Design and implementation of enterprise systems in fine-grained concurrent computation

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1 Available online at Procedia Technology 5 (2012 ) CENTERIS Conerence on ENTERprise Inormation Systems / HCIST International Conerence on Health and Social Care Inormation Systems and Technologies Design and implementation o enterprise systems in ine-grained concurrent computation Kenji Ohmori * Hosei University, Faculty o Computer and Inormation Sciences Kajino-cho, Koganei-shi, Tokyo, Japan Abstract The computational power required to an enterprise system changes dynamically depending on services and the number o users. Massive concurrent computing is excellent in scalability, so that the paper proposes utilizing it or designing and implementing enterprise systems. The proposed accounting system is developed using Agile sotware development method to study the scalability o massive concurrent systems. When combining two subsystems in Agile, an attaching unction is introduced. The system is designed using Model-View-Control sotware architecture and communicating sequential processes and then implemented with JCSP. Beore implementation, the validity o the model is veriied using veriication tools. It reduces development cost and time Published 2012 by Published Elsevier Ltd. by Elsevier Selection Ltd. and/or Selection peer review and/or under peer-review responsibility under o CENTERIS/SCIKA responsibility o - Association CENTERIS/HCIST. or Promotion and Dissemination o Scientiic Knowledge Open access under CC B-NC-ND license. Keywords: Communicating Sequential Processes; Model-View-Control Sotware Architecture; Agile Sotware Development. * Kenji Ohmori. Tel.: ; ax: address: ohmori@hosei.ac.jp Published by Elsevier Ltd. Selection and/or peer review under responsibility o CENTERIS/SCIKA - Association or Promotion and Dissemination o Scientiic Knowledge Open access under CC B-NC-ND license. doi: /j.protcy

2 Kenji Ohmori / Procedia Technology 5 (2012 ) Introduction Massive concurrent computing is the next technology or solving scalability, where required computational power changes dynamically, which is observed in Web database systems including enterprise systems. A Web database system consists o Web component, application and database servers where each server is conventionally composed by single or multiple processors. An application program or the Web database system is usually designed by the sotware architecture o Model-View-Controller (MVC). The model part manages the behavior and data o the services supplied by the application program. The view part renders the model part into a orm suitable or interaction. The controller part receives input and initiates a response by making calls on model objects. The model, view and controller parts are installed in database, Web component and application servers, respectively. Application programs including enterprise systems that are designed or a Web database system are conventionally implemented by coarse-grained concurrency. On the other hand, ine-grained concurency makes the best use o scalability, so that an experimental system o an enterprise system is developed or studying technologies required or accommodating enterprise systems in a massive concurrent computing environment such as a virtual machine in Cloud computing. When using MVC sotware architecture, the model, view and controller parts have to be designed and implemented by ine-grained concurrency by [1]. In addition to that, these parts have to be installed in a parallel computing environment that a virtual machine technology o Cloud computing can realize. This paper describes design and implementation o an accounting system with ine-grained concurrency. The accounting system is designed by an agile sotware development method where the most important unctions o the accounting system are irstly designed, veriied, implemented and tested by [2]. Each unction is desigend using the concept o communicating sequential prosesses (CSP) by Hoare [3]. CSP is a model or concurrent processing and equiped by veriication tools such as FDR2 and PAT3 by Roscoe [4]. JCSP [5] is a Java-like language with enhancement o CSP concepts, is used to implement the model. Functional programming language Clojure [6] is an arternative to CSP, but the lack o veriication tools is its serious disadvantage. Ater the most important unctions have been successully implemented, the second ones are added to the irst ones. This process is repeated until the whole accounting system is completed. When adding unctions, new mathematical concepts called an attaching unction is introduced. Joining o two entities is an important operation or constructing a reliable and secure system. An attaching unction combines two entities holding an equivalence relation [7]. I attaching spaces o two programs combined together are not identical, the combined program causes serious aults, which is avoided using an attaching unction. Conventionally, enterprise systems are designed based on Java 2 Enterprise Edition (J2EE) and Enterprise Java Beens (EJB) technologies by Johnson [8]. For avoiding deadlocks in J2EE and EJB, the development o an application program that guarantees reliability and security to transaction procesing requires a huge amount o time and cost since no veriication tools are provided to detect livelocks and deadlocks. On the other hand, when desing a system using CSP, Failures-Divergences Reinement 2 (FDR2) or Process Analysis Toolkit (PAT) can detect these hazards. As veriication is carried out beore implementation, it reduces development time and cost. 2. Fine-grained concurrency To realize a large scale ine-grained concurrency, the number o processes has to be maximized. When MVC sotware architecture that has been used in the conventional enterprise system is adapted in the large scale ine-grained concurrency, it is important to realize each part o MVC with huge number o processes. In

