mirror of https://github.com/BOINC/boinc.git
341 lines
9.9 KiB
Plaintext
341 lines
9.9 KiB
Plaintext
Abstractions
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"Project": each is described by a URL.
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Each has its own database and control server.
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"Application": a particular program.
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A project may have several applications.
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"Account": each user has a separate account with each project.
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Each account has a unique email address and a server-assigned authenticator.
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--------------------
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Client files
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two files:
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account.xml
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list of projects; for each:
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user ID
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password
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preferences
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client_state.xml
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hostid
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rpc_seqno (per project)
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files, WUs, results etc.
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NOTE: to "clone" an installation on a new computer,
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just need to copy the core client (or run the installer)
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then copy the account.xml file.
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NOTE: a scheduler request can specify that no client_state.xml
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was found, so a new host record should be created.
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If a scheduler gets a request with an unexpected seqno,
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it sends back a reply saying
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--------------------
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When does client contact scheduling server?
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Each result has a max notification delay,
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so when a client completes it there's a deadline for notification.
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Contact a scheduling server if:
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- you're below the low-water mark in work for that project,
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or you have a result past its deadline
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- AND there's no delay in effect for that project.
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A delay may be explicitly returned by the scheduling server,
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or may be because of exponential backoff after failed attempts.
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--------------------
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Given that we can estimate the time it will take to get back
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a result from a given host, it might be possible to assign
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deadlines to results, and only send them to hosts that are fast enough
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--------------------
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Client logging
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write events to log file:
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start/stop client
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start/finish file xfer
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start/finish application execution
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start/finish scheduling server call
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error messages
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logging flag is part of preferences
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--------------------
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division between database and XML
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proposal: move as much info as possible out of the DB into XML files.
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examples:
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- workunits and results
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WUs and results are described by XML files listing
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their inputs, outputs, etc.
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The DB entry for a WU contains only info relevant to scheduling:
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memory/disk/communication requirement
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- user info
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A configuration is an XML file, opaque to the scheduling server
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--------------------
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WUs and results
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- WUs and results are desribed by XML files that describe their
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input and output files.
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- each client computation is represented by a "result" DB record,
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which is created BEFORE the client requests it.
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The application server system must keep the DB supplied
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with result records, or clients will starve.
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NOTE: this is necessary to control where output files go.
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Could also have a scheme where each application has a
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"template" result file.
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This instructs the client to create its own output file names.
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When the client returns the result,
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the server creates the result record and plugs in file names.
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--------------------
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File info
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input files
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"sticky": don't delete after result done
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URL (if not already on client)
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output files
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"sticky": don't delete after result done
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URL (optional; send here after result done)
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--------------------
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file xfer commands
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implemented as WU/result pairs whose app is "file_xfer".
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Can have just one input file, one output.
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Application servers can leaves these in a "message" directory,
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where the scheduling server can find them and give to
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client next time they contact.
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--------------------
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result states in client
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don't have files yet
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have files, not started
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have files, started
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completed, sending output files
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output files sent
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output files sent, some sticky files deleted
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--------------------
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result attributes in DB, sched server
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state:
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unsent
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sent, in progress
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timed out
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file state
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all output files are openly available
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(i.e. have been uploaded)
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WU attributes in DB, sched server
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input file state (set by app server)
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all input files are available
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not all input files available
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--------------------
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Workunit affinity
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This mechanism allows a sequence of WUs to get executed on the same host,
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but allows the sequence to migrate (or be duplicated) if needed.
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result attributes:
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previous_resultid
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This result is a "successor" to the previous one.
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If all the sticky input and output files of the previous WU are present,
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this WU can be executed efficiently.
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has_successor
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This result has a successor.
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How it works:
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The project generates a sequence of WUs,
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each with one or more results.
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It chains the results together into sequences.
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When a client completes a result with successor,
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it retains the result record.
