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ant/proposal/mutant/docs/goals.html

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  1. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

  2. 

  3. <!-- Content Stylesheet for Site -->

  4. 

  5.     

  6. <!-- start the processing -->

  7.     <html>

  8.     <head>

  9.       <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>

  10. 

  11.                       <meta name="author" value="Conor MacNeill">

  12.   <meta name="email" value="">

  13.       

  14.       <title>Mutant Proposal - Mutant Goals</title>

  15.     </head>

  16. 

  17.     <body bgcolor="#ffffff" text="#000000" link="#525D76">

  18.       <table border="0" width="100%" cellspacing="0">

  19.         <!-- TOP IMAGE -->

  20.         <tr>

  21.                 <td colspan="2">

  22.     <a href="http://jakarta.apache.org"><img src="http://jakarta.apache.org/images/jakarta-logo.gif" align="left" border="0"/></a>

  23.     </td>

  24.           </tr>

  25.       </table>

  26.       <table border="0" width="100%" cellspacing="4">

  27.         <tr><td colspan="2">

  28.           <hr noshade="" size="1"/>

  29.         </td></tr>

  30. 

  31.         <tr>

  32.           <!-- LEFT SIDE NAVIGATION -->

  33.           <td valign="top" nowrap="true">

  34.                 <p><strong>Mutant Proposal</strong></p>

  35.     <ul>

  36.           <li>      <a href="./index.html">Introduction</a>

  37.   </li>

  38.           <li>      <a href="./goals.html">Design Goals</a>

  39.   </li>

  40.           <li>      <a href="./features.html">User Features</a>

  41.   </li>

  42.           <li>      <a href="./developers.html">Task Developers</a>

  43.   </li>

  44.           <li>      <a href="./design.html">Design Description</a>

  45.   </li>

  46.         </ul>

  47.             </td>

  48.           <td align="left" valign="top">

  49.         <table border="0" cellspacing="0" cellpadding="2" width="100%">

  50.     <tr><td bgcolor="#525D76">

  51.       <font color="#ffffff" face="arial,helvetica,sanserif">

  52.         <a name="Goals"><strong>Goals</strong></a>

  53.       </font>

  54.     </td></tr>

  55.     <tr><td>

  56.       <blockquote>

  57.                         <p>

  58. This page describes the key goals that have shaped the development of

  59. Mutant.

  60. </p>

  61.                                 <p>

  62. The first section identifies a set of issues with Ant1 that have cropped up as

  63. Ant1 has evolved. The design implications of each issue are then summarized as a

  64. Mutant requirement. I do not want to suggest that these problems are unsolvable

  65. within the Ant1 design. Already I believe we have seen the Ant2 proposals

  66. influencing people trying to extend Ant1. These issues may be solvable, although at

  67. the risk of backward compatability impacts or further complication of the Ant1

  68. codebase.

  69. </p>

  70.                                 <p>

  71. The second section covers a set of additional requirements that have emerged as

  72. the whole concept of Ant2 has developed. Many of these came from the discussions

  73. on the Ant-Dev mailing list.

  74. </p>

  75.                                 <p>

  76. The realisation of these requirements as they impact a user is on the

  77. <a href="features.html">next page</a>. Th implications for task developers and

  78. Ant developers are discussed in the following sections.

  79. </p>

  80.                     </blockquote>

  81.     </td></tr>

  82.   </table>

  83.         <table border="0" cellspacing="0" cellpadding="2" width="100%">

  84.     <tr><td bgcolor="#525D76">

  85.       <font color="#ffffff" face="arial,helvetica,sanserif">

  86.         <a name="Ant1 Issues"><strong>Ant1 Issues</strong></a>

  87.       </font>

  88.     </td></tr>

  89.     <tr><td>

  90.       <blockquote>

  91.                           <table border="0" cellspacing="0" cellpadding="2" width="100%">

  92.     <tr><td bgcolor="#828DA6">

  93.       <font color="#ffffff" face="arial,helvetica,sanserif">

  94.         <a name="Unrestricted core access"><strong>Unrestricted core access</strong></a>

  95.       </font>

  96.     </td></tr>

  97.     <tr><td>

  98.       <blockquote>

  99.                         <p>

  100. The interface between the Ant core and tasks is not controlled. It

  101. allows tasks almost complete access to the internal data structures of the

  102. core. This is poor encapsulation. Whilst most tasks do not need and do not

  103. use this access, its existence nonetheless prevents changes being made to

  104. the core without raising concerns about impacting backward compatability.

