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- From: lloyd@abs.net (Lloyd Taylor)
- Newsgroups: comp.client-server,comp.answers,news.answers,comp.object.corba
- Subject: Client/Server Frequently Asked Questions
- Supersedes: <client-server-faq-1-898954306@abs.net>
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- Message-ID: <client-server-faq-1-903359771@abs.net>
- Reply-To: lloyd@abs.net (Client/Server FAQ Maintainer)
- Summary: This posting contains a list of Frequently Asked Questions
- about Client/Server Computing. Please read it before you
- post questions to the comp.client-server newsgroup.
- Keywords: FAQ CLIENT SERVER DISTRIBUTED COMPUTING
- Date: 17 Aug 1998 09:16:12 -0400
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-
- Posted-By: auto-faq 3.1.1.2
- Archive-name: client-server-faq
- Revision: 1.12 1998/08/17 13:15:27
- Posting-frequency: Monthly, on the 17th
-
- Client/Server Frequently Asked Questions
-
- Information about this document
-
- Contained below is a list of commonly asked questions in
- comp.client-server. Before posting a question to comp.client-server,
- check to see if your question(s) are already answered below.
-
- Additional questions (and answers!) may be emailed to lloyd@abs.net.
- If the question is of general interest, it may be added to the CS-FAQ.
- Questions that relate to specific client/server implementation issues
- may be answered in one or more of the books listed in the FAQ. If
- answers cannot be found there, consider posting your question to
- comp.client-server. Due to the volume of email I receive, I cannot
- respond to individual questions.
-
- Vendors of client/server products and services are welcome to submit
- *brief* summaries of their offerings for inclusion in a separate portion
- of this FAQ. A single paragraph which includes pointers to additional
- information (www, ftp, email, or voice telephone) is welcome.
-
- The most recent (authoritative) version of this FAQ is always available at:
-
- http://www.abs.net/~lloyd/csfaq.txt
-
- In addition, this FAQ is archived at many sites, including the
- following. Any site which mirrors "rtfm.mit.edu" should have a current
- copy as well. If you did not receive the entire posting, please check
- here:
-
- ftp://ftp.uu.net/usenet/news.answers/client-server-faq.Z
- ftp://rtfm.mit.edu/pub/usenet-by-group/news.answers/client-server-faq
-
-
- -- Lloyd Taylor
- comp.client-server FAQ maintainer
- Home Page: <http://www.wp.com/Lloyd.Taylor>
-
- Changes since last release:
-
- Updated contact info for Talarian
-
- ----------------------------------------------------------------------
-
- Subject: Table of Contents
-
- Client/Server Frequently Asked Questions List
- Last Revision: 8/17/98
-
- Part 1: Introduction and Miscellaneous questions
-
- 1.1 What archives/FTP sites carry client-server related material?
-
-
- Part 2: Client/Server Definitions
-
- 2.1 What is Client-server Computing?
- 2.2 What is a Client Process?
- 2.3 What is a Server Process?
- 2.4 What is a Two-Tier Architecture?
- 2.5 What is a Three-Tier Architecture?
- 2.6 What is Middleware?
- 2.7 What is Cooperative Processing?
- 2.8 What is Distributed Processing?
- 2.9 What is an "Intranet"?
-
-
- Part 3: Client/Server Technical Issues
-
- 3.1 What are the characteristics of a Client/Server architecture?
- 3.2 What are the different types of Servers?
- 3.3 What are the different client/server processing styles?
- 3.4 What is Distributed or Remote Presentation?
- 3.5 What is Remote Data Management?
- 3.6 What is Distributed Function Processing?
- 3.7 What is IBM's System Application Architecture?
- 3.8 What is APPLE's VITAL architecture?
- 3.9 What is Sun's Open Network Computing Architecture?
- 3.10 What is Digital's Network Application System (NAS) architecture?
- 3.11 What is OSF-DCE?
- 3.12 What are DOMS (Distributed Object Management Systems)?
- 3.13 What is CORBA?
- 3.14 What is DAE?
-
-
- Part 4: Client/Server Business Issues
-
- 4.1 Business-Focused Client/Server Architecture
- 4.2 Client/Server Business Application Architectures
- 4.3 Business Drivers
- 4.4 Business Benefits
- 4.5 What does business expect from IT?
- 4.6 What is Business Process Reengineering?
-
-
- Part 5: Books and Articles on Client/Server computing
-
- 5.1 Introductory/Overview Books
- 5.2 Detailed Technical Books
- 5.3 Other Books
-
-
- Part 6: Vendor Information
-
- 6.1 Middleware Vendors
- 6.2 Test Software Vendors
- 6.3 Development Tool Vendors
- 6.4 Other Client/Server Vendors
-
-
- ------------------------------
-
- Subject: 1.1 What sites carry client-server related material?
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- Object Management Group:
- http://www.omg.org/
-
- DCE Questions and Answers:
- http://www.osf.org/dce/qna
-
- OSF/DCE FAQ
- http://www.osf.org/dce/faq-mauney.html
- ftp://ftp.dstc.edu.au/pub/DCE/FAQ
-
- Object-Oriented Links at Cetus (Germany)
- http://www.rhein-neckar.de/~cetus/software.html
-
- Client/Server Computing Page
- http://www.wenet.net/~jtmalone/
-
- ------------------------------
-
- Subject: Part 2: Definitions
-
- ------------------------------
-
- Subject: 2.1 What is Client-server Computing?
- From: Steve Hultquist <ssh@vnet.ibm.com>
-
- The short answer:
-
- Client/server is a computational architecture that involves client processes
- requesting service from server processes.
-
- The long answer:
-
- Client/server computing is the logical extension of modular programming.
- Modular programming has as its fundamental assumption that separation of
- a large piece of software into its constituent parts ("modules") creates
- the possibility for easier development and better maintainability.
- Client/server computing takes this a step farther by recognizing that
- those modules need not all be executed within the same memory space.
