cl-prevalence-cvs

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[cl-prevalence-cvs] CVS update: cl-prevalence/src/package.lisp
by Sven Van Caekenberghe 21 Jun '04

21 Jun '04

Update of /project/cl-prevalence/cvsroot/cl-prevalence/src In directory common-lisp.net:/tmp/cvs-serv24685/src Modified Files: package.lisp Log Message: exported sexp serializations functions Date: Mon Jun 21 07:38:39 2004 Author: scaekenberghe Index: cl-prevalence/src/package.lisp diff -u cl-prevalence/src/package.lisp:1.1.1.1 cl-prevalence/src/package.lisp:1.2 --- cl-prevalence/src/package.lisp:1.1.1.1 Sun Jun 20 12:13:39 2004 +++ cl-prevalence/src/package.lisp Mon Jun 21 07:38:39 2004 @@ -1,6 +1,6 @@ ;;;; -*- Mode: LISP -*- ;;;; -;;;; $Id: package.lisp,v 1.1.1.1 2004/06/20 19:13:39 scaekenberghe Exp $ +;;;; $Id: package.lisp,v 1.2 2004/06/21 14:38:39 scaekenberghe Exp $ ;;;; ;;;; Package definitions for the CL-PREVALENCE project ;;;; @@ -14,8 +14,8 @@ (:use :cl) (:export #:serializable-slots - #:serialize-xml - #:deserialize-xml + #:serialize-xml #:serialize-sexp + #:deserialize-xml #:deserialize-sexp #:make-serialization-state) (:documentation "XML and s-expression based serialization for Common Lisp and CLOS")) @@ -72,6 +72,6 @@ #:get-preference #:all-preferences-keys #:tx-set-preference) - (:documentation "A proof of concept Common Lisp Prevalence system")) + (:documentation "An implementation of Object Prevalence for Common Lisp")) ;;;; eof

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[cl-prevalence-cvs] CVS update: public_html/CL-PREVALENCE.html public_html/S-SERIALIZATION.html public_html/index.html
by Sven Van Caekenberghe 21 Jun '04

