PLUG : Presentation Layer Universal Generator

PLUG PLUG Presentation Layer Universal GeneratorPresentation Layer Universal Generator

P&D/SSD/TCE/TFP/ASTP&D/SSD/TCE/TFP/AST

A joint company of Thomson-CSF Airsys and Siemens

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P&D/SSD/TCE/TFP/AST - 3/28/20042

OVERVIEW

� Object Oriented Design to automatic code generation� Compiler & Parser� PLUG (Presentation Layer Universal Generator) through

applications :� Coder generation : Object Message Passing� Stub generation : PATIO API

� Future

* PATIO : Platform for ATM Tools Integration to Pre-operation

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PLUG : Presentation Layer Universal Generator

� OSI layer 6 & 7 services� Manages heterogeneous programming

languages and hardwares� Provides Plug & Play (flexibility)

=> Automatic code generation

=> Object Oriented Design

Application

Presentation

Session

ASN.1*

7

6

5

ASE* ASE ASE ASE

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Object analogy

Implementation Interface

A driver doesn't care of engine's internal working.He only knows the interface

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Specification Language

Network

Node A Node B

IRS (IDL)Struct message1

Item1 : short;Item2 : long;Item3 : char;Item4 : Boolean;Item4 : Struct data

Item1 : :char;Item2 : long;Item3 : char;Item4 : BooleanItem4 : char;

end struct data;end struct message1

Communication Language

ProgrammingLanguage (C++)

ProgrammingLanguage (Ada)

Communication Object Design

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Syntax and Language

� Abstract Syntax : specification language : � ASN.1, IDL, (ADA)

� Working Syntax : programming language : � ADA, C, C++

� Transfert (concrete) Syntax : communication language : � BER/PER, XDR, CDR, � ASTERIX, ADEXP, ICAO

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Compiler VS Parser

� Abstract Syntax is independent of Transfertsyntax :� Automatic code generation : Compilers

� If no Abstract Syntax (AS = TS) :� Manual code generation : Parsers

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PLUG Compilers

� ABSTRACT SYNTAX� PLUG Ada RPC : API� PLUG ASN.1 : ATN� PLUG IDL : CORBA

Front End (FE)

� TRANSFERT SYNTAX� PLUG XDR : API� PLUG BER/PER : ATN� PLUG CDR : CORBA, ESIOP

Back End (BE)

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PLUG Parsers

� PLUG ASTERIX : � Radar, Meteo, Categorie XX

� PLUG ADEXP : � Flight Plan, ATS, AIS, CFMU, IFPS,

OLDI

� PLUG ICAO : � Flight Plan, Meteo, Notam, ATS, OLDI

Tracks

Primaryand secondary RADAR

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XDR

Stub Generator Coder Generator

C Ada

Ada API

C Ada

PLUG : Presentation Layer Universal Generator

(IDL)

(CDR)(IDL,C++)

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PLUG Coder generator

IFF

XDR/C generatedencoding source files

Front End(lex/yacc)

Back End

XDR/ADA generatedencoding source files

AdaGrammar(BNF)

grammar analyzegrammar analyze

XDR Templatesexpansion

XDR Templatesexpansion

XDRTemplates

(TDL)

AdaAPI

Independant Format File

Independant Format File

Abstract Syntax Tree

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PLUG Compilers through applications

� Message passing object design� XDR� Coder generator

� Distributed Object Design : API (IDL) PATIO� UBSS based Ada RPC � Stub generator

� Miscellanous� Symbolic trace and debug functions� Programming Language translator

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Object message passing with PLUG

� UBSS manages pipes not the semantic of transported messages

� PLUG Coder are used to manage FIFO and CDC messages.

� Ada type specification is used as Specification input file (AS)

� IRS documents are replaced by Ada specification

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Plug coder use : FIFO encode/decode

FIFOEnqueue Dequeue

Type AType BType Simple 1Type Simple 2

End Type BType CType Simple 1Type Simple 3Type D

Type Simple 3Type Simple 2

End Type DEnd Type C

End Type A





End Type A

Type Ada Type C

Ada

XDR

XDR

C

Call Back encoding routing

XDR buffer

ToolsUser Tools User

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Plug coder use : CDC encode/decode

Ada

XDR

XDR

C





End Type A





End Type A

Type Ada Type CCall Back encoding routing

CDCCDC_write() CDC_read()

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AdaCSCI

CCSCI

XDR

Ada Compiler C Compiler

XDR : How it works.

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C/XDRCoder

(C)

Struct Message Type 1 Field A

Field BField C

Field DField E

Field FField GField H

Field IEnd struct Message Type1

C structure

Field 1Field 2Field 3Field 4Field 5Field 6Field 7Field 8Field 9

XDR StreamAda/XDRCoder(Ada)


Field BField C

Field DField E



Ada structure

InterfaceSpecification

Abstract Syntax

Transfert Syntax

Programming SyntaxProgramming Syntax

Object Message Passing Syntax

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Coder : Structure Serialization

Struct Message Type 1 Field AField B

Field CField D

Field EField FField G

End struct Message type1

Ada or C structure

XDR Stream

XDR Convertor

Elementary types are : Int, Char, float, Boolean Field 1Field 2Field 3Field 4Field 5 Header

Type 1

A B

C D

E

F G

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C/XDRCoder


Field BField C

Field DField E



C structure


XDR StreamAda/XDRCoder


Field BField C

Field DField E



Ada structure

InterfaceSpecification

C/XDRCoder

Generator

Ada to CTranslator

Ada/XDRCoder

Generator

Ada PackageSpecification

(With)

Code generation output

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PLUG Generated Files

� PLUG/XDR generates 5 Files :� ADA :

� 1. Coder specification (.ads)� 2. Coder body (.adb)

� C :� 3. API header file (.h)� 4. Coder specification (.h)� 5. Coder body (.c)

� The Ada API header file (specification) is the API specification itself.

