In this assignment, the company I will be working with is Villa Care Kenya Company which can be found in the undermentioned nexus hypertext transfer protocol: //www.villacarekenya.co.ke/ and is located in Kenya, Africa. Villa Care Kenya is a existent estate company located in Kenya and it started its operations in 1994. It offers a assortment of existent estate services where it specialises in rental and sale of upfront residential and a assortment of commercial belongingss particularly in Nairobi and Mombasa. In add-on it besides specialises in sale of lands and sites. Having designed the company ‘s database for all its operations i have been requested to buy a suited database direction system to implement this database. Presently, this house is utilizing the traditional database system which is the relational database direction system. “ The vision of Villa Care Kenya Company is to pull off the economic resource available in the most efficient manner possible, to follow the most efficient tools readily available in the market, to ease prompt and satisfactory consequences in their services to their clients ” ( hypertext transfer protocol: //www.villacarekenya.co.ke/ ) . In order to carry through their vision, this house needs to implement the suited database direction systems, which can enable better entree and storage of informations. There is limited usage of database direction system where most services are non rendered through the web, multimedia or image informations is limited, web direction systems are non available and synergistic and dynamic web is limited. In order to make this, i am traveling to analyze the different types of DBMS with their pros and cons, and supply a study proposing the suited DBMS for implementing in this company to its Managing Director.
As Villa Care Kenya Company is presently utilizing the RDBMS, I would urge them to implement ORDBMS. This is because RDBMS is non run intoing all the company needs. On the other manus, the company does non necessitate to implement a new system, that is OODBMS as this system is suited for more complex dealingss with longer minutess and for fabrication and designing houses. Hence go forthing us with ORDBMS, which i extremely recommend as it can be implemented parallel with RDBMS. The house will widen the demands required into RDBMS hence making the ORDBMS. These extensile demands are multimedia or image informations, web direction systems and synergistic and dynamic web. By implementing ORDBMS the company will cut down there costs and will non free any benefits of the former system. Most significantly, it allows the coder and stop user to utilize the object-oriented systems in parallel. As we all know, we all resist to alterations, this is reduced as ORDBMS is a loanblend of object oriented and relational theoretical accounts. ORDBMS is universally accepted unlike OODBMS which has a niche market. I did a comparing of both OODBMS and ORDBMS as follows:
Data modeling comparing: They both support the object individuality, encapsulation, heritage, polymorphism, complex objects and relationships.
Data entree ; they both support making and accessing relentless informations, adhoc question installations, pilotage, object waiter, schema development, On the other manus ORDBMS supports unity restraints while OODBMS does non back up unity restraints.
Data sharing ; they both support ACID minutess and recovery. ORDBMS does non back up advanced dealing theoretical accounts while OODBMS supports where grade of support differs between merchandises ( this is non a needed functionality for Villa Care Kenya limited ) . In add-on ORDBMS strongly supports security and positions while OODBMS has limited support.
From the above comparing, both database systems provide the same functionalities but ORDBMS has extra functionalities which are a demand for this company.I have analyzed all the database direction systems and careworn recommendations for this company.
DATABASE MANAGEMENT SYSTEM ( DBMS )
Database is a shared aggregation of logically related informations and a description of this information designed to run into the information demands of an administration. DBMS is the package that enables users to specify, make, keep, and command entree to database and hence is the package that interacts with the user ‘s application plans and the database. The DBMS is now the underlying model of the information system and has basically changed the manner in which many administrations work.
There are three types of DBMS as discussed below:
RELATIONAL DATABASE MANAGEMENT SYSTEM ( RDBMS )
The RDBMS represents the 2nd coevals of DBMS and is based on the relational informations theoretical accounts proposed by E.F.Codd ( 1970 ) .The relational theoretical account aims were specified as follows
To let a high grade of informations independency.
To supply significant evidences for covering with informations semantics, consistence and redundancy jobs.
To enable the enlargement of set oriented informations use linguistic communication.
This led to the creative activity of RDBMS merchandises during the late seventiess and 1980s. This led to several hundred RDBMS for both mainframe and personal computer environments e.g. office entree and ocular FoxPro from Microsoft.
