole process Build Composition Generate and publish Target Service Manage the orchestration of services
Abstract services rapresentation
We need to abstract from service implementation We rapresent only the service behavior
TRANSTION SYSTEM
Composition actors
Available Services Existing services Rapresented by TS We will consider also non deterministic behavior
Target Is the service requested by the client Rapresented by TS Only deterministic
Orchestrator The composition manager
Composition
Who is orchestrator?
Build composition
1.Enconding the condition:
in a PDL formula and checking its satisfability
2.Via Simulation
Can we reproduce Target’s behavior with any one Available Services combination?
Simulation – The Community
Simulation Relation
Simulation Algorithm
Composition via simulation
Composition via simulation
Composition exists iff Simulation exists
OG the Orchestrator Generator
Non deterministic behavior
Simulation with nondeterminism
OG with nondeterminism
TLV A tool for computing composition
Target + Community
Comp-inv.pf
Synth-inv.tlv
TLVOGor“unrealizable”
Temporal Logic Verifier LTL based Computes composition via simulation indirectly Automatically computes the OG if realizable
TLV / 2
Target + Communityfile smw
TLV / 3
Simulation constraints:
TLV /4
If composition is realizable TLV’s output is the OG
How to create smw file?
WSCE (web service composition engine) it’s like a wrapper for TLV
Creates smw file from target and available services TS descriptions Execute TLV on smw file From TLV result produce sql script to store the OG table into a DB
WSCE
TLV
TS descriptions
WSTSL
OG table
Script sql
WSCE /1 - InputTS of target and services are described with the xml language WSTSL
WSCE /2 - Output
STATE IN_ACT TargetState State_S1 State_S2 State_S3 OUT_ACT
S1 Login 0 0 0 0 1
S2 searchByAuthor 1 1 0 0 2
S3 searchByTitle 1 1 0 0 3
S4 Listen 2 1 1 0 2
S5 Listen 2 1 0 1 3
OG Table – one for each composition case
WSCE produce also NEXTSTATE[source, target] table
Given in_act, Tstate and Si_states
Now, we just need to develop a tool able to manage the orchestration using this table
DIGRESSION – WS technologies
Web services are software systems offering operations to remote clients Available operations are described through the service interface WSDL Clients communicate with service via SOAP messages on HTTP protocol
Example of a Java Web Servicepublic class Login {
int stato = 0; boolean loggedin;
public String doLogin(String user)throws Exception{
if(stato != 0){
throw new Exception(“Illegal operation");
}
stato = 1; loggedin = true;
return “User logged in”;
}
public String doLogout(String user)throws Exception{
if(stato != 1){
throw new Exception(“Illegal operation");
}
stato = 0; loggedin = false;
return “User logged out”;
}
}
0 1login
logout
DIGRESSION - AxisAxis is a open source tool for publishing web services (in this way software modules become WS) Managing clients interaction with WS (request/response)
It runs in a web container (Tomcat)
To publish a service Axis needs Class files and the service’s descriptor file WSDD
<deployment
xmlns="http://xml.apache.org/axis/wsdd/"
xmlns:java="http://xml.apache.org/axis/wsdd/providers/java">
<service name="urn:Login" provider="java:RPC">
<parameter name="className" value=“servicePackage.Login"/>
<parameter name="allowedMethods" value="doLogin, doLogout"/>
<parameter name="scope" value="Session"/>
</service>
</deployment>
Service name
Service class
Service methods
Conversation:
Session = stateful
Request = stateless
Application = singleton
Publishing using command “java adminClient login.wsdd”
DIGRESSION – Service InterfacePublishing the service, axis produce the service interface WSDL with all
informations of service needed by clients Service name and address Methods
Output parameter Input parameters
ComplexType (any non standard Object managed by the service, example Person, Product, Order...)
WSDL are always accessible, to build the WS Target we will need all Available Services WSDL.