- With this architecture, the calling module becomes the "client" (that
- which requests a service), and the called module becomes the "server"
- (that which provides the service).
-
- The logical extension of this is to have clients and servers running on
- the appropriate hardware and software platforms for their functions.
- For example, database management system servers running on platforms
- specially designed and configured to perform queries, or file servers
- running on platforms with special elements for managing files.
-
- It is this latter perspective that has created the widely-believed myth
- that client/server has something to do with PCs or Unix machines.
-
- ------------------------------
-
- Subject: 2.2 What is a Client process?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- The client is a process (program) that sends a message to a server
- process (program), requesting that the server perform a task (service).
- Client programs usually manage the user-interface portion of the
- application, validate data entered by the user, dispatch requests to
- server programs, and sometimes execute business logic. The client-based
- process is the front- end of the application that the user sees and
- interacts with. The client process contains solution-specific logic and
- provides the interface between the user and the rest of the application
- system. The client process also manages the local resources that the
- user interacts with such as the monitor, keyboard, workstation CPU and
- peripherals. One of the key elements of a client workstation is the
- graphical user interface (GUI). Normally a part of operating system
- i.e. the window manager detects user actions, manages the windows on the
- display and displays the data in the windows.
-
- ------------------------------
-
- Subject: 2.3 What is a Server process?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- A server process (program) fulfills the client request by performing the
- task requested. Server programs generally receive requests from client
- programs, execute database retrieval and updates, manage data integrity
- and dispatch responses to client requests. Sometimes server programs
- execute common or complex business logic. The server-based process
- "may" run on another machine on the network. This server could be the
- host operating system or network file server; the server is then provided
- both file system services and application services. Or in some cases,
- another desktop machine provides the application services. The server
- process acts as a software engine that manages shared resources such as
- databases, printers, communication links, or high powered-processors. The
- server process performs the back-end tasks that are common to similar
- applications.
-
- ------------------------------
-
- Subject: 2.4 What is a Two-Tier Architecture?
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- A two-tier architecture is where a client talks directly to a server,
- with no intervening server. It is typically used in small environments
- (less than 50 users).
-
- A common error in client/server development is to prototype an
- application in a small, two-tier environment, and then scale up by
- simply adding more users to the server. This approach will usually
- result in an ineffective system, as the server becomes overwhelmed. To
- properly scale to hundreds or thousands of users, it is usually
- necessary to move to a three-tier architecture.
-
- ------------------------------
-
- Subject: 2.5 What is a Three-Tier Architecture?
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- A three-tier architecture introduces a server (or an "agent") between
- the client and the server. The role of the agent is manyfold. It can
- provide translation services (as in adapting a legacy application on a
- mainframe to a client/server environment), metering services (as in
- acting as a transaction monitor to limit the number of simultaneous
- requests to a given server), or intellegent agent services (as in
- mapping a request to a number of different servers, collating the
- results, and returning a single response to the client.
-
- ------------------------------
-
- Subject: 2.6 What is Middleware?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Connectivity allows applications to transparently communicate with other
- programs or processes, regardless of their location. The key element of
- connectivity is the network operating system (NOS). NOS provides
- services such as routing, distribution, messaging, file and print, and
- network management services. NOS rely on communication protocols to
- provide specific services. The protocols are divided into three groups:
- media, transport and client-server protocols. Media protocols determine
- the type of physical connections used on a network (some examples of
- media protocols are Ethernet, Token Ring, Fiber Distributed Data
- Interface (FDDI), coaxial and twisted-pair). A transport protocol provides
- the mechanism to move packets of data from client to server (some
- examples of transport protocols are Novell's IPX/SPX, Apple's AppleTalk,
- Transmission Control Protocol/ Internet Protocol (TCP/IP), Open Systems
- Interconnection (OSI) and Government Open Systems Interconnection
- Profile(GOSIP)). Once the physical connection has been established and
- transport protocols chosen, a client-server protocol is required before the
- user can access the network services. A client-server protocol dictates the
- manner in which clients request information and services from a server
- and also how the server replies to that request (some examples of client-
- server protocols are NetBIOS, RPC, Advanced Program-to-Program
- Communication (APPC), Named Pipes, Sockets, Transport Level Interface
- (TLI) and Sequenced Packet Exchange (SPX)).
-
- ------------------------------
-
- Subject: 2.7 What is Cooperative Processing?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Cooperative processing is computing which requires two or more distinct
- processors to complete a single transaction. Cooperative processing is
- related to both distributed and client/server processing. It is a form of
- distributed computing where two or more distinct processes are required to
- complete a single business transaction. Usually, these programs interact
- and execute concurrently on different processors. Cooperative processing
- can also be considered to be a style of client/server processing if
- communication between processors is performed through a message
- passing architecture.
-
- ------------------------------
-
- Subject: 2.8 What is Distributed Processing?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- The distribution of applications and business logic across multiple
- processing platforms. Distributed processing implies that processing will
- occur on more than one processor in order for a transaction to be
- completed. In other words, processing is distributed across two or more
- machines and the processes are most likely not running at the same time,
- i.e. each process performs part of an application in a sequence. Often the
- data used in a distributed processing environment is also distributed across
- platforms.
-
- ------------------------------
-
- Subject: 2.9 What is an "Intranet"?
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- The explosion of the World Wide Web is due to the world-wide acceptance
- of a common transport (TCP/IP), server standard (HTTP), and markup
- language (HTML). Many corporations have discovered that these same
- technologies can be used for internal client/server applications with
- the same ease that they are used on the Internet. Thus was born the
- concept of the "Intranet": the use of Internet technologies for
- implementing internal client/server applications.
-
- One key advantage of Web-based intranets is that the problem of managing
- code on the client is greatly reduced. Assuming a standard browser on
- the desktop, all changes to user interface and functionality can be done
- by changing code on the HTTP server. Compare this with the cost of
- updating client code on 2,000 desktops.
