Software Design Document Template Ieee

Multi-user vs. client-server application

There is no denying that the server is a multi-user computer hardware where there are no unusual condition for that a computer into a server and as such must be the preferred hardware platform based on application requirements and financial stringency. Server to client / server applications work when they are configured to none with an operating system that supports the shared memory, application isolation, and preemptive multitasking. An operating system with preemptive multitasking allows a higher priority task or preempt control of the processor from a currently running, lower priority Job. The server provides and controls the shared access to server resources. Applications on a server must be isolated from each other, so that an error not in the other may cause damage. Preemptive multitasking ensures that no single task can take all the resources of the server and prevent other tasks to provide the service. There must be a means of defining the relative priority of the tasks on the server. These requirements are specific to the client / server performance and not on the file server implementation. Because file servers run only the single task of the file service, they can in a limited operational background, without the need for the application and isolated predictive multitasking operating.
The conventional minicomputers and mainframe hosts support as the de facto enterprise server for the network of terminals, they traded have. Because the only functionality available to the user terminal by the host, the personal productivity data and business systems information about this Host server stored. Network services, application services and database services are provided centrally by the host server. Many organizations are downloading data from legacy enterprise server for local manipulation on the job. In the client / server model, the definition of server will continue to include these functions, perhaps even on the same or similar platforms implemented. In addition, the introduction of open systems based servers facilitates the placement of services on many different Platforms. Client / server computing is a phenomenon that developed from the ground up. Remote working groups need to share expensive resources and have connected their Desktop workstations in local area networks LANs grew, until they are ubiquitous in the organization. But often they are isolated from each other. Many organizations have the functionality its dumb terminals integrated into their desktop workstations to support character mode, host-based applications from the individual workplace. The next wave of client / server computing occurring now is, how to start organizations of the mid-1990s, the cheaper and more available processing power of workstation use as part of their enterprise systems. The Novell Network Operating System (NOS), NetWare is the most widely installed LAN. It offers the Premier supports file and print server. However, a limitation of the needs for NetWare reliable client / server applications, the demand for an additional processor is run as a separate database server. The availability of software database server from companies such as Oracle and Sybase, running on the NetWare server that is on a plate spread of this restriction.
Speaking to the functions that make server application File, database, print, fax, image, communications, security, system and network management services. These are each in some detail in the following sections described. It is important to understand that a server is an architectural concept, not a physical implementation declaration. Client and server functions can be physical with the same Device could be provided. With the movement toward peer computing, each device may operate as a client and server in response to requests for the service. Application servers provide business functionality for the operation of the client workstation support. can be provided in the client / server model, these services a all or part of a business function by Inter Process Communication (IPC) is called the request for service. Either message-based RPC requests can be used. A Collection of application servers can work in concert to provide a complete business function. For example, in a settlement system of employee information by ONE Application Server can be managed, the result calculated by another application server and deductions calculated by a third application server. These servers can be different operating systems running on different hardware platforms and can use different database servers. The client application calls those services without regard to the technology or geographical Position of the various servers. Object technology provides the technical basis for the application server and a broad acceptance of the CORBA standards is to ensure the viability this trend. File servers provide data services without a record level database applications. Memory needed for storage is assigned, and the free space is managed by the file server.
Catalog functions from the file server to support file naming and directory structure. File name maximum length ranges 8-256 Characters that support each of the respective server operating system. Stored programs are usually from one file server to run on a client or server platform loaded. Database servers are managed by a database engine such as Sybase, IBM, Ingress, Informix, Oracle or. The file server is the first place, and the database engine provides space for tables in the space of the file made available to server. These hosting services are responsible for the provision of specialized data services, a database product Blackout and automatic recovery after power failure, hardware or software failure required within the file space management, database reorganization, record locking, deadlock detection and management. Print servers provide support for client documents to obtain, prioritize them for the print queue, and run the printer-specific logic required for the selected printer. The print server software has the necessary logic to support the unique characteristics of each printer. Effective Print Server support includes troubleshooting jams and operator notification of errors with instructions for the restart. Fax servers provide similar support as of print servers. Furthermore, fax server queue up outgoing faxes for later distribution when communication costs are lower. Because faxes are distributed in compressed form, either Group III or Group IV compression, the fax server must be able to be dynamic compression and decompression of documents for the Distribution, printing and display. This operation is done usually by the addition of a fax card to the server. If faxing is rare, the software support for the compression and decompression of options can be used. Image servers work in a similar way as fax server.
Infrastructure servers provide support for Wide Area Network (WAN) communications. This support typically includes support for a subset of IBM's System Network Architecture (SNA), asynchronous protocols, X.25, ISDN, TCP / IP, OSI, and LAN-to-LAN NetBIOS communication protocols. In the Novell NetWare implementation of Gateway Communications provides one of the leading communications product. In the LAN Server and LAN Manager environments, OS / 2 Communications Server products are available from IBM and DCA. In the Banyan VINES environment, is the addition of DCA products VINES support for SNA connectivity. UNIX servers provide a number of product-support Add-ons from different providers to the full range of communication requirements. VMS servers support Decent, TCP / IP and SNA as well as various asynchronous serial communication protocols. MVS servers provide support for SNA, TCP / IP, and some support for other asynchronous communication. Security is limited to the server to access software and data access from the server. Communications access is controlled from the communications server. In the Most implementations is the use of user login ID the primary means of security. With LAN servers, some organizations have implemented integrated response Access / Control Facility (RACF) security by creating profiles in the MVS environment, and download those to the LAN server for domain control. System and network management services for the local LAN to be managed by an administrator, LAN, WAN services have to some central location provided. Typically, remote LAN management done from the central data center on site by trained personnel MIS. The discussion in the following sections describe more precisely the functions of the server in a NOS environment provided. Requests are issued by a client to the NOS software services residing on the client computer. These services in an appropriate format of the request and makes the RPC call the application layer of the client protocol stack. This request is received from the application layer of the protocol stack on the server. File Services handle access to the virtual directories and files on the client workstation and the host server in the permanent memory. These services are by the diversion of software as part of the client workstation operating environment implemented made available.
