Corba Performance

8/6/2019 Corba Performance

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ByS.Venkatesan


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In CORBA a Servant is the invocation tar et containin

methods for handling the remote method invocations.

In the newer CORBA versions, the remote object on theserver side is split into the Object (that is exposed to remoteinvocations and Servant to which the former art dele atesthe method calls).


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Stateless Servants is not associated with an a lication

specific state in memory. This does not implies that theCORBA object, which is implemented by the servant, is.

Stateful Servants is associated with some a licationspecific state.


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The number of remote method invocations that are made.

The amount of data that is transferred with each remotemethod invocation.

y u ythe system


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In LAN environment the number of remote method

invocations will often have the greatest impact.

In a high speed network with low latency, the marshallingcosts might become more pronounced.

The performance given for one environment is not commonfor all the environments. The performance will get change

depend up on the configuration of hardware, network,operating system, programming language, and object request


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#include interface Holding;typedef sequence HoldingSeq;interface portfolio {Money getCurrentValue();HoldingSeq getHoldings();};Interface Holding{Unsi ned lon etNumberOfSharesStock getStock();};


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Portfolio Object

Holding Objects

Portfolio Manager Server

getHo ngs

getStock()getStock()

MangerGUI

getSymbol()

getStock()

getSymbol()

getSymbol()

Data Broker Server


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//CORBA IDL .

interface Holding;interface Portfolio{Mone etCurrent ValueSymbolSeq getSymbols();Holding getHoslingBySymbol (in Symbol aSymbol);};

//Javapublic void displaySymbols (_portfolioRdf the Portfolio){SymbolSeq symbols = thePortfolio.getSymbols();or n x= ; x sym o s. eng ; x

{holdingList.add(holdings.buffer[idx]);}


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Portfolio Manager Server

Portfolio Manager Portfolio Object

getSymbols()

GUI


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First Version (1 + 2 * N RMIs)

Second Version (1 RMI)

Duration


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Number of Invocation

Amount of data transfer Marshalling and unmarshalling overhead


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A si nificant amount of time is s ent onlTota cost o RMI wit out

marshalling/unmarshalling of object references.

with marshalling/unmarshalling of object

references

First Version (1 + 2 * N RMIs)


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Each request sent over a network connection imposes a delay,usually referred to as network latency.

each CORBA remote invocation, especially in TCP/IP networks.

The network latency imposed by each request and reply is not theonly cost factor involved in each remote invocation.

There are other factors, like server side lookup, that contribute to aconstant cost factor for each remote invocation.


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Section Message Size Throughput

I Small Low

II Relatively large High


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High throughput rate can usually achieved by using few, ,

instead of many request, each transferring a smallamount of data.

There is also problem with transferring extremely largeamoun s o a a n a s ng e message e messagegets too big, the throughput rate decreases again.

Reason for this decrease in throughput include TCPbuffering issues and growing process sizes.


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Marshalling Overhead for Different IDL Data Types

Octet marshalling overhead is very small

Struct is also very simple, therefore the marshalling overhead is quite small.

Union Unions are slightly more complex than structs, since they can store.

String A string is a variable length data type. The problem with variable lengthdata types is that they usually involve costly memory management operations.

Sequence A sequence is not only a variable length data type, it can also storecomplex IDL types.

Any It is more complex, since it is essentially a dynamic data type and has tohandle dynamic type codes during marshalling and unmarshalling.

Object reference Object references provide a powerful abstraction mechanism.They encapsulate information such as host addresses and object identifiers, andmappings to active network connections.


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Marshalling/Unmarshalling cost of different data types

IDL Type

struct

Octet

Union

String

Sequence

any

Object reference

Marshalling Cost


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IDL data t es do not su ort inheritance.

IDL data types cannot be used describe recursive datastructures.


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Diagram

*

ge apes

Shape1..*

Compound Shapename:string

LineStart: point


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struct CompoundShape {string m_name;sequence m_shapes; (1) Error!}Struct Line {point m_start;point m_end;};union Shape switch (short) {case 1: Line m Line; _case 2 : compoundShape m_CompoundtShape;};


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Struct Shape

Any m_details;};struct Com oundSha e {string m_name;sequence m_shapes; (1) Error!

};

point m_start;point m_end;};

union Shape switch (short) {case 1: Line m_Line;case 2 : any m_CompoundShape;


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Corba Performance

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