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NOTE: one goal of this design is to avoid the scheduler
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having to know about individual files
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--------------------
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Scheduler request
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The client sends all its results with successors
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scheduler algorithm:
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if there any results with predecessors
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for which the client has all sticky files,
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send them in preference to any other results
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--------------------
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database tables
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application
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platform
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app_version
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core_version
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account
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file
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workunit
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applicationid
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file1 name1
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file2 name2
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nresults
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result
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workunitid
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accountid
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fileid
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boolean verified
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host
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--------------------
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State maintained on client
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Config file (XML)
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<config>
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<update-time>123123</update-time>
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// last time user added project or changed CPU shares
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<max-disk-mb>1000</max-disk-mb>
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<min-work-hrs>10</min-work-hrs>
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// if estimated work falls below this, try to get more
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<max-work-hrs>10</max-work-hrs>
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// don't get more work if estimate is above this
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<max_ram_while_user_active>20</max_ram_while_user_active>
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// zero means don't work while user active
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<projects>
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<project>
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<url>http://wjwjwj</url>
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<dont-contact-until>123123</dont_contact_until>
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<control-server>blah.blah</control-server>
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</control-server>blah.blah</control-server>
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<cpu-share>1</cpu-share>
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<max-disk-mb>100</max-disk-mb>
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<cpu-total>5.44</cpu-total>
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// this is zeroed out each time shares updated
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<password>123123123</password>
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// stored on client only; not sent to server in general
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<email-address>foo@bar</email-address>
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</home-project>
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<file>
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<md5>sfkjf</md5>
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<url>akdjsfd</url>
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<size>123123</size>
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<complete/>
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</file>
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<workunit>
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<name>skdjf</name>
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<file>
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<name>foo</name>
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<appname>blah</appname>
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// name by which app refers to file
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</file>
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</workunit>
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<result>
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<workunit-name>12938</workunit-name>
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<result>
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</project>
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...
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</projects>
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</config>
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--------------------
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Security notes:
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--------------------
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Client directory structure
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top-level dir
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project dir (one per project)
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CPU dir (one per CPU)
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contains symbolic links to application file,
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all input and output files
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--------------------
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Client logic
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["network xfer" object encapsulates a set of file xfers in progress]
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["processor" object: one for each CPU]
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read config file
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loop
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check user activity - turn off computations if needed
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start a computation if possible
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all necessary files present,
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and workunit not done or in progress.
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check processes (fail, done)
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start new network xfers if possible
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xfer 16KB if possible (use select)
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if xfer complete, update state
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if estimated work below low-water mark
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while estimated work below high-water mark
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pick project with work due, OK dont_contact_until
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contact a control server; request high-current work
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if can't get connection, update dont_contact_until
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end
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end
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end
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--------------------
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Application logic
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--------------------
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Control RPC protocol
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--------------------
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Web site functions
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--------------------
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Startup scenarios
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- How a user initially signs up:
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Visit the project's URL.
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Create an account:
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enter email address
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wait for password to arrive in email.
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download installer
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installer installs agent, initial config file
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run agent; type in password.
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- How a user adds a project
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Same as above, but don't download agent.
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Go to "home" web site and add project.
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- How a user removes a project
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Go to "home" web site and remove project
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------------------------------
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Versions
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Core client:
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When and how does a scheduler tell a core agent
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that a newer version can/should be downloaded?
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How is compatibility between application agents
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and core agents represented?
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--------------------------------------
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Distributed storage
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Projects can use clients for storage using "sticky" files
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(which are either sent to clients, or generated by the client).
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The core client is free to delete sticky files any time.
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Scheduler requests include a list of the sticky files held by the host.
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This list is stored in a blob in the host record.
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Scheduler replies can include <file_info> tags
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instructing the client to download files.
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These files need not be associated with applications or workunits.
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Scheduler replies can include <file_info> tags
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instructing the client to upload
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--------------------------------
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Preferences
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CPU usage
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don't run or communicate if on batteries
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don't run or communicate if user is active
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confirm before making network connection
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minimum, maximum work buffer
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Disk usage
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use at most X GB
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leave at least X GB free
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leave at least X% free
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Projects
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For each project:
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master URL
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email address
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authenticator
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resource %
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show email address on web site?
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accept emails from project?
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project-specific prefs
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