ADVANTAGES OF RDBMS
The easiness with which users canA create and entree informations and widen it if needed. After the original database is created, new informations classs can be added without the bing application being changed.
It ‘s an first-class beginning of information.
RDBMS has a simple logical construction. BecauseA the tabular arraies are simple, informations is easier to understand and pass on with others
It ‘s suited for on-line dealing processing. RDBMS are flexible, and productive. RDBMS are flexible because users do non hold to utilize predefined keys to input information. Besides, A RDBMS are more productive because SQL is easier to larn. This allows users to pass more timeA inputting alternatively of larning.
It has data independency.
DISADVANTAGES OF RDBMS
RDBMS do non hold adequate storage country to manage informations such as images, digital and audio/video. The system was originally created to manage the integrating of media, traditional fielded information, and templets.
Information must be in tabular arraies where relationships between entities are defined by values.
Poor representation of existent universe entities. The procedure of standardization leads to the creative activity of dealingss that do non match to entities in the existent universe.
Semantic overloading ; the relational theoretical account has merely one concept for stand foring informations and relationships between informations.
Poor support for security, unity and general restraints. Integrity refers to the cogency and consistence of stored informations. Integrity is normally expressed in footings of restraints which are consistence regulations that the database is non permitted to notate. Unfortunately many commercial systems do n’t to the full back up this restraints and it is necessary to construct them into applications.
Homogeneous informations construction. The relational theoretical account assumes both horizontal and perpendicular homogeneousness. Horizontal homogeneousness means that the tuple of a relation must be composed of the same property. Vertical homogeneousness means that the values in a peculiar column must be an atomic value.
This construction is excessively restrictive for many “ real-world ” objects that have a complex construction and it leads to unnatural signifiers which are inefficient.
Limited operations ; The RDBMS has merely a fixed figure of operations, such as set of tuple-oriented operations, Operationss that are provided in SQL specification where SQL does non let new operations to be specified.
Impendence mismatch: Most informations use linguistic communications for RDBMS lack computational completeness.
Transaction in the concern processing are by and large short lived and the concurrence control primitives such as two-phase lockup are non peculiarly suited for long-duration minutess, which are more common for complex design objects.
Trouble in managing recursive questions: Atomicity and informations agencies that reiterating groups are non allowed in the relational theoretical account. As a consequence it is hard to manage recursive questions, that is, questions about a relationship that a relationship has within itself.
Schema alterations are hard. Database decision makers must step in to alter database constructions and typically plans that entree these constructions must be modified to set with the new constructions. To run into the demand of increased flexibleness we need a system that caters for natural scheme development.
RDBMS were designed to utilize content-based associatory entree and have hapless navigational entree ( entree between single records ) . Navigational entrees are of import for many of the complex applications.
In RDBMS there is the complexness of mapping an object-oriented linguistic communication to a relational information base. There has been a broad spread credence of RDBMS for traditional concern applications such as order processing, stock list control, banking and air hose reserves. However, bing RDBMS have proven inadequate for applications whose demands are rather different from those of traditional concern database applications. This applications includes
Computer aided design ( CAD )
Computer Aided Manufacturing ( CAM )
Network direction system
Office Information system ( OIS ) and multi media system
Synergistic and dynamic web sites.
Due to increasing complexness of database applications, two new informations theoretical accounts emerged ( OODBMS and ORDBMS.This development represent 3rd coevals DBMS.
OBJECT ORIENTED DATABASE MANAGEMENT SYSTEM
Object oriented is an attack to package building that has shown considerable promise to work outing some of the authoritative jobs of package development. The underlying construct behind object engineering is that all package should be constructed out of criterion, reclaimable constituents whenever possible. OODBMS is the director of OODM ( OODM is a logical information theoretical account that captures the semantics of objects supported in object oriented scheduling ) . Examples of OODBMS are jasmine Object Database and Versant Object Database. Object-oriented database engineering is a matrimony of object-oriented scheduling and database engineerings ( FIG 1 )
OODBMS is defined by Passage et Al ( 1989 ) as
High-level question linguistic communication with query optimisation capablenesss on the implicit in system.
Support for continuity, atomic minutess and concurrence and recovery control.
Support for complex object storage, indexes and entree methods for fast and efficient retrieval.