To reduce the burden and impact of the installation and maintenance of software should be loaded on the server software to run on the client be. New versions can be updated on the server and immediately available to all users. In addition, installation in a central location reduces the cost for each Workstation users need to complete the installation process button. Because each client workstation user uses the same software installation, optional parameters are consistent and remote help desk operator are aware of them. This simplifies the analysis, which occur must be supported. The exchange of information, such as word processing documents is easier if all on the same release level, and uses the same basic setting within the software. Central productivity services such as style sheets and macros can be used for the general Use are set. Allow the most personal productivity products to local parameters such as colors, default printer, and so on locally and set up. Backups may be the server to support planned and supervised by a trained person. Backups of client workstations can be scheduled by the server, and data on the server will be stored to facilitate recovery. Tape or optical backup units are typically used for data backup, these devices can easily Support for many users. Place the server and its backups in a safe place helps prevent theft or accidental destruction of backup. A central Location is slightly out by a person, the support that the backup functions can be added safely monitored. With more organizations look to multimedia and imaging technology, large optical storage devices are most appropriately implemented as shared servers. High-quality printer, workstation-generated faxes, and plotters are natural candidates to support a shared server. The server can accept input from many clients, it is after the priority of the request and deal with when the equipment available is queue. Many organizations realize significant savings by fax output to generate the user from their jobs and queue it to a fax server for the transfer, if communication costs are lower. Incoming faxes on the server placed in a queue and to the appropriate client either at the entrance or on request. In Concert with workflow-management techniques, images can be captured and distributed to the appropriate client workstation from the image server. In the client / server model will work Queues at the server by a supervisor in consultation with the standard algorithms, as we continue to determine the queue distribute work. Incoming mail can image paper documents Form is converted into the post office and the appropriate client on the LAN rather than through internal mail. Central collection and distribution allow images to be indexed centrally. This index can be maintained by the database services to all authorized users to query. In this way, the images are recorded once and are available from the Sales immediately to all authorized users. Clearly defined standards on electronic document management allows this technology fully integrated into the desktop experience. There are dramatic opportunities for cost savings and efficiency gains, when this technology is properly implemented and used. Article 10 describes in detail the issues of electronic document management.
In the early morning hours, the database server actually file server with a different interface. Products such as dBase, Clipper run, FoxPro, Paradox, and the database engine in the first line on the client machine and use the file services through the file server to record and provided access Free-space management. These are new and more efficient implementations of the original flat-file models with indices extracted for direct access to the record. Currency control is managed by the application program that issues lock requests and lock controls and by the database server, which queried a lock table when a data access lock check is generated and created. Because access is at the record level that all records of the primary key must be on the client workstation for filtering are returned. There are no facilities to procedural code running on the server to perform joins, rows before or filter to them again to work. This lack of capability dramatically increases the likelihood of records will be locked when multiple clients access the same database and increases the network traffic While many unnecessary lines are to be rejected on the workstation just returned. The lack of server execution logic prevents these products by providing automatic update partial blackout and recovery after an application, system or hardware failure. For this reason, systems that operate in this environment, need support to support an experienced system programmer to restore after a failure. If the applications very simple and require only a single row updated in every interaction will occur this recovery is not problem. However, many client / server applications are required to update more than a single line as part of a logical unit of work. Client / server database engines such as Sybase, IBM's Database Manager, Ingress, Oracle, Informix and support in the server-server application calls on the client workstation issued to execute. The file services are still used for the allocation of places and basic directory services, but all other services directly from the Database server available. Relational database management systems are the current technology for data management. The major disadvantage of the technique is hierarchical that only applications that access data about their physical memory Sequence benefit from locality of reference. Changes to the conditions for the application, that a different procedure requiring access require data to be reorganized. This process, reading, sorting and rewriting of the database is in a new sequence, not transparent for applications that rely on the original physical sequence. Indices, to provide direct access to the database to look for the ability and access on the information in a sequence other than the physical order. However, these indices are known, the user develops the time of application. The developer explicitly refers to the index to get the data of interest. Thus, indexes can not be added later without changing any programs that need this access, To use the index directly. Indexes can not without changing the programs that are currently access the index removed. Most implementations force the application developer be sensitive to the order and the appearance of columns within the record. Thus, no columns are added or removed without any programs that are sensitive to these records. Application sensitivity to physical implementation is the major problem with hierarchical database systems. Application sensitivity to physical Memory introducing significant complexity in the navigation as an application programmer traverse the hierarchy in search of their desired data. Attempts by database vendors, to improve the performance in general have increased the complexity of access. If life is simply to try today, you create a bidirectional virtually paired logical IMS Relationship, and therefore organizations with products such as IMS and IDMS are usually highly paid employees of the database technical support. developed as hardware technology, it is important to develop data management, use the new possibilities. Relational database technology provides the current information management solution for many of the inherent problems in the flat file, hierarchical technologies. In the late 1970s and early 1980s, products such as Software AG ADABAS system and 2000 in an attempt to provide the flexibility required in the application introduced by the systems of the day. IBM's IMS and IDMS Cull network tries, features to add their products, these to increase flexibility. The first products were introduced by relational DB and ADR with Dotcom Computer Corporation of America with the model 204th Each of these implementations used Indices are extracted to direct access to stored data without the scroll sort in the database or flat files offer. All products, trying some of the Performance advantages granted by the locality of reference (storage of related columns and records as close as possible to the primary column and maintain record).
