Chapter 131 Distributed Processing, Client/Server, and Clusters Chapter 13

2 Distributed Data Processing Allows processors and data to be dispersed Provides a system that is more responsive to a users needs Minimize communication costs by comparison with a centralized approach

Chapter 133 Distributed Data Processing Personal computers many employees have one support user-friendly applications such as word processing, spreadsheet, and presentation graphics Mainframe corporate database sophisticated software for database management

Chapter 134 TCP/IP Protocol Architecture Developed during work on the packet- switched network ARPANET Five independent layers application hot-to-host internet network access physical

Chapter 135 TCP/IP Protocol Architecture Physical layer physical interface between a data transmission device and a network deals with signals, data rate, etc.

Chapter 136 TCP/IP Protocol Architecture Network access layer concerned with the exchange of data between and end system and the network software used depends on type of network concerned with access to and routing data across a network

Chapter 137 TCP/IP Protocol Architecture Internet layer used when two devices attached to different networks internet protocol (IP) is used to provide the routing function routers are used to relay data from one network to another

Chapter 138 TCP/IP Protocol Architecture Transport layer provides logic for assuring that data exchanged between host is reliably delivered protocol at this layer is the transmission control protocol (TCP)

Chapter 139 TCP/IP Protocol Architecture Application layer contains protocols for specific user applications

Chapter 1310 Operation of TCP and IP TCP may break a block into smaller pieces to make it more manageable TCP appends information to each piece destination port sequence number checksum TCP hands the message down to IP with instructions to send it to a host

Chapter 1311 Operation of TCP and IP IP hands the message down tot he network access layer with instructions to send it to the router IP appends a header of control information now called an IP datagram destination host address Network access layer appends header information to create a packet or frame

Chapter 1312 Protocol Data Units in the TCP/IP Architecture TCP Header Network Header IP Header User data Application Byte Stream TCP Segment IP Datagram Network-Level Packet

Chapter 1313 TCP Header Source PortDestination Port Sequence Number Acknowledgement Number Header Length UnusedFlagsWindow ChecksumUrgent Pointer Options + Padding Bit: Octets

Chapter 1314 User Datagram Protocol (UDP) Connectionless server Does not guarantee delivery It adds a port addressing capability to IP Source PortDestination Port Segment Length Checksum Bit: Octets

Chapter 1315 TCP/IP Applications Simple Mail Transfer Protocol (SMTP) provides basic electronic mail facility provides mechanism for transferring messages among separate hosts includes mailing lists, return receipts, and forwarding

Chapter 1316 TCP/IP Applications File Transfer Protocol (FTP) used to send files form one system to another under user commands allows user IDs and passwords to be transmitted allows the user to specify the file and file actions desired

Chapter 1317 TCP/IP Applications TELNET provides remote log-on capability, which enables a user at a terminal or personal computer to log on to a remote computer user functions as if directly connected to the computer remote terminals appear as local to the application

Chapter 1318 OSI Protocol Architecture Open Systems Interconnection Developed by the International Organization for Standardization (ISO) Consists of seven layers Protocols are developed to perform the functions at each layer

Chapter 1319 OSI Layers Application Presentation Session Transport Network Data Link Physical

Chapter 1320 Client/Server Computing Client machines are generally single-user PCs or workstations that provide a highly user-friendly interface to the end user Each server provides a set of shared user services to the clients The server enables many clients to share access to the same database and enables the use of a high-performance computer system to manage the database

Chapter 1321 Client/Server Computing Involves splitting an application into tasks and putting each task on the platform where it can be handled most efficiently Processing for the presentation on the user’s machine Data management and storage on a server Involves a network

Chapter 1322 Generic Client/Server Environment

Chapter 1323 Client/Server Applications Platforms and the operating systems of client and server may differ These lower-level differences are irrelevant as long as a client and server share the same communications protocols and support the same applications

Chapter 1324 Client/Server Applications Actual functions performed by the application can be split up between client and server Optimize platform and network resources Optimize the ability of users to perform various tasks Optimize the ability to cooperate with one another using shared resources

Chapter 1325 Database Applications The server is a database server Interaction between client and server is in the form of transactions the client makes a database request and receives a database response Server is responsible for maintaining the database

Chapter 1326 Client/Server Architecture for Database Applications Client Workstation Presentation Services Application Logic Database Logic Communications Software Client Operating System Hardware Platform Server Database Logic Communications Software Database Management System Server Operating System Hardware Platform Request Response Protocol Interaction

Chapter 1327 Client Server Presentation Logic Application Logic Database Logic DBMS Classes of Client/Server Applications Host-based processing not true client/server computing traditional mainframe environment

