Changeset 3591
- Timestamp:
- Jul 23, 2007, 2:04:24 PM (16 years ago)
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trunk/doc/src/docbook/developerdoc/plugin_developer.xml
r3585 r3591 3295 3295 <sect2 id="plugin_developer.other.secondary"> 3296 3296 <title>Secondary file storage plugins</title> 3297 <para> 3298 This documentation is only available in the old format. 3299 See <ulink url="http://base.thep.lu.se/chrome/site/doc/development/plugins/storage/index.html" 3300 >http://base.thep.lu.se/chrome/site/doc/development/plugins/storage/index.html</ulink> 3301 </para> 3297 3298 <sect3 id="plugin_developer.other.secondary.vsprimary"> 3299 <title>Primary vs. secondary storage</title> 3300 <para> 3301 BASE has support for storing files in two locations, the primary storage and 3302 the secondary storage. The primary storage is always disk-based and must be 3303 accessible by the BASE server as a path on the file system. The path to the 3304 primary storage is configured by the <varname>userfiles</varname> setting in the 3305 <filename>base.config</filename> file. The primary storage is internal to 3306 the core. Client applications don't get access to read or manipulate the 3307 files directly from the file system. 3308 </para> 3309 3310 <para> 3311 The secondary storage can be anything that can store files. It could, for 3312 example, be another directory, a remote FTP server, or a tape based archiving 3313 system. A file located in the secondary storage is not accessible by the 3314 core, client applications or plug-ins. The secondary storage can only be accessed 3315 by the secondary storage controller. The core (and client) applications uses 3316 flags on the file items to handle the interaction with the secondary storage. 3317 </para> 3318 3319 <para> 3320 Each file has an <property>action</property> attribute which default's to 3321 <constant>File.Action.NOTHING</constant>. It can take two other values: 3322 </para> 3323 3324 <orderedlist> 3325 <listitem> 3326 <para> 3327 <constant>File.Action.MOVE_TO_SECONDARY</constant> 3328 </para> 3329 </listitem> 3330 <listitem> 3331 <para> 3332 <constant>File.Action.MOVE_TO_PRIMARY</constant> 3333 </para> 3334 </listitem> 3335 </orderedlist> 3336 3337 <para> 3338 All files with the action attribute set to <constant>MOVE_TO_SECONDARY</constant> 3339 should be moved to the secondary storage by the controller, and all files 3340 with the action attribute set to <constant>MOVE_TO_PRIMARY</constant> should be 3341 brought back to primary storage. 3342 </para> 3343 3344 <para> 3345 The moving of files between primary and secondary storage doesn't happen 3346 immediately. It is up to the server administrator to configure how often and 3347 at what times the controller should check for files that should be moved. 3348 This is configured by the <varname>secondary.storage.interval</varname> 3349 and <varname>secondary.storage.time</varname> settings in the 3350 <filename>base.config</filename> file. 3351 </para> 3352 </sect3> 3353 3354 <sect3 id="plugin_developer.other.secondary.interface"> 3355 <title>The SecondaryStorageController interface</title> 3356 3357 <para> 3358 All you have to do to create a secondary storage controller is to 3359 create a class that implements the 3360 <interfacename>net.sf.basedb.core.SecondaryStorageController</interfacename> 3361 interface. In your <filename>base.config</filename> file you then specify the 3362 class name in the <varname>secondary.storage.driver</varname> setting and it's 3363 initialisation parameters in the <varname>secondary.storage.init</varname> setting. 3364 </para> 3365 3366 <para> 3367 Your class must have a public no-argument constructor. 3368 The BASE application will create only one instance of the class for 3369 lifetime of the BASE server. Here are the methods that you must implement: 3370 </para> 3371 3372 <variablelist> 3373 <varlistentry> 3374 <term> 3375 <methodsynopsis language="java"> 3376 <modifier>public</modifier> 3377 <void /> 3378 <methodname>init</methodname> 3379 <methodparam> 3380 <type>String</type> 3381 <parameter>settings</parameter> 3382 </methodparam> 3383 </methodsynopsis> 3384 </term> 3385 <listitem> 3386 <para> 3387 This method is called just after the object has been created with it's argument 3388 taken from the <varname>secondary.storage.init</varname> setting in your 3389 <filename>base.config</filename> file. This method is only called once for 3390 an object. 