The development of a relational algebra defines the operations that can be carried out between the tables, has enabled an efficient implementation of RDBMS. The establishment of industry standards for defining and accessing relational tables to accelerate the acceptance of RDBMS as the de facto standard for all client / server applications today. Similar standards do not exist yet for OODBMSs. There is a place for both models. Thus, often used to integrate OODBMSs must be transparent, with RDBMS technology. Table 4.1 compares the terminology of RDBMS and OODBMS proponents used. Relational databases are characterized by a simple data structure. All requests on data and relationships between tables based on values based. A data value occurrence is uniquely determined by the concatenation of the table names, column names, and the value of the unique ID of the row (primary key). Relations between tables by a common occurrence of the determined values of the primary key. to create applications that for information from tables, adding a link on the basis of common values. The result of the link is a different table, that a combination of column values contains from the tables involved in the stick together. There remain some applications for the RDBMS have not achieved acceptable performance. Primarily, these applications the very complex data structures needed. Thousands of tables can be defined between them, with many relationships. Frequently, the series will be sparsely populated, and the Applications often require many lines connected, often recursively to the required display. The main players in this market are objectivity Inc., design object, on, and Versant. Other vendors such as HP, Borland and Ingress object features have included in their products. To use properties, leading to an OODBMS choice are shown in Figure 4.3. OODBMS, production is in a position for these types of applications with the introduction of 16Mbps D-RAM and the establishment of persistent (permanent) Databases in D-RAM. Only the logging functions using real I / O. At regular intervals, D-RAM databases are backed up to magnetic or optical disk storage real. In 1993, a significant number of production has been implemented OODBMS applications. With the confidence and experience from these applications, builds the momentum and in 1994 and 1995 is a clear Increase in the use of OODBMSs to see for business-critical applications. OODBMSs have a maturity level is reached with the demand for multimedia-enabled applications. The complexity of dealing with multimedia needs the features of OODBMS for efficient storage and manipulation.
Client / server applications require LAN and WAN Communication services. Basic LAN Services are an integral part of the NOS. WAN services are provided by various communications server products. Article 5 provides a complete discussion of connectivity issues in client / server model. Client / server applications require similar security services to host environments Made available. Each user should be required to log in to be with a user ID and password. If passwords can not be visible to authorized users should the security server to insist that passwords are changed regularly. The company is on the desk assumes that a single application ID and Logon sequence is used to gain the authority again to all information and procedures for user access has a need and a right of access. Since the data can be stored in a less physically secure area, it should be possible to store data in encrypted form. A combination of user ID and the password should be required to decrypt the data. New options, such as floppy less workstation with integrated Data Encryption Standard (DES) coprocessors, are used by manufacturers such as Beaver Computer Company available. These products automatically encrypt or decrypt data read or written to disk or a Communication line. The encryption and decryption is done with the DES algorithm and the user password. This will ensure that no unauthorized user can or data access communications data. This type of security is particularly useful for laptop computers participating in client / server applications, as laptops in locations work with the same physical safety of an office. To access the system from a laptop without the proper use of an ID number and password would be unfortunate to . Flirt NetWare is a family of LAN products with support for IBM-compatible PC and Apple Macintosh clients and IBM-compatible PC servers. NetWare is a proprietary NOS strict sense that it is not necessary a different operating system such as DOS, Windows, Windows NT, OS / 2, UNIX or Mac System 7 to run on a server. A separate Novell NetWare Product-Portable for UNIX server offers support for leading RISC-based UNIX implementations run IBM PC-compatible systems Windows NT, OS / 2, high-end Apple Macs Mac with System 7 and Digital Equipment Corporation VAXs running VMs. NetWare LAN offers the premier environment for file and printer resource sharing. It had 62 percent market share in 1993. It is widely installed as the standard product in many organizations.
