unit 2

• Converting 3270/5250 Screens    – Some of the common capabilities       • Multiple host screens can be combined on one display         panel       • Support for the Windows DDE interface allows data from         windows pgms, such as MS-Excel or lotus1-2-3 for         windows       • Supported GUI objects include file folders, fields , tables,         icons, action bars, drop down menus, radio buttons,         dialog boxes and check boxes. • EASEL    – from Easel Corp. was the first product to capture 3270/5250      screens and convert them into a windowing environment.    – This allowed companies to build intuitive interfaces that      required less app. training and improved user productivity.

• Flashpoint:    – developed by viewpoint Systems, which was      purchased by KnowledgeWare.    – Permits developers to add a front-end to existing      3270/5250 screens and perform data validation.    – Flashpoint converts 3270/5250 screens by accessing      their data streams and parsing screens. • MOZart    – Mozart from Mozart Systems Corporation provides      screen emulation from 3270/5250 host screens and      has built in routines for performing data entry      validation.    – Mozart supports DOS or Windows or OS/2.

Database Access Tools

– These tools are provided by third-party vendors or DBMS      suppliers.    – Third party tools offer access to a wide variety of data      sources • Accesspoint    – Accesspoint from KnowledgeWare –formerly from      Viewpoint Systems.    – Accesspoint is a Windows based product for accessing      data from LAN based SQL servers and host databases. • Builder Xcessory 2.0    – Builder Xcessory 2.0 from Integrated Computer Solutions      is a building , prototyping, and testing tool for X-Window      and motif interfaces.

• Data Workbench

– Data workbench is a subset of SYBASE SQL Toolset,   provides a query tool, interactive SQL support, a   report writer, data entry tool and data dictionary   facility. – Can access data in SQL Server and non-Sybase data   structures such as ORACLE, INGRES, DB2,   INFORMIX, and Rdb using SYBASE gateways. – Visual Query Language allows users to develop and   execute complex SQL statements without knowing   the details of SQL . – Report Workbench uses defaults; handles control   breaks, totals and subtotals. – The other tools in Data Workbench include:

• Data Entry- default screens for data entry. • Utilities- list of previously executed queries • Data Dictionary- information about the databases and their   objects. • SQR(Structured Query Report Writer)- a combination of   SQL and a procedural programming language

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Impromptu  – Impromptu from Cognos Inc. is a windows based Query tool.  – User can develop and execute SQL queries using a point and    click interface without knowing SQL. Quest  – Quest is a member of the Gupta SQL System family of products.  – is a graphical data access tool for accessing SQL databases    without knowledge of SQL.  – Four activities of the Quest      • Table- create,browse and edit SQL tables.      • Query      • Report      • Catalog- mgs the data definitions in the database and review        definitions SequeLink  – From TECHGnOsIs, Inc. provides direct, transparent access to    data and services from a variety of client app.  – SequeLink consists of core modules on both the client and    server platforms with interfaces.      • Ref: Fig 6.2 Architecture of SequeLink Pg. No. 92

Client Requirements

• • • • •

GUI Design Standards Open GUI Standards Interface Independence Testing Interfaces Development Aids

• GUI Design Standards   – Assume that its users know how to build effective GUI     app.   – GUI devp. must begin to incorporate some     intelligence for building tasks, such as screen design   – Each org should develop standards and preferences     for GUIs.   – All OK buttons will be green and All cancel buttons     will be red.

• Open GUI standards

– Some basic principles of effective GUI Design.    • Know the users- Developers must understand the      users orientation and work profile    • Simplify often-used tasks- These tasks should      be on a tool bar for quick access    • Provide feedback to the user- the cursor should      be changed to an hourglass to signify a short wait      while the system is processing.    • Beeps should be used only actions that require      immediate attention.    • Be consistent- Don’t let developers stretch their      creative juices too consistency guidelines should      include grammar, syntax, icons, and color.    • Test early and often- the users of the app. GUI      should be tested by other developers and users of

• Interface Independence- For a GUI to be truly portable,   The GUI interfaces should be able to be moved, for ex.   From Motif to Windows 3.x. • Fig 7.2 API libraries for each GUI environment-Pg98.

