Volunteer Computing withClient-Server perspectivePresented by:Diamantino CruzRicardo Madeira

BOINC (Berkeley Open Infrastructure for Network Computing)What is BOINC?BOINC is middleware system created to simplify the implementation of volunteer computing projects.What is volunteer computing?Volunteer computing is an arrangement in which people (volunteers) provide internet-connected computers, to be used as a source of computing power and storage.Why use volunteer computing?Volunteer computing uses computational resources that would otherwise be unused, to solve computationally intensive projects, for lower costs them other available solutions.

Task Server ComponentsEach BOINC-based projects operates a server consisting of several components:Web interfaces for account and team management, message boards, and other features.A task server that creates tasks dispatches them to clients, and processes returned tasks.A data server that downloads input files and executables, and that uploads output files.The clients periodically communicates with the task server to report completed work and to get new work.

Task Server ComponentsWhat are the functions of the programs?The work generatorprepares new jobs to be sent and their input files.The scheduler deals requests from the clients. The requests include a description of the host, a list of completed instances, and a request for additional work. The reply includes a list of instances and their corresponding jobs. The scheduler also maintains the records for the user account and team, the host, and the various jobs and instancesThe feederfacilitates the scheduler’s database access, maintaining a shared-memory segment containing static database tables, and a fixed-size cache of unsent instance/job pairs.The transitionerexamines jobs for which a state change has occurred if needed generates new instances, flag the job as having a permanent error, or trigger validation or assimilation of the job.

Task Server ComponentsThe validatorcompares the instances of a job and selects a canonical instance representing the correct output. It determines the credit granted to users and hosts that return the correct output, and updates those database records.The assimilatorhandles job that are “completed” (has an canonical instance or a permanent error has occurred). Handling a successfully completed job might involve writing outputs to an application database or archiving the output files.The file deleterdeletes input and output files that are no longer needed.The database purgerremoves jobs and instance database entries that are no longer needed, first writing them to XML log files.The programs communicate using the BOINC database.

Persistent redundant computingBecause incorrect output may result from a hardware and software problems, an incorrect modification to the application, or a intentional attack by the volunteer, mechanisms to ensure that outputs are correct (validation)and that tasks eventually get done (retry). BOINC provides a mechanism called persistent redundant computing that accomplishes both goals.This mechanism involves performing each task independently on various computers, comparing the outputs, looking for a “quorum” of equivalent outputs, and generating new instances as needed to reach a quorum.

How The Magic is done Client SideCore ClientClient has 2 “modes”ManagerScreensaver

Boinc Manager

How The Magic is done Client SideThe core client communicates with applications by shared-memory message passing

Failure ProtectionBOINC uses heartbeat messagesBOINC API finalization routine writes a ‘finished file’BOINC supplies a set of printf()-replacement functions that buffer output in memory, and flush these buffers during checkpointAll information about a task (exit code, signal number, standard error output, volunteer host platform) is stored in a relational database on the server

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Conclusion, Why use BoincSuppose you need a lot of computing power - say, 100 TeraFLOPS for 1 year. Here are some ways you can get it: Use Amazon's Elastic Computing Cloud $175 Million: Based on $0.10 per node/hour. Build a cluster $12.4 Million: This includes power and air-conditioning infrastructure, network hardware, computing hardware, storage, electricity, and sysadmin personnel. Use BOINC $125,000: Based on the average throughput and budget of the 6 largest volunteer computing projects.