BOINC client-server technology
Encyclopedia
BOINC client–server technology refers to the model under which BOINC works. The BOINC framework consists of two layers which operate under the client–server architecture
. Once the BOINC software is installed in a machine, the server
starts sending tasks to the client
. The operations are performed client-side
and the results are uploaded to the server-side
.
, PHP
, and MySQL
as a basis for its web and database
systems.
Scientific computations are run on participants' computers and results are analyzed after they are uploaded from the user PC to a science investigator's database and validated by the backend server. The validation process involves running all tasks on multiple contributor PCs and comparing the results.
BOINC servers also provide these features
The server consists of two CGI
programs and (normally) five daemons
, written in C++
. Computations to be performed by clients are called workunits. A result describes an instance of a workunit, even if it hasn't been completed. A project does not explicitly create results; the server creates them automatically from workunits.
The scheduler CGI program handles requests from clients, receiving completed results and sending new work to compute. The scheduler doesn't get available results directly from the database. Instead, there is a feeder daemon that loads tasks from the database, and keeps them in a shared memory
block, which the scheduler reads. The feeder periodically fills empty "slots" in the shared memory block after the scheduler has sent those results to a client.
When all the results from a workunit are completed and returned, the validator compares them. The validator can have custom project code to do fuzzy comparison between results, or it can be just a bitwise comparison. If the results match, the workunit is marked valid, users are granted credit
for it, and a "canonical result" is chosen.
Next, the assimilator daemon processes the canonical result using project-specific code. For example, some projects may parse the file and store information in a database, others may just copy the file somewhere else. An assimilator may also generate more workunits based on the returned data.
The file_deleter daemon deletes output files after the assimilator has processed them, and deletes input files that aren't needed anymore.
The transitioner daemon handles state transitions of workunits and results. It also generates results from workunits when they are first created, and when more are needed (for example, if a result turns out invalid).
(RPC) mechanism.
These component applications are:
A BOINC network is similar to a hacker
/spammers
botnet
. In BOINC's case, however, it is hoped that the software is installed and operated with the consent of the computer's owner.
Since BOINC has features that can render it invisible to the typical user, there is risk that unauthorized and difficult to detect installations may occur. This would aid the accumulation of BOINC-credit points by hobbyists who are competing with others for status within the BOINC-credit subculture.
Network architecture
Network architecture is the design of a communications network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation.In...
. Once the BOINC software is installed in a machine, the server
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
starts sending tasks to the client
Client (computing)
A client is an application or system that accesses a service made available by a server. The server is often on another computer system, in which case the client accesses the service by way of a network....
. The operations are performed client-side
Client-side
Client-side refers to operations that are performed by the client in a client–server relationship in a computer network.Typically, a client is a computer application, such as a web browser, that runs on a user's local computer or workstation and connects to a server as necessary...
and the results are uploaded to the server-side
Server-side
Server-side refers to operations that are performed by the server in a client–server relationship in computer networking.Typically, a server is a software program, such as a web server, that runs on a remote server, reachable from a user's local computer or workstation...
.
Design and structure of BOINC
- BOINC is designed to be a free structure for anyone wishing to start a distributed computing project.
- BOINC consists of a server system and client software that communicate with each other to distribute, process, and return workunits.
Server structure
A major part of BOINC is the backend server. The server can be run on one or many machines to allow BOINC to be easily scalable to projects of any size. BOINC servers run on Linux based computers and use ApacheApache HTTP Server
The Apache HTTP Server, commonly referred to as Apache , is web server software notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server software to surpass the 100 million website milestone...
, PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
, and MySQL
MySQL
MySQL officially, but also commonly "My Sequel") is a relational database management system that runs as a server providing multi-user access to a number of databases. It is named after developer Michael Widenius' daughter, My...
as a basis for its web and database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
systems.
Scientific computations are run on participants' computers and results are analyzed after they are uploaded from the user PC to a science investigator's database and validated by the backend server. The validation process involves running all tasks on multiple contributor PCs and comparing the results.
BOINC servers also provide these features
- homogeneous redundancy (sending workunits only to computers of the same platformPlatform (computing)A computing platform includes some sort of hardware architecture and a software framework , where the combination allows software, particularly application software, to run...
-- e.g.: Win XP SP2 only.) - workunit trickling (sending information to the server before the workunit completes)
- locality scheduling (sending workunits to computers that already have the necessary files and creating work on demand)
- work distribution based on host parameters (workunits requiring 512 MB of RAM, for example, will only be sent to hosts having at least that much RAM)
The server consists of two CGI
Common Gateway Interface
The Common Gateway Interface is a standard method for web servers software to delegate the generation of web pages to executable files...
programs and (normally) five daemons
Daemon (computer software)
In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...
, written in C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
. Computations to be performed by clients are called workunits. A result describes an instance of a workunit, even if it hasn't been completed. A project does not explicitly create results; the server creates them automatically from workunits.
The scheduler CGI program handles requests from clients, receiving completed results and sending new work to compute. The scheduler doesn't get available results directly from the database. Instead, there is a feeder daemon that loads tasks from the database, and keeps them in a shared memory
Shared memory
In computing, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors...
block, which the scheduler reads. The feeder periodically fills empty "slots" in the shared memory block after the scheduler has sent those results to a client.
When all the results from a workunit are completed and returned, the validator compares them. The validator can have custom project code to do fuzzy comparison between results, or it can be just a bitwise comparison. If the results match, the workunit is marked valid, users are granted credit
BOINC Credit System
Within the BOINC platform for volunteer computing, the BOINC Credit System helps volunteers keep track of how much CPU time they have donated to various distributed computing projects. The credit system is designed to avoid cheating by validating results before granting credit on projects...
for it, and a "canonical result" is chosen.
