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Multi-User Client Vs Application Server
There is no denying the fact that the server is a multi-user computer where there is no hardware Prior unusual that transforms a computer into a server and as such the hardware platform should be preferred, based on application demands and fiscal discipline. Server applications for client / server work unmatched when they are configured with an operating system that supports support shared memory, application isolation, and preemptive multitasking. A preemptive multitasking operating system allows to a task greater priority to short-circuit or take control of the processor from a running, the priority task lower. The server provides and controls access to shared server resources. Applications on a server should be isolated from each other in so that an error in one can not damage another. Preemptive multitasking ensures that not a single task can handle all resources Server and counteract other duties to provide services. It must be a way to define the relative priority of tasks on the server. These requirements are specific to achieving client / server and not the implementation of the file server. Because the file servers to execute the task only single file service, they can operate in a more limited operating without the need to isolate applications and anticipation multitasking.
The classic mini-computer and mainframe hosts acted as a de facto corporate servers to the network of terminals they support. Because the feature is only available to the user terminal is the host, data and personal productivity business information systems is stored on the server host. Network services, application services, databases and services are centrally from the host server. Many organizations to download data from enterprise servers to handle the legacy local workstations. In the client / server, the server definition will continue to include these functions, perhaps even implemented on platforms identical or similar. In addition, the advent of open systems-based servers is to facilitate the implementation of services on many different platforms. Client / server computing is a phenomenon that has developed from scratch. remote workgroups need to share expensive resources and have linked their workstations LANs grew until they permeate the organization. However, often they are isolated from each other. Many organizations have integrated the functionality of their dumb terminals in their workplaces to support character mode, based applications to host the single workstation. The next wave of client / server computing is happening now, that organizations the mid-1990s began to use the processing power cheaper and more accessible at the workplace as part of their enterprise systems. The Novell network operating system (NOS), NetWare, is the most widely installed LAN. It provides the premier file and print server takes supported. However, a limitation of NetWare client needs reliable / server applications was the requirement for an additional separate for processors operating as a server database. The availability of the database server software companies such as Sybase and Oracle to run on the NetWare server is to disseminate this base limitation.
About functions, to provide application servers, file, database, printing, fax, image, communications, security, systems and network management services. These are each described in detail in following sections. It is important to understand that the server is an architectural concept, not a physical explanation implementation. client and server functions can be provided by the same physical device. With the move to peer computing, each device will potentially operate as a client and the server in response to requests for service. Application servers provide enterprise functionality to support the functioning of the client workstation. In the model client / server services can be provided for a total or partial management function invoked by an Inter Process Communication (IPC) service request. Or requests based RPC messages can be used. A collection of application servers can work together to ensure a function of all activities. For example, in a payroll system for information appliances can be managed by an application server, the gains calculated by another server applications, and deductions calculated by a third party application server. These servers can run different operating systems on different hardware platforms and servers may use different databases. The client application calls those services regardless of technology or geographic location of different servers. Object technology provides the technical basis for the application server, and acceptance generalized CORBA standards is to ensure the sustainability of this trend. File servers provide record-level data services to any application database. memory space required for storage is allocated and free space is managed by the file server.
catalog functions are provided by the file server to support file naming and directory structure. File name maximum length ranges from 8 to 256 characters, depending on the support server operating system specific. Recorded programs are usually loaded from a file server running on a client or server platform host. Database servers are managed by a database engine such as Sybase, IBM, index, Informix and Oracle. Server file provides the initial space and the database engine allocates space for arrays in the space provided by the file server. These services home are responsible for the delivery of specialized data required of a blackout product database and auto-recovery after power, hardware, or software, management of space in the file, the reorganization of database record locking, deadlock detection, and management. The print servers provide support for customers to receive the documents, the queues for printing, prioritize, and implement the logic specific print driver for the selected printer. The print server software must be the logic necessary to support the unique characteristics of each printer. The effectiveness of the print server include support recovery error for jams and operator error notification with instructions to reboot. Fax servers provide similar support to that provided by print servers. Furthermore, fax server queue outgoing faxes for distribution later, when communication costs are lower. As documents are distributed by fax in a compressed format using either Group III A or IV compression, the fax server must be able to compress and decompress documents dynamically distribution, printing and display. This is usually done by adding a fax card to the server. If fax is rare, the software support options for compression and decompression can be used. Image servers work similarly to servers fax.
Provide infrastructure support for network servers (WAN) communication. This support typically includes support a subset of IBM System Architecture Network (SCN), asynchronous protocols, X.25, ISDN, TCP / IP, OSI, and LAN to LAN NetBIOS communication. In setting implement Novell NetWare, Gateway Communications provides leading product communications. In the LAN Server and LAN Manager environments, OS / 2 communications products Server available from IBM and DCA. Environmental Banyan Vines, an addition of DCA to VINES provides support for connectivity ANS. UNIX servers offer a range of add-ons from various vendors to support all communication needs. VMS servers decent support, TCP / IP, SNA and asynchronous and various protocols and serial communications. MVS servers provide support for SNA, TCP / IP, and some support for other asynchronous communications. Security on the server restricts access to software and data available from the server. Communications access is controlled from Communication Server. In most implementations, the use of a login user ID is the primary means of security. Use server LAN, some organizations have implemented integrated response access / Control Facility (RACF) creating security profiles in the MVS and downloading these to the LAN server for domain control. Systems and network management services for LAN are managed by an administrator of the LAN, WAN, but the services must be provided by a central location. Typically, remote network management is made from the site of central data center by trained MIS. The discussion in the following sections more accurately describes the functions provided by the server in a NOS. Applications are issued by a client for the resident OUR software services on the client. These services application format in an appropriate RPC and issuing the request to the application layer client protocol stack. This request is received by the application layer protocol stack on the server. File services manage access to virtual directories and files on the client and the permanent storage server. These services are provided by the redirector software set work within the client operating environment workstation.
