Dağıtık veritabanı mantığına dayalı değişken tarifeli faturalama otomasyonu

Abstract

Bu çalışmamda havacılık sektöründe, birden fazla coğrafi yerel yapı üzerinde yer hizmeti veren bir şirket üzerindeki faturalama sisteminin ihtiyaçlarını karşılayan bir uygulama geliştirdim. Uygulama Konusu, şirketin organizasyonel yapısı ve konuyla ilgili işlemlerin yerel yapılar itibanyla farklılık göstermesinden dolayı dağıtık veritabanı yönetim sistemi mantığıyla tasarlanmıştır. Şirket üzerinde bir bilgisayar ağına bağlı farklı coğrafi yerlerde altı adet Unix makine mevcutttur. Bu makineler birbirleri ile X.25 ağı ile bağlıdır. Her makinenin kendi yerel veritabanı mevcuttur.Her veritabanını kullanan uygulamalar yerel yapılar itibanyla birbirinden bağımsız çalışmaktadır. Fakat gerektiği zaman kullanılan veritabanı yönetim sisteminin sağladığı Client- Server mantığı ile veritabanları arasındaki bilgi akışı veya güncellemeler sağlanmaktadır. Bu da veritabanları arasındaki mantıksal korelasyonu mümkün kılmaktadır. Mümkün olduğu kadar bütün yerel uygulamalar bir başka makinedeki veritabanınına bağımlı olmadan kesintisiz çalışmaktadır. Tez konu itibarı ile üç ana bölüm bazında hazırlanmıştır, ilk bölümde; dağıtık veritabanı yönetim sistemleri ile ilgili temel tanımlar, problemler, avantaj ve dezavantajlar, dağıtık veritabanı olma kuralları ve TCP/IP - OSI referans modeli hakkında bilgi verilmektedir. İkinci bölümde; Uygulamanın geliştirildiği Progress Veri Tabanı Yönetim Sistemi hakkında dağıtıklık ve veritabanı değerlendirme kriterleri baz alınarak değerlendirme yapılmaktadır. Üçüncü bölümde; uygulama: amacı, geliştirilme yöntemi, bilgi akışı, programlar ve çıktılar vs. yer almaktadır.