Suffice it to say that LAN Manager and IBM-derivative, LAN servers, the standard products are designed for use in client / server implementations with OS / 2 as a server operating system. LAN Manager / X is the standard product for client / server implementations of UNIX System V as a server operating system. Microsoft released its Windows NT Advanced Server product in the third quarter of 1993. In 1994, it comes with support for the Microsoft network management services that currently are known more as "Hermes" and Banyan Enterprise Network Services (ENS). Advanced Server is the natural Migration path for existing Microsoft LAN Manager and IBM LAN Server customers. Existing LAN Manager / X customers are not likely, Advanced Server, an answer to their dreams before 1995. AT & T has taken over responsibility for the LAN Manager / X version. Manufacturers such as Hewlett-Packard (HP) have reservations about the product from AT & T. AT & T and Microsoft has an agreement to compatible APIs to maintain for all basic functions. LAN Manager Advanced Server and client have support for DOS, Windows, Windows NT OS / 2 and Mac System 7 Server support covers NetWare, AppleTalk, UNIX, Windows NT and OS / 2 Client workstations can access data from both NetWare and LAN Manager servers at the same time. LAN Manager supports NetBIOS and Named Pipes LAN communication between clients and OS / 2 server. Redirection services to files and map provided for remote printer job for client use. Advanced Server also supports TCP / IP communications. In early 1994 Advanced Server is still a young product are many missing pieces. Even more annoying, competitiveness between Microsoft and Novell delayed the release of client software and requestor NetWare Core Protocol (NCP) should be supported. Microsoft added TCP / IP support for LAN Manager 2.1 and Advanced Server with Net View and Simple Network Management Protocol (SNMP) Agents. Thus, the tools are in place to provide remote management LAN for LAN Manager LAN. Microsoft has announced support for IBM 6000 for Net View Advanced Server management.
Advanced Server provides support for peer-to-peer processing and client / server applications integrated. Existing Support for Windows NT, OS / 2, UNIX, and Mac System 7 customers can run applications, database and communications server on the same machine as the file and print server. This feature is attractive in small LANs. The native operating system support for preemptive multitasking and storage will ensure that these server applications do not reduce the reliability from other services. Even as Windows NT is rolled to the database, application and provide communications-server applications, the use of Novell as the LAN NOS Client choice will continue to peripheral resources sharing applications. Microsoft has tried the small LAN market with its Windows for Workgroups preempt product. These attacks on the same market NetWare Lite as a low-cost product, is integrated with Windows. It is an attractive option for small organizations without a requirement for larger LANs. The complexity of the system makes it less attractive to management in an enterprise environment already with Novell. WWW can be used with Novell for a working group to some WFW services such as scheduling group can be used. IBM has entered into an agreement to resell and integrate the Novell NetWare product in environments where both IBM LAN Server and Novell NetWare are required. NetWare provides more functional, easy to use and higher performance file and print services. In environments in which these are the only LAN functions, is preferable, NetWare, LAN Manager Derivatives. The ability of the world SNA Interconnect IBM LAN Server makes the product more attractive organizations for both products prefer to run. Most large organizations have department working groups need only the services that Novell also offers LAN server, but for the Client / Server SNA applications with services such as APPN. IBM and Microsoft had to make an agreement on the APIs for the two products are equivalent. But the dispute between the two companies on Windows 3.x and OS / 2, this cooperation has been completed. The most recent versions of NT LAN Manager and LAN Server 3 3 are closer to the agreed equivalence, but it There is no guarantee that this will continue. In fact, there is every indication that the products vary with the different server operating system, focuses on the two companies. IBM LAN Server is a very attractive price so that when OS / 2 clients are used, LAN Server is a cost effective option for small LANs. LAN Server supports DOS, Windows and OS / 2 clients. No support for Mac announced System 7, although it is possible to interconnect AppleTalk and LAN Server LANs to share files and communications services.
Street Talk enables resources to be clearly identified in the network so that it easier to access and manage. All resources, including file services, users and printers, are defined as objects. Each object has a name connected Street Talk with him. Talk Street name followed by a three-level hierarchical format: Item @ @ Organization Group. For example, a user can be identified as Psmith @ @ Cerritos TNET. All network objects are distributed in a Database that can be accessed worldwide, saved. Novell's NDS is similar in Street Talk functionality. However, there are significant differences. NDS partition can and replicate the database to improve performance and reliability in general. NDS is X.500 compliant and allows several levels of hierarchy. Street Talk supports a fixed three-tier hierarchy. The NDS architecture provides more flexibility, but with appropriate complexity and Street Talk is less flexible complexes, to manage and less. One advantage of the current version of Street Talk has about NDS is that Street Talk unlimited objects attributes available for selection may have. Novell and Microsoft have announced support to be in their products for Banyan ENS available in Q2 1994th Banyan and DCA SNA provide services to the vines environment. VINES support UNIX, DOS, Windows, OS / 2 and Mac System 7 customers. NFS is the standard file system support for UNIX. PC NFS support is available from Sun Select and FTP services, to file from a UNIX server on Windows, OS / 2, Mac, UNIX, and offer clients. Client / server computing requires that LAN and WAN topologies exist to make the necessary internetworking to provide for shared applications and data. Gartner surveyed estimated the Group1 and appear Microsystems' integration topologies for the period 1986-1996, the results in Figure 4.6. Of particular interest is the projection that most jobs will be within LANs by 1996, but only 14 percent are in a corporate LAN, up to this time be involved. These figures represent a fairly pessimistic outlook for the transmission companies LAN and enterprise-to-LAN connectivity. These figures probably prove to be significantly underestimated when organizations adopt an architectural perspective for the selection of their platforms and tools and the use of these tools in a organizational systems optimized development environment (SDE). Routers and communication servers will be used to provide communication between local area networks and services in the WAN. In the client / server model, these links are provided transparently by the SDE tools. There is a significant impact on performance when the large volume of traffic are. IBM's implementation in LU6.2 APPC and TCP / IP provides the best support for high-volume, LAN-to-LAN/WAN communication. DEC DECnet implementation has always been good LAN-to-WAN connectivity made available. Built-in support for TCP / IP, LU6.2, and IPX provides a solid platform for client / server LAN-to-WAN implementation within DECnet.
