1. | Aug 9, 2013

Hi Jim, thanks for letntig me know about this. The WordPress module seems to work fine with Safari, but the Joomla module doesn't. I'm going to look into it and will be back as soon as possible with the solution.

2. | Aug 9, 2013

There is no denying the fact that the seervr is a multi-user computer where there is no unusual hardware prerequisite that turns a computer into a seervr and as such the hardware platform needs to be preferred based on application demands and financial stringency. Servers for client/seervr applications work unsurpassed when they are configured with an operating system that supports shared memory, application isolation, and preemptive multitasking. An operating system with preemptive multitasking enables a higher priority task to preempt or take control of the processor from a currently executing, lower priority task. The seervr provides and controls shared access to seervr resources. Applications on a seervr must be isolated from each other so that an error in one cannot damage another. Preemptive multitasking ensures that no single task can take over all the resources of the seervr and thwart other tasks from providing service. There must be a means of defining the relative priority of the tasks on the seervr. These requirements are specific to the client/seervr accomplishment and not to the file seervr implementation. Because file seervrs execute only the single task of file service, they can operate in a more limited operating background without the need for application isolation and anticipatory multitasking. The conventional minicomputer and mainframe hosts have acted as de facto enterprise seervrs for the network of terminals they support. Because the only functionality available to the terminal user is through the host, personal productivity data as well as business systems information is stored on this host seervr. Network services, application services, and database services are provided centrally from the host seervr. Many organizations download data from legacy enterprise seervrs for local manipulation at workstations. In the client/seervr model, the definition of seervr will continue to include these functions, perhaps still implemented on the same or similar platforms. Moreover, the advent of open systems based seervrs is facilitating the placement of services on many different platforms. Client/seervr computing is a phenomenon that developed from the ground up. Remote workgroups have needed to share expensive resources and have connected their desktop workstations into local area networks LANs have grown until they are pervasive in the organization. However, frequently, they are isolated one from the other. Many organizations have integrated the functionality of their dumb terminals into their desktop workstations to support character mode, host-based applications from the single workstation. The next wave of client/seervr computing is occurring now, as organizations of the mid-1990s begin to use the cheaper and more available processing power of the workstation 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 seervr supports. However, a limitation of NetWare for the needs of reliable client/seervr applications has been the requirement for an additional separate processor running as a database seervr. The availability of database seervr software—from companies such as Sybase and Oracle—to run on the NetWare seervr, is plateful to disseminate this limitation. Apropos to the functions, Servers provide application, file, database, print, fax, image, communications, security, systems, and network management services. These are each described in some detail in the following sections. It is important to understand that a seervr is an architectural concept, not a physical implementation explanation. Client and seervr functions can be provided by the same physical device. With the movement toward peer computing, every device will potentially operate as a client and seervr in response to requests for service. Application seervrs provide business functionality to support the operation of the client workstation. In the client/seervr model these services can be provided for an entire or partial business function invoked through an Inter Process Communication (IPC) request for service. Either message-based requests RPCs can be used. A collection of application seervrs may work in concert to provide an entire business function. For example, in a payroll system the employee information may be managed by one application seervr, earnings calculated by another application seervr, and deductions calculated by a third application seervr. These seervrs may run different operating systems on various hardware platforms and may use different database seervrs. The client application invokes these services without consideration of the technology or geographic location of the various seervrs. Object technology provides the technical basis for the application seervr, and widespread acceptance of the CORBA standards is ensuring the viability of this trend. File seervrs provide record level data services to no database applications. Required memory space for storage is allocated, and free space is managed by the file seervr. Catalog functions are provided by the file seervr to support file naming and directory structure. Filename maximum length ranges from 8 to 256 characters, depending on the particular seervr operating system support. Stored programs are typically loaded from a file seervr for execution on a client or host seervr platform. Database seervrs are managed by a database engine such as Sybase, IBM, Ingress, Informix, or Oracle. The file seervr provides the initial space, and the database engine allocates space for tables within the space provided by the file seervr. These host services are responsible for providing the specialized data services required of a database product—automatic blackout and recovery after power, hardware, or software failure, space management within the file, database reorganization, record locking, deadlock detection, and management. Print seervrs provide support to receive client documents, queue them for printing, prioritize them, and execute the specific print driver logic required for the selected printer. The print seervr software must have the necessary logic to support the unique characteristics of each printer. Effective print seervr support will include error recovery for jams and operator notification of errors with instructions for restart. Fax seervrs provide support similar to that provided by print seervrs. In addition, fax seervrs queue up outgoing faxes for later distribution when communications charges are lower. Because fax documents are distributed in compressed form using either Group III or Group IV compression, the fax seervr must be capable of dynamically compressing and decompressing documents for