To reduce the effort and the effect of the installation and maintenance software, the software must be loaded from the server running on the client. New versions can be updated on the server and immediately available to all users. In addition, the facility in a central location reduces the effort required for each user workstation button the installation procedure. Because each user uses the same client software installation, optional parameters are compatible, and remote help desk operators are aware of them. This simplifies the analysis that must take place to provide support. Information sharing, such as word processing documents, is easier when everyone is the same version level and uses the default configuration in the software itself. Services plant productivity such as style sheets and macros can be configured for general use. Most personal productivity products do local parameters such as colors, default printers, and so forth to be set locally as well. The backup server can be Regular and sustained by a trained support person. Backups of client workstations can be programmed from the server, and data can be stored on the server for easy retrieval. Optical or tape backup units are typically used for backup and these devices can easily provide support for many users. Setting up the server and its backups in a safe place to help prevent theft or accidental destruction of backups. A central location is easily controlled by a support person who ensures that the backup functions are fulfilled. With more organizations focusing multimedia technology and the image, large optical storage devices are properly implemented as shared servers. Printers High quality fax workstation generated, and tracers are natural candidates for the support of a shared server. The server can accept input many customers in the queue according to the priority of the request and handle when the device is available. Many organizations are making savings by allowing users to generate output faxes from their desktop and the queue to a fax server for transmission when communication costs are lower. Incoming faxes can be queued on the server and transmitted to the appropriate client or reception or on request. Together with workflow management techniques, images can be captured and distributed to the appropriate client workstation from Image Server. In the client / server model, the queues of work are maintained at the server by a supervisor in conjunction with algorithms default as to determine how to distribute the backlog. incoming paper mail can be converted to image in the mail room and sent to the appropriate client through the LAN rather than by internal mail. capture and distribution centralized enable images centrally indexed. This index can be maintained by the services database for all authorized users to query. In this way, images are captured once and are immediately available for distribution to all authorized users. well-defined standards for electronic document management will allow this technology to fully integrate in the environment of office work. There are opportunities for dramatic cost savings and efficiency improvements if this technology is properly implemented and used. Article 10 deals in more detail the issues of electronic document management.
In the early hours of the servers database were actually file servers with a different interface. Products such as dBase, Clipper, FoxPro, Paradox and run the engine base mainly on the client device and use file services provided by the file server to store and access management space Free. These are new and more powerful models implemented file original dishes with indices extracted directly access disks. Exchange Control is managed by the application program which issues lock requests and lock control, and the server database, creating a lock table that is queried each time a check lock access record is generated. Because access is at record, all records that match the primary key must be returned to the client workstation for filtering. There are no facilities for perform the procedure code at the server, perform joins, or filter rows before returning them to the workstation. This lack of capacity greatly increases the likelihood that documents are locked when multiple clients are accessing the same database and network traffic increases when the number of unnecessary lines are returned to the workstation should be dismissed. The lack of execution logic server prevents these products offer partial automatic update interdiction and recovery from application, system or hardware failure. For this reason, systems that operate in this environment requires an experienced programmer support system to assist in the recovery after a failure. When applications are very simple and require only a single line to be updated in each interaction, this question does not arise recovery. However, Many client / server applications are necessary to update more than one line within a logical unit of work. Client / server database engine such as Sybase, IBM Database Manager, Index, Oracle, Informix and provide support at the server to run applications APPLICATION SERVER issued from the client. File services are still used for space allocation and directory services database, but all Other services are provided directly by the server database. management systems relational databases are the current technologies of data management. The major drawback of the hierarchical technique is that only applications that access data according to its physical benefits of storage sequence locality of reference. Amendments to the requirements of applications that require an approach different access require data to be reorganized. This process involves reading, sorting, and rewriting the database into a new sequence, not transparent applications that rely on the physical origin sequence. Indices that allow access directly into the database will provide the ability to view and access information in an order other than the physical sequence. However, these indices must be known to the user at the time of application is developed. The promoter makes explicit reference to the index to get the data of interest. Thus, the indices can not be added later without changing any programs that need such access to the direct use of the index. Indexes can not be removed without change programs that are currently accessing the index. Most implementations force the application developer to be sensitive to order and the presence of columns in the record. Thus, columns can not be added or removed without changing any programs that are sensitive to these issues. Application to the physical implementation sensitivity is the main problem with systems of hierarchical database. Application sensitivity to physical storage introduces considerable complexity in navigation that application programmers to browse the hierarchy of research their desired data. Attempts by suppliers of databases to improve performance have generally increased the complexity access. If life is too easy today, try to create a bidirectional virtually paired logical relationship IMS, so organizations using products such as IMS and IDMS are generally well paid support staff of technical database. As technology hardware evolves, it is important for building data management to evolve to use the new features. Technology Database The solution provides relational data management's current many problems inherent in flat files and hierarchical technologies. In the end 1970s and early 1980s, products such as Software AG ADABAS System 2000 and were introduced in order to provide application flexibility required by the systems of the day. IBM IMS and IDMS net with reform attempted to add features to their products to increase this flexibility. The first products were introduced by relational ADR Dotcom DB and Computer Corporation of America with the model 204. Each of these implementations used extracted indices provide direct access to stored data without having to navigate the database or flat file sorting. All products have tried to maintain some performance advantages offered by locality of reference (column storage and records relating thereto as close as possible to the primary column and record).
