Comparison Between Rpc Rmi and Webservices

8/13/2019 Comparison Between Rpc Rmi and Webservices

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ByJihed Othmani

Jing WangKarim Jouini

Mathieu Martin

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The Need More and more devices are connected, tempting us to

take advantage of their computational capabilities.

We would like to communicate, reuse code, share

services. There are a lot of opportunities to leverage services

offered by others and to make your application publiclyavailable.

Provide a service without sharing code. So : we need a standardization of protocols to ease

communication at the application layer. Thats what we call middlewares.

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RPC

Quick Introduction First system to addressthe need to communicate

across process and machines boundaries.

RPC was first described in 1976 by the RFC707.

Xerox used RPC in the popular software courier, 1981.

Paradigm:

The client process has to know the serving process andinstantiates the communication.

The client process calls a distant procedure and waits forthe response (or fail).

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RPC

SamplesA simple server (part 1)

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A simple server (part 2)

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A simple client using our previous server

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RPC

AdvantagesAdvantages :

Very simple logic and very low level, gives to theprogrammer a lot of freedom to implement differentmechanisms on top of it.

Can be implemented by any language (including C !).

RPC exists since 1976, so its maturity and solidity areundoubted.

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RPC

Disadvantages Using RPC can become very complex

The complexity is exposed as the number of procedures Interaction with such a module requires using all these

interfaces in the right way and sequence. A lot of code is needed for even simple applications. RPC gives no answer to fundamental questions:

How to find peers ? How to distribute the workload over multiple servers? How failure and recovery should be handled? How to send/receive complex data structures. Security? Sasser, blaster, etc Are RPC-vulnerability exploits

There are multiple different and incompatible RPCprotocols.

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RPC

Future ? RPC is way too complex to be used as middleware in

modern software.

RPC can be used as low level layer for more powerfulmiddleware layers, that would be able to provide uswith :

OOP

Load balancing Failure detection/correction

Etc

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RMI

Quick Introduction The Java Remote Method Invocation API, or Java RMI,

is a Java application programming interface forperforming the object equivalent of Remote Procedure

Calls.

There are two common implementations of the API. Java Remote Method Protocol (JRMP)

In order to support servers running in a non-JVMcontext, a CORBA version was later developed.

Uses HTTP or IIOP as communication layer.

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RMI

Samples Here is a Server publishing a Hello Object

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RMI

Samples Here is client invoking the previous Hello Object and

calling HelloFromServer() On it !

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RMI

Advantages & disadvantagesAdvantages

Java, so portable and Oriented Object.

NAT-Firewall traversal capabilities. Asynchronous possibilities with ARMI (Async-RMI).

Easier to use and setup than CORBA.

RDMI enables dynamic invocation.

First attempt to address security. Latest versions are CORBA-compatible (using IIOP).

Disadvantages

Java only

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RMI

Future ? RMI still needs to find answers to:

How to implement real server-level security ?

How to perform load balancing ? How to use RMI in other languages ?

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Web Services

Quick IntroductionA software system designed to support interoperable

machine-to-machine interaction over a network.

It refers to clients and servers that communicate overthe HTTP protocol used on the Web.

Web services range from such major services as storagemanagement down to much more limited servicessuch as the furnishing of a stock quote.

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Web Services

Advantages Universal Support. Protocol not Platform. Low Product Costs. Evolutionary thanks to XML.

Business Oriented. The standardized nature of the pieces that implement a Web service solves

many problems related to intersystem communication. For example: The HTTP standard allows more systems to communicate with one another. SOAP (built on XML) standardizes the messaging capability on different systems. UDDI standardizes the publishing and finding of Web services. WSDL standardizes the description of Web services, so providers and requesters speak

the same language.

Opportunities to take advantage of services offered by others and to make yourapplications available to others as a Web service. Mashups (ex: Jogli.com)

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Web Services

Disadvantages No security standards: Web services are exposed to the public

using http-based protocols. Adopting open security standards like SSL or XML-encryption may

be a solution.

Processing time and data traffic costs are significantly higher Very verbose : Multiplication of the conveyed information mass.

But: To buy a faster CPU is cheaper than employing a programmer and

systems administrator capable of handling RMI.

Performance differences less marked for more realistic applications thanfor toys like calculator.

You can use cloud systems to easily scale.

No load balancing at the protocol level.

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Web Services

Samples Google's Web Service - access the Google search

engine.

Amazon's Web Service - access Amazon's productinformation .

XMethods - collection of information about existingWeb services.

Getting the last stock quote.

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Recap

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RPC RMI Web Services

Birth 1976 - 1981 ~ 1990 ~ 2000

Platform Library and OS-dependant

Java Independent

Transport OS-Dependent HTTP or IIOP HTTP(s)

Dev Cost Huge Reasonable Low

Security None Client-level Transport Level

Overhead None OOP + HTTP XML + HTTP

Dynamic invocation None Yes, using RDMI Natural

Versioning Huge problem Possible usingRDMI

Natural

Service lookup Impossible Java Naming andDirectory

UDDI


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Comparison Between Rpc Rmi and Webservices