distribution, printing, and display. This operation is usually done through the addition of a fax card to the seervr. If faxing is rare, the software support for the compression and decompression options can be used. Image seervrs operate in a manner similar to fax seervrs. Infrastructure seervrs provide support for wide area network (WAN) communications. This support typically includes support for a subset of IBM System Network Architecture (SNA), asynchronous protocols, X.25, ISDN, TCP/IP, OSI, and LAN-to-LAN NetBIOS communication protocols. In the Novell NetWare implementation, Gateway Communications provides a leading communications product. In the LAN Server and LAN Manager environments, OS/2 communications seervr products are available from IBM and DCA. In the Banyan VINES environment, the addition of DCA products to VINES provides support for SNA connectivity. UNIX seervrs provide a range of product add-ons from various vendors to support the entire range of communications requirements. VMS seervrs support Decent, TCP/IP, and SNA as well as various asynchronous and serial communications protocols. MVS seervrs provide support for SNA, TCP/IP, and some support for other asynchronous communications. Security at the seervr restricts access to software and data accessed from the seervr. Communications access is controlled from the communications seervr. In most implementations, the use of a user login ID is the primary means of security. Using LAN Server, some organizations have implemented integrated Response Access/Control Facility (RACF) security by creating profiles in the MVS environment and downloading those to the LAN seervr for domain control. Systems and network management services for the local LAN are managed by a LAN administrator, but WAN services must be provided from some central location. Typically, remote LAN management is done from the central data center site by trained MIS personnel. The discussion in the following sections more specifically describes the functions provided by the seervr in a NOS environment. Requests are issued by a client to the NOS services software resident on the client machine. These services format the request into an appropriate RPC and issue the request to the application layer of the client protocol stack. This request is received by the application layer of the protocol stack on the seervr. File services handle access to the virtual directories and files located on the client workstation and to the seervr's permanent storage. These services are provided through the redirection software implemented as part of the client workstation operating environment. To diminish the effort and effect of installation and maintenance of software, software should be loaded from the seervr for execution on the client. New versions can be updated on the seervr and made immediately available to all users. In addition, installation in a central location reduces the effort required for each workstation user to knob the installation process. Because each client workstation user uses the same installation of the software, optional parameters are consistent, and remote help desk operators are aware of them. This simplifies the analysis that must occur to provide support. Sharing information, such as word processing documents, is easier when everyone is at the same release level and uses the same default setup within the software. Central productivity services such as style sheets and macros can be set up for general use. Most personal productivity products do permit local parameters such as colors, default printers, and so forth to be set locally as well. Backups of the seervr can be scheduled and monitored by a trained support person. Backups of client workstations can be scheduled from the seervr, and data can be stored at the seervr to facilitate recovery. Tape or optical backup units are typically used for backup; these devices can readily provide support for many users. Placing the seervr and its backups in a secure location helps prevent theft or accidental destruction of backups. A central location is readily monitored by a support person who ensures that the backup functions are completed. With more organizations looking at multimedia and image technology, large optical storage devices are most appropriately implemented as shared seervrs. High-quality printers, workstation-generated faxes, and plotters are natural candidates for support from a shared seervr. The seervr can accept input from many clients, queue it according to the priority of the request and handle it when the device is available. Many organizations realize substantial savings by enabling users to generate fax output from their workstations and queue it at a fax seervr for transmission when the communication costs are lower. Incoming faxes can be queued at the seervr and transmitted to the appropriate client either on receipt or on request. In concert with workflow management techniques, images can be captured and distributed to the appropriate client workstation from the image seervr. In the client/seervr model, work queues are maintained at the seervr by a supervisor in concert with default algorithms that determine how to distribute the queued work. Incoming paper mail can be converted to image form in the mail room and sent to the appropriate client through the LAN rather than through interoffice mail. Centralized capture and distribution enable images to be centrally indexed. This index can be maintained by the database services for all authorized users to query. In this way, images are captured once and are available for distribution immediately to all authorized users. Well-defined standards for electronic document management will allow this technology to become fully integrated into the desktop work environment. There are dramatic opportunities for cost savings and improvements in efficiency if this technology is properly implemented and used. Article 10 discusses in more detail the issues of electronic document management. In the early hours database seervrs were actually file seervrs with a different interface. Products such as dBase, Clipper, FoxPro, and Paradox execute the database engine primarily on the client machine and use the file services provided by the file seervr for record access and free space management. These are new and more powerful implementations of the original flat-file models with extracted indexes for direct record access. Currency control is managed by the application program, which issues lock requests and lock checks, and by the database seervr, which creates a lock table that is interrogated whenever a record access lock check is generated. Because access is at the record level, all records satisfying the primary key must be returned to the client workstation for filtering. There are no facilities to execute procedural code at the seervr, to execute joins, or to filter