-
- A second advantage is that if the corporation is already using the
- Internet, no additional code needs to be licensed or installed on client
- desktops. To the user, the internal and external information servers
- appear integrated.
-
- A rapidly-disappearing disadvantage is that there is limited ability to
- provide custom coding on the client. In the early days of the Web,
- there were limited ways of interacting with the client. The Web was
- essentially "read-only". With the release of code tools such as Java
- and JavaScript, this limitation is no longer a major issue.
-
- ------------------------------
-
- Subject: Part 3: Client/Server Technical Issues
-
- ------------------------------
-
- Subject: 3.1 What are the characteristics of client/server architecture?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- The basic characteristics of client/server architectures are:
-
- 1) combination of a client or front-end portion that interacts with the user,
- and a server or back-end portion that interacts with the shared resource.
- The client process contains solution-specific logic and provides the
- interface between the user and the rest of the application system. The
- server process acts as a software engine that manages shared resources
- such as databases, printers, modems, or high powered processors.
-
- 2) the front-end task and back-end task have fundamentally different
- requirements for computing resources such as processor speeds, memory,
- disk speeds and capacities, and input/output devices.
-
- 3) the environment is typically heterogeneous and multivendor. The
- hardware platform and operating system of client and server are not
- usually the same.Client and server processes communicate through a
- well-defined set of standard application program interfaces (API's) and
- RPC's.
-
- 4) An important characteristic of client-server systems is scalability. They
- can be scaled horizontally or vertically. Horizontal scaling means adding
- or removing client workstations with only a slight performance impact.
- Vertical scaling means migrating to a larger and faster server machine or
- multiservers.
-
- ------------------------------
-
- Subject: 3.2 What are the different types of servers?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- The simplest form of servers are disk servers and file servers. With a file
- server, the client passes requests for files or file records over a network to
- the file server. This form of data service requires large bandwidth and can
- slow a network with many users down considerably. Traditional LAN
- computing allows users to share resources, such as data files and
- peripheral devices, by moving them from standalone PCUs onto a
- Networked File Server (NFS).
-
- The more advanced form of servers are database servers, transaction
- server and application servers (Orfali and Harkey 1992). In database
- servers, clients passes SQL (Structured Query Language) requests as
- messages to the server and the results of the query are returned over the
- network. The code that processes the SQL request and the data resides on
- the server allowing it to use its own processing power to find the requested
- data, rather than pass all the records back to a client and let it find its own
- data as was the case for the file server. In transaction servers, clients
- invoke remote procedures that reside on servers which also contains an
- SQL database engine. There are procedural statements on the server to
- execute a group of SQL statements (transactions) which either all succeed
- or fail as a unit. The applications based on transaction servers are called
- On-line Transaction Processing (OLTP) and tend to be mission-critical
- applications which require 1-3 second response time, 100% of the time
- and require tight controls over the security and integrity of the database.
- The communication overhead in this approach is kept to a minimum as the
- exchange typically consists of a single request/reply (as opposed to
- multiple SQL statements in database servers). Application servers are not
- necessarily database centered but are used to server user needs, such as.
- download capabilities from Dow Jones or regulating a electronic mail
- process. Basing resources on a server allows users to share data, while
- security and management services, which are also based in the server,
- ensure data integrity and security.
-
- ------------------------------
-
- Subject: 3.3 What are the different client/server processing styles?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Gartner group came out with the five ways of describing the different c/s
- styles based on how they split the three components of any application:
- user interface, business or application logic, data management. The five
- styles are distributed presentation, remote presentation, distributed
- function, remote data management, and distributed data management.
-
- (Note: This is an arbitary classification and others may do it differently)
-
- ------------------------------
-
- Subject: 3.4 What is distributed or remote presentation?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- For people whose roots are embedded in the mainframe IBM world,
- client-server is essentially distributed or remote presentation. This style
- maps a workstation Graphical User Interface (GUI) front end onto an
- existing application's text-based screen. This is also called Remote,
- Mapping, Front-ending or HLLAPI (High-Level Language Application
- Programming Interface). The mode of operation is typically intelligent
- workstations intercepting and interrogating text-screen (e.g. 3270) data
- streams sent from a host for display in a windowed environment.This is
- "frontware" solution, where a GUI front end is added to an IBM/MVS
- 3270/5250 application and is placed on a workstation. However, most
- processing remains on the host or server, with the exception of user
- interface translation logic and possibly validation logic. For example,
- data from an application program is sent to a 3270 screen program on the
- mainframe to be displayed. The merged data is sent to the workstation as
- a 3270 data stream.The workstation interprets the data and converts it to
- graphical form in a window. (Typically every mainframe screen used by
- the application has a corresponding window on the workstation and vice
- versa). When the user enters the data in a GUI window, it is transformed
- by the frontware application into a corresponding 3270 data format and is
- sent to the host computer.
-
- ------------------------------
-
- Subject: 3.5 What is Remote Data Management?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- In remote data management, the entire application resides on the client and
- the data managment is located on a remote server/host. Remote Data
- Management is relatively easily to program for because there is just one
- application program. The client communicates with the server using SQL,
- the server then responds with data that satisfies the query. RDBMS
- products that offer remote data management provide a layer of software on
- the client to handle the communication with the DBMS server.This style
- represents a more traditional LAN database server or file server approach.
- Workstations support the presentation and function logic and interface
- with the data server through the data manipulation language.Distributed
- data management is an extension of remote data management and uses the
- distributed facilities of the DBMS to access distributed data in a manner
- transparent to users. This is most relevant for architectures having data
- spread across several servers and when access to a DBMS on another
- server is required.