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PLUG Generated Files

AdaAPI

.h.h

.c.c

.ads.ads .h.h .ads.ads

.adb.adb

1 2 4

53Ada and C structure

Ada and C XDR Coder

=

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Ada Program C ProgramXDR format disk file

PUT (Ada Type)

GET ( Ada Type)

read (C Type)

write (C Type)

Plug coder use : Off line file universal format

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C/XDRCoder


Field BField C

Field DField E



C structure


XDR StreamC/XDRCoder


Field BField C

Field DField E



C structure

C/XDRCoder


Field BField C

Field DField E



C structure




Field BField C

Field DField E



Ada structure

Ada/XDRCoder


Field BField C

Field DField E



Ada structure




Field BField C

Field DField E



Ada structure

Coder context

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PATIO API paradigm� Software components Plug & Play

� Vertical services, Frame work, Design Patterns

� Business Middleware = OSI layers 7,5,6 = ORB Core services

� Business APIs = OSI layer 7 ASEs = CORBA objects

� Business Middleware is also called API layer because it exhibitsonly application APIs.

� An API (as an ASE) is :� A protocol and � A logical interface (API = abstract syntax) : IRS

* IRS : Interface Requirements Specification.

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API protocol

UBSS

API(SKELETON)

APPLI

UBSS

API(STUBS)

APPLI

ServerClient

API PROTOCOL

UNIX

LAN

UNIX

API

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API : How it works

� API protocol is equivalent to Sun RPC (Remote Procedure Call) with asynchronous events

� Servers Publish service interface and clients subscribe to services

� Client invokes remote procedures executed by the server or receives asynchronous event

� Each server exports interfaces.� RPC encapsulates network access :

� Send/Receive are hidden by Application functions call� RPC protocol manages parameters passing between client to

server.� XDR (External Data Representation) manages heterogeneous

programming language and hardware : Ada, C, C++.

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RPC principle

Library

Main

Push

Pop

Unix process

Library

Main

Send

Receive

Unix process

Client Server

Marshalling

Unmarshalling

=>XDR

XDR

Unix process

S = A+ B

A, B, +

S

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API : Ada distributed Package

Ada Packagespecificationc

Ada PackageImplementation

OperationsOperations

DATAand

Operations Implementation

DATAand



EmptyImplementation

Comms

EmptyImplementation

Comms


DATAand


DATAand


Client side Server side

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Heterogeneous Distributed System : Language or Hardware

Operations

DATAand


Operations

DATAand


Operations

DATAand


Operations

DATAand


Main API interface Operations

DATAand


Operations

DATAand


Operations

DATAand


Operations

DATAand


Ada ServerUnix Process

C ServerUnix Process

C++ ServerUnix Process

Ada or C or C++Client

Unix Process

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API Programming model : Client Register; Start Supervision APIRegister with supervisor; Subscribe to supervision eventsProgram Main Loop

Wait next event Case API

Supervision :peek event from supervision :

process supervision events : Initialise, start, stop, killAPI1 :

peek event from API 1 :process AP1 events : ............

API2 :peek event from API 2 :

process AP2 events : ............End loopStop event processingStop API1, API2Stop supervision APIUnregister

Underlying code is the stubautomatically generatedby PLUG.

Itallic code is written by applicationprogrammer.

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S u p e r v i s e d

I n i t i a l i s e d

R u n n in g

I n i t i a l i s e / S t a r t S e r v i c e s & S u b s c r i b e

S t a r t / P r o c e s s E v e n t s

K i l l / U n r e g i s t e r

U n s u p e r v i s e d

/ S t a r t s u p e r v i s i o n , R e g i s t e r & S u b s c r i b e

U n r e g i s t e r e d

/ R e g i s t e rE v e n t / A c t i o n

F r o z e n

U n f r e e z e / P r o c e s s E v e n t s

S t o p / S t o p s e r v i c e s

K i l l / S t o p S e r v i c e s & U n r e g i s t e r

F r e e z e / D o n ' t p r o c e s s E v e n t s

Client state diagram

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PLUGStub Generator

Register; Start Supervion APIRegister with supervisor; Subscribe to supervision eventsProgram Main Loop

Wait next event Case API

Supervision :peek event from supervision :

process supervision events : Initialise, start, stop, killAPI1 :

peek event from API 1 :

process AP1 events : .


process AP2 events : ............


process AP2 events : ............End loopStop event processingStop API1, API2Stop supervision APIUnregister

• Program skeltons are automatically generated by PLUG.• Stub generation is template driven.• Templates are written with PLUG Template Description Language (TDL).

Template

All Technical Middelware details are hidden to the programmer : Registry, Supervision, Subscription.

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Plug other possible applications

� Symbolic trace and debug functions� Complex structure symbolic dump

� Programming Language Translator� Ada to C, Ada to C++

� Off line and recording files management� XDR standard file format

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Sum Up

� Object Oriented Design is mandatory to manage heterogeneous programming language and hardware to provide P&P.

� Three kinds of services� Ada abstract syntax for Object Message Passing� UBSS based Object Middleware : API� Handcrafted Parser for ATC specific Transfer

Syntax

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IFF

IDL Front End

CORBAIDL

PLUG modularity

ADa Front End

AdaAPI

ASN.1 Front End

ASN.1

CDR Back End

CDR generated encoding source files

XDR Back End

XDR generated encoding source files

BER/PER BE

BER/PER generated encoding source files

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Future

� IDL based ASTERIX compiler� States chart based code generation for Object

dymanic� ASE Skelton automatic generation� Business Object Skelton automatic generation� Ada/C++ translator

PLUG : Presentation Layer Universal Generator

Software

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