rows prior to returning them to the workstation. This lack of capability dramatically increases the likelihood of records being locked when several clients are accessing the same database and increases network traffic when many unnecessary rows are returned to the workstation only to be rejected. The lack of seervr execution logic prevents these products from providing automatic partial update blackout and recovery after an application, system, or hardware failure. For this reason, systems that operate in this environment require an experienced system support programmer to assist in the recovery after a failure. When the applications are very straightforward and require only a single row to be updated in each interaction, this recovery issue does not arise. However, many client/seervr applications are required to update more than a single row as part of one logical unit of work. Client/seervr database engines such as Sybase, IBM's Database Manager, Ingress, Oracle, and Informix provide support at the seervr to execute SERVER APPLICATION requests issued from the client workstation. The file services are still used for space allocation and basic directory services, but all other services are provided directly by the database seervr. Relational database management systems are the current technology for data management.The major disadvantage with the hierarchical technique is that only applications that access data according to its physical storage sequence benefit from locality of reference. Changes to application requirements that necessitate a different access approach require the data to be reorganized. This process, which involves reading, sorting, and rewriting the database into a new sequence, is not transparent to applications that rely on the original physical sequence. Indexes that provide direct access into the database provide the capability to view and access the information in a sequence other than the physical sequence. However, these indexes must be known to the user at the time the application is developed. The developer explicitly references the index to get to the data of interest. Thus, indexes cannot be added later without changing all programs that need this access to use the index directly. Indexes cannot be removed without changing programs that currently access the index. Most implementations force the application developer to be sensitive to the ordering and occurrence of columns within the record. Thus, columns cannot be added or removed without changing all programs that are sensitive to these records. Application sensitivity to physical implementation is the main problem with hierarchical database systems. Application sensitivity to physical storage introduced considerable complexity into the navigation as application programmers traverse the hierarchy in search of their desired data. Attempts by database vendors to improve performance have usually increased the complexity of access. If life is too easy today, try to create a bidirectional virtually paired IMS logical relationship; that is why organizations using products such as IMS and IDMS usually have highly paid database technical support staff. As hardware technology evolves, it is important for the data management capabilities to evolve to use the new capabilities. Relational database technology provides the current data management solution to many of the problems inherent in the flat-file and hierarchical technologies. In the late 1970s and early 1980s, products such as Software AG's ADABAS and System 2000 were introduced in an attempt to provide the application flexibility demanded by the systems of the day. IBM with IMS and Cull net with IDMS attempted to add features to their products to increase this flexibility. The first relational products were introduced by ADR with Dotcom DB and Computer Corporation of America with Model 204. Each of these implementations used extracted indexes to provide direct access to stored data without navigating the database or sorting flat files. All the products attempted to maintain some of the performance advantages afforded by locality of reference (storage of related columns and records as close as possible to the primary column and record). The development of a relational algebra defining the operations that can be performed between tables has enabled efficient implementations of RDBMS. The establishment of industry standards for the definition of and access to relational tables has speeded the acceptance of RDBMS as the de facto standard for all client/seervr applications today. Similar standards do not yet exist for OODBMSs. There is a place for both models. To be widely used, OODBMSs need to integrate transparently with RDBMS technology. Table 4.1 compares the terminology used by RDBMS and OODBMS proponents. Relational databases are characterized by a simple data structure. All access to data and relationships between tables are based on values. A data value occurrence is uniquely determined by the concatenation of the table name, column name, and the value of the unique identifier of the row (the primary key). Relationships between tables are determined by a common occurrence of the primary key values. Applications build a view of information from tables by doing a join based on the common values. The result of the join is another table that contains a combination of column values from the tables involved in the stick together. There remain some applications for which RDBMS have not achieved acceptable performance. Primarily, these are applications that require very complex data structures. Thousands of tables may be defined with many relationships among them. Frequently, the rows are sparsely populated, and the applications typically require many rows to be linked, often recursively, to produce the necessary view. The major vendors in this market are Objectivity Inc., Object Design, onto, and Versant. Other vendors such as HP, Borland, and Ingress have incorporated object features into their products. The application characteristics that lead to an OODBMS choice are shown in Figure 4.3. OODBMS will become production capable for these types of applications with the introduction of 16Mbps D-RAM and the creation of persistent (permanent) databases in D-RAM. Only the logging functions will use real I/O. Periodically, D-RAM databases will be backed up to real magnetic or optical disk storage. During 1993, a significant number of production OODBMS applications were implemented. With the confidence and experience gained from these applications, the momentum is building, and 1994 and 1995 will see a significant increase in the use of OODBMSs for business critical applications. OODBMSs have reached a maturity level coincident with the demand for multimedia enabled applications. The of dealing with multimedia demands the features of OODBMS for effective storage and manipulation.