21 Jun '04

Update of /project/cl-prevalence/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv15463 Modified Files: index.html Added Files: CL-PREVALENCE.html S-SERIALIZATION.html Log Message: added more info Date: Mon Jun 21 07:34:01 2004 Author: scaekenberghe Index: public_html/index.html diff -u public_html/index.html:1.3 public_html/index.html:1.4 --- public_html/index.html:1.3 Sun Jun 20 13:11:49 2004 +++ public_html/index.html Mon Jun 21 07:34:01 2004 @@ -15,12 +15,61 @@ <p>CL-PREVALENCE is an implementation of <a href="http://www.prevayler.org">Object Prevalence</a> for Common Lisp.</p> +<p> + Object Prevalence is a simple but interesting concept first proposed by Klaus Wuestefeld in 2001. IBM developerWorks has a reasonable <a href="http://www-106.ibm.com/developerworks/library/wa-objprev/">Introduction to Object Prevalence</a> article. The main Java implementation is called <a href="http://www.prevayler.org">Prevayler</a>, with a (chaotic) wiki site with lots of information and discussions. Basically, the idea is this: +</p> +<ul> + <li>Most databases are only a couple of hundreds of megabytes big, often even less.</li> + <li>Most computers can easily take a couple of hundreds of megabytes of data in RAM, big servers can hold many gigabytes.</li> + <li>Mapping objects to databases is at least tedious and time consuming, but often also complex and error prone.</li> + <li>Let's throw away the database and just consider the domain model objects as the database.</li> + <li>Let's make sure we can serialize and deserialize our objects to and from a some presistent medium such as a file system.</li> + <li>If we store our complete set of domain model objects to a persistent medium we create a <em>snapshot</em>.</li> + <li>We query by using the data structure manipulation functionality of our programming language, running from RAM, queries will be extremely fast.</li> + <li>Let's agree to only change our object model using transaction objects that combine the data and the functionality to execute the transaction.</li> + <li>In order to preserve the ACID properties of our system, we log each transaction to some persistent medium by serializing it after we execute it. The is called the <em>transaction log</em>.</li> + <li>When the system goes down (intentionally or unintentionally) we restore its latest state by first reading in the latest snapshot and by re-executing each transaction from the transaction log.</li> + <li>Transactions must be deterministic and re-entrant (so they also need to record the current time if necessary).</li> + <li>In a multi-threaded system, transactions are globally serialized.</li> +</ul> +<p> +That is all there is to the concept of object prevalence. Here are some more details as well as some advantages and limitations: +</p> +<ul> + <li>A good implementation on a modern machine can achieve thousands of transactions per second, and recover them at about the same speed.</li> + <li>Transactions must be short because they block the system - since everything is in RAM this is not a problem.</li> + <li>Queries that need to see a completely consistent system state must also block on the system - other less critical queries could run in parallel.</li> + <li>It is practical for a transaction to first check its preconditions, throw an error if necessary, and to only modify the system when everything is consistent. During a transaction you are the sole active thread. Queries are as fast as they can get. In this implementation transactions are logged after succesful execution.</li> + <li>In this implementation there is an option to do a rollback (by doing a system restore) when an unexpected error occurs during transaction execution. You can specifiy that a condition doesn't need a rollback when it occurs inside a transaction by implementing the <tt>initiates-rollback</tt> to return false (or by using the <tt>no-rollback-error</tt> condition or inheriting from it).</li> + <li>Long running transactions are an open question.</li> + <li>Application server techniques are used to offer multiple clients access to the same prevalence system.</li> + <li>We can easily do replication (and query load balancing) by distributing the master transaction log stream to replica's that can host queries, execute backups (snapshots) or serve as hot fail-over. This implementation does not yet contain replication.</li> +</ul> +<p> + This code was written by Sven Van Caekenberghe. +</p> + <h3>Download</h3> + <p> This project is currently starting up, please use <a href="http://common-lisp.net/cgi-bin/viewcvs.cgi/?cvsroot=cl-prevalence">CVS</a> access for now, which also offers a tarball. </p> +<h3>API</h3> + + <p> + You can consult the LispDoc generated API is the files <a href="CL-PREVALENCE.html">CL-PREVALENCE.html</a> + and <a href="S-SERIALIZATION.html">S-SERIALIZATION.html</a>. + </p> + +<h3>Release History</h3> + +<ul> + <li>release 3, today: move to common-lisp.net, added s-expression based serialization</li> + <li>release 2, Januari 13, 2004: added managed-prevalence layer, generic persistent preferences and a blob feature, as well as several useful functions to support development and deployment</li> + <li>release 1, June 10, 2003: first public release</li> +</ul> <h3>Mailing Lists</h3> @@ -30,7 +79,7 @@ <li><a href="http://common-lisp.net/mailman/listinfo/cl-prevalence-announce">CL-PREVALENCE-ANNOUNCE mailing list info</a></li> </ul> - <p>CVS version $Id: index.html,v 1.3 2004/06/20 20:11:49 scaekenberghe Exp $</p> + <p>CVS version $Id: index.html,v 1.4 2004/06/21 14:34:01 scaekenberghe Exp $</p> <div class="footer"> <p>Back to <a href="http://common-lisp.net/">Common-lisp.net</a>.</p>

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[cl-prevalence-cvs] CVS update: public_html/index.html
by Sven Van Caekenberghe 20 Jun '04

20 Jun '04

Update of /project/cl-prevalence/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv6586 Modified Files: index.html Log Message: wrong cvs link Date: Sun Jun 20 13:11:49 2004 Author: scaekenberghe Index: public_html/index.html diff -u public_html/index.html:1.2 public_html/index.html:1.3 --- public_html/index.html:1.2 Sun Jun 20 12:31:03 2004 +++ public_html/index.html Sun Jun 20 13:11:49 2004 @@ -18,7 +18,7 @@ <h3>Download</h3> <p> This project is currently starting up, please use - <a href="http://common-lisp.net/cgi-bin/viewcvs.cgi/?cvsroot=s-xml">CVS</a> access for now, which also offers a tarball. + <a href="http://common-lisp.net/cgi-bin/viewcvs.cgi/?cvsroot=cl-prevalence">CVS</a> access for now, which also offers a tarball. </p> @@ -30,7 +30,7 @@ <li><a href="http://common-lisp.net/mailman/listinfo/cl-prevalence-announce">CL-PREVALENCE-ANNOUNCE mailing list info</a></li> </ul> - <p>CVS version $Id: index.html,v 1.2 2004/06/20 19:31:03 scaekenberghe Exp $</p> + <p>CVS version $Id: index.html,v 1.3 2004/06/20 20:11:49 scaekenberghe Exp $</p> <div class="footer"> <p>Back to <a href="http://common-lisp.net/">Common-lisp.net</a>.</p>