-
- ------------------------------
-
- Subject: 3.6 What is distributed function processing?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Here the split occurs in the application functionality, one part going to the
- client, other to the server. Distributed function applications are the most
- complex of the three typologies since two separately compiled application
- programs must be developed. Developers must analyze where each
- function should reside and what type of dialog must occur between the
- two programs. The underlying communications facilities may implement
- either a message-based or remote procedure call (RPC) mechanism for
- transfer of dialog and data. However, there are many variants of this
- typology. One variant of the distributed function style is where data
- management and application function occur at both the client and server.
- In this instance, data management at the client would include referential,
- read-only data. Data frequently updated or accessed by many users would
- reside on the server.
-
- ------------------------------
-
- Subject: 3.7 What is IBM's System Application Architecture?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- SAA is a collection of selected software interfaces, conventions, and
- protocols that are used as a framework for developing consistent,
- integrated applications across the major IBM computing environments.
-
- Four major components of this architecture are:
- - Common User Access (CUA) defines conventions for GUI look and feel.
- - Common Programming Interface (CPI) provides languages, tools, and
- APIs that give applications greater portability and more consistent user
- interfaces across multiple platforms.
- - Common Communication Support (CCS) supports existing
- communications standards, such as LU 6.2.
- - Common Applications, written by IBM, will serve as demonstrations of
- SAA concepts and make it easy for users to migrate between systems.
-
- ------------------------------
-
- Subject: 3.8 What is APPLE's VITAL architecture?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- VITAL provides a way of building information systems constructed from
- generalized modules that can be reused and shared.It specifies how to
- construct and provide interfaces for these modules. A cornerstone of
- Apple's client/server architecture is Data Access Language (DAL). DAL
- consists of software components for the client and the server (Macintosh
- System 7 includes the client component, DOS and Windows clients are
- sold separately). DAL sits between the client and server components.
- This approach allows varied clients to communicate with many different
- servers. With DAL, a change in the DBMS does not affect the front-end;
- it simply requires the appropriate DAL link.
-
- ------------------------------
-
- Subject: 3.9 What is Sun's Open Network Computing Architecture?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Open Network Computing (ONC) is the Sun architecture, with third party
- alliances providing the missing pieces. Sun's RPC is licensed by more
- than 300 companies, including DEC, IBM, and Apple Computer. It is a
- lean, efficient RPC that is particularly effective for installations
- not requiring WAN support. Transport Independent Remote Procedure
- Calls (TI-RPC) were co-developed by Sun and AT&T. TI-RPC runs
- independent of the underlying network transport, allowing applications
- to run unmodified over multiple transport protocols including NetWare,
- PCNFS, AIX/6000, Solaris, UNIX/SVR4, AIX/ESA. NetWise developed the
- TI-RPC Application Toolkit source code generation technology.
-
- ------------------------------
-
- Subject: 3.10 What is Digital's Network Application System (NAS) architecture?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- NAS is a software suite that enables applications to be integrated across a
- distributed network of multivendor systems: NAS services are divided
- into four main groups:
- - Application Access Services which support user interface (forms based,
- graphical or character terminal based)
- - Communication and Central services which support communications
- using electronic mail and EDI
- - Information and resource sharing, which supports database access and
- compound documents (collection of images, graphics and conventional
- text)
- - System Access services which provides a standard operating system
- interface.
-
- ------------------------------
-
- Subject: 3.11 What is OSF-DCE?
- From: Jon Mauney <mauney@jtec.mauney.com>
-
- (Extracted, with permission, from the DCE FAQ, available at
- http://www.osf.org/dce/faq-mauney.html)
-
- DCE is the Distributed Computing Environment, from the Open Software
- Foundation. (It is called "the DCE" by sticklers for grammatical
- consistency.)
-
- DCE consists of multiple components which have been integrated to work
- closely together. They are the Remote Procedure Call (RPC), the Cell
- and Global Directory Services (CDS and GDS), the Security Service, DCE
- Threads, Distributed Time Service (DTS),and Distributed File Service
- (DFS). The Threads, RPC, CDS, Security, and DTS components are
- commonly referred to as the "secure core" and are the required
- components of any DCE installation. DFS is an optional component.
-
- DCE is called "middleware" or "enabling technology." It is not
- intended to exist alone, but instead should be integrated or bundled
- into a vendor's operating system offering. DCE's security and
- distributed filesystem, for example, can completely replace their
- current, non-network, analogs.
-
- ------------------------------
-
- Subject: 3.12 What are Distributed Object Management Systems (DOMS)?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- DOMS provide a way of pulling diverse components together and
- managing their communications. They are aimed at addressing the
- following:
- - A single interface to manage the complexities of a heterogeneous
- environment
- - A uniform framework, based on standards and extensibility, to build,
- integrate, and deploy open distributed-computing applications
- - A method for creating location independence for client applications.
-
- ------------------------------
-
- Subject: 3.13 What is CORBA?
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- CORBA stands for the Common Object Request Broker Architecture. It is a
- set of standard mechanisms for naming, locating, and defining objects in
- a distributed computing environment.
-
- (For technical details, peruse the Object Management Group web site at
- http://www.omg.org)
-
- ------------------------------
-
- Subject: 3.14 What is DAE?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Distributed Application Environment is designed to allow businesses to
- use IBM's RISC System/6000 and PS/2 computers in a client/server
- network (or standalone) for their business applications. DAE consists (1)
- MESSAGING services; (2) DATABASE services ; (3) PRESENTATION
- services; (4) DEVICE services to capture data and to control a broad
- category of controllers, devices, equipment and sensors.
-
- ------------------------------
-
- Subject: Part 4: Client/Server Business Issues
-
- ------------------------------
-
- Subject: 4.1 Business-Focused Client/Server Architecture
- From: Bernard Robertson-Dunn <brd@netinfo.com.au>
-
- When analysing a business there are three views of the organisation:
-
- - A functional model, which reflects organisational responsibilities
- and the way in which the people who use the system view their work.
-
- - A process model, which details the business functions of the
- organisation (eg accept orders, make goods, deliver goods, bill
- customers, receive money). The functional structure and process model
- rarely, if ever, agree.
