INSULATED GATE BIPOLAR TRANSISTORS BASED REVERSIBLE
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1. 3 a cs selmp ort Call Access Instantiate gt gt sree ort Call Instantiate gt gt gt A gt a z E 7 mie age a z A eT mport Call Instantiate gt gt 7 E dsn manager net E dsn client N m MA M M 3 B dsn client qui l _ _ _ _ u lt lt Import Call Access Instantiate lmplement gt gt Fig 1 The package dependency diagram The manager server client communication roles are Fig 2 DSNManager acts as a server for the DSNServer and for the DSNClient DSNServer acts as a server for the DSNClient and as a client for the DSNManager DSNClient acts as a client for the DSNManager and for the DSNServer manager Fig 2 The manager server client communication The communication is based on the request response principle in all three communication situations manager server manager client and server client Firstly a connection is created then the client makes a request and the server responds and closes the connection The advantage of this approach is that if a client is behind a firewall as long as he can connect to a server he may use all the features of the application The drawback is the inability of the manager to initiate a connection with a client in order to send information but this problem is solved with a request 66 Adrian Alexandrescu and Mihai Horia Zaharia initiated by the client2. The application uses a specific protocol for communication between the three components The server list and the file tree are transferred between the manager and the client The manager is notified of the changes in the file structure between the manager and server The file tree and the execution commands are transmitted to the servers between the server and the client The manager keeps track of the servers and of the file tree The tree contains information about the files and directories from all the servers The manager waits on a specific port for incoming connections from servers When a server connects it sends the port number and the list with the changes in the file tree If the server is already in the list of servers it is identified 1f not a unique id is assigned to the server while its hostname and port are added to the list On another port the manager waits for connections from clients When a client connects depending on the received request the manager sends the list of servers or the file tree The server has two roles On the one hand the server keeps track of the changes to the file structure within a directory in which the shared data is stored The server sends the list with these changes to the manager On the other hand the server responds to requests initiated by clients For each list of changes sent a TCP connection is created Immediately afterwards once the list is received the connect
3. certificates and the private key are stored in a keystore which is identified by an alias The certificates are extracted from the generated keystores and then are saved The extracted certificates or rings of certificates are imported into a truststore For example if the server authentication to the client is needed then follow the next steps 8 Generate a keystore on the server which contains the certificate containing the public key and the private key The keystore may be password encrypted Extract the certificate from the keystore Insert the certificate in a new keystore called truststore Keep the keystore on the server and the truststore at the client Thus when the client requires server authentication the client sends a request for the server s certificate The certificate 1s compared with the list of certificates from the client s truststore If the certificate from the server is found then a secure communication can be used whereas if it cannot be found the communication fails 4 Case of Study Let us consider a distributed system of Web servers controlled by a manager of servers If the hosting of a website with dynamic pages on this system and all the servers to handle the workload is needed a very good solution would be to use a single point of entry in the system preferably different from the manager In other words all initial requests must reach a specific server that makes
4. each server and is able to make the redirection 5 Conclusions The Distributed File Management System 1s an application that makes it easy to work with files and directories in a distributed system Each server has a directory that is being monitored and when a change in the structure of files and directories appears a notification is sent to the manager that refreshes the list of servers and the file tree The communication is done using TCP and the security 1s provided by the cryptographic protocol SSL TLS In this system only the client can initialize a connection to the manager or the server This approach has the advantage that a client can use it without restriction even if the application is in a local subnet The client has the possibility to change the file and directory structure on the servers to copy information from multiple servers simultaneously and using multiple threads to launch the various applications both locally and on the servers using the program s command line Using the client application the Distributed File Management System offers the possibility to copy and send requests and to startup various applications on servers directly from the user interface Therefore the application can be deployed on multiple workstations in a fast and secure way The application can be optimized in regards to protocol by using a byte to specify the type of application by compressing the file names and directories and by repl
