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Developing of Node.Js Module for Working with an Effective Temporal Model in Nosql Data Bases

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Developing of Node.Js Module for Working with an Effective Temporal Model in Nosql Data Bases Science, EngineeringDimitar Pilev, & Education, Ventzislav 1, Nikolov (1), 2016, 75-82 Developing of Node.js module for working with an effective temporal model in NoSQL data bases Dimitar Pilev, Ventzislav Nikolov * University of Chemical Technology and Metallurgy, 8 Kl. Ohridski, 1756 Sofia, Bulgaria Received 15 March 2016, Accepted 05 September 2016 ABSTRACT The ever growing user requirements to access information demands using temporal database models. In such cases not only the data but the time intervals of their validity should be saved. The present communication describes the develop- ment of Node.js software module to process temporal data in the non-relational DBMS MongoDB. Asynchronous software model leads to extremely fast processing of large data amounts of temporal databases. Keywords: temporal databases, Node.js, NoSQL database, MongoDB, asynchronous programming. known Java EE [1], Apache PHP [2] and ASP. INTRODUCTION NET [3], as well as the new, but recently increas- ingly popular Node.js [4, 5] are among them. The continuous increase of the number of The Node.js [6] platform is quickly gaining users utilizing the internet as means of com- popularity amongst web developers thanks to the munication, payment, shopping, etc. imposes ease and speed of processing user queries. The the use of new technologies when implementing use of the Node.js technology is exponentially web-based applications. The latter should direct increasing. Leading companies such as PayPal, a large number of user queries towards the large LinkedIn, WalMart [7] have rewritten their ap- amount of information stored in the databases. plications using Node.js. One of the main requirements towards any In a number of cases, the data base appears contemporary web-application is related to its as the primary source of delay in processing user quick response time. The main objective is to queries. The delay increases proportionately to decrease the response time of submitted user que- the processed data amount. This is the reason why ries regardless of their number and complexity. leading companies such as Google, Facebook and At present there is a number of platforms Amazon are making the transition towards using for building web-based applications. The well- a new type of databases called non-relational * Correspondence to: Ventzislav Nikolov, University of Chemical Technology and Metallurgy, 8 Kl. Ohridski, 1756 Sofia, Bulgaria, E-mail: [email protected] 75 Science, Engineering & Education, 1, (1), 2016 databases (NoSQL - Not only Structured Query the extreme popularity of the problem, however, Language) [8, 9]. commercial DBMS such as Oracle and Teradata The NoSQL database provides a mechanism have already published [10], [11] new specifica- for storage and restoration of data using a free, tions of DBMS with temporal support. An addi- coordinated model of data unlike the relational tional surface layer has been developed in [12] model of DB. A non-relational database is an op- to DBMS MySQL to implement it. timized depository containing information of the The purpose of the development described in type key-value. Its design purpose is to ease the this communication is to implement a module for processes of restoration and addition of informa- the Node.js platform providing a effective time tion aiming to optimize the efficiency under the temporal support of data stored in MongoDB conditions of introduction and storage of large database. The module allows the processing of amounts of data. queries related to addition, deletion, modifica- Traditional models of DB and DBMS are tion and searching of temporal information in capable of storing and processing only the pres- the database. ent state of the modeled subject area. These are normally present states, whose old values are An effective temporal model destroyed when change is necessary. The constantly increasing demand of infor- The effective temporal model (ETM) is us- mation imposes the use of temporal DB, where ing effective time representing a combination of not only data is stored, but also the period of valid and transactional time. The beginning of its validity. One of the major reasons for non- the effective period is set at the current time, i.e. reporting the change of data states in the course the moment of recording the cortege in DB (the of time refers to the lack of adequate maintenance beginning of the period marking the transactional of the temporal factor in DBMS. Until recently time, Ts), and its end is set at the time marking the existing DBMS would not allow temporal the end of the period of the valid time, Ve. processing of data. Taking into consideration The addition of data to the relation under ( , ( 1, … , ), ) = ′ {(1,… , | )} ( 1, … , | ) ( 1, … , | ) ( , ) ′ ′ ∪ ∄ � ∈ � ⋁ ∃ � ∈ ⋀ ∄ ∈ � ⎧ {( 1, … , | )} {( 1, … , | ( , ))} ( 1, … , | ) ( , ) ⎪ ′ ′ − ∪ ℎ ∃ � ∈ ⋀ � ⎨ ⎪ a) addition of data ⎩ ( , ( 1, … , )) = {( , … , | )} {( , … , | ( , ))} ( , … , | ) 1 1 1 in opposite case − ∪ ∃ � ∈ ⋀ ∈ � � b) deletion of data ( , ( , … , ), ) = ( ( , ( , … , )), ( , … , ), ) 1 1 1 ′ ′ Fig. 1. Updating data in relation. 