The lack of real estate on the desktop, most organizations promoted in order to form a single unit with terminal-emulation of workstation-access existing mainframe applications. There is a lot of time and effort before any existing host-based applications to be replaced in an organization, the client / server applications. In the long run, the host is still the ideal location for companies to store in databases and the provision of security and network management are services. Mainframes are expensive to buy need to maintain and hard to use, inflexible and large, but they provide stability and capacity of many organizations conduct their business. As Figure 4.7 Notes the opinion of the International Data Corporation, they will not go away soon. Their role will change, but they are about as part of the enterprise infrastructure for many more years. Only organizations that an enterprise architecture strategy and plans for transforming the migration to client-server reached in less than a few years to create. Without a well architected strategy will produce gradual evolution failure. Information that is of value or interest to the entire business by a central data management functions are managed and appear to be saved each user's desk. These applications are traditionally seen as online transaction processing (OLTP) be to the mainframe minicomputer or implemented. With the client / server model, it is possible to use database technology to replicate or migrate data on distributed Servers. Wherever data is stored or used must be the place for the hood and the developers. Data should be stored where it best meets economic need. Online Transaction Processing applications are in industries such as insurance, finance, government and sales process, all found large numbers of transactions. Each of these processes requires a minimum of user think time to process. In these industries, data are often collected at the source of knowledgeable workers. As such The systems are high demands on availability, data integrity, performance, concurrency, growth potential, security and manageability. Systems in these environments implemented to prove its worth, or they are rejected by an organization that has the power. You must be an integral part of the contract process to be implemented. OLTP is traditionally the domain of large mainframe vendors such as IBM and DEC and special machines, fault-tolerant processors from companies such as Tandem and Stratus. The client / server model has the ability to offer all the services for OLTP to much lower cost than traditional platforms required. All standard client / server requirements for a GUI application portability, client / server partitioning function, software distribution and efficient development tools exist for OLTP applications. The first vendor to a deliver production-quality product in this area is cooperative solutions with its product ellipse. required before the ellipsis, OLTP systems to ensure the integrity developer questions to manage the unit-of-work processing, including currency and transaction rollback. Elliptical offers all the necessary components to build systems with these properties. Ellipse currently operates with Windows 3.x, OS / 2 clients and OS / 2 server with the Sybase database engine. Novell is working to port with cooperative solutions ellipse as Novell NetWare Loadable Module (NLM). It provides a powerful graphical development environment with the help of a template-language as shorthand for the development. This language provides a solid basis for the development of organizational SDE and is well suited for the installation of standard components. Since UNIX has matured, it has found many of the functions has other commercial operating systems such as VMS and MVS. Meanwhile, there are several offers for OLTP with UNIX. IBM CICS is to promote 6000 as downsizing strategy for CICS MVS. Database services provided using a combination of AIX and MVS server.
With the release of Windows NT (New Technology) in September 1993, Microsoft's unique location with a server operating system staked. Microsoft's previous development of OS / 2 with IBM did not create the single standard UNIX alternative that was hoped. NT provides preemptive multitasking necessary Services to a working server. It offers extensive support for Windows clients and includes the services necessary to protect the memory for a reliable server operating system is required. Its implementation of the C2-level security goes far beyond that provided by OS / 2, and most UNIX implementations. It is most of the year 1994 to the applications and robust ZING necessary receive an offer industrial strength platform for business critical applications. With Microsoft's Prestige and marketing muscle, NT will be installed by many organizations as their server of choice. IBM MVS provides a platform for large applications. Many existing application services, the organizations working on the system have acquired 370-compatible hardware running MVS. The default network environment for many large organizations SNA is a component of MVS. IBM pulls it before, proprietary systems Label today under the umbrella of the SAA. The goal of the SAA is to provide all services on all IBM platforms in a compatible way, the IBM version of the single-system image. It is a commitment by IBM to provide support for the LAN server runs natively on MVS. This is an attractive option for companies with large existing investments in MVS applications. The very large data storage capabilities of System 370-compatible platforms with MVS provided make the use of MVS for LAN services more attractive to large Organizations. MVS offers a powerful database server with DB2 and LU6.2. With broad industry support for LU6.2, Calls for DB2 databases as part of their view may be issued from a client / server application. Products such as Sybase provides high-performance server application static support, so this implementation viable for high-performance applications production. Digital Equipment Corporation, OpenVMS provides a server platform of choice. VMS has a long history in the distributed computing arena, and contains many of the features necessary to a server in the client-act / server model. December was slow to recognize the importance of this technology, and only recently has the company Arena entered as a serious manufacturer. NetWare supports the use of OpenVMS server for file services. December provides its own interface with a LAN Manager server derivative Product called patchwork. Patchworks run natively on the VAX and Alpha RISC RXP. This is a particularly attractive configuration because it provides access to the same processor to the application, Database and file services through a combination of OpenVMS, NetWare and LAN Manager provided. Digital and Microsoft have announced joint agreements on cooperation provide a seamless integration of Windows, Windows NT, OpenVMS and patchwork. Will greatly facilitate the migration of OpenVMS customers to the client / server model. OpenVMS VAX-support database for products such as RDB, Sybase, Oracle Ingress and allows the platform to effectively execute as the database server for the client / server applications. Many organizations have large investments in hardware VAX and DECnet networking. The possibility of using these as part of the client / server applications as a way to the to maximize the value of this investment attractive. DECnet provides ideal support for the single-system image model. LAN technology is of fundamental importance for the architecture of DECnet. Many large companies moving into the client / server world have the computer on standardized DECnet WAN for processing. For example, selected Kodak Digital networking company and after selection of IBM mainframe and outsourcing company.