3 346 Kenji Ohmori / Procedia Technology 5 ( 2012 ) this paper, a process stands or a process o CSP. Processes o CSP are executed each other concurrently. Communications among processes are carried out by message sending and receiving through a channel The granularity o model part MVC consists o three parts. Among them, the model part handles persistent data. In the conventional system, persistent data are processed in the database system where the unit o an access is deined by the database system itsel. Usually, a table or multiple tables are an access unit. In this system, all persistent data are kept in the main memory. The consistency between the database system and the main memory is kept by another system, so that the database system is not considered in this paper. Each persistent data is processed by a single process. When it is implemented in an object oriented method, one class is provided or each persistent data and only one instance is created or each class and handles accesses to the persistent data, so that deadlocks are easily avoided. In the accounting system, account items are typical persistent data. In this system, an account item is represented as a process. Cash, deposit, receivable and payable are examples o account items. Some account item has subordinate accounts. For example, a deposit account consists o several types. Each type is also represented as a process. For example, a checking account is a process. As a big company uses several banks, the account item o the checking account has subordinate account items corresponding to each bank. As CSP is a model or describing concurrent processing, a programing language has to be selected when implementing its model as a sotware system. Communicating Sequential Processes or Java (JCSP) is used in this paper. JCSP provides a process template as an interace o Java, which is called CSProcess. A Java class or realizing a process is realized by implementing the interace. Each process o CSP is realized by an instance o its class. Thereore, each class has one or multiple instances when implementing the model represented by CSP. The relation o deposit account, checking account and bank is depicted in Figure 1, which construct a class hierarchy by inheriting the properties o the upper classes to a lower class. The process o a deposit account is created in a JCSP program by the ollowing procedure. By implementing CSProcess, a class Account is created as a general account item. As a subclass o Account, a class Deposit is provided, which has common properties o deposit and withdrawal operations. A variable amount is provided as a class variable to show the current remaining amount in Deposit. To restrict the access to amount, only one instance is provided or the class, so that only this instance can read, write and update amount, which avoids conlicts o the resource amount among processes. Interace Process Class Hierarchy Account Instances Deposit Deposit Process Checking Bank Checking Process Bank A Fig. 1. Class, instance and process hierarchies

4 Kenji Ohmori / Procedia Technology 5 (2012 ) As a checking account inherits a deposit account, a class Checking is provided as a subclass o Deposit. New properties such as no interest rate are added to this class. Only one instance is also provided to Checking. In the same way, a class and instance are also provided to bank A. A speciic process example o CSP is now described using a cash account item. Increase or decrease o the amount o money in the cash account item is received by a channel cash?. The process o cash is represented here by CASH (y). y is the current amount o money. When x, which shows the amount o increase or decrease, is received by the channel, the process expressing this behavior is described as ollows, CASH ( y) cash? x CASH( y + x). = (1) The program corresponding to the process is depicted as ollows. The irst class that has to be deined is a class Account, which implements the interace CSProcess and an input channel conigure is provided and conigured. public class Account implements CSProcess { ChannelInput conigure; public Account(ChannelInput conigure) this.conigure = conigure; public void run() {} } The next class is Cash, which is deined as a subclass o Account. When receiving inc that is the amount o increase or decrease, the class variable accumulated is accumulated by inc. class Cash extends Account { static Integer accumulated = new Integer(0); public void run() { while (true) { Object inc = conigure.read(); i (inc == null) break; else i (inc instanceo Integer) accumulated = new Integer(accumulated.intValue() + ((Integer) inc).intvalue()); else System.error.println( Cash Operation Error ); }}} 2.2. The granularity o view part The view part o MVC provides graphical user interaces (GUI) o homepages. The granularity o the view part mainly depends on JCSP unctions. The current version o JCSP supports Abstract Window Tools (AWT) in such a way that widgets such as buttons, scroll bars and pop-up menus are provided as independent concurrent processes so that JCSP gives ine-grained granularity to the view part. A homepage o an accounting system is provided by a Java applet implemented by AWT. Java Swing that becomes available in JCSP in uture gives more elegant and sophisticated GUI than the current system. However, there are no dierences rom the view point o concurrency. Thereore, AWT gives enough unctions to examine ine-grained concurrency regardless o poor GUI.