Chapter 1328 Client Server Presentation Logic Application Logic Database Logic DBMS Classes of Client/Server Applications Server-based processing server does all the processing user workstation provides a user-friendly interface

Chapter 1329 Client Server Presentation Logic Database Logic DBMS Application Logic Database Logic Classes of Client/Server Applications Client-based processing all application processing may be done at the client data validation routines and other database logic function are done at the server

Chapter 1330 Client Server Presentation Logic Application Logic Database Logic DBMS Application Logic Classes of Client/Server Applications Cooperative processing application processing is performed in an optimized fashion complex to set up and maintain

Chapter 1331 File Cache Consistency File caches hold recently accessed file records Caches are consistent when they contain exact copies for remote data File-locking prevents simultaneous access to a file writing causes the server cached to be updated

Chapter 1332 Middleware Set of tools that provide a uniform means and style of access to system resources across all platforms Enable programmers to build applications that look and feel the same Enable programmers to use the same method to access data

Chapter 1333 Middleware Use of a standard programming interface and protocols There is both a client and server component to middleware Provides uniform access to different systems

Chapter 1334 The Role of Middleware in Client/Server Architecture Client Workstation Presentation Services Application Logic Middleware Communications Software Client Operating System Hardware Platform Server Middleware Communications Software Application Services Server Operating System Hardware Platform Protocol Interaction Middleware Interaction

Chapter 1335 Logical View of Middleware Platform: OS Hardware Application Platform: OS Hardware Middleware (distributed system services) APIs Platform Interfaces

Chapter 1336 Distributed Message Passing Message passed used to communicate among processes Send and receive messages as used in a single system OR Remote procedure calls

Chapter 1337 Basic Message-Passing Primitives Message-passing Module Sending Process Receiving Process Message-passing Module ProcessIDMessage

Chapter 1338 Message-oriented Middleware Client Server Application-specific messages Application Message-oriented Middleware Message-oriented Middleware Transport Network

Chapter 1339 Remote Procedure Calls Allow programs on different machines to interact using simple procedure call/return semantics Widely accepted Standardized client and server modules can be moved among computers and operating systems easily

Chapter 1340 Remote Procedure Call Mechanism Client Application Client Application Remote Server Application Remote Server Application Local Application or Operating System Local Application or Operating System Local Stub RPC Mechanism RPC Mechanism Local Stub RPC Mechanism RPC Mechanism Remote Procedure Call Local Response Local Response Local Response Local Procedure Call Local Procedure Calls Remote Procedure Call

Chapter 1341 Client/Server Binding Binding specifies the relationship between remote procedure and calling program Nonpersistent binding logical connection established during remote procedure call Persistent binding connection is sustained after the procedure returns

Chapter 1342 Remote Procedure Calls Client Server Application-specific Procedure Invocations and Returns Transport Network Application RPC Stub Program Application RPC Stub Program

Chapter 1343 Object Request Broker Client Server Transport Network Application RPC Stub Program Object Server Object Requests and Responses Object Requests and Responses Object Request Broker Transport Network

Chapter 1344 Clusters Alternative to symmetric multiprocessing (SMP) Group of interconnected, whole computers working together as a unified computing resource illusion is one machine system can run on its own

Chapter 1345 Clusters Separate server each computer is a separate server no shared disks need management or scheduling software data must be constantly copied among systems so each is current

Chapter 1346 Clusters Standby Server with No Shared Disk High-Speed Message Link I/O P MM PPP

Chapter 1347 Clusters Shared nothing reduces communication overhead servers connected to common disks disks partitioned into volumes each volume owned by a computer if computer fails another computer gets ownership of the volume

Chapter 1348 Clusters Shared Disk High-Speed Message Link I/O P MM PPP RAID

Chapter 1349 Clusters Shared disk multiple computers share the same disks at the same time each computer has access to all of the volumes on all of the disks

Chapter 1350 Windows NT Wolfpack Wolfpack is code name for clustering technology Shared-nothing cluster Groups combine resources that are easily managed Resources are implemented as dynamically linked libraries (DLLs)

Chapter 1351 Windows NT Wolfpack Physical Resource DLL Logical Resource DLL App Resource DLL App Resource DLL Cluster API DLL Cluster Management Tools Cluster-aware App Database Manager Global Update Manager Event Processor Communication Manager Node Manager Non-aware app Resource Monitors Resource Management Interface Cluster Service RPC Other Nodes Failover Mgr Resource Mgr

Chapter 1352 Solaris MC Prototype distributed operating system built as a set of extensions to Solaris UNIX Provides cluster with a single-system image

Chapter pages53 Solaris MC Structure Other Nodes Network File SystemProcess C++Object Framework Existing Solaris 2.5 Kernel Applications Object Invocations Solaris MC System Call Interface