Invoicing Automation with Changeable Price List, On the Idea Of Distributed Database System It's well known that during the 1970's computers were extensively used for building powerful, integrated database systems. The database systems has become the basic element of yhe information systems. One of the most important problems of database systems whch they were slow, is becoming not a problem with the development of the computer technology. Because of this development a lot of data processsing center in an action from software's which is coded with by a third generatiom language to software's which is coded by any fourth generation language on a database management system. After this development of database systems, computer networks have been extensively developed, allowing the connection of different computers and the exchange of data and other resources between them. In recent years the availability of databases and computer networks has given rise to a new field: distrubuted databases. A distrubuted database is, in brief, an integrated database which is built on top of a computer network rather than on a single computer. The data which constitute the database are stored at the different sites of the computer network, and the application programs which are run by the computer access data of different sites. In this study, it is developed an application which is built on the idea of distrubured processing and distrubuted database system, on the Airports Ground Handling Company called HAVAS. HAVAS is a sub company of the State Airport Authority founded in March 1 987. The basic facility of Havas is to give every kind of Handling Services to scheduled and non-scheculed aircrafts and their passengers, baggages and cargo. Havas is performing services at five international Turkish Airports. These airports are Istanbul - Atatürk, Ankara - Esenboga, izmir - Adnan Menderes, Antalya and Muğla - Dalaman. Havas is giving Handling Services to sixteen national and one hundered and four foreign, total one-hundered and twenty air transporting firms. There world top airlines among these firms such as Air France, British Airways, KLM, Aerolloyd, Delta, Singapore. Havas's personnel number is 2375, 222 out of this qualified personnel are employed at the General Management and the rest 21 35 personnel are working at the airports mentioned above. x- The services given by Havas are generally : i.) Representation and Communications ii.) Load Control and Communications iii.) Unit Load Device Control iv.) Passenger and Baggage v.) Cargo and Mail vi.) Ramp vii.) Aircraft Servicing viii.) Fuel and Oil ix.) Flight Operations and Crew Administration x.) Surface Transport xi.) Catering Services (Catering Ramp Handling) xii.) Supervision and Administration Figure 1. Passenger and Baggage Havas as a company which has a very big effect in the development of Turkish tourism and as company which is very important in Turkish Air Transportation aims high quality in Ground Handling Services more than profit. The Havas computer automation project has been in progress since 1 988. Until 1 992 there were only PC's, at the stations in the use for the Fligths connected the SITA network (A Common Airline Companies Network) and at General Manage ment for some management applications. Since the last of 1 992, all the application on PC's and the new applications which would be used also at the stations which would be related with General Management has been moved the new multi user systems (UNIX) connected by the X.25 (TURPAK) network. One of these projects is Ground Handling Charge Notes and Invoicing auto mation project, it is about the charging and entry of the services which is given at the stations and the invoicing of these services to the interested firms. -XI- Ground Handling Charge Notes (shortly GHCN) represents the services and the prices without discount which is given for a flight. The real prices for services are being represented in the invoices in the invoices. There are two kinds of invoices: Cash Invoices, for the firms which are contracted as Cash and Credit invoices, for the firms which are contracted as Credit. For the services, the source for invoices are GHCN's. For the Cash firms every GHCN corresponds to an invoice and forthe Credit firms all GHCN's from individual stations which in the period of time credit, correspond to only one invoice. Cash firms arebeing invoiced at the stations which give the services. Credit firms are being invoiced at the General Management at Istanbul for ever station, every period of time credit and every kind of speciality (flight type, flight place etc.) As it is clearly seen that some works are being done at some individual local places and some works are not being done at some local places: i.) Every station manages only the services which they give. ii.) GHCN's are being formed only at the stations. ii.) Cash firms are only being invoiced at the stations which the services are given. iv.) Credit firms are only being invoiced for the services given at the stations in the General Management. v.) The firms are being contracted at the General Management and the stations have to obey these contracts. In this position for the reasons which are examined in this study, distrubuted database system are the most reliable with the advantages of distrubuted process ing and storage capabities. Distrubuted Processing uses more than one processor to divide the processing for a set of related jobs. Distrubuted processing reduces the processing load on a single processor by allowing diffrent processors to concentrate on a subset of related tasks, thus improving the performance and capabities of the system as a whole. A database system should easily take advantage of distrubuted processing by using its client-server architecture. In this architecture, the database system, is divided in two parts: a front-end or a client portion and a back-end or server portion. -xii- The Client portion is the front-end database application and interacts with a user through the keyboard, display, and the pointining device such as a mouse.The client portion has no data access responsibilities; it concentrates on requesting, processing and presenting data managed by the server portion. The client workstation can be optimized for its job. For example it might not need a large disk capacity or it might benefit from graphic capabilities. The server portion runs the RDBMS software and hendles the functions required for concurrent, shared data access. The server portion receives and processes SQL or any other 4GL statements originating from client applications. The com puter that manages the server portion can be optimized for its duties. For example, it can have large disk capacity and fast processors. Figure 2. A distributed database system on a geographical dispersed net- A distrubuted database is a collection af data which belong logically to the same system but are spread over the sites of a computer network. This definitions emphasizes two equally important aspects of distrubuted database: -xiii i.) Distribution: i.e. The fact, that the data are not resident at the same site (processor), so that we can distinguish a distrubuted database from a single, centralized database. ii.) Logical Correlation: i.e. the fact that the data have some properties which tie them together, so that we can distinguish a distrubuted database from e set of local databases or files which -are resident at different sites of a computer network. All of the application is developedby Progress RDBMS. In recent years Progress has made a big development in Database Management Systems Area. It is a new product in this area. With the advantages and easines in developing an application Progress 4GL is very helpful. It has an individual 4GL very different from SQL, which is the base of the other database systems such as Oracle, Informix, Sybase. But it also supports the first level of ANSI SQL fully and also the second level partly. In Progress : select * from customer and For each customer: Display customer, end. produces the same report. In Progress 4GL.with the abilities of block structures which is very close to 3GL's.makes the programmer stronger to produce complex parametric applica tions. In the study I used only the.Progress 4GL to develop applications. General Management has full compiler, run time end the other Progress components. The other machines have only Progress Run-Time module. So the applications are developed on the General Management. The other machines only runs the generated Progress run-time code. For the distrubuted scenario on the project, The Client - Server Architecture and the database connection properties of Progress were used. TCP/IP protocol was used to make database connections between different machines. There are six Unix Machine at different local places (General Management and Istanbul - Atatürk, Ankara - Esenboga, Izmir - Adnan Menderes, Antalya - Antalya, Muğla - Dalaman Airports). All sites have their own local database. All Machines are connected each other with packet switching X.25 (Turpak) network. Database connections on TCP/IP is being dver X.25. For file transfers between systems ftp or uucp are used. And for remote logins "pad" over X.25 and telnet over TCP/IP are used. The main definitions on distrubuted'processing and distrubuted databases, on overview of the characteristics the problems, the advantages and disadvantages of distrubuted databases, the compilaion of 1 2 rules by the author C. J. DATE are being represented in the first section. -xiv- In the second section, Progress RDBMS, which is used to manage this distributed system and to develop application, is examined by depending on the specialities which characterizes a Database Manageement System and Distributed Database Management Systems. In the next section the information about the application, the system and also some explanations on the programmes about distrubution from the apllication with the chosen examples is given. At the last section some important programmes and outputs are placed.