-
- - An information model, which details the information that the
- organisation needs to function.
-
- ------------------------------
-
- Subject: 4.2. Client/Server Business Application Architectures
- From: Bernard Robertson-Dunn <brd@netinfo.com.au>
-
- Traditional applications architectures have been based on function.
- Today, to meet the needs of the business an application architecture
- should reflect the complete range of business requirements.
-
- Therefore, client/server computing demands a three layer view of the
- organisation.
-
- 1 The user interface layer, which implements the functional model
-
- 2 The business function layer, which implements the process model
-
- 3 The data layer, which implements the information model
-
- It should be noted that this application architecture does not demand
- multiple hardware platforms, although such technology can be utilised,
- if the environment is robust and reliable enough and the business is
- prepared to pay the additional costs associated with workstation and
- LAN technology.
-
- ------------------------------
-
- Subject: 4.3 Business Drivers
- From: Bernard Robertson-Dunn <brd@netinfo.com.au>
-
- Client/server computing has arisen because of a change in business
- needs. Businesses today need integrated, flexible, responsive and
- comprehensive applications to support the complete range of business
- processes.
-
- Problems with existing systems include:
- - applications were developed to model vertical applications
- - applications were built in isolation
- - applications were implemented as monolithic systems
- - applications were complex
- - the supporting technology was based on a centralised control model
-
- Information technology, which is an enabling factor in systems
- building, has almost reached the stage where these systems can be
- designed and created. Unfortunately, most businesses have existing
- systems based on older technology, which must be incorporated into the
- new, integrated environment.
-
- The development and implementation of client/server computing is more
- complex, more difficult and more expensive than traditional, single
- process applications. The only answer to the question "why build
- client/server applications?" is "because the business demands the
- increased benefits.
-
- ------------------------------
-
- Subject: 4.4 Business Benefits
- From: Bernard Robertson-Dunn <brd@netinfo.com.au>
-
- - There is a perceived need for vendor independence. This includes
- application development methodologies, programming paradigms, products
- and architectures.
-
- - Organisation have changed from steep hierarchies to flattened
- hierarchies
-
- - Network management is replacing vertical management
-
- - There is a change to team based management
-
- - The customer should have a single point of contact for all business
- with the organisation
-
- - The customer should deal with the same person over multiple contacts.
-
- - The user will perform as much processing as possible during customer
- contact time
-
- - The time required to complete the work will be minimised
-
- - There is a need for empowerment of staff and audit trail of actions
-
- - Multi-skilled and multi-function teams need access to multiple
- applications
-
- ------------------------------
-
- Subject: 4.5 What does business expect from IT?
- From: Bernard Robertson-Dunn <brd@netinfo.com.au>
-
- - New applications should be aligned with both the user's view and the
- business process view. Existing functionally aligned systems are not
- appropriate
-
- - Applications need to provide a consistent user interface
-
- - Application complexity needs to be hidden
-
- - The user interaction must be flexible
-
- - Consistent information across all applications
-
- - A variety of user interface styles to reflect the needs of the work
-
- - Users should be able to modify business rules without reference to IT
- staff
-
- - IT systems will support all activity performed by the user, not just
- a part
-
- - An ability to evolve IT systems to reflect changing business
- requirements
-
- - It is essential that there be integrity of transactional processes
-
- ------------------------------
-
- Subject: 4.6 What is Business Process Reengineering?
- From: Ravi Kalakota <kalakota@uhura.cc.rochester.edu>
-
- Reengineering is the organizational process required to align people,
- processes and technology with strategies to achieve business integration. It
- can also be thought of as taking a business in its current state and forming
- an organizational and operational blueprint to redirect skills, policies,
- information (data), cultural values, organizational structures, processing
- and incentives towards targeted improvements.
-
- ------------------------------
-
- Subject: Part 5: Books on Client/Server Computing
-
- ------------------------------
-
- Subject: 5.1 Introductory/Overview Books
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- AUTHOR: Orfali, Robert, et. al.
- TITLE: Essential Client/Server Survival Guide
- PUBLISHED: New York : Van Nostrand Reinhold
- ISBN: 0-442-01941-6
-
- AUTHOR: Berson, Alex
- TITLE: Client-server architecture / Alex Berson.
- PUBLISHED: New York : McGraw-Hill, c1992.
- SERIES: J. Ranade series on computer communications
- ISBN: 0070050767
-
- AUTHOR: Smith, Patrick.
- TITLE: Client/server computing
- PUBLISHED: Carmel, Ind. : SAMS, c1992.
- SERIES: Professional reference series.
- ISBN: 0672300656
-
- AUTHOR: Linthicum, David
- TITLE: David Linthicum's Guide to Client/Server and Intranet
- Development
- PUBLISHED: Wiley, c1997.
- ISBN: 047117467X
-
-
- ------------------------------
-
- Subject: 5.2 Detailed Technical Books
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- AUTHOR: Orfali, Robert, Dan Harkey.
- TITLE: Client/server programming with OS/2 2.0
- PUBLISHED: New York : Van Nostrand Reinhold, c1992.
- SERIES: VNR computer library
- ISBN: 0442012195
-
- AUTHOR: Dewire, Dawna Travis
- TITLE: Client/server computing
- PUBLISHED: New York : McGraw-Hill, c1993.
- SERIES: James Martin/McGraw-Hill productivity series
- ISBN: 007016732X
-
- AUTHOR: Renaud, Paul E., 1957-
- TITLE: Introduction to Client/Server Systems, 2nd Edition
- PUBLISHED: New York : Wiley, c1996.
- SERIES: Wiley professional computing
- ISBN: 0471133337
-
- ------------------------------
-
- Subject: 5.3 Other Books
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- AUTHOR: Baker, Richard H.