Our part in this project
We want to complete the whole composition and orchestration process, developing missing elements
Orchestrator: a tool able to manage requests from Target Service, finding and delegating the operation to the right Available Service, using informations stored in the OG Table produced by WSCE. Basically Target will demand all client requests to the orchestrator
TargetGenerator: a direct extension of WSCE, reading OG and Available Service WSDL produces and publishes the Target Web Service on Axis
Orchestrator /1 General Scenario
Implementation of orchestrator program P(h,a) = i, and even more
Client invokes Target operation Target demands client operation request to the orchestrator The Orchestrator access OG Table to find the index of the Available Service
able to resolve the operation The Orchestrator invoke the operation to selected service Result is returned to client through Target Service.
To get the index of available service from the OG, the orchestrator needs: Requested action Target state All Available Services states
Orchestrator /3 Services statesIs orchestrator able to retrieve the status of services?
Target State: Yes always Target is deterministic Orchestrator can get Target initial state from OG Table At each step the orchestrator can get the new TargetState given “Input Action”
and “Orchestrator State” using the NEXTSTATE table Available Services states: depends
Deterministic: yes it could easily retrieve it from the OG Table Non deterministic: No, orchestrator must query all AS to retrieve their status
Available Services have to manage their status They must offer a “int getStatus()” remote operation Connection with between Orchestrator and all services must be stateful
Orchestrator /2 Architecture
- Unique component for every target (reuse) - An instance of orchestrator for each target - Orchestrator must be able to manage requests from Concurrent Clients
Orchestrator /4 Composition infos
Orchestrator is indipendent from composition case
The component must be usable from any target
Target has to initialize his own orchestrator with composition infos: Name of OG table List of avalable service
Service index Service name Service address
Complex type classes list
Orchestrator /5 Initialization
Orchestrator Initialization: Receives all informations from Target For each Available Service establish a stateful connection: Call, mantained
during the whole conversation with that client Registers all ComplexType’s classes
Operation invocation Using Calls to retrieve states from services Using Call to invoke operation to selected service
Orchestrator /6 ConcurrencyEach Client has a Session with an instance of WS targetEach Target has instance of orchestratorEach Orchestrator has a Session with every available services.
This way Concurrency is guaranteed
Orchestrator /7 OP invocation
Initialization: only for the first invocation
Operation invocation
Orchestrator /8 Implementation
Orchestrator /9 Distribution
Distributed as library
Targets generated automatically are already made to use this library
User can also build manually their own Target using Orchestrator’s API
Target Generator /1How do we build the Target Service?• User can make the java class, publishing it manually• User can use the TargetGenerator to build it in 1 minute
INPUT• OG script provided by WSCE• WSDL files one for each available service
OUTPUT• Target web service published on Axis ready to receive requests• OG Table stored in Mysql DB
Target Generator /2 Operations
To register a service Axis needs class file of target service, wsdd file, class files of ComplexType
Creates java file of target and complextypes (ex person, product) Compiles all files Creates wsdd of target Publishes target service on Axis using “AdminClient”
Target Generator /3 The whole process
Target Generator /4 Class Schema Target must import orchestrator.jar Class header, class name is taken from input Global variable of the Orchestrator Constructor
Prepare all informations needed for composition OG tablename Array of ServiceInfo (name, address) //index is cabled in the array structure List of ComplexTypes’ classes