76 Dimitar Pilev, Ventzislav Nikolov ETM is implemented in case facts that are not is still active), then data modification, rather than recorded in DB (a1, … , an) have to be registered. data addition, is required. The latter are usually valid for a definite period of The updating of the values of data (a1, … , an) time. The effective time coincides with the valid which is part of the current state of the rela- time, which starts with the recording of the facts tion, requires the use of the following function: in DB. This means that the facts are valid in the changeETP(te, te) - this function changes the reality modeled being recorded in DB. The data effective time period,′ during which the data in recording brings back a new updated version of the cortege is identically marked regardless of the the relation. meeting or overlapping of the old and the new Functions referring to work with effective periods (te and te ‘). temporal intervals are defined in the model with The deletion of a certain cortege consists of its the aim to present the semantics of data updat- logical removal from the current state of the rela- ing. They are: tion (Fig. 1b). The logical removal of the cortege l the function meets(te, te’ ) performing a test is performed by correcting the time period during for meeting of two intervals: which the non-temporal attributes (a1, … , an) are - ( , ) marked. Such correction is performed by setting ′ the time for ending the effective time period, ( = ) which time is current at the moment of deletion. ′ − For this purpose we use the function ( ). l the function ( , ) performing a − [ , ) ( ) test for partial overlap of two intervals:′ - ( , ) − 0 else ∈ ′ ( < ) If− the values of attributes in the cortege ′ (a1, … , an) do not exist or, if they do exist but − are not part of the current state of the relation, then − There are three cases referring to the addition the deletion of the cortege will produce no effect. of new data to the relation (Fig. 1а). The modification of an existing cortege is Case one: Let the values of attributes performed through the “update” operation (Fig. (a1, … , an) , which do not depend on time, be 1c). It is defined as consecutive execution of the unrecorded in the relation until now, or comprise operations “delete” and “insert”. The proposed part of its previous states (Fig. 1а). In that case ETM reduces significantly the stored data vol- there is no record when the effective period of ume. There is significant reduction in the excess time overlaps the new period. In that situation we of information stored in the DB. At the same time add a new cortege to the relation. we can obtain a precise evaluation of the data Case two: If the values of attributes (a1, … , an) validity over time. are recorded in the relation and a record exists, An asynchronous programming model with then its period of validity te meeting the new te’, i.e. the effective period which is used to mark the Node.js cortege, will be updated to [Es, Ee). Case three: If the values of attributes′ are part Node.js is a platform built on the basis of of the current state of the relation (the effective Google V8 JavaScript [13] for easy building of period, when the data in the cortege is marked, quick and scalable network applications. Node. 77 Science, Engineering & Education, 1, (1), 2016 js uses an “event-driven” asynchronous input/ also switching between separate threads. output model of operation based on a single The Node.js platform is only an environ- process, which makes it easy and efficient for ment, which means that the programmer must real-time applications. do everything by himself. By default there is Node.js allows the development of applica- neither HTTP, nor any other server. A single tions written in JavaScript, which are executed by script contains the entire communication with the server. The platform contains the most popular the users. This significantly reduces the number operation systems such as Windows, Mac and of resources used by the web application. Linux. The environment provides an opportunity to interact with input/output devices through its A data model at MongoDB API written in C++. This allows a connection to other external libraries written in different lan- MongoDB [14] is a document-oriented data- guages by using JavaScript code. base management system, which stores structured Node.js has a module architecture to simplify information in JSON format [15] with dynamic the creation of complex applications. It contains scheme. This makes the information integration built-in asynchronous input/output libraries for in certain applications much easier and faster. working with files, sockets and HTTP commu- MongoDB has gradually become one of the most nication. popular non-relational DB, often referred to as With traditional and well-known platforms of NoSQL.
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