The development of a relational algebra defining the operations that could be made between the tables allowed implementations Effective RDBMS. The establishment of industry standards for defining and accessing relational tables has accelerated the acceptance of RDBMS as the de facto standard for all client / server applications today. Similar standards do not yet exist for OODBMS. It is a place for both models. To be widely used, OODBMS need to integrate seamlessly with RDBMS technology. Table 4.1 compares the terminology RDBMS and OODBMS used by developers. Relational databases are characterized by a simple data structure. All access to data and relationships between tables are based on values. An event of the data value is determined solely by the concatenation of the table name, column name, and the value of the unique identifier of the row (primary key). Relations between tables are defined by a common phenomenon of key values primary. Build applications for information from the tables by making a join based on common values. The result of the join is another table that contains a combination of column values of the tables involved in sticking together. There are a few applications which have not reached RDBMS performance acceptable. Primarily, these are applications that require very complex data structures. Thousands of tables can be defined with great relationships them. Often, the lines are sparsely populated, and applications generally require many lines to be bound, often recursively to produce point of view necessary. The main suppliers in this market are objectivity Inc., design object, on, and Versant. Other vendors such as HP, Borland and infiltration have been incorporated features into their products. The application characteristics that lead to a choice OODBMS are presented in Figure 4.3. OODBMS become capable of producing these types of applications with the introduction of 16Mbps D-RAM and the establishment of persistent (permanent) of databases D-RAM. Only functions logging actual use I / O. Periodically, databases D-RAM will be saved to Real storage magnetic or optical disk. In 1993, a significant number of production applications have been implemented OODBMS. With confidence and experience From these applications, the momentum is building, and in 1994 and 1995 will see a significant increase in the use of OODBMS for critical applications. OODBMS have reached a level of maturity that coincides with the demand for multimedia-enabled applications. The complexity of dealing with multimedia demands OODBMS features of effective storage and handling.
client / server LAN and WAN require communication services. Basic services are part of LAN integral to the NSA. WAN services are provided by different communication products for the server. Section 5 provides a comprehensive analysis of connectivity problems in client / server. The client / server applications require security services similar to those provided by the host environments. Each Users should be required to log in with a user ID and password. If passwords can become visible to unauthorized users, the security server should insist that passwords be changed regularly. The company's office implies that the unique login ID and the opening sequence session is used to obtain authorization to access all information and process the user has a need and right of access. Because data can be stored in an area less physically secure, the possibility should exist to store data in encrypted form. A combination of user ID and password must be necessary to decrypt the data. New options, such as workstation less disk with standard data encryption system (DES) coprocessors are available from suppliers such as Beaver Computer Company. These data, generated automatically encrypt or decrypt written or read from disk or a communication line. Encryption and decryption are done using the DES algorithm and password user password. This ensures that unauthorized users can access data or data communication. This type of security is particularly useful for laptops participating in client / server applications, because the laptops do not work in an environment with the same security physical desk. To be able to access the system from a laptop without properly use an identification number and password would be courting disaster. NetWare is a family of LAN products with support for customers of IBM PC-compatible and Apple Macintosh and IBM PC-compatible servers. NetWare is OUR property in the strict sense it does not need another OS such as DOS, Windows, Windows NT, OS / 2, Mac System 7, or UNIX operating on a server. A separate Novell NetWare portable product for UNIX provides support to conduct server RISC UNIX implementations, the IBM compatible PC running Windows NT, OS / 2, high-end Apple Mac running Mac System 7, and Digital Equipment Corporation VAXs running VMS. NetWare provides the environment LAN of choice for sharing files and printing resources. He had 62 percent market share in 1993. It is widely installed as standard product in many organizations.