Orchestrator = new Orchestrator(tablename, serviceInfos, complexTypes) Sequence of dummy methods representing remote operations of Service
Method header Output parameter Input parameters
Operation demanded to orchestrator, orchestrator.invoke(op) Result returned to client
Target Generator /5 Architecture
All informations needed are retrieved from WSDL files of Available Services using WSDLParser
Target Generator /6 Execution flow
Target Generator /7 init Data
Target Generator parses WSDL of Available Services to retrieve composition infos
Services name, address ComplexTypes Methods
Running Tools
Example 1 – Test1ND: a Web Service to listen songs
Example 2 – MediaStore: tipical E-Commerce application with interactive client
Other example can be found on the documentation
TS
Example – Test1ND
Example of WSTSL
SearchByAuthorND.wstsl
<?xml version="1.0" encoding="UTF-8"?><TS xmlns='http://www.dis.uniroma1.it/WS-TSL' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://www.dis.uniroma1.it/WS-TSL file:/D:/sviluppo SW/FSMJ5Updated/FSM/ts.xsd' service="SearchByAuthorND"> <STATE name="S0" tipology="initial-final"> <TRANSITION action="SearchByAuthor"> <TARGET state="S1"></TARGET>
<TARGET state="S0"></TARGET> </TRANSITION> </STATE> <STATE name="S1" tipology="transient"> <TRANSITION action="Listen"> <TARGET state="S0"></TARGET> </TRANSITION> </STATE></TS>
Example – Test1ND
Java file of service package test1NDCommunity; public class SearchByAuthorND{ int stato = 0; public String SearchByAuthor(String author) throws Exception{ if(stato != 0){ throw new Exception("Service is not able to execute this operation in this state"); } String canzone = ""; if(!author.equals("Paul")){ stato = 1; canzone = "yesterday"; } else{ //ND the service doesn't work with input Paul, keep state 0 canzone = "NOT FOUND"; } return canzone; } public String Listen(String name)throws Exception{ if(stato != 1){ throw new Exception("Service is not able to execute this operation in this state"); } stato = 0; return name+"...yesterday, all my troubles seems so far away..."; } public int getStatus(){ return stato; } }
Example – Test1ND
Example of WSDD
Example – Test1ND
SearchByAuthorND.wsdd
<deployment
xmlns="http://xml.apache.org/axis/wsdd/"
xmlns:java="http://xml.apache.org/axis/wsdd/providers/java">
<service name="urn:SearchByAuthorND" provider="java:RPC">
<parameter name="className" value="test1NDCommunity.SearchByAuthorND"/>
<parameter name="allowedMethods" value="SearchByAuthor, Listen, getStatus"/>
<parameter name="scope" value="Session"/>
</service>
</deployment>
After published all service User has to download WSDL of Available Service to prepare the
wsdl directory
1 Execute WSCE C:\wsce-lite-dist_0.1>java -jar wsce.jar test1ND
2 Generate targetC:\wsce-lite-dist_0.1>java -jar targetgenerator.jar test1nd
3 Execute client C:\wsce-lite-dist_0.1\Composizioni\test1ND\services\ClientTest1ND.java
Example – Test1ND
Another example - TS
Example – MediaStore
Example of WSTL
Example – MediaStore
CartManagement.wstsl
<?xml version="1.0" encoding="UTF-8"?><TS xmlns='http://www.dis.uniroma1.it/WS-TSL' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://www.dis.uniroma1.it/WS-TSL file:/D:/sviluppo SW/FSMJ5Updated/FSM/ts.xsd' service="CartManagement"> <STATE name="S0" tipology="initial-final"> <TRANSITION action="addToCart"> <TARGET state="S0"></TARGET> </TRANSITION>
<TRANSITION action="viewCart"> <TARGET state="S1"></TARGET> </TRANSITION> </STATE> <STATE name="S1" tipology="final"> <TRANSITION action="removeFromCart"> <TARGET state="S1"></TARGET> </TRANSITION> <TRANSITION action="addToCart"> <TARGET state="S1"></TARGET> </TRANSITION> <TRANSITION action="viewCart"> <TARGET state="S1"></TARGET> </TRANSITION> </STATE></TS>
Example of WSDD with complex type
CartManagement.wsdd
<deploymentxmlns="http://xml.apache.org/axis/wsdd/"xmlns:java="http://xml.apache.org/axis/wsdd/providers/java"><service name="urn:CartManagement" provider="java:RPC"><parameter name="className" value="mediaStoreCommunity.CartManagement"/><parameter name="allowedMethods" value="viewCart, addToCart, removeFromCart, getStatus"/><parameter name="scope" value="Session"/><beanMapping qname="myNS:Product" xmlns:myNS="urn:CartManagement" languageSpecificType="java:mediaStoreCommunity.Product"/></service></deployment>