Next, the assimilator daemon processes the canonical result using project-specific code. For example, some projects may parse the file and store information in a database, others may just copy the file somewhere else. An assimilator may also generate more workunits based on the returned data.
The file_deleter daemon deletes output files after the assimilator has processed them, and deletes input files that aren't needed anymore.
The transitioner daemon handles state transitions of workunits and results. It also generates results from workunits when they are first created, and when more are needed (for example, if a result turns out invalid).
Server design weaknesses
Server Deployment- The BOINC Server is really only designed to be deployed on UnixUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
, or Unix-likeUnix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
systems. - BOINC Servers are not really as simple to deploy as the BOINC Client as they are based mainly on a large number of scripts.
- The BOINC Server project website does a very bad job of storing a compiled database of server side scripts for those wishing to create a BOINC project.
- The BOINC Server can be deployed on Windows XPWindows XPWindows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
and Windows VistaWindows VistaWindows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
systems (as they are POSIXPOSIXPOSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
compliant) but the design structure of Windows makes this difficult and more expensive than just using off the shelf Linux.
Client structure
BOINC on the client is structured into a number of separate applications. These intercommunicate using the BOINC remote procedure callRemote procedure call
In computer science, a remote procedure call is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space without the programmer explicitly coding the details for this remote interaction...
(RPC) mechanism.
These component applications are:
- The program boinc (or boinc.exe) is the core client.
- The core client is a processProcess (computing)In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
which:- Takes care of communications between the client and the server.
- The core client also downloads science applications, provides a unified logging mechanism, makes sure science application binaries are up-to-date, and schedules CPU resources between science applications (if several are installed).
- Although the core client is capable of downloading new science applications, it does not update itself. BOINC's authors felt doing so posed an unacceptable security risk, as well as all of the risks that automatic update procedures have in computing.
- On UnixUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
, the core client is generally run as a daemonDaemon (computer software)In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...
(or occasionally as a cron job). - On Windows, BOINC initially was not a Windows service, but an ordinary application. BOINC Client for Windows, Versions 5.2.13 and higher add, during installation, the option of "Service Installation".
- Depending on how the BOINC client software was installed, it can either run in the background like a daemon, or starts when an individual user logs in (and is stopped when the user logs out). The software version management and work-unit handling provided by the core client greatly simplifies the coding of science applications.
- One or several science applications. Science applications perform the core scientific computation. There is a specific science application for each of the distributed computation projects which use the BOINC framework. Science applications use the BOINC daemon to upload and download workunits, and to exchange statistics with the server.
- boincmgr (or boincmgr.exe), a GUIGraphical user interfaceIn computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
which communicates with the core application using remote procedure callRemote procedure callIn computer science, a remote procedure call is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space without the programmer explicitly coding the details for this remote interaction...
s. By default a core client only allows connections from the same computer, but it can be configured to allow connections from other computers (optionally using password authentication); this mechanism allows one person to manage a farm of BOINC installations from a single workstation. A drawback to the use of RPC mechanisms is that they are often felt to be security risks because they can be the route by which hackers can intrude upon targeted computers (even if it's configured for connections from the same computer). - The GUI is written using the cross-platform WxWidgetsWxWidgetswxWidgets is a widget toolkit for creating graphical user interfaces for cross-platform applications. wxWidgets enables a program's GUI code to compile and run on several computer platforms with minimal or no code changes...
toolkit, providing the same user experience on different platforms. Users can connect to BOINC core clients, can instruct those clients to install new science applications, can monitor the progress of ongoing calculations, and can view the BOINC system message logs. - The BOINC screensaverScreensaverA screensaver is a type of computer program initially designed to prevent phosphor burn-in on CRT and plasma computer monitors by blanking the screen or filling it with moving images or patterns when the computer is not in use...
. This provides a frameworkSoftware frameworkIn computer programming, a software framework is an abstraction in which software providing generic functionality can be selectively changed by user code, thus providing application specific software...
whereby science applications can display graphics in the user's screensaver window. BOINC screensavers are coded using the BOINC graphics API, Open GL, and the GLUTOpenGL Utility ToolkitThe OpenGL Utility Toolkit is a library of utilities for OpenGL programs, which primarily perform system-level I/O with the host operating system. Functions performed include window definition, window control, and monitoring of keyboard and mouse input...
toolkit. Typically BOINC screensavers show animated graphics detailing the work underway, perhaps showing graphs or charts or other data visualisation graphics. - Some science applications do not provide screensaver functionality (or stop providing screensaver images when they are idle). In this circumstance the screensaver shows a small BOINC logo which bounces around the screen.
A BOINC network is similar to a hacker
Hacker (computer security)
In computer security and everyday language, a hacker is someone who breaks into computers and computer networks. Hackers may be motivated by a multitude of reasons, including profit, protest, or because of the challenge...
/spammers
Spam (electronic)
Spam is the use of electronic messaging systems to send unsolicited bulk messages indiscriminately...
botnet
Botnet
A botnet is a collection of compromised computers connected to the Internet. Termed "bots," they are generally used for malicious purposes. When a computer becomes compromised, it becomes a part of a botnet...
. In BOINC's case, however, it is hoped that the software is installed and operated with the consent of the computer's owner.
Since BOINC has features that can render it invisible to the typical user, there is risk that unauthorized and difficult to detect installations may occur. This would aid the accumulation of BOINC-credit points by hobbyists who are competing with others for status within the BOINC-credit subculture.