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Distributed Object Computing using XML-SOAPDistributed Object Computing using XML-SOAP

Kevin WhiteJames Kebinger

Fall 2000

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Introduction to XMLIntroduction to XML

XML it s a text-based markup language that is XML it s a text-based markup language that is becoming a standard to store databecoming a standard to store data

XML tags tell you what the data XML tags tell you what the data meansmeans, rather than , rather than how to display it.how to display it.

Elements are the holding blocks for data in an Elements are the holding blocks for data in an XML object.XML object.

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XML ExampleXML Example

The following is a XML example of a pizza item:The following is a XML example of a pizza item:

<pizza>

<name>The Texan</name>

<toppings>

<topping>barbeque brisket</topping>

<topping>dill pickles</topping>

<topping>onions</topping>

<topping>mozzarella cheese</topping>

<topping>tomato sauce</topping>

</toppings>

<description>Put the lone in lone star state!</description>

</pizza>

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What is XML?What is XML?

XML objects can also consist of the following XML objects can also consist of the following items: items:

• Elements: holding blocks for data

• Attributes: Name-value pairs that occur inside start-tags after the element name.

• Entity references: Created to allow entity to be created and used in places where multiple instances of the same text will be use in many places.

• Processing instructions: used to provide information specific to applications.

• Comments: User comments

• CDATA: A section of character data that will not be interpreted by the XML parser.

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Why is XML important?Why is XML important?

Plain TextPlain Text XML is it stored as plain ASCII text Allows for viewing and editing the XML data

with any text editor

Data IdentificationData Identification Tag names relate to the data it holds Produces easily parable data with reference to

tag names

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Why is XML important?Why is XML important?

Display stylesDisplay styles XML is only a way to store data. A separate

file can be created to display this data XSL

HierarchicalHierarchical XML documents benefit from their hierarchical

structure Like stepping through a table of contents

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Present Distributed Object ModelsPresent Distributed Object Models

Java RMI for Java applicationsJava RMI for Java applications DCOM for Windows applicationsDCOM for Windows applications CORBA for cross platform applicationsCORBA for cross platform applications

Each have overhead and large scale interoperability Each have overhead and large scale interoperability issuesissues

Answer: SOAP = Simple Object Access ProtocolAnswer: SOAP = Simple Object Access Protocol

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Java RMIJava RMI

Design goal for the RMI architecture was to create Design goal for the RMI architecture was to create a Java distributed object modela Java distributed object model

RMI works in 3 layersRMI works in 3 layers The first layer intercepts method calls made by the client and

redirects these calls to a remote RMI service.

This second layer understands how to interpret and manage references made from clients to the remote service objects.

The final layer is the transport layer and is based on TCP/IP connections between machines in a network.

Java RMI works for Java applications onlyJava RMI works for Java applications only

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DCOMDCOM

DCOM: DCOM: DDistributed istributed CComponent omponent OObject bject MModelodel

Microsoft’s solution for distributed computingMicrosoft’s solution for distributed computing

Allows one client application to remotely start a Allows one client application to remotely start a DCOM server object on another machine and DCOM server object on another machine and invoke its methodsinvoke its methods

DCOM provides the ability to use and reuse DCOM provides the ability to use and reuse components dynamically, without recompiling, on components dynamically, without recompiling, on any platform, from any language, at any timeany platform, from any language, at any time

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CORBACORBA

CORBA: CORBA: Common Object Request Broker ArchitectureCommon Object Request Broker Architecture CORBA is platform and language independentsCORBA is platform and language independents

CORBA Object Request Broker (ORB) provides a CORBA Object Request Broker (ORB) provides a way to connect a client application with an object way to connect a client application with an object that it needsthat it needs

When creating CORBA applications, two main When creating CORBA applications, two main classes, a stub and a skeleton, are created along classes, a stub and a skeleton, are created along with several helper classeswith several helper classes

The ORB is the glue that connects the stubs and The ORB is the glue that connects the stubs and skeletons. skeletons.