Suffice it to say that LAN Manager and its derivative IBM LAN Server, are standard products for use implementations in client / server using OS / 2 operating system server. LAN Manager / X is the standard for customer implementations / Server running UNIX System V as the server operating system. Microsoft has released its Advanced Server product with Windows NT in the third quarter of 1993. In 1994, it will be improved with support for Microsoft services network management, currently called "Hermes", and Banyan Enterprise Network Services (ENS). Advanced Server is the natural migration path for existing Microsoft LAN Manager and IBM LAN Server clients. Existing LAN Manager / X clients probably will not find Advanced Server, not an answer to their dreams before 1995. AT & T has taken responsibility for the LAN Manager / X version. Vendors such as Hewlett-Packard (HP) have the reluctance of AT & T products AT & T and Microsoft reached an agreement to maintain consistent API for all the basic functionality. LAN Manager and Advanced Server to provide customers with support for DOS, Windows, Windows NT, OS / 2, Mac System 7. Server support extends to NetWare, AppleTalk, UNIX Windows NT and OS / 2. client workstations can access data on both NetWare and LAN Manager servers simultaneously. LAN Manager supports NetBIOS and Named Pipes LAN communications between clients and servers OS / 2. Redirection services are provided to map files and printers from remote workstations to use by the customer. Advanced Server also supports TCP / IP. In early 1994, Advanced Server is still a young product with many parts missing. Yet More troublesome, the competition between Microsoft and Novell is delaying the release of the software requesting client and NetWare Core Protocol (NCP) support. Microsoft has added support TCP / IP LAN Manager 2.1 and Advanced Server with Net View and Simple Network Management Protocol (SNMP) agents. Thus, the tools are in place to manage the remote LAN LAN Manager. Microsoft has announced support for IBM 6000 for Net View Advanced Management Server.
Advanced Server provides integrated support for treatment peer-to-peer and client / server applications. Existing support for Windows NT, OS / 2, UNIX, Mac System 7 allows application clients, database, communication servers and run on the same machine as the file server and print. This feature is attractive for small local networks. The native operating system support preemptive multitasking and storage protection ensures that server applications do not reduce the reliability other services. Even as Windows NT is implemented to provide the database, applications and communications services to client / server applications, using Novell as NOS LAN devices of choice continue to resource sharing applications. Microsoft has attempted to preempt the market for small LAN with a Windows for Workgroups product. The attack in the same market as NetWare Lite with low cost product that is tightly integrated with Windows. It is an interesting option for small organizations without requiring major local networks. The complexity of management systems make it less attractive in a business environment that is already using Novell. WWW can be used in conjunction with Novell for a working group wishing to use certain services WFW, such as group scheduling. IBM has signed a reseller agreement to integrate the product and Novell NetWare environments where both IBM LAN Server and Novell NetWare are necessary. NetWare provides more functional, easier to use, and high-performance file and print services. In environments where it is the functions LAN only, NetWare, LAN Manager is preferable products. Interconnection capacity for the world ANS makes the product attractive to IBM LAN Server organizations who prefer to run the two products. Most large organizations have working groups department that require services that Novell provides good, but can use the LAN server for client / server applications using services such as SNA APPN. IBM and Microsoft had an agreement to make the API for the two equivalent products. However, the dispute between the two companies on Windows 3.x and OS / 2 has ended this cooperation. The latest versions of LAN Manager 3 NT and LAN Server 3 are closest associates agree, but there is no guarantee that this will continue. In fact, there is every indication that the products will differ with the server operating system is different for the two companies. IBM has a very attractive price LAN Server so that if OS / 2 clients are used, LAN Server is a low cost option for small LANs. LAN Server supports DOS, Windows and OS / 2 customers. There was no support announced for Mac System 7, although it is possible to interconnect and AppleTalk LANs Server to share files and data services communication.
Street Talk by allowing resources to be identified on the network, making them easier to access and manage. All resources, including file services, users and printers, are defined as objects. Each object has a name Talk Street associated with it. Street Talk names follow a hierarchical three-tier format: Item @ Group @ Organization. For example, a user can be identified as Psmith @ @ Tnet Cerritos. All network objects are stored in a distributed database that can be accessed worldwide. Novell NDS is similar to Street Talk in functionality. However, there are differences essential. NDS can partition and copy the database, which will generally improve performance and reliability. NDS is X.500-compliant and allows multiple levels of hierarchy. Street Talk supports a fixed hierarchy at three levels. The NDS architecture provides more flexibility, but with a complexity Street Talk is relevant and less flexible and less complex to manage. An advantage of the current version of Street Talk is that most NDS objects Street Talk can have attributes unlimited available for selection. Novell and Microsoft have announced support for Banyan ENS in their products to be available in Q2 1994. Banyan and DCA provide services to the SNA environment VINES. VINES support UNIX, DOS, Windows, OS / 2, System 7 and Mac clients. NFS is the standard file system support for UNIX. NFS PC is available from Sun and FTP select the file to provide support services from a UNIX server to Windows, OS / 2, Mac and UNIX customers. Client / Server requires LAN and WAN topologies be in place to provide interconnection of networks needed to shared applications and data. Gartner Group1 evaluated and considered the integration topologies Microsystems for the period 1986-1996, the results are shown in Figure 4.6. A particular interest is the projection that most jobs will be in local area networks in 1996, but only 14 percent are involved in a network Local company at that time. These figures represent a rather pessimistic for LAN-to-LAN interconnected and enterprise connectivity. These figures probably will prove to be substantially underestimated if organizations adopt a perspective of architecture for the selection of their platforms and tools and use these tools in an organizational system optimized development environment (SDE). Routers and communication servers will be used to provide communications services between LANs and the WAN. In the client / server model, these connections be seamlessly delivered by SDE tools. There are significant performance implications if traffic volumes are high. implementing LU6.2 IBM APPC and TCP / IP provides the best support for large volumes, LAN-to-LAN/WAN communications. implementation in December DECnet has always provided excellent connectivity LAN-to-WAN. Built-in support for TCP / IP, LU6.2, and IPX provides a solid platform for client / server implementation of LAN to WAN in DECnet.