3391 </para> 3392 </listitem> 3393 </varlistentry> 3394 <varlistentry> 3395 <term> 3396 <methodsynopsis language="java"> 3397 <modifier>public</modifier> 3398 <void /> 3399 <methodname>run</methodname> 3400 </methodsynopsis> 3401 </term> 3402 <listitem> 3403 <para> 3404 This method is called whenever the core thinks it is time to do some 3405 management of the secondary storage. How often the <methodname>run()</methodname> 3406 method is called is controlled by the <varname>secondary.storage.interval</varname> 3407 and <varname>secondary.storage.time</varname> settings in the 3408 <filename>base.config</filename> file. 3409 When this method is called the controller should: 3410 </para> 3411 3412 <itemizedlist> 3413 <listitem> 3414 <para> 3415 Move all files which has <constant>action=MOVE_TO_SECONDARY</constant> to 3416 the secondary storage. When the file has been moved call 3417 <methodname>File.setLocation(Location.SECONDARY)</methodname> to tell the 3418 core that the file is now in the secondary storage. You should also call 3419 <methodname>File.setAction(File.Action.NOTHING)</methodname> to reset the 3420 action attribute. 3421 </para> 3422 </listitem> 3423 3424 <listitem> 3425 <para> 3426 Restore all files which has <constant>action=MOVE_TO_PRIMARY</constant>. 3427 The core will set the location attribute automatically, but you should 3428 call <methodname>File.setAction(File.Action.NOTHING)</methodname> to reset 3429 the action attribute. 3430 </para> 3431 </listitem> 3432 3433 <listitem> 3434 <para> 3435 Delete all files from the secondary storage that are not present 3436 in the database with <constant>location=Location.SECONDARY</constant>. 3437 This includes files which has been deleted and files that have been 3438 moved offline or re-uploaded. 3439 </para> 3440 </listitem> 3441 3442 </itemizedlist> 3443 3444 <para> 3445 As a final act the method should send a message to each user owning 3446 files that has been moved from one location to the other. The message 3447 should include a list of files that has been moved to the secondary 3448 storage and a list of files moved from the secondary storage and a 3449 list of files that has been deleted due to some of the reasons above. 3450 </para> 3451 </listitem> 3452 </varlistentry> 3453 3454 <varlistentry> 3455 <term> 3456 <methodsynopsis language="java"> 3457 <modifier>public</modifier> 3458 <void /> 3459 <methodname>close()</methodname> 3460 </methodsynopsis> 3461 </term> 3462 <listitem> 3463 <para> 3464 This method is called when the server is closing down. After this the object 3465 is never used again. 3466 </para> 3467 </listitem> 3468 </varlistentry> 3469 </variablelist> 3470 </sect3> 3471 3472 <sect3 id="plugin_developer.other.secondary.settings"> 3473 <title>Configuration settings</title> 3474 3475 <para> 3476 The configuration settings for the secondary storage controller is located in the 3477 <filename>base.config</filename> file. Here is an overview of the settings. 3478 For more information read <xref linkend="appendix.base.config" />. 3479 </para> 3480 3481 <variablelist> 3482 <varlistentry> 3483 <term><property>secondary.storage.driver</property></term> 3484 <listitem> 3485 <para> 3486 The class name of the secondary storage plug-in. 3487 </para> 3488 </listitem> 3489 </varlistentry> 3490 <varlistentry> 3491 <term><property>secondary.storage.init</property></term> 3492 <listitem> 3493 <para> 3494 Initialisation parameters sent to the plug-in by calling the 3495 <methodname>init()</methodname> method. 3496 </para> 3497 </listitem> 3498 </varlistentry> 3499 <varlistentry> 3500 <term><property>secondary.storage.interval</property></term> 3501 <listitem> 3502 <para> 3503 Interval in seconds between each execution of the secondary storage 3504 controller plug-in. 3505 </para> 3506 </listitem> 3507 </varlistentry> 3508 <varlistentry> 3509 <term><property>secondary.storage.time</property></term> 3510 <listitem> 3511 <para> 3512 Time points during the day when the secondary storage controller plugin 3513 should be executed. 3514 </para> 3515 </listitem> 3516 </varlistentry> 3517 </variablelist> 3518 </sect3> 3302 3519 </sect2> 3303 3520
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