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The SOAP ProtocolThe SOAP Protocol

SOAP stands for Simple Object Access Protocol SOAP stands for Simple Object Access Protocol

SOAP doesn't care what operating system, SOAP doesn't care what operating system, programming language, or object model is being programming language, or object model is being used on either the server side or the client side used on either the server side or the client side

SOAP is a cross-platform way to make remote SOAP is a cross-platform way to make remote method calls, serialize and de-serialize objects method calls, serialize and de-serialize objects using XML using XML

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The SOAP ProtocolThe SOAP Protocol

For a protocol it commonly uses HTTP, which is For a protocol it commonly uses HTTP, which is simple to implement and used universally simple to implement and used universally

SOAP works over many protocols, not limited to SOAP works over many protocols, not limited to HTTPHTTP

Using HTTP for transport gives SOAP an Using HTTP for transport gives SOAP an advantage over other previous middleware advantage over other previous middleware solutions because it does not require changes be solutions because it does not require changes be made to network routers and proxy serversmade to network routers and proxy servers

An inherent advantage of SOAP being able to use An inherent advantage of SOAP being able to use HTTP is that it is a universally deployed protocolHTTP is that it is a universally deployed protocol

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SOAP ProcessSOAP Process

SOAP request would be processed in the following SOAP request would be processed in the following steps:steps:1. Get a request on the listen port.2. Parse the request for the method id to call.3. Consult a configuration file for what class/function to

call to handle the request.4. De-serialize the parameters for the method call.5. Call the function with the given de-serialized parameters6. Serialize the return value from the function and send it

back to the requestor

SOAP is not rocket-science. SOAP is simple to SOAP is not rocket-science. SOAP is simple to understand, implement and deploy.understand, implement and deploy.

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Basic SOAP SampleBasic SOAP Sample

Here is a SOAP request:Here is a SOAP request:

POST /StockQuote HTTP/1.1POST /StockQuote HTTP/1.1Host: www.stockquoteserver.comHost: www.stockquoteserver.comContent-Type: text/xml; charset="utf-8"Content-Type: text/xml; charset="utf-8"Content-Length: nnnnContent-Length: nnnnSOAPAction: "Some-URI"SOAPAction: "Some-URI"

<SOAP-ENV:Envelope<SOAP-ENV:Envelope  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">   <SOAP-ENV:Body>   <SOAP-ENV:Body>       <m:GetLastTradePrice xmlns:m="Some-URI">       <m:GetLastTradePrice xmlns:m="Some-URI">           <symbol>DIS</symbol>           <symbol>DIS</symbol>       </m:GetLastTradePrice>       </m:GetLastTradePrice>   </SOAP-ENV:Body>   </SOAP-ENV:Body></SOAP-ENV:Envelope></SOAP-ENV:Envelope>

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Basic SOAP SampleBasic SOAP Sample

And the matching response is:And the matching response is:

HTTP/1.1 200 OKHTTP/1.1 200 OKContent-Type: text/xml; charset="utf-8"Content-Type: text/xml; charset="utf-8"Content-Length: nnnnContent-Length: nnnn

<SOAP-ENV:Envelope<SOAP-ENV:Envelope  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>   <SOAP-ENV:Body>   <SOAP-ENV:Body>       <m:GetLastTradePriceResponse xmlns:m="Some-URI">       <m:GetLastTradePriceResponse xmlns:m="Some-URI">           <Price>34.5</Price>           <Price>34.5</Price>       </m:GetLastTradePriceResponse>       </m:GetLastTradePriceResponse>   </SOAP-ENV:Body>   </SOAP-ENV:Body></SOAP-ENV:Envelope></SOAP-ENV:Envelope>

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Apache SOAPApache SOAP

Used Apache SOAP v 2.0 for implementation.Used Apache SOAP v 2.0 for implementation.

Java library for both client and serverJava library for both client and server

Application need not parse nor create XMLApplication need not parse nor create XML

Server implemented as a servletServer implemented as a servlet

Server application programmed without regard to Server application programmed without regard to SOAPSOAP

Client SOAP calls easy to construct using APIClient SOAP calls easy to construct using API

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SOAP National BankSOAP National Bank

Prototype client-server application

Supports basic banking tasks:

Balance inquiries Deposits/withdrawals Transfers View transaction history

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Use CasesUse Cases

Check Balance (s)

Transfer Funds

Deposit/Withdraw

Close Account

Transaction HistoryCreate New Account

Customer

Login to Account

<<include>>

<<include>>

<<include>>

<<include>>

<<include>>

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Class DiagramClass Diagram

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System ArchitectureSystem Architecture