  105. </p>

  106.                                 <p>

  107. The uncontrolled nature of the task-core interface also makes it difficult

  108. to reuse tasks and types in a different context without almost completely

  109. duplicating the Ant core

  110. </p>

  111.                                   <div align="left">

  112.     <table cellspacing="4" cellpadding="0" border="0">

  113.       <tr>

  114.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  115.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  116.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  117.       </tr>

  118.       <tr>

  119.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  120.         <td bgcolor="#ffffff">

  121.                           

  122. <p>

  123. A tightly defined interface between the core and the components (tasks and

  124. types) will allow the core implementation to be changed without the risk

  125. of impacting tasks. It will also allow components to be reused in other

  126. contexts.

  127. </p>

  128. 

  129.                     </td>

  130.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  131.       </tr>

  132.       <tr>

  133.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  134.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  135.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  136.       </tr>

  137.     </table>

  138.   </div>

  139.                     </blockquote>

  140.     </td></tr>

  141.   </table>

  142.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  143.     <tr><td bgcolor="#828DA6">

  144.       <font color="#ffffff" face="arial,helvetica,sanserif">

  145.         <a name="Lack of embedding support"><strong>Lack of embedding support</strong></a>

  146.       </font>

  147.     </td></tr>

  148.     <tr><td>

  149.       <blockquote>

  150.                         <p>

  151. Ant1 does not provide strong support for embedding Ant in other systems,

  152. particularly a GUI or IDE. The development of Antidote highlighted this

  153. difficultly. Antidote was forced to perform its own XML parsing so it could

  154. build its own model of the build. There is no communication medium for a GUI to

  155. communicate with the core. Without this capability any GUI will be limited to

  156. simply editing the XML representation of the build.

  157. </p>

  158.                                   <div align="left">

  159.     <table cellspacing="4" cellpadding="0" border="0">

  160.       <tr>

  161.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  162.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  163.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  164.       </tr>

  165.       <tr>

  166.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  167.         <td bgcolor="#ffffff">

  168.                           

  169. <p>

  170. The definition of a project model, a Java-based object-model of a build

  171. description would decouple Ant from the XML representation. This allows

  172. other representations to be used. Such an object model also forms the basis

  173. for communications between systems which want to embed Ant. An IDE could

  174. manipulate this project object model directly and pass to the core for

  175. processing without needing to convert to and from an external

  176. representations such as XML.

  177. </p>

  178. 

  179.                     </td>

  180.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  181.       </tr>

  182.       <tr>

  183.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  184.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  185.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  186.       </tr>

  187.     </table>

  188.   </div>

  189.                     </blockquote>

  190.     </td></tr>

  191.   </table>

  192.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  193.     <tr><td bgcolor="#828DA6">

  194.       <font color="#ffffff" face="arial,helvetica,sanserif">

  195.         <a name="Configuration done at Parse-Time"><strong>Configuration done at Parse-Time</strong></a>

  196.       </font>

  197.     </td></tr>

  198.     <tr><td>

  199.       <blockquote>

  200.                         <p>

  201. The original implementation of Ant1 performed all task configuration at the

  202. time the XML description of the build was parsed (parse-time). This approach

  203. could not handle dynamically created tasks very well since in some

  204. instances the type of the task to be configured was not known at parse-time.

  205. This limitation was overcome with the introduction of the UnknownElement and

  206. RuntimeConfigurable classes. While these work well, they are confusing and at

  207. times surprising to most Ant developers. Also some operations still occur at

  208. parse-time, notably creation of nested elements of known types. This could be

  209. overcome by going to a fully dynamic model but the fear of backward

  210. incompatability constrains this change from occuring.

  211. </p>

  212.                                   <div align="left">

  213.     <table cellspacing="4" cellpadding="0" border="0">

  214.       <tr>

  215.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  216.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  217.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  218.       </tr>

  219.       <tr>

  220.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  221.         <td bgcolor="#ffffff">

  222.                           

  223. <p>

  224. Execution-time configuration of tasks allows for the latest information to be

  225. used for configuration. It is also necessary to support the concept of the

  226. project model. The project model cannot contain execution-time information as it

  227. does in Ant1

  228. </p>

  229. 