5 348 Kenji Ohmori / Procedia Technology 5 ( 2012 ) The granularity o control part The control part gets data rom the view part, processes the data and sends the processed data to the model part. Reversely, it gets data rom the model part, processes them and rendered them to the view part. Thereore, at least one process is given to each user at the control part. The accounting system basically provides the view part or transaction services including sales and purchasing. The control part gets transaction data, sorts it to credit and debt accounts and generates a journal. According to the journal, the control part updates the corresponding credit and debt account items. Suppose that a company is selling goods by cash. The journal or this transaction is provided with a cash account item with sales amount as the debt and a sales account item with the same amount as the credit. Ater asking or recording the journal, the control part requires the model part to update these accounts by increasing or decreasing the accumulated amount o these account items by the sales amount. A process SELLING is describes as ollows, SELLING = submit content? y journal! y cash! x3 sales! x3 SELLING, where y { x1, x2, x3, x4}, x1 date, x2 goods, x3 prise, x4 customer. (2) 3. Process integration It is unlikely that the enterprise system equipped in a company will not change. The accounting system is exposed by the revision o tax laws. The concept o accounting system itsel changes. The enterprise system is required to adapt to various changes such as modiication, addition and elimination o unctions or services. As modiication can be carried out by elimination and addition, the system is required to be adaptable o addition and elimination. An attaching unction gives mathematical oundation when designing and implementing addition and elimination Attaching unctions Let us start with a topological space and attach another topological space to it. Then, = = / ~ is an attaching space obtained by attaching to by an attaching map (or by identiying each point y with its image ( y) by a continuous map ). 0 0 denotes a disjoint union, which is usually represented by a square cup symbol. An attaching map is a continuous map such that : 0, where 0. The attaching space = / ~ is a case o quotient spaces / ~ = = /( x ~ ( y) y 0. A matchmaking party gives a good example to explain how separate groups are merged together using an attaching map. There are a group o girls, which is represented by a set G = { Betty, Michel, Alice, Chelsea, Jackie}, and another group o boys described by a set B = { Tom, Mike, Peter, Jack, Alex}. A member o the girl group has never met a member o the boy group. Suppose that these groups have a matching party. The situation beore the meeting is represented by the disjoint union o two groups. The situation ater the meeting is described using an attaching map, which describes new partners that have been made at the party. The disjoint union o these sets is represented by G B = { Betty, Michel, Alice, Chelsea, Jackie, Tom, Mike, Peter, Jack, Alex}. (3)