• Alex Technologies’- ALEX s/w converts character   based interfaces into interfaces for the x-window system • Neuron Data Open Interface from Neuron Data is a tool   kit for building GUIs that are instantly portable and   support the active look and feel of the five major   windowing environments- windows, PM,Motif, OpenLook   and Macintosh. • It provides an object oriented, extensible development   tool kit – Object oriented features , such as   encapsulation and inheritance, improve development   time.

• Portable Application Services    – Pre-built services include standard C libraries for such      fns as memory and window mgt.    – ORACLE Toolkit- uses s layered architecture to      provide a common API for Windows, X Window, Motif,      Macintosh.    – PC-Xview- from Spectragraphics Corp. lets X window      app. Appear on micros that normally run windows      app. And allows both to appear simultaneously on the      same screen.    – XVT(Extensible Virtual Toolkit) is a Library of GUI      programming tools that allow developers to develop      src code that will run with PM, windows, Motif,      Openlook and character based interfaces.

• Testing Interfaces

– Testing character based screens is easy –do   a screen capture and compare screens. If   they match , success; if not , the detective   work begins. – Windowed interfaces are not tested that   easily. – A user can customize a window by changing   its color, size and position. – Automatic Testing Facility(ATF) from   Softbridge, inc. supports unattended testing of   single or multiuser app. Running OS/2 or   windows – Performance analysis software includes two

• SQA:Manager and SQA: Robot for windows    – SQA: Robot for windows is a capture/ playback/      comparison tool that captures windows instead of      screens.    – It requires VB- which can be used to provide a range of      options for running and managing scripts.    – Robot Image Comparator is used to view failures along      side file images.    – SQA: Manager serves as a project MGT tool for s/w      testing    – It helps developers plan, design, and organize      resources, track problems, apply measurements and      generate reports.

– Other integrated utilities offer users testing   flexibility. These include: – Test Dialog- Capture and compare windows controls   such as menus, buttons and dialog boxes. – Test screen- captures and compares screen bitmaps. – Test Event and Test control are DLLs that simulate   any combination of mouse or keyboard input. – Test Driver- includes an enhanced version of the   BASIC lang., a Recorder and a debugger with single   stepping and breakpoints.

• Development Aids

– Products that allow developers to focus more   on the business pbm and less on the   programming details will improve productivity. – This is usually accomplished through built-in   interface intelligence. – They are GUI, Data Access(SQL access and   data dictionaries) – Smart OLTP Interfaces

• Smart GUI Interfaces

– Use object technology to facilitate the building   of GUIs – Items can be displayed on the screen – icons,   file folders, action bars, radio buttons, menus,   dialog boxes, and tables. – Support object inheritance – New object to inherit attributes from existing   objects.

• Smart SQL Interfaces    – To provide transparent access to corporate data, no      mater where it is located.    – A smart SQL interface determines the appropriate      joins if more than one table is involved in a query • Data Dictionaries and Repositories    – Data dictionaries contain all the business data      available through the IS-infrastructure.    – A repository is a very robust data dictionary    – IBM’s Repository Manager/MVS    – Data Dictionary/Solutions(DD/S)- DB2 based data      dictionary    – DB Excel    – InfoSpan

• Smart OLTP interfaces-

– Can be broken down into fairly std steps. – Ex- to update a customer address rec, a   developer would have to code the following   steps

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Verify user authorization to update database. Ask for the customer number Verify it is valid Retrieve the record and populate the screen Position the cursor on the address Accept user input Verify input against any rules Ask for user feedback on correctness Rewrite the record.

• Server is a broad term for any computer that   provides a service to other machines on a   network- be it file sharing, network bridging, or   applications processing. • In most corporate setting, a server is usually a   m/c that provides multi user access to shared   files. • Types of server: database, data, compute   communications,application-specific,and   organization-wide.

The Server

Server Hardware

• In the C/S archi.- the back end server mgs the   data resource: it stores, retrieves and protect   data. • The server reviews the data request and , if   necessary, generates and sends data requests   for other servers. • A server could be a business-specific server,   such as departmental server

• Server for an entire organization

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Benchmarks Used to compare server hardware. Transaction processing counsel (TPC)-is a consortium of major hardware and s/w companies world wide. 3 major benchmark test are: TPC-A- uses a single, update-intensive transaction to load the test system and measures how many transactions per second. TPC-B is considered database test-measures the batch oriented transaction processing performance. TPC-C, a new bench mark modeled on an order entry work load, designed to test processing capabilities in client /server environment.