- TITLE: Networking the enterprise : how to build client/server
- systems that work
- PUBLISHED: New York : McGraw-Hill, c1994
- SERIES: McGraw-Hill series on computer communications
- ISBN: 0070050899 : 0070050902 (PBK)
-
- AUTHOR: Khanna, R. (Editor)
- TITLE: Distributed Computing: Implementation and
- Management Strategies
- PUBLISHED: New Jersey: Prentice Hall, c1994
- ISBN: 0-13-220138-0
-
- AUTHOR: Inmon, William H.
- TITLE: Developing client/server applications
- PUBLISHED: Boston : QED Pub. Group, c1993.
- ISBN: 0894354582
-
- AUTHOR: Boar, Bernard H., 1947-
- TITLE: Implementing client/server computing : a strategic
- perspective
- SERIES: McGraw-Hill systems design & implementation
- ISBN: 0070062153
-
- ------------------------------
-
- Subject: Part 6: Vendor Information
-
- Vendors may submit information for possible inclusion in this section
- to lloyd@abs.net. Please limit your submission to one paragraph, and
- include contact information. If you want to be taken seriously by the
- readership of comp.client-server, it is strongly suggested that you
- include a pointer to your WWW page. If you don't have one, get one.
-
- No endorsement is to be inferred from inclusion in the CS-FAQ.
-
- ------------------------------
-
- Subject: 6.1 Middleware Vendors
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- =======
-
- NobleNet specializes in providing high quality middleware tools for
- client-server development. Our premier product is EZ-RPC, an RPC
- precompiler tool kit that includes our enhanced XDR (packaged as an
- IDL), precompiler, and various libraries. EZ-RPC is available on more
- than 40 platforms, including most UNIXes, most Windows, Macs, Vms,
- OS/2, and several others. We also publish a Windows rpcgen and
- distribute the IONA coporation's Orbix Object Request Broker
- development toolkit. A new product, a distributed two-tier ODBC driver
- SDK, is available for those working with databases. We provide free
- evaluation copies of EZ-RPC to qualified programmers. For more
- information, contact NobleNet, Inc. at 508-460-8222, send email to
- sales@noblenet.com, or browse <http://www.noblenet.com/>. An EZ-RPC
- mailing list is available. Subscribe by sending a message to
- ezrpc-request@world.std.com with the single word "subscribe" in the
- message body.
-
- =======
-
- Piccolo(tm), from Cornerstone Software, Inc. is a message-oriented
- middleware product that provides application developers with peer-to-peer
- connectivity without regard for the underlying communications transport
- (i.e. TCP/IP, NetBios, Async). Piccolo is supported on UNIX versions AIX,
- SCO, HP-UX (HP9000/700 & 800), Tandem S2 Integrity, Solaris 2.1, and Silicon
- Graphics (SGI). It is also supported on Windows 3.x, Windows NT, and the
- Tandem NonStop Kernel. Application developers use the Piccolo API to access
- data and applications residing on any of the supported platforms on a
- network. The developers need no programming knowledge of the underlying
- transport protocol. For more information, point your Web browser to
- http://www.corsof.com/, or E-mail piccolo@corsof.com, or call Piccolo Sales
- at 603-595-7480.
-
- =======
-
- PIPES Platform, from PeerLogic, is message-oriented middleware that
- provides the essential communications services for distributing
- applications across the enterprise. PIPES Platform's process-to-process
- messaging allows development of applications with an asynchronous,
- non-blocking, event-driven architecture. A dynamic name service lets
- you find at run-time and communicate with any application resource in
- the PIPES Platform network. PIPES Platform automatically maintains
- information on all PIPES Platform resources, even as machines and
- applications are added or moved. Session management services provide
- guaranteed message delivery, integrity, prioritization, sequencing,
- dynamic re-routing, and error handling. PIPES Platform's cross-platform
- and multiprotocol support provide a consistent communications interface
- that allows developers to focus on business logic, not communications.
- Contact Jennifer Hart, Director, Product Marketing, 800-733-7601,
- jhart@peerlogic.com; http://www.peerlogic.com/
-
- =======
-
- SmartSockets (tm), from Talarian Corporation, is a rapid application
- development toolkit which enables processes to communicate quickly,
- reliably, and securely across different operating system platforms,
- through the use of messages. The communicating processes can reside
- on the same machine, on a LAN, on a WAN, or anywhere on the Internet.
- SmartSockets is an industrial-strength package which takes care of
- network interfaces, guarantees delivery of messages, handles communication
- protocols, and deals with recovery after system/network failures.
- SmartSockets's programming model is built specifically to offer
- high-speed interprocess communication, scalability, reliability and
- fault tolerance. It supports a variety of communication paradigms
- including publish-subscibe, peer-to-peer, and RPC. Included as part of
- the package are graphical tools for monitoring and debugging your
- application. SmartSockets is available on most UNIX, OpenVMS, Windows
- 3.1, Windows 95, Windows NT, and OS/2. For more information, contact
- Kelly Bernardo at 650-965-8050 ext. 145. Also, visit our home page at
- http://www.talarian.com/, or E-mail info@talarian.com.
-
- =======
-
- Entersoft Systems Corporation supplies NCR's TOP END (tm)
- Transaction Request Broker middleware. TOP END has been used by
- customers in banking, retail, telecomm and other industries to
- build some of the largest transaction processing systems
- connectiong 100s of nodes and up to 10,000s users. TOP END runs
- on Windows (all versions), UNIX, and legacy platform, and
- includes support for Java and Active/X applications. Entersoft
- is the sole supplier of TOP END on most platforms. Entersoft
- also provides add-on products for transaction processing, such
- as the TOP END-Tuxedo Message Gateway. Customers can contact
- Entersoft at http://www.entersoft.com or at 908-575-9100.
- Customers can also get additional TOP END information at NCR, at
- http://www.ncr.com/product/topend/index.htm.