The lack of real estate on the desktop encouraged most organizations to move to a single device using terminal emulation workstation to access the existing mainframe applications. It will take time and considerable effort before all existing applications based on the host organization are replaced by applications client / server. In the long term, the host will continue to be a destination of choice for storing basic data warehouse and for providing management of security and network services. Mainframes are expensive to buy and maintain, difficult to use, inflexible, and great, but they provide stability and the ability required by many organizations to run their businesses. As Figure 4.7 ratings, the opinion of the International Data Corporation, they will not disappear anytime soon. Their role will change, but they will be there as part of enterprise infrastructure for many more years. Only organizations that create an enterprise architecture strategy and transformation plans will accomplish the migration to client / server within a few years. Without well-architected strategy, the progressive failure occur. The information that is of value or interest the entire company should be managed by a management function of a central database and appear to be stored on each user desktop. These applications are traditionally implemented Online Transaction Processing (OLTP) to the mainframe or minicomputer. With client / server, is possible to use the technology database to replicate or migrate data to distributed servers. When the data resides or is employed, the location should be transparent to the user and the developer. Data must be stored where it best meets the needs Company. Online Transaction Processing applications are in areas such as insurance, finance, government, and sales-all that a great deal number of transactions. Each of these operations requires a minimal amount of user think time to process. In these industries, data are often collected at source by the competent worker. As such, the systems have high requirements for availability, integrity data, performance, concurrency, growth potential, security and manageability. Systems implemented in these settings must prove themselves or they will be rejected by an authorized body. They must be implemented as part of the work process. OLTP has traditionally been the domain of the mainframe vendors such as IBM and DEC and special purpose processors to fault-tolerant vendors such as Tandem and Stratus. The client / server model has the ability to provide all the services required for OLTP a much lower cost than traditional platforms. All clients current needs for portability of server-application GUI, client / server partitioning function, software distribution and efficient development tools, exist for OLTP applications. The first vendor to deliver a quality product production in this area is cooperative solutions with its product Ellipse. Before Ellipse, OLTP systems necessary for developers to manage the problems of integrity of the unit of processing work, including exchange controls and cancellation of the transaction. Ellipse offers all the necessary components to build systems with these characteristics. Ellipse is currently operating Windows 3.x, OS / 2 and OS / 2 servers using the engine Sybase database. Novell is working with cooperative solutions to the port Ellipse as a loadable module Novell NetWare (NLM). It provides a powerful graphical development environment using a template language as a shortcut to development. This language is a solid foundation to build an organization SDE and lends itself well to the integration of standard components. As UNIX has matured, it added many features in other operating systems such as VMS and MVS. There are now several deals with OLTP UNIX. IBM promotes CICS 6000 as a strategy Downsizing for CICS MVS. database services will be provided by a combination of AIX and MVS servers.
With the release of Windows NT (New Technology) in September 1993, Microsoft has staked its position with a single server operating system. the previous development of Microsoft's OS / 2 IBM has not create the only alternative standard UNIX as hoped. NT provides the services required for preemptive multitasking a functional server. It provides an excellent support for Windows clients and integrates services necessary for the protection of storage required for a reliable server operating system. Its implementation implementation of the C2-level security goes well beyond that provided by OS / 2 and most implementations of UNIX. It will take more than 1994 applications for robust and zing needed to provide a platform for industrial-strength business-critical applications. With the prestige of Microsoft and the marketing muscle, NT will be installed by many organizations as a server of choice. IBM MVS provides a platform for broad applications. Many existing application services that organizations have purchased run on hardware MVS 370-compatible system running. The network environment standard for many large organizations-is-SCN a component of MVS. IBM prefers the label proprietary systems now under the auspices of the SAA. The objective of SAA is to provide all services on all platforms in a manner compatible IBM-IBM version of the single system image. There is a commitment from IBM provide support for the LAN server runs natively on MVS. It is an attractive option for organizations with large existing investments in applications MVS. Capacity data storage provided by the very important platform system compatible with 370-MVS MVS to use for DSL services attractive to large organizations. MVS provides a server to DB2 database using powerful and LU6.2. With industry support for LU6.2, applications that include DB2 database as part of their point of view may be issued from a client / server application. Products such as Sybase provide high performance APPLICATION SERVER static support, making this implementation for sustainable production applications to high performance. Digital Equipment Corporation provides OpenVMS as a server platform of choice. VMS has a long history in the field of distributed computing and includes many features to act as a server in the client / server model. December was slow to realize the importance of this technology, and is only recently that the company in the arena as a serious supplier. NetWare supports the use of OpenVMS servers for file services. December provides its own server interface using a product called LAN Manager Patchworks. Patchworks native execution on the VAX and Alpha RISC RXP. This is a particularly interesting because it provides access to the same processor application, database and file services provided by a combination of OpenVMS, NetWare and LAN Manager. Digital and Microsoft have announced joint agreements to work together to provide seamless integration of Windows, Windows NT, Patchworks, and OpenVMS. This will greatly facilitate the migration of customers to the OpenVMS client / server model. OpenVMS VAX product support database such as RDB, Sybase, penetration, and Oracle allows this platform to effectively deliver a server database applications for client / server. Many organizations have large investments in hardware VAX and DECnet network. The possibility of using part of these client / server applications is attractive as a means of maximizing the value of this investment. DECnet is an ideal model for the single system image. LAN technology is fundamental to the architecture of DECnet. Many large organizations worldwide movement client / server computing have standardized on DECnet for WAN treatment. For example, Kodak Digital selected as his company's network, even after selecting his company as IBM mainframe outsourcing.