Hence OODBMS = object oriented system +1 +2+3
The OODBMS has the undermentioned mandatary characteristics
Complex objects must be supported: must be possible to construct complex objects by using builders to basic objects.
Objects must hold a alone individuality that is independent of its property values.
Encapsulation must be supported. Encapsulation is achieved by guaranting that coders have entree to the interface specification of methods, and informations and execution of this method is hidden in the objects.
Types or categories must be able to inherit from ascendants. A subclass or subtype should inherit properties and methods from its ace type or ace category severally.
Dynamic binding must be supported. Methods should use to objects of different types ( overloading ) .
The information use linguistic communication ( DML ) should be a general -purpose scheduling linguistic communication.
The set of informations types must be extensile ; the user must be able to construct new types from the set of predefined types.
The database must be capable of pull offing really big databases, support concurrent users and supply a simple manner of questioning informations.
The OODBMS evolved so as to work out three countries that are debatable in RDBMS. That is long continuance minutess, version and scheme. These issues are addressed in OODBMS as follows
A dealing is a logical unit of work which should ever transform the database from one consistent province to other.The types of minutess found in concern applications are typically of short continuance. In contrast minutess affecting complex objects such as those found in technology and design applications, can go on for several hours or even yearss. Clearly, to back up this long continuance minutess, different protocols from those used in traditional database applications, in which minutess are typically of short continuance are needed.In an OODBMS, the unit of concurrence control and recovery is logically an object. Locking-based protocols are the most common type of concurrence control mechanism used by OODBMS to forestall struggle from happening.
Versions ; The procedure of keeping the development of objects is known as version direction. There are many applications that need entree to the old province of an object. Example, the development of a peculiar design is frequently an experimental and incremental procedure, which changes with clip, therefore, it ‘s necessary in databases that shops design to maintain path of the development of design objects and the alterations made to a design by assorted minutess. Versioning should let alterations to the belongingss of objects to be managed in such a manner that object mentions ever point to the right version of an object.
ADVANTAGES OF OODBMS
OODBMS can supply appropriate solutions for many types of advanced database applications.
Enriched patterning capablenesss ; the object oriented theoretical account allows the “ existent universe ” to be modelled more closely. The object which encapsulates both province and behavior is a more natural and realistic representation of the existent universe objects. An object can hive away all the relationships it has with other objects, including many to many relationships and objects can be formed into complex objects that traditional theoretical accounts ca n’t get by with easy.
Extensibility: OODBMS allow new informations types to be built from bing types ; Allows formation of ace category that are shared with sub categories therefore cut downing redundancy within the system ; Allows overriding and the reusability of categories therefore advancing faster development and easier care of database and its application.
Removal and imminence mismatch. A individual linguistic communication interface between DML and the scheduling linguistic communication overcomes the imminence mismatch hence extinguishing many of the inefficiencies that occur in mapping declaratory linguistic communication such as SQL to an imperative linguistic communication such as C++ .
More expressive Query linguistic communication: Navigational entree from one object to the following is the most common signifier of informations entree in OODBMS. This is suited for managing recursive questions
Support of schema development: The tight yoke between informations and application in an OODBMS makes schema development more executable. Inheritance and coevals allow the scheme to be better structured, be more intuitive and gaining control more of the semantics of the application.
Support of long continuance minutess unlike RDBMS.
Applicability to progress database application: RDBMS cant support CAD, CASE, OIS and multi media but the enriched capablenesss of OODBMS, has made them suited for these applications.
Improved public presentation: a figure of benchmarks have suggested that OODBMS provides important betterment over RDBMS.
Lack of cosmopolitan informations theoretical account: There is no universally agreed upon informations theoretical account and standard object oriented query linguistic communication, therefore most theoretical accounts used lack a theoretical foundation.
Lack of experience: It ‘s still much geared towards the coder instead than the terminal user. There is still existence to acceptance to this engineering and it ‘s limited to a little niche market.
Competion ; There is high competition posed by the RDBMS and ORDBMS merchandises. These merchandises have an established user base with important experience available. SQL is an sanctioned criterion and relational informations theoretical account has a solid theoretical foundation and relational merchandises have back uping tools to assist both terminal users and developers.
