Transcript Soap Events - Indiana University

SOAP RMI
A New-Old Programming Model
for Web Services
Aleksander Slominski, Madhusudhan Govindaraju,
Randall Bramley, Dennis Gannon
Indiana University Extreme! Lab
Outline
Web Services and RMI (Triangle)
 RMI and SOAP
 RMI system for Java and C++
 Is XML enough for interoperability?
 Can RMI/XML be fast (enough)?
 Further Steps
 Conclusions
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Web Services Today
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Apache SOAP, MS SOAP, …
Optionally:
WSDL or IDL
Optionally:
Create IDL..
Interact
Client
Service
Web Services Tomorrow
Registry
Publish
Lookup
Interact
Client
Service
Classical RMI Overview
Lookup
RMI
Registry
Client
Remote Reference
Publish
Server
Remote Object
Interact
Stub
Transport
Layer
Skeleton
Improving RMI
Reusing instead of inventing …
 Language independent RMI model
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needs common protocol: SOAP
 making C++ and Java work together …
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Naming = <name, remote reference>
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well known naming service: LDAP
Working with future standards

UDDI, WSDL, …
Implementation Goals:
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Compatibility with non-RMI SOAP
implementations (platform neutral)
 over
40 available now
Minimal overhead on application writer
 Easier Naming Service (JNDI, LDAP)
 Multi-protocol fail-over (prototyped)
 Allow subscription to services from
behind firewall (prototyped)
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SoapRMI and Java/C++
SOAP is wire protocol
 Binding to language constructs
 For C++
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Stub
Skeleton
XML related classes (mapping)
For Java
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Can be static: as in C++
Or dynamic:
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Only interfaces and XML mapping info
Dynamic vs. Static Stubs
Static stubs: classic stubs compiled from IDL
– faster but needs to be regenerated each
time IDL changes
 Dynamic stubs: created with use of advanced
reflection in JDK 1.3 (java.lang.reflect.Proxy)
– runtime overhead
 Good to have both (and be able to run in JDK
1.2 as well – maybe …)
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SoapRMI/Java Design
Subset of RMI like API
 Transport Layer
 RPC services
 Pluggable client and server protocols
 XML mapping
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Design: RMI API
RMI Server API
UnicastRemoteObject
Naming.bind
RMI Client API
Remote, RemoteException
Naming.lookup()
Design: Transport Layer
RMI Server API
UnicastRemoteObject
Naming.bind
RMI Client API
Remote, RemoteException
Naming.lookup()
HTTP
SoapEmbeddedServer
HTTP
java.net.HttpURLConnection
Design: RPC Layer
RMI Server API
UnicastRemoteObject
Naming.bind
RMI Client API
Remote, RemoteException
Naming.lookup()
SOAP RPC
SoapServices
HTTP
SoapEmbeddedServer
HTTP
java.net.HttpURLConnection
Design: Protocol Providers
RMI Server API
UnicastRemoteObject
Naming.bind
RMI Client API
Remote, RemoteException
Naming.lookup()
SOAP RPC
SoapServices
Dispatcher
(dynamic-skeleton)
HTTP
SoapEmbeddedServer
Invoker
(dynamic-stub)
HTTP
java.net.HttpURLConnection
Design: SOAP/XML layer
RMI Server API
UnicastRemoteObject
Naming.bind
RMI Client API
Remote, RemoteException
Naming.lookup()
SOAP RPC
SoapServices
Dispatcher
(dynamic-skeleton)
SOAP Encoding
with Mapping
HTTP
SoapEmbeddedServer
Invoker
(dynamic-stub)
HTTP
java.net.HttpURLConnection
XML mapping objectives
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interoperability on the wire
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easy to process
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mapping described in XML and object model
flexible enough
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supporting multi-ref, xsi:type, …
XML schema types
IDL port types (interfaces)
powerful enough to allow
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code generation
dynamic stubs
SOAP serialization, deserialization
Performance and beyond XML
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XML is not designed for performance
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our paper in SC ’00
… but for robustness!!!
 Intranet/Internet: Java RMI/IIOP/SOAP
 SOAP – simplicity is important but
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our take: Simple Open Access Protocol
RMI abstraction layer
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Multi-protocol approach possible
Further work
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Standardized remote references
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dynamic WSDL or future standards
Multi protocol selection (prototyped)
 Security aspects (under consideration)
 Exception model (needs more work)
 Fail-over (prototyped)
 Routing
 Transactions
…
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Conclusions
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Web Services
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ubiquitous and Internet ready
RMI model
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simple but typically only Java
Coexistence of New and Old Systems
 Open Source SoapRMI 1.1 is available now!
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http://www.extreme.indiana.edu/soap