Categories of Servers

• The concept of a server developed as organizations needed   to share expensive peripherals, such as laser printers, CD   ROM readers, and FAX m/c. • The six types of servers are:    – File server    – Application server    – Data server    – Compute server    – Database server    – Communication server • The differences are based on where data is handled and   how it is transferred.

File Server

• File servers manage a work group’s applications   and data files, so that they may be shared by the   group. • File servers are very I/O oriented • They pull large amounts of data of their storage   subsystems and pass the data over the network. • When data from the file is requested , a file server   transmits all records of a file and its index to the   client • File server require many slots for network   connections and a large capacity, fast hard disk   subsystem. • File locking is handled by locking the entire file or by

• Two tech. used to minimize the amount of data   that passes over the network are: 1) Organizing data so that the data needed by a   particular application request is stored in a   single contiguous block. 2) Storing copies of data accessed by more than   one user to help with concurrency problems.

Application Server

• App. Server is a m/c that serves as a host   replacement. • When app. Are downsized from a host, one   option is to install the app. On a smaller m/c that   runs same s/w and to hook all the users to the   new box. • This process requires no modifications to the   host based app. s/w

Data Server

• A data server is data oriented and used only for   data storage and management. • A data server is used in conjunction with a   compute server and may be used by more than   one compute server. • A data server does not perform any app. Logic   processing

Compute Server • Compute server passes client requests for   data to a data server and forwards the   results of those requests to clients

Database Server

• This is the most typical use of server technology in   client/server app. • Most, if not all, of the app. Is run on the client. • The database server accepts requests for data,   retrieves the data from its database and passes the   results of the request back to the client. • Using the database server or a combination or data   and compute servers, the data mgt fn is on the   server, client pgm consists of app logic and   presentation logic.

Communication Server

• Provides the gateway to other LANs, networks,   midrange computers and mainframes.

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Features of Server Machines Multiprocessing Multithreading Disk arrays Memory subsystems Redundant components

• To increase processing speed or productivity • Multiple processors permit servers to do either symmetric or   functional multiprocessing. • Symmetric multiprocessing allows a task to be dynamically   assigned to any processor as in the fig.

Multiprocessing

• Processing resources are maximized. • Processor does not sit idle if there is work to be done. • App. s/w must be able to support multiprocessing as well.

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LAN OS, Banyan’s VINES SMP and Santa Cruz Operations SCO MP:X currently support symmetric multiprocessing

• Functional Multiprocessing permanently assigns a   set of tasks to a processor as in the fig.

• Multiprocessing supports multithreading- the   concurrent execution of multiple tasks. • To run as different tasks on different processors.

Multithreading

• A thread is the smallest unit of execution that the   system can schedule to run • A path of execution through a process • Each thread consists of a stack, an instruction   pointer, a priority, the CPU State ,and an entry in   the systems scheduler list. • A thread may be blocked , scheduled to execute or   executing. • Threads communicate by sending messages to   each other and they compete for ownership of   various semaphores- which govern the allocation of   computing resources between the individual   threads.

Disk arrays

• Fault –tolerant disk arrays, which are referred to as   redundant arrays of inexpensive disks (RAID),   are std on superservers and optional on other   platforms. • Disk arrays usually include a 486 file server and   software that controls access to the individual   drivers. • Multiple drivers are treated as a single logical drive   by the server operating system.

• Data is broken into chunks and simultaneously   written to multiple disks, a process called   stripping • If a disk fails, the data can be reconstructed by   reviewing the remaining pieces of data. • RAID currently has five levels of data protection   and error correction.

• A proposed sixth level would include the ability to   recover from multiple concurrent disk failures. • The levels of RAID are: • RAID-1- mirrored disks to provide complete data   redundancy on a one to one basis. Each disk has a   twin –contain same data as the primary disk. • RAID2- provides for multiple parity drives with a   slightly lower cost per mega byte. • RAID-3- also called disk guarding, provides for a   minimum of two data drives plus a dedicated parity   drive-used to maintain error correction code (ECC).

• RAID-4-also uses dedicated ECC drives to   provide data integrity and stripes files in blocks   rather than in bytes. • RAID-5-Also distributed data guarding,   eliminates the need for a dedicated ECC drive   by striping data and ECC information. • Two versions of RAID-1.    – Disk mirroring: which uses two drives      attached to the same disk controller    – Disk duplexing: which uses individual      controllers for each drive • Two tech for reliability    – Parity checking- improves reliability    – Data stripping – improve I/O performance

Memory sub systems • Error correction code (ECC) memory and   parity checking is used to prevent   corruption of data travelling within the   server.