5. the file directory name followed by the value 1 if the resource isn t found on the server file dir name Name tente Name 0 Other files dirs Name atena nasi Fig 6 The client server communication protocol Copying from the server When file or directory from the server is moved we have a case that is similar to the above If the requested resource is valid the file 1s deleted on the server Fig 7 Bul Inst Polit Iasi t LVI LX f 2 2010 69 Ed file dir name Fig 7 The client server communication protocol Moving from the server When a file or directory from the server is deleted if the resource is valid then the file directory on the server is deleted and the result of the operation is returned whether completed successfully or not as it is presented in Fig 8 F file dir name Fig 8 The client server communication protocol Deleting from the server When a file or directory from the server is renamed the case following the first character r the client sends the name of the resource to be renamed one byte with the value 0 and the new name of the resource Fig 9 Fig 9 The client server communication protocol Renaming from the server file dir name new file dir name When copying a file or directory on the server the client sends a file to be saved on the server While copying the file on the server is locked therefore no other processes or threads
6. BULETINUL INSTITUTULUI POLITEHNIC DIN IASI Publicat de Universitatea Tehnic Gheorghe Asachi din Iasi Tomul LVI LX Fasc 2 2010 Sec ia AUTOMATIC i CALCULATOARE A JAVA BASED LIGTH DISTRIBUTED FILE SYSTEM BY ADRIAN ALEXANDRESCU and MIHAI HORIA ZAHARIA Abstract In this paper a light distributed file system implemented from scratch is presented The system has all base characteristics that are typical for this kind of systems The Java technology was elected because nowadays the mobility and platform independence is a common requirement for most of the application As result this system can be used in any kind of cluster either static or dynamic no matter of the geographic distribution scale Key words distributed computing SSL DFS 2000 Mathematics Subject Classification 68P25 68N19 1 Introduction DFS Distributed File System is a distributed file system 1 which allows the user to access files on other computers within a network Users do not have direct access to the storage resources but the data access is accomplished by communicating over the network using a custom protocol An DFS must have some minimal base characteristics as follows Transparent access from the client that is using it point of view there is no diference between a centralised and a distributed system Of course some suplementary latencies can not be fully avoided Common Data this refers to the manner that data coherency and
7. acing the transmitted objects with byte arrays thus eliminating the extra code introduced when serializing the data Received March 30 2010 Gheorghe Asachi Technical University of Iasi Department of Computer Science and Engineering e mails mike cs tuiasi ro avalexandrescu gmail com REFERENCES l Distributed computing Wikipedia the free encyclopedia 2010 available at http en wikipedia org wiki Distributed_ computing 74 Adrian Alexandrescu and Mihai Horia Zaharia 2 Mih escu C Scortan S O analiz comparativ a solu iilor de securitate la nivel de aplica ie oferite de Sun i Microsoft Craiova 2002 3 RFC 4346 The T ransport Layer Security TLS Protocol Version 1 1 2006 available at http xww faqs org rfes rfc4346 html 4 Transmission Control Protocol Wikipedia the free encyclopedia 2009 available at http en wikipedia org wiki Transmission_ Control Protocol Java TM Cryptography Architecture Standard Algorithm Name Documentation for JavaTM Platform Standard Edition 6 2009 available at http java sun com javase 6 docs technotes guides security StandardNames html 6 JavaTM Secure Socket Extension JSSE Reference Guide for JavaTM Platform Standard Edition 6 2009 available at http java sun com javase 6 docs technotes guides security jsse JSSERefGuide html 7 Java SSL Keystores Objectware Community Wiki 2009 available at http wiki community objectware no display securi
8. can modify the file unless the copying is completed see Fig 10 i ere ra Len file 8bytes Fig 10 The client server communication protocol Copying on the server When we test the response time of the server the client sends the number of bytes to the server on 4 bytes nol as well as a set of 1 s followed by a byte with a value of 0 The server responds with the required number of bytes of 1 and a 0 byte Fig 11 70 Adrian Alexandrescu and Mihai Horia Zaharia De IL 1 1 0 Fig 11 The client server communication protocol Testing the response time on the server In the situation of copying a chunk of a file from the server the client sends a request to the server for a given number of bytes It sends the name of the file in question the position at which to begin copying 8 bytes and the number of bytes to be copied 8 bytes see Fig 12 DA filename start Ten Fig 12 The client server communication protocol Copying a file chunk from the server When running a process on the server in fact refers the launching of a command on the server the client sends the location from which to launch the process followed by a byte with a value of 0 and the command as it is presented in Fig 13 Fig 13 The client server communication protocol Launching a command on the server 3 Security A great way to ensure the security and the integrity of data communications over the ne