UNIX is a key player in a server system in client / server. Certainly, the history of Unix in the field of distributed computing and open interfaces provide excellent opportunity for her to be a server of choice. To understand what makes an open operating system, examine the components of the system. UNIX was designed in the early 1970s by AT & T employees as an operating environment for providing services to software developers who been discouraged by the incompatibility of new computers and lack of development tools for application development. The original intent of the UNIX architecture was to define a standard set of services to be provided by the UNIX kernel. These services are used by a shell that provides the command line interface. Functionality is enhanced by the provision of a library of programs. Applications are constructed from the program library and custom code. The power and appeal of UNIX are in a common core and casing and the large amount of software that was built and is available. Applications built around these standards can be worn on various platforms. The objectives of the original UNIX was very complete and could be reached except that the original operating system was developed under the auspices of AT & T. legal ramifications of the consent decree governing the breakup of the Bell operating companies (RBOCs) AT & T prevented from entering the field of computing. Accordingly, the company had little incentive to promote early UNIX as a product. To remedy this, and in an attempt to achieve an implementation of UNIX best suited to the needs of developers, the University of California at Berkeley and other institutions to develop better varieties of UNIX. Consequently, the initial target of a portable platform has been compromised. The new products have certainly been better, but they are not compatible with each other or the implementation of origin. Until mid-1980s, many versions of UNIX that has more functionality have been released. IBM, of course, entered the fray in 1986 with its own derivative UNIX, AIX. Finally, in 1989, an agreement was reached on the basis of the UNIX kernel, shell functions, and APIs. The computing community is near consensus on what the UNIX kernel and shell will look like and defining specific APIs. Figure 4.8 shows the components of the future standard architecture UNIX operating system.
During these fluctuations, a major problem that has persisted UNIX differentiates it from DOS, Windows NT and OS / 2 the client / server world. Because the hardware platforms on which UNIX is sourced from manufacturers and rely on many different chip sets, the off-the-shelf "software for PC that is sold is not yet available for UNIX. The software is sold and distributed in executable form, so it must be compiled and linked by the developer for the target platform. This means that organizations wishing to purchase software to buy for the UNIX platform specific target they use. This also means that when they use multiple platforms in a distributed client / server, companies must buy different software versions for each platform.
UNIX is particularly desirable as a server platform for client / server because of the wide range of platform sizes available and the huge amount of application and software development available. Universities are contributing to the momentum UNIX graduating students who see only UNIX for their years of study. Government agencies are insisting on the UNIX platform, as for all government projects. The combination of these pressures and technological change should ensure that compatibility will be mandatory for UNIX server platforms in the latter half of this decade. OSF Motif initially developed a GUI for UNIX, which became the de facto standard UNIX GUI. The environment distributed computing (DCE) is increasingly recognized as the standard for distributed application development that has its Distributed Management Environment not yet attained such support. OSF / 1, OSF UNIX kernel defined, was adopted by December, while most other vendors have made promises to support it. OSF / 1 offers the promise of a UNIX kernel microphone more suitable for desktop environment than existing products. The desire for UNIX standard encourages other organizations. For example, the IEEE has addressed the issue by creating a unified UNIX group to develop an operating system mobile standard called POSIX. The objective is to develop an ANSI standard operating system. POSIX is not UNIX, but UNIX. Standards POSIX (most suppliers to undertake to respect) exist today. December OpenVMS operating system, for example, takes support POSIX standards published. POSIX at this stage, however, does little to promote interoperability and portability, because so few the total standard was finalized. Simple applications that will run across different platforms POSIX will be written. However, they will be applications limited because developers can not use any of the rich, non-POSIX features and functions that vendors offer beyond the core basic POSIX. X / Open began in Europe and has spread to include most major U.S. computer manufacturers. X / Open has a significant impact on the market because its objective is to establish a standard set of application programming interfaces (APIs) that enable interoperability. These interfaces are published in the X / Open Portability Guide. Applications running on operating systems that conform to these interfaces will connect with each other and interact, even if the operating systems underlying different. This is the key objective of the client / server model. The COSE announcement by HP, IBM, SCO, Sun, and Univel (Novell / USL) in March 1993 at the Conference is the latest attempt to create uniforms for common ground between the UNIX operating systems. COSE The initial announcement only covers the desktop environment of the user and the user interface graph, although the time it is expected to go further. COSE is a more pragmatic group is trying to "do." Another major difference previous attempts to create universal standards UNIX is the participation of the SCO and Sun. Both organizations have a substantial market share UNIX and tended to promote exclusive approaches to the desktop interface. SCO provides its Open Desktop environment, and Sun offers Open Look. Commitment Reason to be an important concession on their part and offer the first real opportunity for interoperability and full transparency seller Users the platform.