SOAP

GUI

ClientServer

Servlet Runner

Access DB

JDBC

DBAccess

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System ImplementationSystem Implementation

Client and Server written in Java v 1.22Client and Server written in Java v 1.22 Client GUI uses Java Swing APIClient GUI uses Java Swing API Server uses JDBC to connect to MS Access DBServer uses JDBC to connect to MS Access DB Client and Server communicate using Apache’s Client and Server communicate using Apache’s

Java SOAP libraryJava SOAP library

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ScreenshotScreenshot

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Bank System ConclusionsBank System Conclusions

System successful, all functions workSystem successful, all functions work Implementation fairly painless once we learned Implementation fairly painless once we learned

SOAP APISOAP API Only major snag was learning how to configure the Only major snag was learning how to configure the

SOAP servletSOAP servlet Application rather slow: what causes slowness?Application rather slow: what causes slowness?

MS Access calls SOAP itself

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SOAP BenchmarkingSOAP Benchmarking

Compare RMI to SOAPCompare RMI to SOAP Build a small client-server system to exchange the Build a small client-server system to exchange the

current data and timecurrent data and time As a java.util.Date object As a java.lang.String object

Different objects will compare efficiency and Different objects will compare efficiency and scalability of serializationscalability of serialization

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SOAP Serialization ExampleSOAP Serialization Example

StringString<return xsi:type="xsd:string">Thu Nov 23 17:24:46 <return xsi:type="xsd:string">Thu Nov 23 17:24:46

EST 2000EST 2000</return></return>

DateDate<return xsi:type="ns1:date"><return xsi:type="ns1:date"><time xsi:type="xsd:long">975013920065</time><time xsi:type="xsd:long">975013920065</time><minutes xsi:type="xsd:int">12</minutes><minutes xsi:type="xsd:int">12</minutes><seconds xsi:type="xsd:int">0</seconds><seconds xsi:type="xsd:int">0</seconds><date xsi:type="xsd:int">23</date><date xsi:type="xsd:int">23</date><day xsi:type="xsd:int">4</day><day xsi:type="xsd:int">4</day><hours xsi:type="xsd:int">16</hours><hours xsi:type="xsd:int">16</hours><year xsi:type="xsd:int">100</year><year xsi:type="xsd:int">100</year><timezoneOffset <timezoneOffset

xsi:type="xsd:int">300</timezoneOffset>xsi:type="xsd:int">300</timezoneOffset><month xsi:type="xsd:int">10</month><month xsi:type="xsd:int">10</month></return></return>

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Benchmark SetupBenchmark Setup

250 Remote Calls per trial250 Remote Calls per trial Took average of 3 trials for final resultsTook average of 3 trials for final results

Tests run on Pentium 2 266 Laptop with 288 Megs Tests run on Pentium 2 266 Laptop with 288 Megs of RAMof RAM

Tests run locally, therefore do not reflect cost of Tests run locally, therefore do not reflect cost of network time.network time.

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SOAP SerializationSOAP Serialization

SOAP Serialization Times

0.92

0.94

0.96

0.98

1

1.02

1.04

1.06

1.08

1.1

1.12

1.14

Date String

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RMI SerializationRMI Serialization

RMI Serialization Times

0.97

0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

1.06

Date String

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RMI v. SOAPRMI v. SOAP

SOAP v. RMITime Per Call

0

20

40

60

80

100

120

140

160

SOAP-Date SOAP-String RMI-Date RMI-String

ms

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Benchmark ConclusionsBenchmark Conclusions

RMI about ten times faster than SOAPRMI about ten times faster than SOAP Agrees with published results from Indiana

University

RMI Serialization may scale better than SOAPRMI Serialization may scale better than SOAP SOAP using possibly inefficient generic

serializer in test

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SOAP ConclusionsSOAP Conclusions

SOAP could use an automatic stub generator like SOAP could use an automatic stub generator like RMIRMI Would have sped up development greatly

Lots of people using SOAPLots of people using SOAP IBM, Microsoft, Compaq etc.

SOAP not a standard yetSOAP not a standard yet Could change a lot before settling down

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SOAP ConclusionsSOAP Conclusions

SOAP very usable todaySOAP very usable today Some questions concerning interoperability

between SOAP implementation

SLOWSLOW May be OK for some web apps Not for high performance computing

Would recommend use for small systemsWould recommend use for small systems