-
- ------------------------------
-
- Subject: 6.2 Test Software Vendors
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- =======
-
- EMPOWER/CS is load testing software for client/server applications. Load
- testing is the process of analyzing the effect of many users on an
- application. EMPOWER/CS listens to the traffic between a client and
- server. It builds scripts that can be replayed with or without the
- client devices. Scripts can be enhanced with C language to extend
- captured activity and vary the data in queries and updates. EMPOWER/CS
- charts the time each user must wait for his or her screen response
- before an application is deployed. Performix, Inc., 8200 Greensboro
- Drive, Suite 1475, McLean, VA 22102 (703)448-6606, (703)893-1939 (fax),
- Email: info@performix.com
-
- ------------------------------
-
- Subject: 6.3 Development Tool Vendors
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- =======
-
- ICONIX Software Engineering, Inc. is the maker of ICONIX PowerTools,
- CASE tools for object-oriented and structured development. ICONIX
- offers a free white paper on combining OMT with Objectory for
- client/server development, along with special offers and product
- information about ICONIX PowerTools, by visiting the new ICONIX WWW
- PowerPage site: <http://www.biap.com/iconix/>. For further information,
- contact Alyse Rome, Director, New Media Marketing & Communications,
- ICONIX. Voice: 310-458-0092; email: ICONIX@eworld.com.
-
- =======
-
- Unisys TransIT Open/OLTP Software is a suite of development tools and
- runtime management software that provides transaction processing
- extensions for Windows and Windows NT and UNIX based applications.
- Enterprises can quickly develop distributed and highly scaleable
- business application systems, based on standard (X/Open and ISO)
- high-level APIs, networks and protocols. These applications can then
- seamlessly blend the attributes of UNIX, Windows, Windows NT and
- mainframe systems and can integrate and synchronize the many different
- databases used on each of these platforms. This Client/Server
- middleware works with Microsoft or third party development tools and
- includes the libraries for C, C++ or COBOL, plus Windows and Windows NT
- Dynamic Link Libraries (DLLs). The Windows and Windows NT support also
- includes OLE point-and-click features for application development. On
- every platform, these tools enhance normal data access (e.g., ODBC or
- SQL) capabilities with transaction processing, naming/location services
- and the store and forward (queuing) of messages. Runtime environments
- are highly tunable with the ability to locate and/or replicate server
- applications as desired without any impact to the client applications.
- Likewise, server applications are immune to client changes due to new
- platforms, applications or interfaces. For more information, please
- reference <http://www.unisys.com/>, or contact Phil Wimpenny via
- telephone at +1-215-986-5765 or via email at wimpenny@po3.bb.unisys.com
-
- =======
-
- JYACC is the maker of JAM 7, a cross-platform tool for building
- client/server and distributed applications. It consists of a graphical
- screen painter, its own scripting language called JPL, a Visual Object
- Repository to allow creation of complex objects that can be shared
- across screens and updated through inheritance, 100's of C library
- function calls, and various tools and utilities. JAM applications can
- run unmodified on more than 100 platforms and operating environments,
- including DOS, MS-Windows, Motif, OS/2 Presentation Manager, Macintosh,
- VAX/VMS, and virtually every implementation of UNIX, both in
- character-mode and in Motif. JAM also integrates seamlessly with more
- than twenty of the most popular RDMBS products, including native drivers
- for Oracle, Sybase, Informix, ODBC, DB/2, and others. JAM works with
- the leading Transaction Monitors, including Tuxedo, so that developers
- can create true Three-Tier applications. For more information, please
- reference: <http://www.jyacc.com>, Email: jazzin@jyacc.com,
- Phone:800-458-3313 or 212-267-7722
-
- =======
-
- INTERSOLV is a leading provider of open client/server development
- solutions. INTERSOLV development solutions are available for
- object-oriented development, open client/server development, software
- configuration management and data warehousing. Customers benefit from
- INTERSOLVs common look and feel, broad coverage and rich functionality.
- INTERSOLV, with annual revenues exceeding $120 million, has more than
- 375,000 product licenses at 16,000+ customer sites around the world.
- The INTERSOLV World Wide Web site can be accessed at
- http://www.intersolv.com/.
-
- =======
-
- CS/8000 is the first development system that seamlessly integrates
- methodology, expert systems and client/server system architectures.
- With CS/8000 you have all the tools you need to manage client/server
- projects of any level of complexity. Use it to select your system
- architecture, develop your project plan, and generate all of your
- project documentation. CS/8000 keeps you organized and keeps you on
- track. Learn more about Client/Server Connection by visiting us at
- http://www.cscl.com or contacting us. Voice: 914-241-9100 email:
- cscl@cscl.com
-
- =======
-
- Cornut Informatique provides a range of client/server products. CI-Link is a
- powerful middleware that connects SQL database with Macintosh and PC/Windows
- applications. Eclipse Query is an easy to use query tool for Macintosh and
- PC/Windows. Eclipse Report is graphical multi data source report generator.
- Eclipse Builder is C/S development environment for Macintosh and PC/Windows.
- Don't read our lips, try and judge. The Cornut Informatique Web site can be
- accessed at http://www.cornut.fr/. Frederic Bouquet, fbouquet@cornut.fr
-
- =======
-
- MAGNA X from Magna Software Corporation provides a safe growth path to the
- open systems environments of the 1990's, a path that preserves and leverages
- your existing IS investment. MAGNA X is an open OLTP application
- development system that simplifies growth into the complex world of
- distributed computing involving PCs, UNIX servers, and mainframes. MAGNA X
- generates three-tier client/server TP systems, concentrating on the SERVER
- portion of distributed systems. Services are generated for UNIX and/or
- CICS/ESA; Windows NT support has been announced. Unlike competing 3-tier
- products, MAGNA X is strictly open. There is no run-time software.