In October 1993, Novell decided to grant the rights to the UNIX name to X / Open, so that all vendors can develop the UNIX standards and use the UNIX name for their products. Largely symbolic gesture that will eliminate the confusion in the marketplace over what software is really UNIX. COSE is the looking beyond the desktop graphics, multimedia, object technology, and management systems. Networking support includes Novell NetWare UNIX network products client, OSF DCE and SunSoft Open Network Computing. Novell has agreed to submit the NetWare UNIX client to X / Open for publication as a standard. In the field of graphic design, COSE participants plan to support a set of graphics facilities of X Consortium, the developer of X Windows. Addressing media, participants COSE intend to present two common specifications in response to the request of the Association for Interactive Multimedia Technology. One of these specifications, called Distributed Media Services (DMS), defines an independent network infrastructure to support an integrated API and a protocol data stream. Other Integrated Office in the media environment will develop tools to access and multimedia collaboration, including at least a basic tool for each data type supported by the infrastructure of DMS. The resulting standard will provide users with consistent access to multimedia tools in MultiFinder environments. COSE also deals with object technology, an area targeted by IBM and Sun. The group will support the efforts of the Object Management Group (OMG) and Common Object Request Broker (CORBA) standard for the deployment and use of distributed objects. IBM already has a system of objects CORBA-compliant in beta test for AIX. Sun built an operating system code named this spring as a proof of concept in 1992. Sun has launched a major project, called distributed objects everywhere (DOE), which produces results very exciting productivity. Finally, COSE will focus on systems management distributed file distribution, groups and users, print manager, license to install the software, and storage. This is no coincidence that these providers meet to define a standard UNIX at this time. The effort COSE is a defensive reaction to the release of Microsoft Windows NT. With this commitment to a workstation and 32-bit server operating system, Microsoft has caught wind of most assertions UNIX technical superiority. Despite its many advantages as a desktop and server operating system, UNIX has never been widely accepted in the wider world of business that promotes DOS / Windows and Novell NetWare. A key drawback for UNIX in the social field, has been the absence of a single standard UNIX. UNIX has an established position as the operating system of choice for distributed relational databases by vendors such as Informix, Index, Oracle and Sybase. Most of these providers, however, wearing their products for Windows NT as well. Any effort to reduce problems associated with multiple UNIX variants will do much to enhance the stature of UNIX as an interesting alternative to Windows NT.
Spin around this fantasy in your mind. All major equipment and software to meet and agree to install a black box in their system which, in effect, wipe their technological barriers. This black box will provide a variety of operating systems for small different hardware platforms, incompatible communication protocols, all kinds of applications and database systems, and even contrary to security systems. And the black box will do it all seamlessly, not only for end users but also for system managers and applications developers.2 OSF proposes the distributed computing environment (DCE) that this black box. DCE is the most important architecture defined for client / server model. It makes the link between investment in existing applications and new applications based on current technology. Figure 4.10 shows the architecture defined by the OSF. The first product of DCE components were released in the third quarter of 1991. WFD in direct competition with Sun's open network computing (ONC) environment and, indirectly, to many network standards. OSF / 1 and DCE are almost certain to win this battle because of the presence the mass market OSF sponsors. IBM has now committed to making its product AIX OSF / 1 compatible in early 1994. It will be 1995 before the product is mature and sufficiently complete to be widely used in enterprise applications. In the meantime, product vendors and systems integrators will use to build products and portable applications. The general availability of the code developed for previous product components similar will be to accelerate the process and enable the development of new shape to the previous versions. DCE has been described as another layer of consolidation in the OSI model.3 WFD establishes the link between pure communication on the lower layers and applications to end users.
These elements become active whenever an application requests data from local, services, processes or somewhere. The OSF DCE said that will a network of systems from different vendors appear as a single standalone computer for application developers, system administrators and end users. Thus, the single system image is reached. Remote Procedure Call (RPC) and presentation services: Interface Definition Language (IDL) CPR and allow programmers to transfer control and data over a network in a transparent manner that hides the network complexity. DCE RPC uses the originally developed by HP Apollo Network Computing System (NCS), with some improvements by DEC and IBM. NCS also provides the Network Data Representation (NDR), a virtual representation of data. NDR allows the exchange of data between different vendor products seamlessly. Conversions (if necessary) will take place without the intervention of the appellant. type conversions naming, security, file system and data can be instead the data is transported between different platforms. Naming: The user-oriented names, specifying, files, and people must be easily accessible in a distributed environment. These directory services to provide the appearance of standard rules for all customers. DCE supports X.500 directory services standard, adding service extensions CED (Domain Name DECdns). The code is standard X.500 Siemens Nixdorf DIR-X X.500 service. Security: Distributed applications and services must identify users, control access to resources and preserve the integrity all applications. DCE uses Kerberos Authentication Service, developed by MIT as part of its Network Project Athena and reinforced by Hewlett-Packard. This service is one of the major challenges for the provision of products quickly, because very few products are now designed with a catch Awareness of this specification. Topics: This terminology is a method of supporting parallel execution by the management of multiple threads control within a process operating in a distributed environment. Threads allow the systems to start multiple processes and forget on them until they are completed. This is particularly important for network servers which may have to handle many requests many customers simultaneously. They must be able to do so without waiting for the previous request to complete. DCE is using multithreaded December Concert Architecture (MAC) implementation. Service time: A time service synchronizes all system clocks in a distributed environment so that applications execution may depend clock equivalent between processes. Consider that many machines operating in multiple time zones can provide processes within a single application solution.