9. consistency is automatically handled by the system without no intervention from the user Location transparency the real location of user data must be hiden from him That is this location can be authomatically changed by the system in 64 Adrian Alexandrescu and Mihai Horia Zaharia order to satissfy his internal optimisation constraints The only think that is constant regarding user data refers to the applied security level Distributed control as 1s espected the control can be distributed anyhow the level of distribution not reach in any situation the borders of the DFS Security because of the inherent data distribution and the need for confidencility the highest possible security approach must be used Of course there is an equilibrium given by the performance constraints The Distributed File Management System DFMS is an application written in Java language which consists of three components the manager the server and the client In the implemented distributed system there may be a single manager multiple servers and multiple clients DFMS has a security module to protect the data transmitted over the network The security module uses for communication the SSL TLS Protocol which is mapped over the TCP layer The protocol supports the newest and most secure cryptographic algorithms available Using a script it can generate authentication certificates both for the client and server 2 General Structure The
10. e Management System are configurable by using the arguments given at the command line These arguments allow you to change the address in order to connect to the servers to use the application in a secure mode or not and to specify the security parameters The server connects to the manager in order to send the list of changes in the structure of directories monitored by the server The server port through which the server connects to the manager and the IP address are used to uniquely identify a server Thus you can have multiple servers running on the same computer IP but on different ports The classes involved in this communication are Fig 3 dsn server Server on the server side dsn manager net ServerManager on the manager side Fig 3 The server manager communication protocol manager The client connects to the manager to get the tree with the list of files and directories from each server in the system FilelnfoTree and the list of servers with their identification numbers serverld The classes involved in this communication are Fig 4 dsn client ServerManagerConnection on the client side dsn manager net ClientHandler on the manager side manager object FilelnfoTree Fig 4 The client manager communication protocol the file and directory tree servermap client object Map lt Serverlnfo Integer gt Fig 5 The client manager communication prot
11. following external libraries were used in developing the application Apache log4j allows a more efficient control over debugging the application log4j 1 2 15 jar Liquid L amp F o modern look and feel liguidinf jar Common a proprietary library which contains various reusable classes common jar The application is structured in five source folders as follows a data contains the classes used by the manager server and client components dsn data package b client contains the classes exclusively used by the client e dsn client package e dsn client gui package the client s GUI component c manager contains the classes exclusively used by the manager e dsn manager package e dsn manager net package the manager s communication component d server contains the classes exclusively used by the server dsn server package e resources contains various resources like images UML diagrams and the user s manual Bul Inst Polit Iasi t LVI LX f 2 2010 65 In Fig 1 the package dependency of the implementation is presented ah bli a Selmpart Send Call Access Instantiate gt gt 3 dsn manager H dsn data i m i Se eae H dsn server Ti gt pr Li zi cela ort Send Call Instantiate gt gt id i Si ci H i E A lt Imp asi Call Access Instantiate gt gt a S a si LE a ai a Pr Eg a EV EN y a 2 ne wie he gee
12. ion is closed A method which involves scanning the directory every 10 sec is chosen and if there are changes they will be sent to the manager The request initiated by the client falls into one of the following cases copying moving renaming or deleting a file or directory on the server creating a directory on the server copying a file or directory from the server testing the response time copying a portion of a file on the server or starting a process on the server The client connects to the manager to get the list of supported servers as well as the file and directory tree The client is able to copy and move files and directories on off servers it can rename delete or create new directories In addition a testing of the servers response and a method of copying a file simultaneously on multiple servers using multiple threads is implemented A special case of copying a file is the Multi Threaded Copy MTC Depending on the selected parameters the copying is done in parallel from multiple servers and multiple threads The MTC process goes through the following steps calculate the number of threads used to copy the file calculate the number of segments in which the file is divided Bul Inst Polit Iasi t LVI LX f 2 2010 67 for each thread create a connection to the appropriate servers one segment is copied from each server All three components of the Distributed Fil
13. ocol the server list The client connects to the server in the following situations 68 Adrian Alexandrescu and Mihai Horia Zaharia To make a request for a file or directory from the server To make a request to move a file or directory from the server To make a request to delete a file or directory from the server To make a request to rename a file or directory from the server To make a request to create a directory on the server To send a file or directory to be copied on the server To test the response time of the server To make a request to copy a portion of a file To start a process on the server The classes involved in this communication are dsn client ClientConnection on the client side dsn server FileTransferClientHandler on the server side The client sends to the server strings finished with n lines of text sometimes depending on the protocol The communication ends when the line read is empty that is when only the character n is sent Depending on the first character received the appropriate operation is chosen Every communication between the client and the server ends by sending the value 0 on 4 bytes followed by either a value of 1 if the operation has been completed successfully or 0 otherwise When copying a file or directory from the server the three server response instances are Fig 6 send a file send a directory send
