6 - OOP - LAN Example
Download as PPT, PDF1 like916 views
This document discusses simulating a local area network (LAN) using objects. It describes three main kinds of objects: Nodes, Packets, and a NetworkManager. Nodes represent devices connected to the LAN like workstations and printers. Packets represent information that flows between Nodes. The NetworkManager manages how Nodes are connected. It provides examples of creating these objects, transmitting a Packet between Nodes, and defining Classes and Methods in Smalltalk.
![S.Ducasse 7
Interactions Between Nodes
accept: aPacket
send: aPacket
nodePrinter aPacket node1
isAddressedTo: nodePrinter
accept: aPacket
print: aPacket
[true]
[false]](https://image.slidesharecdn.com/stoop-006-lanexample-101025143347-phpapp02/85/6-OOP-LAN-Example-7-320.jpg)
![S.Ducasse 13
How to define a method?
message selector and argument names
"comment stating purpose of message"
| temporary variable names |
statements
LanPrinter>>accept: thePacket
"If the packet is addressed to me, print it. Otherwise just
behave like a normal node."
(thePacket isAddressedTo: self)
ifTrue: [self print: thePacket]
ifFalse: [super accept: thePacket]](https://image.slidesharecdn.com/stoop-006-lanexample-101025143347-phpapp02/85/6-OOP-LAN-Example-13-320.jpg)
6 - OOP - LAN Example
- 1. S.Ducasse 1 QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture. Stéphane Ducasse Stephane.Ducasse@univ-savoie.fr http://www.listic.univ-savoie.fr/~ducasse/ Let’s Play Objects
- 2. S.Ducasse 2 License: CC-Attribution-ShareAlike 2.0 http://creativecommons.org/licenses/by-sa/2.0/
- 3. S.Ducasse 3 Outline • Simulate a LAN physically • Set up a context for • future chapters • Exercises • Some forward references to intriguate you
- 4. S.Ducasse 4 A LAN Simulator A LAN contains nodes, workstations, printers, file servers. Packets are sent in a LAN and each node treats them differently. mac node3 node2 pcnode1 lpr
- 5. S.Ducasse 5 Three Kinds of Objects Node and its subclasses represent the entities that are connected to form a LAN. Packet represents the information that flows between Nodes. NetworkManager manages how the nodes are connected
- 6. S.Ducasse 6 LAN Design Node WorkstationPrinter NetworkManager Packet addressee contents originator isSentBy: aNode isAddressedTo: aNode name accept: aPacket send: aPacket hasNextNode originate: aPacket accept: aPacket print: aPacket accept: aPacket declareNode: aNode undeclareNode: aNode connectNodes: anArrayOfAddressees nextNode
- 7. S.Ducasse 7 Interactions Between Nodes accept: aPacket send: aPacket nodePrinter aPacket node1 isAddressedTo: nodePrinter accept: aPacket print: aPacket [true] [false]
- 8. S.Ducasse 8 Node and Packet Creation |macNode pcNode node1 printerNode node2 node3 packet| macNode := Workstation withName: #mac. pcNode := Workstation withName: #pc. node1 := Node withName: #node1. node2 := Node withName: #node2. node3 := Node withName: #node2. printerNode := Printer withName: #lpr. macNode nextNode: node1. node1 nextNode: pcNode. pcNode nextNode: node2. node3 nextNode: printerNode. lpr nextNode: macNode. packet := Packet send: 'This packet travelled to' to: #lpr.
- 9. S.Ducasse 9 Objects sends Messages • Message: 1 + 2 – receiver : 1 (an instance of SmallInteger) – selector: #+ – arguments: 2 • Message: lpr nextNode: macNode – receiver lpr (an instance of LanPrinter) – selector: #nextNode: – arguments: macNode (an instance ofWorkstation) • Message: Packet send: 'This packet travelled to' to: #lpr – receiver: Packet (a class) – selector: #send:to: – arguments: 'This packet travelled to' and #lpr
- 10. S.Ducasse 10 Transmitting a Packet | aLan packet macNode| ... macNode := aLan findNodeWithAddress: #mac. packet := Packet send: 'This packet travelled to the printer' to: #lpr. macNode originate: packet. -> mac sends a packet to pc -> pc sends a packet to node1 -> node1 sends a packet to node2 -> node2 sends a packet to node3 -> node3 sends a packet to lpr -> lpr is printing -> this packet travelled to lpr
- 11. S.Ducasse 11 How to Define a Class (Sq) • Fill the template: NameOfSuperclass subclass: #NameOfClass instanceVariableNames: 'instVarName1' classVariableNames: 'ClassVarName1 ClassVarName2' poolDictionaries: '' category: 'LAN’ • For example to create the class Packet Object subclass: #Packet instanceVariableNames: 'addressee originator contents ' classVariableNames: '' poolDictionaries: '' category: 'LAN'
- 12. S.Ducasse 12 Smalltalk defineClass: #Packet superclass: #{Object} indexedType: #none private: false instanceVariableNames: 'addressee originator contents' classInstanceVariableNames: '' imports: '' category: 'LAN' How to Define a Class (VW)
- 13. S.Ducasse 13 How to define a method? message selector and argument names "comment stating purpose of message" | temporary variable names | statements LanPrinter>>accept: thePacket "If the packet is addressed to me, print it. Otherwise just behave like a normal node." (thePacket isAddressedTo: self) ifTrue: [self print: thePacket] ifFalse: [super accept: thePacket]
- 14. S.Ducasse 14 In Java In Java we would write void accept(thePacket Packet) /*If the packet is addressed to me, print it. Otherwise just behave like a normal node.*/ if (thePacket.isAddressedTo(this)){ this.print(thePacket)} else super.accept(thePacket)}
- 15. S.Ducasse 15 Summary Define a class Define a method