UNIX is a primary player as a server system in client / server model. Certainly, the history of Unix in the distributed computing arena, and its open interfaces an excellent opportunity for them on a server of choice. to understand what makes it an open operating system, Look at the components of the system. UNIX has to offer in the early 1970s by AT & T employees a work environment services for software developers designed, discouraged by the incompatibility of new computers and the lack of development tools for application development were. The original intention of the UNIX architecture, it was to define a standard set of services, provided by the UNIX kernel. These services are used by a shell that the command-line interface provides used. The functionality is improved by providing a library of programs. Applications are built up from the program library and custom code. The power and attraction UNIX are the common definition of the kernel and the shell and the large amount of software that was built and is available. Applications built around these standards will be able to many different hardware platforms to be ported. The objectives of the original UNIX were very broad and could have been reached except that the original operating system under the auspices of AT & T-developed legal effects of consent decree on the dissolution of the Regional Bell Operating Companies (RBOCs), AT & T prevents the penetration of the computer industry. As a result, the company had little motivation to promote early on UNIX as a product. To overcome this, and in a Attempt to achieve an implementation of UNIX better suited to the needs of developers, developed by the University of California at Berkeley and other institutions better varieties of UNIX. As a result, the original goal of a portable platform has been compromised. The new products have certainly been better, but they were not compatible or the original implementation. By the mid-1980s, many versions of UNIX, the increasing functionality had been released. IBM, of course, joined in 1986 fight with his own AIX UNIX derivative. Finally, in 1989, an agreement on the most important UNIX kernel was reached, shell functions and APIs. The computer world is close to consensus as to what will the UNIX kernel and shell, and on the definition of the specific APIs. Figure 4.8 shows the components of the future standard UNIX operating system architecture.
While all these turns, a large UNIX has made problem that distinguishes it from DOS, Windows NT and OS / 2 in the client / server world. Since the hardware platforms, on which UNIX lives come from many manufacturers and are in many different chipsets, the "off-the-shelf" software that is sold is not yet available for PCs for UNIX. Software is distributed in its executable form, so it must be compiled and linked from the developer for the target platform. This means that organizations want, Buy a UNIX software, it must be for the specific target platform to buy it used. This also means that if they use many platforms in a distributed client / server application companies need to buy different software versions for each platform.
UNIX is particularly desirable as a server platform for client / server computing because the large range of platform sizes available and the huge base of application and development software. Universities are on the UNIX dynamics contribute by graduates who see only UNIX during their student days. Government agencies are on UNIX as the platform for all projects of the government. The combination of these Pressures and technological changes should ensure that all the UNIX-compatibility for server platforms compulsory in the latter half of this decade. OSF Motif originally developed as a graphical user interface for UNIX that has become the de facto standard UNIX GUI. The Distributed Computing Environment (DCE) of acceptance wins as a standard for the development of distributed applications even though its Distributed Management Environment to achieve must still so widely supported. OSF / 1, which defines OSF UNIX kernel has been adopted only by DEC, although most other vendors have made promises to support them. OSF / 1 brings the promise of a UNIX micronucleus better suited to the desktop environment than existing products. The desire for a standard UNIX encourages other organizations. For example, the IEEE's unified UNIX problem addressed by the establishment a group to a standard operating system called the sustainable development POSIX. The objective of an ANSI-standard operating system is developed. POSIX is not UNIX, but it's UNIX-like. POSIX standards (Which most vendors promise compliance) exist today. DEC OpenVMS operating system that supports, for example, published POSIX standards. POSIX at this point, however, does little to ensure interoperability and portability, because so little to promote the overall standard is completed. Simple applications that have different POSIX-compatible Platforms is running to be written. You will be limited, because the developers are not all applications use the rich, non-POSIX features and functions, the providers of the basic POSIX-compatible core offer. X / Open began to spread to Europe and include most major U.S. computer manufacturers. X / Open is a significant impact on the market, because their goal is to provide a standard set of Application Programming Interfaces (APIs) that enable interoperability, to establish. These interfaces are published in the X / Open Portability Guide. Applications run on operating systems that comply with these interfaces, with each other work together and communicate, even if the underlying operating systems differ. This is the main objective of the client / server model. The COSE announcement from HP, IBM, SCO, Sun and Univel (Novell / USL) in March 1993 in the conference is to create the uniforms latest attempt to provide a common basis between UNIX operating systems. The first announcement COSE addresses only the user's desktop environment and graphical user interface, although with time it is expected to go further. COSE, a pragmatic group is trying to actually "But having made it." Another important difference from earlier efforts to create universal UNIX standards, the participation of SCO, and Sun. These two Organizations themselves a significant share of the UNIX market and have more proprietary approaches to the desktop surface to promote. SCO provides its Open Desktop environment, Sun offers open and look. The commitment to Motif is a significant concession on their part and provides the first real opportunity for a full interoperability Manufacturer and transparent to the user platform.