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[cl-prevalence-cvs] CVS update: public_html/index.html
by Sven Van Caekenberghe 20 Jun '04

20 Jun '04

Update of /project/cl-prevalence/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv27228 Modified Files: index.html Log Message: fixed a link Date: Sun Jun 20 12:31:03 2004 Author: scaekenberghe Index: public_html/index.html diff -u public_html/index.html:1.1 public_html/index.html:1.2 --- public_html/index.html:1.1 Sun Jun 20 12:22:58 2004 +++ public_html/index.html Sun Jun 20 12:31:03 2004 @@ -13,7 +13,7 @@ <h1>CL-PREVALENCE</h1> </div> - <p>CL-PREVALENCE is an implementation of <a href="http://www.advogato.org/article/398.html">Object Prevalence</a> for Common Lisp.</p> + <p>CL-PREVALENCE is an implementation of <a href="http://www.prevayler.org">Object Prevalence</a> for Common Lisp.</p> <h3>Download</h3> <p> @@ -30,7 +30,7 @@ <li><a href="http://common-lisp.net/mailman/listinfo/cl-prevalence-announce">CL-PREVALENCE-ANNOUNCE mailing list info</a></li> </ul> - <p>CVS version $Id: index.html,v 1.1 2004/06/20 19:22:58 scaekenberghe Exp $</p> + <p>CVS version $Id: index.html,v 1.2 2004/06/20 19:31:03 scaekenberghe Exp $</p> <div class="footer"> <p>Back to <a href="http://common-lisp.net/">Common-lisp.net</a>.</p>

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[cl-prevalence-cvs] CVS update: public_html/index.html public_html/style.css
by Sven Van Caekenberghe 20 Jun '04

20 Jun '04

Update of /project/cl-prevalence/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv10699 Added Files: index.html style.css Log Message: first content Date: Sun Jun 20 12:22:58 2004 Author: scaekenberghe

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[cl-prevalence-cvs] CVS update: Module imported: public_html
by Sven Van Caekenberghe 20 Jun '04

20 Jun '04

Update of /project/cl-prevalence/cvsroot/public_html In directory common-lisp.net:/tmp/cvs-serv31021 Log Message: Project Creation Status: Vendor Tag: svc Release Tags: start No conflicts created by this import Date: Sun Jun 20 12:14:29 2004 Author: scaekenberghe New module public_html added

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[cl-prevalence-cvs] CVS update: Module imported: cl-prevalence
by Sven Van Caekenberghe 20 Jun '04

20 Jun '04

Update of /project/cl-prevalence/cvsroot/cl-prevalence In directory common-lisp.net:/tmp/cvs-serv26888 Log Message: Project Creation Status: Vendor Tag: svc Release Tags: start N cl-prevalence/cl-prevalence.asd N cl-prevalence/Makefile N cl-prevalence/src/blob.lisp N cl-prevalence/src/debug-prevalence.lisp N cl-prevalence/src/managed-prevalence.lisp N cl-prevalence/src/package.lisp N cl-prevalence/src/prevalence.lisp N cl-prevalence/src/serialization.lisp N cl-prevalence/test/demo1.lisp N cl-prevalence/test/demo2.lisp N cl-prevalence/test/test-prevalence.lisp N cl-prevalence/test/test-serialization.lisp No conflicts created by this import Date: Sun Jun 20 12:13:42 2004 Author: scaekenberghe New module cl-prevalence added

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