Changes between Version 2 and Version 3 of BasicConcepts

Timestamp:

Jun 9, 2008, 9:21:54 AM (16 years ago)

Author:

davea

Comment:

--

BasicConcepts

@@ +1 @@
+[[PageOutline]]
+
 = Basic concepts =
 
-1) BOINC high-level architecture
-                projects, URLs
-                accounts
-                clients, attachment
-                preferences
-                applications
-                app version
-                platforms
+== Project ==
+
+A '''project''' is an entity that does distributed computing using BOINC.
+Projects are independent; each one has its own applications, database, web site, and servers,
+and is not affected by the status of other projects.
+Each project is identified by a [ServerComponents#ThemasterURL master URL],
+the URL of its web site.
+
+It the implementation level, a project consists of
+ * a directory tree, containing files related to the project, and
+ * a MySQL database.
+
+Multiple projects can coexist on a single server computer.
+
+The components of a project include:
+
+=== Application ===
+
+An '''application''' includes several programs (for different platforms)
+and a set of [JobIn workunits] and [JobOut results].
+A project can include multiple applications.
+
+=== Platform ===
+
+A '''platform''' is a compilation target - typically a combination of a CPU architecture and an operating system.
+BOINC defines a set of standard platforms, but a project can define its own.
+
+=== Application versions ===
+
+An application program may go through a sequence of versions.
+A particular version, compiled for a particular platform,
+is called an '''application version'''.
+An application version consists of one or more files.
+
+=== Workunit ===
+
+A '''workunit''' is a computation to be performedi, i.e. a "job".
+It may include any number of input files.
+It has various attributes, such as resource requirements and deadline.
+
+A work is associated with an application, not with an application version.
+In other words, you don't specify what platform the job is to be run on.
+
+=== Result ===
+
+A '''result''' describes an instance of a computation, either unstarted, in progress, or completed.
+Each result is associated with a workunit.
+In some cases there may be several instances, or "replicas", of a given workunit.
+
+=== Account ===
+
+Each volunteer in a project has an '''account''', identified by an email address and password.
+An account has an associated amount of '''credit''',
+a numerical measure of the work done by that volunteer's computers.
+
+== Client and attachment ==
+
+Volunteers run a program called the '''BOINC client''';
+this is the only software they manually download.
+
+A given computer running the BOINC client can be '''attached''' to
+accounts on one or more project.
+Each attachment has a '''resource share'''.
+If a computer is attached to multiple projects,
+its resources are divided among them in proportion
+to their resource shares.
+
+== BOINC in a nutshell ==
+
+The overall flow of BOINC:
+
+ * When a BOINC client runs low on work, it issues a '''scheduler request''' to one of its attached projects.  The request message specifies the client's platform.
+ * The project's '''scheduler''' (a daemon running on its server) scans the project's database for jobs that can be handled by the client, and returns one or more.
+ * The client downloads the files associated with the application versions and workunits, and executes the programs.
+ * When the jobs are completed, the client uploads the resulting output files.
+
+This cycle is repeated indefinitely.