In October 1993, decided that Novell's rights to the UNIX name X / Open, so that all providers to develop the UNIX standards and apply can give to the UNIX name for their products. These largely symbolic gesture, part of the confusion in the market about what software is really eliminate UNIX. COSE is beyond the desktop to look for graphics, multimedia, object technology, and system management. Networking support includes Novell's NetWare UNIX client networking products, OSF DCE's, and SunSoft's Open Network Computing. Novell has decided to submit the NetWare UNIX Client X / Open for publication as a standard. In the area of Graphic plan, COSE participants to a core temperature of graphics devices from the X Consortium, the developer of X Windows support. Addressing media plan, the participants COSE present two common specifications in response to the Interactive Multimedia Association request for technology. One of these data, called Distributed Media Services (DMS) defines a network-independent infrastructure to support an integrated API and protocol data stream. The other-the Desktop Integrated Media Environment will define multimedia access and collaboration tools, including at least a basic tool for any data type supported by the DMS infrastructure. The resulting standard is consistent with users Access to multimedia tools in multi Finder environments. COSE also addresses object technology, one hosted by IBM and Sun. The group will support the efforts of the Object Management Group (OMG) and its Common Object Request Broker (CORBA) standard for the provision and use of distributed objects. IBM already has a CORBA-compliant object system in the beta test for AIX. Sun built an operating system code-named Spring as a proof of concept in 1992. Sun has a big project in progress, as Distributed Objects Everywhere (DOE), which is very exciting Manufacturing productivity performance. Finally, COSE is on the management of distributed file systems, sales, groups and users, pooling, the installation of the software to concentrate on licensing, and storage. It is no coincidence that these providers are coming together to define a standard UNIX at this time. The COSE is a defensive effort Response to the release of Microsoft's Windows NT. With this commitment to a 32-bit desktop and server operating system, Microsoft has the wind out of many UNIX Claims of technical superiority made. Despite its numerous advantages such as a desktop and server operating system, UNIX has never been generally accepted in the world, the general Corporate purposes favors DOS / Windows and Novell NetWare. A major drawback of Unix in the corporate arena has been the lack of a uniform standard UNIX. UNIX is a good established position as an operating system of choice for distributed relational databases from vendors such as Informix, Ingress, Oracle and Sybase. Most of these providers, however, its harbor Products to Windows NT as well. Any attempt to reduce the problems with which several UNIX variants will do much to enhance the stature of UNIX as a worthwhile alternative to Windows NT.
To spin this fantasy in my head. All the major hardware and software vendors together and agree on a black box in their systems to install, which is in effect, wiping their technological barriers. This black box will be connected to a large number of small operating systems, different hardware platforms, incompatible communications protocols, all Types of applications and database systems and even in contrast to security systems. And the "Black Box" is all this to make it transparent, not only for end users, but also for systems and applications managers developers.2 suggests the OSF Distributed Computing Environment (DCE), as this "Black Box". DCE is the most important Architecture defined for the client / server model. It forms the bridge between the existing investments in applications and new applications based on the current state of the art. Figure 4.10 shows this architecture, defined by the OSF. The first product of the DCE components have been published in the third quarter of 1991. DCE is in direct competition with open network of Sun Computing (ONC) environment and indirectly with many other network standards. OSF / 1 and DCE are almost certain this fight because of the massive market presence of the OSF to gain sponsors. IBM now has sought to require the AIX product OSF / 1 compatible with early 1994. It will be 1995 before the product is mature and complete enough to broad-based used as part of business applications. In the meantime, product vendors and system integrators will use it to build portable products and applications. The general availability code for the previous similar product components are developed to speed up the process and allow new development in the earlier versions modeled be. DCE has been described as another layer of the OSI group in model.3 DCE provides the link between pure communication through the lower layers and end-user applications.
These components are active when a local application requests data, services or processes from somewhere. The OSF DCE says that to make a network of different systems Provider appear as a single stand-alone computer application developers, system administrators and end users. Thus, the single-system image is reached. Remote Procedure Call (RPC) and Presentation Services to control: the Interface Definition Languages (IDLs) and RPCs enable programmers and data over a network in a transparent manner, the Transfer helps mask complexity of the network. DCE RPC uses the originally developed by HP Apollo Network Computing System (NCS), with some improvements from DEC and IBM. NCS also offers the Network Data Representation (NDR), a virtual representation of the data. NDR allows data to be exchanged between different manufacturers products transparent. Conversions (if necessary) will be without the intervention of the caller to take. can take place naming, security, file system and data type conversions, such as data between different Platforms to be transported. Naming: User-oriented names, specifying computers, files and people should be easily accessible in a distributed environment. These directory services must offer standard appearance and rules for all customers. DCE supports the standard X.500 directory services, by extensions of DEC's Domain Name Service (DECdns). The standardized X.500 code Siemens Nixdorf DIR-X is X.500 service. Security: Distributed applications and services need to identify users, control access to resources and guard the integrity of all applications. DCE uses Kerberos Authentication Service, MIT Athena as part of their networking project developed and improved by Hewlett-Packard. This Service is one of the main challenges for the manufacturing of products available quickly, because very few products now being developed with the awareness of this specification. Threads: This terminology is a method to support the parallel execution of multiple threads within a process control manager, in a distributed environment. allow threads to run multiple processes and systems forget about them until they are completed. This is especially important for network servers, the it can handle too many requests from many customers. You must be able to do so without waiting for the original application to complete. DCE with DEC's Concert Multi Thread Architecture (CMA) implementation. Service Time: A time-service system synchronizes all the clocks of a distributed environment so that running applications may depend on the same timing between processes. Consider that many machines in many time zones operational processes as part of a single application solution to offer.