- Industry-standard middleware (Encina, CICS, Tuxedo, Entera) is used for
- connectivity. Service programs are generated in COBOL and/or C++ (available
- late '96) and are fully compiled, efficient. Front-end clients can be
- written in any language, including Power Builder, Visual Basic, Delphi,
- Java, C or C++. If PB or VB is used, MX "Wizards" automate the construction
- of fully functional "test clients" with no programming required. The MAGNA
- X development environment is currently available on most major UNIX
- platforms. Oracle, DB2/AIX, DB2/MVS, Sybase and Informix are supported.
- Local service and support is available in the U.S, Europe, Japan and Korea.
- For more information: info@magna.com, www.magna.com or call 212/691-0300.
-
- =======
-
- Blyth Software is an international supplier of modular application
- development tools for building, deploying, and maintaining workgroup,
- departmental and enterprise client/server applications. Blyth has
- more than 25,000 registered developers and 450 ISVs worldwide. Blyth
- Software is headquartered in Foster City, California, with
- international offices in London, England; Hamburg, Germany; and
- distributors throughout Europe, Asia Pacific and Latin America.
- URL: http://www.blyth.com email: info@blyth.com
- US Sales: 1.800.346.6647 email: us_sales@blyth.com
- US TechSupport: 415.570.2220 email: us_support@blyth.com
- UK/EUC Sales: (44) 1344.482258 email: uk_sales@blyth.com
- UK/EUC Tech Supp: (44) 1344.482258 email: alistair_killick@blyth.com
-
- =======
-
- Dynasty is a true Enterprise Client/Server development environment.
- It provides a truly Open solution, generating runtime-free C code,
- native to the target platforms. Presentation can be targeted at Windows
- 3.x/95/NT, OS/2, Motif and Macintosh. Services can be automatically
- partitioned in various ways, from standalone with the client, to out on
- NT, OS/2, Unix or Tandem servers, with no limit to the number of tiers.
- It is also possible to create servers that can be accessed from Visual
- Basic, Powerbuilder and Internet clients. Standard communication
- protocols such as IMC and TCP/IP are supported, as well as Tuxedo for
- more complex distributed applications requiring TP. SQL for Oracle,
- Sybase, Informix, SqlBase, Nonstop SQL, DB2/2, SQL Server and ODBC is
- automatically generated, with the option to modify it if necessary.
- For more information see http://www.dynasty.com where local country
- information is also available.
-
- ======
-
- Systemator is produced by Sysdeco, a well-known Scandinavian software
- company. Systemator provides support for all phases of the
- development process, from modeling through to implementation,
- testing and maintenance of information systems. Systemator
- supports a wide range of machine platforms, database systems and
- user interfaces. Its powerful repository and conceptual modeling
- abilities ensure cost effective development as well as much lower
- maintenance costs. Thanks to its graphical dialog modeling and editing
- tools, Systemator provides a powerful GUI prototyping capability which
- greatly facilitates user involvement in the initial stage of
- prototyping. In Systemator's model designer you can build abstract
- models of the structure, the functions and the information of
- your enterprise. Data modeling is used for describing the structure of
- the information handled by the organization. The data model is the
- basis for generating both database structures and user dialogs. Such
- an abstract model of the data ensures portability between several
- database management systems and windowing systems. More information is
- available on the WWW at http://www.sysdeco.no/tools/systemator/
- or by contacting Vivian Ra (vra@sysdeco.no, tel:+47 22 09 65 00,
- fax: +47 22 09 65 01)
-
- =======
-
- Nat Systems builds and supports the NatStar development tool. NatStar
- offers an pragmatically object oriented and user friendly environment for
- rapidly developing applications that can be deployed enterprise-wide, from
- the mainframe to the desktop, making native use of middleware. NatStar's
- development environment offers three separate but tightly integrated
- modules for graphically defining the presentation, data model and workflow
- model of the application. NatStar automatically generates code and SQL
- that can be deployed in a multi-tier environment, enabling a dynamically
- partitioned application. NatStar is a perfect tool for Component Based
- Development and today offers a catalog of tried and tested technical
- components, and business components for the near future. NatWeb
- is Nat Systems' solution for developing Internet applications that
- front-end legacy systems. Nat Systems offers support for the entire
- software development cycle, enabling integration with upper CASE tools,
- Configuration & Change management, workflow tools, document management,
- etc. See www.natsys.com for more info.
-
- ------------------------------
-
- Subject: 6.4 Other Client/Server Vendors
- From: Lloyd Taylor <Lloyd.Taylor@jhuapl.edu>
-
- =======
-
- The IBM Client/Server Computing Unit maintains a web page at
- http://www.csc.ibm.com dedicated to information related to client/server
- computing. It addresses both business and technical issues.
- The business side includes a Consultant's Corner where there are articles
- from industry experts. The technical side includes a web demo of
- IBM's Client/Server Advisor System and many client/server success
- stories from around the world. There is also a Client/Server Spotlight
- section that contains a C/S Newsletter and information on other C/S
- resources. Suggestions on additional content are welcome.
-
- =======
-
- Sequent Computer Systems, Inc. is a leading architect and provider of
- open client/server solutions for enterprise business computing. With
- an installed base of nearly 8,000 systems, Sequent leads all other
- vendors of high-end UNIX systems supporting very large-scale on-line
- transaction processing (OLTP), decision support (DSS)/data warehousing
- and Internet-based applications. Sequent's project-oriented offerings
- include consulting, educational and professional services geared to
- help organizations re-architect their existing information technology
- infrastructures. Sequent successfully commercialized symmetric
- multiprocessing (SMP), and today, architects enterprise-class computing
- environments based on open systems. Symmetry servers incorporate up to
- 30 industry-standard processors to provide superior price/performance and
- scalability for on-line transaction processing (OLTP), data warehouses
- and the application of internet technologies to business communications
- (including intranets). NUMA-Q systems, Sequent's next-generation, will
- scale to more than 250 processors and manage 100 terabytes of data.
- Call (530) 626-5700, or browse our website at http://www.sequent.com/.
-
- =======
-
- End of Client/Server FAQ
-