6 Kenji Ohmori / Procedia Technology 5 (2012 ) At the meeting, Betty and Mike like each other and become a partner. Also, Chelsea and Peter do another partner. I a partner is considered to be identical by an attaching map, then, G B = {( B, M ) = {( Betty, ),( Mike, m)},( Michel, ),( Alice, ),( C, P) = {( Chelsea, ), ( Peter, m)},( Jackie, ),( Tom, m),( Jack, m),( Alex, m)}, where G B, G = {( Betty, ),( Chelsea, )}. : 0 0 (4) The party caused the change o relation between girl and boy groups. The change is depicted using an identiication unction g as ollows, g : G B G B (5) As g can be deined as a continuous unction, disjoining the attaching space G B A consolidated accounting system 1 g gives the two original disjoint spaces G and B by The consolidated accounting system gives the inancial situation o a group o companies tightly related by inancial alliance. In general, an accounting system depends on a business type. I dierent business companies are combined into a consolidated accounting system, the same or similar account items o both companies should be merged into one account item. Also, the internal transactions that have been carried out between combined companies should be merged and then eliminated. Suppose that a product company is a subsidiary o a trade company. Both companies have individual accounting systems and give sales and purchasing services. The account items related to these services are depicted in Fig. 2. has suppliers and Z and customers Purchase and A, B and C. These suppliers Sales, respectively. A set o and customers constitute subordinate account items o subordinate account items o Purchase is { Sup, SupZ }. has also suppliers and customers. The sets o account items o these companies are represented as ollows. = { Purchase = { Sup, SupZ }, Sales = { CustA, CustB, CustC }}, Purchase = { SupW }, Sales = { Cust, CustA, CustD }}. = (6) { Thereore, the set o the accounting systems o two companies is represented by as the disjoint union o and. By introducing topology into the set such as the discrete topology and using an attaching unction that attaches the same or similar account items o both companies together, the ollowing set is obtained.

7 350 Kenji Ohmori / Procedia Technology 5 ( 2012 ) Consolidated Companies Purchase Sales W Z A B C D Trade Company Product Company Purchase Sales Purchase Sales Z A B C W A D Fig. 2. Accounting systems or the consolidated, trade and product companies. = { Purchase = { null = { Sup, Cust }, SupZ, SupW }, Sales CustA = { CustA, CustA }, CustB, CustC, CustD }}. = (7) { Suppose that purchases products rom. The accounting system o records it in the purchase account item rom and one o does it in the sales account item rom. As the products produced by becomes only goods being sold by, Sup is equivalent to Cust in the consolidated accounting system. Sup is a debt account item and Cust a credit one. Both account items have the same amount o money. I one o them is selected as the representative, another account is moved to the other side (in the above expression, Cust is moved rom the credit side to the debt) where the amount o money is negated, so that the amount o money o the representative item becomes zero. Thereore, both accounting items can be eliminated. In, the representative is expressed as null. (In the same way, Payable meaning that has to pay the product cost to and rom are also equivalent and eliminated.) and have A as a customer, which is represented as Re ceivable meaning that can receive the product cost CustA and CustA in the accounting systems, respectively. By, both o them are attached together and is expressed by the representative CustA in the consolidated accounting system. The selling process o in CSP is obtained by the ollowing procedure. Selling date, product name, selling amount and customer name are entered at a homepage o the sales service when products have been sold. When pushing the enter bottom at the homepage, a celling process SELLING is executed.

8 Kenji Ohmori / Procedia Technology 5 (2012 ) Selling (Instance or process) Cash (Instance or process) Cash? (Instance or channel) Fig. 3. Two channels are attached together to construct a multiple-input and single-output channel. An identiication map g : gives the transormation rom the set o individual accounting systems to the consolidated accounting system. In this transormation, the attaching map plays an important role. A process example in the consolidated accounting system is now described. By receiving selling inormation rom the homepage, the selling process sends selling inormation to the account item provided or each customer, which is dierent rom the process in Section 2.1 where the sales account item is not divided into individual customers. SELLING as a CSP process is described as ollows. SELLING = submit content? y journal! y (( receiivable! x3 sales! x3) x4 = Company ( receiivable! x salesi! x3 receiivablec! x3 salesc! x3) x4 SELLING, where i { A, D}. i 3 = Companyi In the above expression, the statement o the 2 nd line is related to an internal transaction between and. Thereore, the transaction is recorded not in the consolidated accounting system, but only in the accounting system o. The 3 rd line statement is or an external transaction between and A or D. The transition is recorded not only in the accounting system o, but also in the accounting system o. In each case, the debt account is receiivabl e and the credit is sales. 4. The implementation o an accounting system Using agile sotware development, the accounting system has been constructed rom a simple system to the inal system. The simple system provides only one service or sales, which has one homepage as the view part, one process SELLING as the control part and two processes CASH (y) and SALES (y) as the model CASH (y are described by expressions 2 and 1, respectively. part. SELLING and ) Purchasing (Instance or process) ) (8)