Query optimisation via media encapsulation. This requires an apprehension of the underlying execution to entree the database expeditiously. This compromises the construct of encapsulation.
Locking an object degree may hold an impact on public presentation. Many OODBMS usage lockup as the footing of concurrence control protocol. However if lockup is applied at the object degree, locking of an heritage hierarchy may be debatable and may impact public presentation.
Complexity ; The increased functionality provided by OODBMS, e.g. individual degree storage theoretical account, arrow swizzling, long continuance minutess, version direction and scheme developments, is inherently more complex than that of RDBMS. Hence complexness leads to merchandises that are more expensive to purchase and more hard to utilize
Lack of support for positions and security: Most OODBMS do n’t supply equal security and position mechanism. Most mechanism are based on a harsh coarseness and the user buzzword grant entree rights to single objects or categories.
In response to the failing of RDBMS and in defense mechanism of the possible menace posed by the rise of OODBMS, the RDBMS community extended the RDBMS with object-oriented characteristics giving rise to ORDBMS. There is no individual extended relational theoretical account ; instead, there is a assortment of these theoretical accounts, whose features depend upon the manner and the grade to which extensions are made. However all the theoretical accounts do portion the same basic relational tabular arraies and query linguistic communication, all incorporate some construct of “ object ” and some have the ability to hive away methods ( or processs or triggers ) every bit good as informations in the database. ORDBMS indicates that the system integrate some impressions of “ OBJECT ” . The construct of ORDBMS as a loanblend of the RDBMS and OODBMS is really appealing, showing the wealth of cognition and experience that has been acquired with the RDBMS.
ADVANTAGES OF ORDBMS
The chief advantages of widening the RDBMS resolves many of the failings of RDBMS as discussed before. This theoretical account comes from reuse and sharing. Reuse comes from the ability to widen the DBMS waiter to execute standard functionality centrally, instead than hold it coded in each application therefore leting the functionality to be shared by all applications. This advantage gives rise to increased productiveness, both for the developer and the terminal user.
The ORDBMS preserves the important organic structure of cognition and experience that has gone into developing relational applications. This is a important advantage, as many administrations would happen it prohibitively expensive to alter. If the new functionality is designed suitably, this attack should let administrations to take advantage of the new extensions in an evolutionary manner without losing the benefits of the current database characteristics and maps.
The SQL ; 2008 criterion is designed to be compatible with the SQL2 criterion, and so any ORDBMS that compiles with SQL ; 2008 should supply this compatibility.
ORDBMS allows organisations to go on utilizing their bing systems, without holding to do major alterations.
It besides allows users and coders to get down utilizing object-oriented systems in analogue.
In add-on, three of the taking RDBMS sellers – Prophet, Microsoft and IBM have all extended their systems into ORBMS, although the functionality provided by each is somewhat different.
DISADVANTAGES OF ORDBMS
The chief disadvantage is of complexness and associated increased costs.
The advocates of the relational attack believe the initial simpleness and pureness of the relational theoretical account are lost with these types of extensions.
ORDBMS sellers attempt to portray object theoretical accounts as extensions to the
relational theoretical accounts with some extra complexnesss.
As Villa Care Kenya Company is presently utilizing the RDBMS, I would urge them to buy ORDBMS.
In add-on since the company is utilizing RDBMS, the new required functionality can be designed suitably, therefore leting the company to take advantage of the new extensions in an evolutionary manner without losing the benefits of the current database characteristics and maps. This would be cost effectual.
By implementing ORDBMS, it will heighten:
Office information system: This will hive away informations associating to the computing machine control of information in the concern including electronic mail, paperss, and bills among others. It can manage exposure and voice commentary.
Multi media systems: The company can utilize:
Image informations where clients can be able to question utilizing graphical images of the characteristics that may be found in desirable belongingss ( such as bay Windowss or roof horticulture ) .
Audio information where the client can utilize characteristics for the coveted belongings to find the noise degree from the close by traffic.
Video informations: A client may question utilizing a picture characteristics of the coveted belongingss such as positions of the sea.
Synergistic and dynamic web sites: This can be used enable users to seek for points that match their user defined standards, enable user to happen an point based on their customised specification and choosing a voiceover commentary giving inside informations of the coveted belongings.