Redundant components

• Redundant server components such as disk   drives, power supplies, fans, and automatic   recovery features are option on micro/servers   and std on super servers. • Some super servers offer mirrored processors   and include remote alarms that immediately   warn of network trouble.

Classes of server machines

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Micro/Server Super servers IBM Server 295 COMPAQ SystemPro

Micro/Server

• An upright(vertical) micro that can fit under   a desk • M/S use Intel 486 chips, run at 33MHz or   higher. • Expanded memory capabilities-Hard drive   –from 80 Mbytes to 500 Mbytes. • Intelligent disk subsystem(disk arrays) • Multiprocessing

Super servers

• Developed specially for the client/server   architecture • Multiple processors, large amounts of   memory and high speed disk arrays • Advantages than micro server

– Increased processing power – Increased I/O capabilities – Increased disk capacity – Improved memory mgt – Improved reliability – Improved maintainability

Comparison of micro/servers and          superservers

IBM Server 295

• IBM purchased a minority stake in   Parallan Computer, Inc in June 1992 • Under the agreement, Parallan, no longer   selling its series 290 servers- assumes   IBM development Lab focussing its series   290 multiprocesors • IBM Server 295 was released late 1992. • Parallan server 290 series uses Intel 50   MHz 486 chips • Parallan server 290 series maintained by   remote or local administrators.

COMPAQ SystemPro

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COMPAQ SystemPro 486 series, introduced in 1990   Intel486 processors running at 33MHz or higher   Multiple I/O Bus masters   Compaq Intelligent Drive Array controller   Compaq servers to provide performance, security,   configuration and fault management capabilities include-   The Compaq Insight Manager and The Compaq Server   Manager • Compaq Insight Manager

– Windows based server mgt app. – Greater network control of servers

• The Compaq Server Manager

– Provides advanced remote monitoring

Server Environment

• It manages the network, provides access   to data residing on its storage devices,   generates data requests for data residing   on other nodes and transmit the requests   to the appropriate nodes

• Eight layers of software

– N/w Mgt environment – N/w computing environment and extensions – N/w OS – Loadable modules – Database manager – Database gateways – application

Network Mgt Environment

• Works towards a distributed computing   environment • products

– Distributed management environment – Object Management Architecture – UI-Atlas

• DME- focusing on building   computing and mgt s/w.

distributed

• DME provides:

– An Object oriented application interface – A std API to manage wide range of networked systems – A common GUI across different network management   app. And services

• Object Management Architecture

– Combines distributed processing with object oriented   computing – It provides a std method for creating, preserving, locating   and communicating objects – OMA components

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Object request broker Object services Common facilities Application objects

• UI-Atlas

– UI-Atlas open systems solution from UNIX   International Inc. – Specifies how to create an open systems   architecture using h/w, s/w, networking. – UI-Atlas includes:

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OSI seven layer n/w services model To support both Motif and OpenLook An expanded version of sun’s Network File system Global naming support system A system management framework Distributed object mgt model

Network Computing Environment

• Allow app. To be distributed among   heterogeneous platforms and s/w. • Support this architecture is distributed   computing environment.

• Distributed Computing Environment

• DCE provides two sets of services:

– Basic distributed services- allow developers to   build app. – Data –Sharing services -require no pgming by   the end users, diskless system support.

• The tools provided by DCE as basic   distributed services are:

– Remote procedure calls – Distributed Directory Service – Threads service – Time service – Security service

Distributed File System • Allow users to access data on another   system via n/w • Distributed file system features:

– Access Security and Protection – Data Reliability – Data availability

• Desktop support- power among large   amount of computers • DCE Client/Server Model

Open n/w Computing

• DCE and SunSoft open Network   Computing architectures are similar, there   major differences are:

– Data translation – Location transparency – Transport independence – Multithreading – Security

Extensions

• Tuxedo/T

– New product differ from Tuxedo in the   following areas

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Administration Security Communication Timer services Load leveling

• Network Operating System

– Manages the services of the server

• Loadable Module

– Loadable modules are s/w modules that are   loaded onto the server to improve the   functionality of the servers operating system.