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Glossary of programming and network terms - Part two


Kilobyte Ė A measure of storage capacity equal to 1024 bytes. An 8-bit computer with a capacity of 32k locations will have 32768 bytes or 32 kilobytes. A 16-bit computer with 512k words of main memory might have 2 bytes in each word with a capacity of 1048576 bytes or 1048 kilobytes.

ODBC - Open Database Connectivity - A standard database access method developed by Microsoft Corporation. ODBC makes it possible to access any data from any application, regardless of which database management system (DBMS) is handling the data concerned. ODBC inserts a middle layer, called a database driver, between an application and the DBMS. The layer then translates the applicationís data queries into commands that the DBMS understands. Both the application and the DBMS must be ODBC-compliant, therefore the application must be capable of issuing ODBC commands and the DBMS must be capable of responding to them.

ORB - Object Request Broker - The ORB is the middleware that establishes client-server relationships between objects. An ORB allows a client to invoke a method on a server object, which can be on the same machine or across a network. The ORB intercepts the call to find an object to implement the request, pass it the parameters, invoke its method, and return the results.

Perl - Practical Extraction and Report Language is a programming language developed by Larry Wall, especially designed for processing text, which has made it one of the most popular languages for writing CGI scripts. Perl is an interpretive language and is easy to build and test simple programs

Process - A task performed by an operating system concept that refers to the combination of a program being executed and bookkeeping information used by the OS. Whenever you execute a program, the operating system creates a new task for it. The task is like an envelope for the program to identify the programs task number and attach it to other bookkeeping information to. A multithreading operating system allows the process to branch for multiple tasking.

Relational Database - A database that stores data in the form of tables. The same database can be viewed in many different ways because they do not assume how data is related or how it will be extracted.

Scalability - A term referring to a client-server systemís ability to meet increased traffic. In performance terms, a system that scales linearly doesnít incur an increase in system overhead as traffic increases; in management terms, the cost per user remains constant as the number of users increase

SQL - Structured Query Language is a standard query language for requesting information from a database. SQL calls can be submitted to a database server or invoked as stored procedures. Nearly all the job applications for technicians in London require you to know about SQL.

Thin Client - A universal client where the functionality is provided by downloadable components when the user connects to the server. It provides other computers to use the programs on a server.

Thread Ė This is a part of a program that can execute independently of other parts. Operating systems and programming languages supporting multithreading enables programmers to design programs whose threaded parts to execute concurrently.

Tiered Architecture - The number of tiers in a systemís architecture refers to the connections made during a transaction. A Two-Tier is a client connected to a server. A Three-Tier is a client communicating with a server that connects with another server or application.

Transaction Processing is computer processing in which sets of operations are grouped together by rules similar to a user making an electronic payment. This involves two operations: debiting the userís account and crediting the merchantís account. Both attempted operations should be aborted if either fails, called rolling back the transaction. If both operations succeed, then the transaction is made permanent and becomes a commitment.

Transaction Monitor - The system that controls transaction processing and maintains database integrity. Either all the databases are updated or none of them, so that the databases remain synchronised. Database changes required by a transaction are first stored temporarily by each database. The transaction monitor then issues a pre-commit command to each database and requires an acknowledgment. If the monitor receives the appropriate response from each database, the monitor issues the commit command, which causes all databases to simultaneously make the transaction changes permanent