14. the redirection to other servers thus creating a tunnel between the client and the server that will send the requested information Taking into account the HTTP protocol and the fact that html pages are dynamic e g JSP pages you can make your next optimization using a pseudo random manner for each image a server is chosen and in the returned html page the image s URL will point to the chosen server address When accessing a page in a Web browser first a request for the HTML page is made and then a request for each required resource is initiated Thus using the mentioned optimization it will result in a shorter loading time because the page is taken from the main server and the resources are taken from the other servers depending on the load There are two disadvantages to this tweaking servers must have real IP addresses and the use of different addresses for resources may have a negative effect in terms of SEO Search Engine Optimization To implement this concept a way to deploy the site on all stations Bul Inst Polit Iasi t LVI LX f 2 2010 73 involved is required This can be done very easily and quickly with the File Management Distributed System When changes in the structure of the site are needed the manager side can be used to copy the appropriate files in parallel on the servers Also the main Web server has access through the manager to the list of available servers and to the list of files and directories on
15. to protect the private key The above method belongs to the class dsn data SecurityFactory which contains methods to create SSLServerSocket and SSLSocketFactory objects In Fig 14 the class diagram for the security module is presented SecurityFactory aay getSecuresocketFactory keyFileMame trustFilehame storePassvword keyPassword trustPassword SocketFactory c createSSLContext keyFileMame truztFilellame storePassvord kePazzweord trustPassword SSLContext ae getSecureserverSocket port keyFileName trustFileName storePassyord keyPassvord trustPassyword cipherSutes ServerSocket Call SecurityS ocketCreator a sf Send Import o SecuritysoacketCreator keyFileName trustFileMame storePassyyord keyPassyvord trustPaseyvord 2 createSecuresocket host porti Socket Send Instantiate Import 9 SecurityException a SecurtyException S SecurityException messade d SecurtyException cauze Ci SecurityExceptionimessage Cauze Fig 14 The class diagram for the security module In order to generate the keys and certificates a script is used The script to generate keys and certificates follows these steps For each communication manager server manager client server client it generates key pairs public key private key The public key is placed in an X 509 v3 auto signed certificate which is stored in a ring of certificates 72 Adrian Alexandrescu and Mihai Horia Zaharia The ring of
16. twork is to use the TLS Transport Layer Security 2 3 This cryptographic protocol allows one to encrypt the connection segments at the transport layer without affecting the communication protocol TLS is an enhanced version of the SSL Secure Sockets Layer protocol SSL v2 is no longer used by the main Internet browsers The initial state of a TLS connection during handshake uses the cipher suite TLS NULL WITH NULL NULL No useful data is transmitted before finishing the handshake protocol Each application that uses TLS must Bul Inst Polit Iasi t LVI LX f 2 2010 71 implement at least the TLS RSA WITH 3DES EDE CBC SHA cipher suit If a secure client server communication over TCP Transmission Control Protocol 4 is needed the TLS protocol which is able to encrypt all messages sent through a secure connection can be used One of the most secure cipher suites that can be used by TLS is TLS RSA WITH AES 128 CBC SHA the TLS standard uses the key exchange algorithm RSA with an AES cipher with a key size of 128 bits using CBC and the SHA hash function To use the TLS protocol we have chosen a more advanced approach employing SSLContext objects in order to enhance the level of security 5 7 Thus we have implemented a static method to create SSLContext objects which receive as arguments the name of the keystore and truststore files the passwords to protect the keystore and truststore integrity storepass and the password
17. ty Java SSL Keystores keytool Key and Certificate Management Tool 2009 available at http java sun com javase 6 docs technotes tools windows keytool html N a SISTEM DISTRIBUIT DE FI IERE IMPLEMENTAT FOLOSIND TEHNOLOGIA JAVA Rezumat n aceast lucrare este prezentat proiectarea i implementarea independent de ma in a unui sistem minimal distribuit de fi iere Stocarea distribuit uzual sub form de fi iere a devenit rapid important o dat cu succesul arhitecturilor de tip re ea i sta ii de lucru In acest model n afar de resursele de calcul existente pe o ma in central accesate de terminale multe sta ii de lucru au nlocuit terminalele O sta ie de lucru coopereaz cu altele comunicarea f c ndu se pe un anumit tip de re ea cum ar fi Ethernetul de exemplu Un DFS este un sistem de servicii de fi iere a caror clien i servere i dispozitive de stocare sunt dispersate n loca iile unui sistem distribuit Este opusul abordarii tip warehause Replicarea fi ierelor pe ma ini diferite este o definitorii pentru un astfel de sistem Tehnologia Java a fost aleas deoarece la ora actual mobilitatea i independen a de platform a aplica iilor este critic Ca rezultat aceast aplica ie poate fi folosit n orice tip de sistem distribuit
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