Example – MediaStore
Java file of an Available Service
Example – MediaStore
CartManagement.java
package mediaStoreCommunity;import java.util.*;public class CartManagement {
private int state = 0;private Vector cart;
public CartManagement() { cart = new Vector(); } public Vector viewCart(){ state = 1; return cart; } public Product addToCart(Product p){ cart.add(p); return p; } public void removeFromCart(Product p) throws Exception{ if(state!=1){ throw new Exception("Invalid operation request for this state"); } Iterator it = cart.iterator(); while(it.hasNext()){ Product p2 = (Product)it.next(); if(p2.getCode() == p.getCode()) it.remove(); } } public int getStatus(){ return state; }}
Java file of complex type
Example – MediaStore
Product.java
package mediaStoreCommunity;import java.io.*;public class Product implements Serializable{
private int code;private String name;private String type;private double price;
public Product(){}
public int getCode(){return code;
}
public void setCode(int c){code = c;
} //set e get di tutti i metodi
}
After published all service java org.apache.axis.client.AdminClient <file>.wsdd
1 Execute WSCE C:\wsce-lite-dist_0.1>java -jar wsce.jar MediaStore
2 Generate targetC:\wsce-lite-dist_0.1>java -jar targetgenerator.jar MediaStore
3 Execute client C:\wsce-lite-dist_0.1\Composizioni\MediaStore\services\ClientMediaStore.java
Example – MediaStore
Target createdMediaStore.java
package MediaStore;import orchestrator.*;import javax.xml.rpc.ServiceException;import java.util.*;public class MediaStore {
private Orchestrator orchestrator;private String tablename;public MediaStore() throws Exception{
tablename = "MediaStore";ServiceInfo[] services = new ServiceInfo[4];services[0] = new ServiceInfo("http://127.0.0.1:8080/axis/services/", "urn:CartManagement");services[1] = new ServiceInfo("http://127.0.0.1:8080/axis/services/", "urn:ProductList");services[2] = new ServiceInfo("http://127.0.0.1:8080/axis/services/", "urn:CheckOutService");services[3] = new ServiceInfo("http://127.0.0.1:8080/axis/services/", "urn:BuyService");LinkedList<Class> complexTypes = new LinkedList<Class>();complexTypes.add(Product.class);orchestrator = new Orchestrator(services, tablename, complexTypes);
}public Product addToCart(Product in0)throws Exception{
Object[] params = {in0};Object risposta = orchestrator.invokeOperation("addToCart", params);return (Product)risposta;
}public java.util.Vector viewCart()throws Exception{
Object[] params = {};Object risposta = orchestrator.invokeOperation("viewCart", params);return (java.util.Vector)risposta;
}public void removeFromCart(Product in0)throws Exception{
Object[] params = {in0};Object risposta = orchestrator.invokeOperation("removeFromCart", params);
}public java.util.Vector getProductList()throws Exception{
Object[] params = {};Object risposta = orchestrator.invokeOperation("getProductList", params);return (java.util.Vector)risposta;
}public String buy(double in0)throws Exception{
Object[] params = {in0};Object risposta = orchestrator.invokeOperation("buy", params);return (String)risposta;
}public double checkOut(java.util.Vector in0)throws Exception{
Object[] params = {in0};Object risposta = orchestrator.invokeOperation("checkOut", params);return (Double)risposta;
}public int getStatus(){ return orchestrator.getTargetState(); }
}
Example – MediaStore
Conclusions Users can build their Target Service in 5 minutes componing existing services
Build Target manually using orchestrator’s API Build Target automatically ComplexTypes are managed
The whole orchestration process is now completely working Client concurrency Target itself may be an Available Service for another case of Composition
Problems Available Services have to manage their state and offer the getStatus
operation We could spread in internet a “Componible” interface to be implemented
Extensions Intergration of WSCE and TargetGenerator The tool should be accessible remotely, with user friendly interface Extension to RMI services