It is essential that they agree on the time to manage scheduled events and events sequenced. DCE is using a modification of the CTA service distributed time synchronization. Distributed File Services: Extending the local file system through the network, users have complete access to files on remote configurations. DCE uses Sun Network File System (NFS) Version 2 and provides capabilities for the next generation with the Andrew File System (AFS), developed at Carnegie-Mellon University and marketed by operations Transact Diskless Corp. under AFS are supported by the development work done by Hewlett-Packard. PC Integration: Integration enables PCs running MS-DOS, Windows NT and OS / 2 to access file services and printing outside of the MS-DOS. DCE uses LAN Manager Microsoft / X. Management: Although partially addressed by the previous items, the management is so complex in a distributed, heterogeneous configuration that OSF has defined a new architecture: distributed management environment (DME). DME provides a common framework for managing distributed and autonomous systems. This framework provides consistent tools and techniques for managing different types of systems and allows providers to create applications for system management that work on a variety of platforms. OSF DME based on technology from Hewlett-Packard OpenView product.
ASA is the distributed environment of IBM. SAA was defined by IBM in 1986 as an architecture to integrate all IBM computers and operating systems, including MVS, VM / CMS OS/400 and OS/2-EE. SAA sets the standards for common user access (CUA) method, common programming interfaces (CPI), and a common communication link (APPC). To support the development of SAA-compliant applications, IBM executives described the PAC (which look a bit APIs). The first frame SAA is AD / Cycle strategy PAC for the development of CAS applications. AD / Cycle is designed to use third party tools in IBM mainframe hardware and ASA Repository Manager / MVS installation data storage. Several vendors have been selected by IBM as partners Round AD /, namely: Intervolve, knowledge ware, Bachman, Synod, a systematic and easel Corp. Several products are already available, including the toolbox Easel Workbench, DB2 Bachman, tools for DSP Ware and Knowledge Repository and tools for MVS. Unfortunately, the most important, the repository manager, has not yet reached the quality of production in its implementation MVS and yet there are no plans for a client / server implementation. Many original IBM customers involved in the assessment of the repository manager returned the product of frustration. Recently, there has been much discussion about the need for production quality, object-oriented management system database to support the entity-relationship (ER) model underlying repository. Only that, for example some sources, will make the implementation and performance practices. Another flaw in the strategy of SAA is the lack of support systems open. Although some standards such as Motif, Application Server, and LU6.2, are identified as part of the SAA, the lack of support for AIX has prevented Many organizations adopt PAC. IBM has published all the standards of the ASA and gave various protocols such as LU6.2. The company has tried ASA to open the world of software development. director of IBM's strategy of open systems, George Siegel says that IBM believes in openness by interfaces. Thus, the complete definition of API allows other vendors to develop products that interface with IBM and with each other. Recent announcements, such as support for CICS AIX, point to a progressive movement to include the ASA AIX platforms. The first SAA application that IBM has published, Office Vision, has been a disaster. Product systematically missed shipping dates and was missing a large part functionality promised. IBM has largely abandoned the product and now works closely with Lotus and its plans for workgroup computing. IBM has always defined common database, user interface and communication standards across all platforms. This certainly offers the possibility of building ASA compliant client / server applications.
IBM said its product system view as DME. View system defines APIs to enable interoperability between products from different manufacturers. It should be the vehicle linking sites AIX mainframe. IBM said the display system open structure for the integration of OSI, SNA and TCP / IP. At this time, System View is a set of guidelines to help developers Third-party software and customers to integrate systems and storage management applications, data definitions and access methods. Lines Guidelines are intended to further support the concepts of single system image.
Given the foregoing, it is a significant fact that the introduction Recent CICS for OS / 2, AIX and OS/400 and the announcement of support for AIX not mean that a single platform for transaction processing is set to any product line. Applications developed under OS / 2 can be focused on interoperability between OS / 2, OS/400, MVS, AIX, and finally, without modification. COBOL and C programming languages common to each platform. Application Server is the common language of data access across all platforms. The failure of ASA is due to the complexity of heterogeneous product lines of IBM and the desire of many organizations to move away owners to open systems solutions. This acknowledgment tested IBM plans to announce its new Open Enterprise to replace the old system Application Architecture (SAA) plane with an open network strategy. System View is a network linking key product IBM OS / 2, UNIX, AS/400 and operating systems. Traditional Systems Network Architecture (SNA) networking will be replaced by new technologies such as Advanced Peer-to-Peer Communications (APPC) and Advanced Peer-to-Peer.
Written by: Kh. Atiar Rahman
Part cons Agent
Financial reform program Management
About the Author
written by: Kh. Atiar Rahman
Counter Part Officer
Financial Management Reform Programme
Ministry of Finance, Finance Division
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