9 352 Kenji Ohmori / Procedia Technology 5 ( 2012 ) Then, another important service o purchasing is independently provided with a homepage or purchasing, a process PURCHASING or the control part and a process PURCHASE (y) or the model part. Then, the two services are combined using an attaching unction. When combining the two services, the channel CASH? o SELLING is identical to the one o PURCHASING, so that the two channels are attached together by the attaching unction. The channel is implemented by JCSP as shown in Fig 3. The channel has multiple inputs and single output where an amount o money is received rom the SELLING instance or the PURCHSING instance and sent to the CASH instance. Based on the bottom-up method o agile sotware development, two accounting systems dedicated or trade and product companies are independently provided by adapting the sales and purchasing services to more realistic ones by replacing CASH (y) o SELLING and PURCHASING with RECEIVABLE(y) and PAABLE (y), respectively and adding more services. Then, the two accounting system is combined so as to be part o the consolidated accounting system as shown in the previous chapter. 5. Evaluations The number o processes o each homepage is as many as the number o widgets used in the homepage. As multiple users utilize a service, total number o threads o the view part is (the average number o widgets per service the number o services the average number o users per service). I about 1000 users or each service are concurrently using the system and several tens o services are provided with about 10 widgets, the number o threads becomes The control part receives a request rom the view part. For each service, one or multiple processes are provided. As the number o threads required in the control depends on the number o active uses, it becomes (the number o users the number o processes per service). The model part manages the persistent data o the accounting system. Generally, the number o account items is several thousands, which is the number o threads in the model part. Consequently, the required number o the accounting system depends on the number o users when the system is used by a large number o people. As the system can increase the number o threads lexibly according to the number o users, the system works eectively when it is installed in a massive concurrent system. 6. Conclusion A new mathematical model using an attaching unction is very useul in agile sotware development where a new developing subsystem is added to the developed subsystem so that the validity o combining two subsystems is guaranteed by the equivalence relation o an attaching unction, which reduces development cost and time. CSP is useul in designing concurrency. Serious hazards in concurrency are avoided using channels since resource conlicts are controlled by channels. Furthermore, validation tools or CSP are eective to detect hazards, which allow guaranteeing valid design beore implementation. JCSP is a very experimental tool or CSP. It has enough capability to veriy or demonstrate an expected system. In particular, as JCSP provides a network environment, it is useul to test an experimental system in a network environment where many personal computers are connected. However, JCSP needs to be enhanced when using it or developing a practical system.

10 Kenji Ohmori / Procedia Technology 5 (2012 ) Reerences [1] Pacheco, P., An Introduction to Parallel Programming, Morgan Kaumann. Burlington. [2] Martin, R., Agile Sotware Development, Principles, Patterns, and Practices, Prentice Hall. [3] Hoare, C. A. R., Communicating Sequential Processes. In: CACM, 21(8), [4] Roscoe, A., Understanding Concurrent Systems, Springer. London. Liu,., Sun, J., Dong, J., PAT3: An Extensible Architecture or Building Multi-domain Model Checkers, In: ISSRE IEEE [5] Welch, P., Brown, N., Moores, J., Chalmers, K., Sputh B., Integrating and Extending JCSP, Communicating Process Architecture [6] Emerick C., Carper B., Grand C., Clojure Programming, O Reilly. Sebastopol. [7] Ohmori, K., Kunii, T., Visualized Deormation o Joinery to Understand Jointing Process by Homotopy Theory and Attaching Maps, Cyberworlds 2011, IEEE Computer Society, [8] Johnson, R., Expert One-on-One J2EE Design and Development, Wrox. Indianapolis.