It is important that they agree on the time to manage scheduled events and time events sequenced. DCE is a change in the Distributed Time Synchronization Service DEC. Distributed File Services: The extension of the local file system across the network, users get full access to files on remote configurations. DCE uses Sun's Network File System (NFS) version 2, offering the next generation of the Andrew File System (AFS), developed at Carnegie-Mellon University Transact Corp. and marketed by AFS Diskless support operations conducted by the development of the work of Hewlett-Packard. PC integration: Integration enables PCs MS-DOS, Windows NT and OS / 2 access file and print services outside of the MS-DOS environment. DCE uses Microsoft LAN Manager / X Management: Although some of the previous Parts is addressed, as complex management in distributed, heterogeneous configuration, OSF has defined a new architecture: Distributed Management Environment (DME). DME provides a common Framework for the management of stand-alone and distributed systems. This framework provides consistent tools and techniques for managing the different systems and allows Vendors to system management applications that are based on a variety of platforms work. OSF is on the technology of Hewlett-Packard's Open View Base DME product.
SAA is IBM's distributed environment. SAA was by IBM in 1986 as an architecture defined to integrate all IBM computers and operating systems, including MVS, VM / CMS, OS/400 and OS/2-EE. SAA defines standards for a common user access (CUA) method, common programming interface (CPI), and a common communication link (APPC). To Support the development of the SAA-compliant applications are described, IBM SAA frameworks (APIs that something like that). The first part is SAA AD / Cycle strategy for SAA CASE application development. AD / Cycle is developed to third-party tools within the IBM SAA hardware and mainframe Repository Manager / MVS to use data storage. Several suppliers have by IBM as AD / Cycle partners, namely elected: Intervolve, Knowledgeware, Bachman, synod, a systematic, and Easel Corp. Some products are already available, including the Easel Workbench toolkit, Bachman DB2, CSP tools and the knowledge repository of goods and MVS tools. Unfortunately, the most important component repository manager, is still not in its production quality implementation of MVS and yet it has no plans for a client / server implementation. Many original IBM customers in the evaluation of the participating Repository managers have the product back in frustration. Recently there was much discussion about the need for a production-quality, object-oriented database management system on the Entity-Relationship (ER) model underlying support of the repository. Only this, say some sources do, is practical implementation and performance. Another failure in the SAA strategy is the lack of open systems support. Although certain standards such as Motif, server application, and LU6.2, are identified as part of the SAA, the lack of support for AIX has prevented many organizations from adopting SAA. IBM has published all SAA standards and licenses various protocols such as LU6.2. The company has tried to the opening of SAA software development worldwide. IBM Director of Open Systems Strategy, George Siegel, says that IBM is the openness of the view that the interfaces. So, the complete definition of APIs allows other vendors to develop products that interface with IBM products and with each other. Recent announcements, such as CICS support for AIX, suggest a gradual movement to include in the SAA AIX platforms. The first application, the SAA, IBM, Office Vision released, was a disaster. The product consistently missed delivery dates and it lacked much of the promised functionality. IBM has now largely abandoned the product and works closely with Lotus and its workgroup computing initiatives. IBM has consistently shared database, user interface and communication standards defined on all platforms. This certainly provides an opportunity to SAA-compliant client / to create server applications.
IBM System has clarified his view as DME products. System Profile defines APIs to ensure interoperability between different vendor products to allow. It is expected that the vehicle be for linking AIX in central mainframe sites. IBM has stated that system view is an open structure for the integration of OSI, SNA and TCP / IP networks. At this point, View system help a number of guidelines for third-party software developers and customers, integration of systems access and storage management applications, data definitions and methods. The guidelines are intended to further support the single-system image concepts.
In light of the above Observations, it is meant an important fact that the recent introduction of CICS for OS / 2, AIX and OS/400, as well as the announcement of support for AIX, that a single transaction-processing platform is defined over the entire range of products. Applications under OS / 2 ported designed to work between OS / 2, OS/400, MVS, AIX, and finally, without modification. COBOL and C are the common programming languages for each platform. Server application is the common language of data access on all platforms. The failure of the SAA is the complexity of heterogeneous product lines and plans of the desire of many organizations away from proprietary systems to open solutions. Such confirmation piloted replace IBM's new Open Enterprise plan, the old System Application Architecture (SAA) with plan to announce an open network strategy. System View is a central product of IBM Network OS / 2 links, UNIX, AS/400 and operating systems. Traditional Systems Network Architecture (SNA) networks are replaced by new technologies, such as Advanced peer-to-Peer Communications (APPC) and advanced peer-to-peer networking.

Posted by: Kh Atiar Rahman
Counterpart officer
Financial Management Reform program

About the Author

written by: Kh. Atiar Rahman
Counter Part Officer
Financial Management Reform Programme
Ministry of Finance, Finance Division