  230. <p>

  231. The decoupling of the parsing and exection phases, communicating through the

  232. medium of the project model will allow the core to be modularized. The parsing

  233. and execution phases can be separated and one replaced without impacting the

  234. other.

  235. </p>

  236. 

  237.                     </td>

  238.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  239.       </tr>

  240.       <tr>

  241.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  242.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  243.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  244.       </tr>

  245.     </table>

  246.   </div>

  247.                     </blockquote>

  248.     </td></tr>

  249.   </table>

  250.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  251.     <tr><td bgcolor="#828DA6">

  252.       <font color="#ffffff" face="arial,helvetica,sanserif">

  253.         <a name="Multiple execution"><strong>Multiple execution</strong></a>

  254.       </font>

  255.     </td></tr>

  256.     <tr><td>

  257.       <blockquote>

  258.                         <p>

  259. In Ant1, a task, once configured, may be used more than once - i.e. its

  260. execute method may be called more than once. This occurs when the Ant

  261. command line specifies the evaluation of two targets. If those targets have

  262. overlapping dependencies, the tasks in those overlapping dependencies will

  263. be executed twice. This arrangement requires task writers to preserve the

  264. state configured by Ant during the execution of the task so that the next

  265. execution has the correct configuration.

  266. </p>

  267.                                 <p>

  268. Many task writers are not aware of this requirement. Frequently the task's

  269. state is changed during the execution method, which can lead to mysterious

  270. falures during subsequent executions. This need to preserve the configuration

  271. state makes writing tasks much harder.

  272. </p>

  273.                                   <div align="left">

  274.     <table cellspacing="4" cellpadding="0" border="0">

  275.       <tr>

  276.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  277.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  278.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  279.       </tr>

  280.       <tr>

  281.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  282.         <td bgcolor="#ffffff">

  283.                           

  284. <p>

  285. Once a task is configured, it should be executed once. If the execution of

  286. multiple targets is required, a new task instance should be created and

  287. configured from the same project model. If reuse of task instances is desired

  288. each instance must be reinitialized and reconfigured before use.

  289. </p>

  290. 

  291.                     </td>

  292.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  293.       </tr>

  294.       <tr>

  295.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  296.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  297.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  298.       </tr>

  299.     </table>

  300.   </div>

  301.                     </blockquote>

  302.     </td></tr>

  303.   </table>

  304.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  305.     <tr><td bgcolor="#828DA6">

  306.       <font color="#ffffff" face="arial,helvetica,sanserif">

  307.         <a name="No automatic deployment of tasks"><strong>No automatic deployment of tasks</strong></a>

  308.       </font>

  309.     </td></tr>

  310.     <tr><td>

  311.       <blockquote>

  312.                         <p>

  313. Ant1 has a set of well-known tasks (and types). A well-known task is one

  314. for which a mapping between the taskname and its implementing class is

  315. predefined in Ant. This mapping is provided by the two defaults.properties

  316. files in Ant's code. These well-known tasks do not need to be taskdef'd to

  317. make them available in a build file. Conversely tasks which are not in this

  318. list need to be explicitly taskdef'd.

  319. </p>

  320.                                 <p>

  321. Note that this distinction is not the same as the core/optional

  322. distinction found in Ant1. An Ant1 core task is notionally supported by Ant

  323. without requiring any additional external libraries - it just requires the

  324. classes available in the 1.1 JDK, in Ant and in the libraries Ant uses such

  325. as the XML parser. An optional task is a task which requires JDK 1.2+

  326. features or the support of an external library, such as jakarta-regexp.

  327. </p>

  328.                                 <p>

  329. The problem with this system is that there is no namespace management. If a

  330. new task is added to Ant, it may invalidate buildfiles which are already

  331. using that taskname via a taskdef. Actually the taskdef may continue to work or

  332. it may not - it will depend on the nested elements that the task definitions

  333. support (see above discussion of regarding cofiguration at parse-time)

  334. </p>

  335.                                   <div align="left">

  336.     <table cellspacing="4" cellpadding="0" border="0">

  337.       <tr>

  338.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  339.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  340.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  341.       </tr>

  342.       <tr>

  343.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  344.         <td bgcolor="#ffffff">

  345.                           

  346. <p>

  347. Tasks need to be deployed in libraries by either placing them in well known

  348. directories of an Ant install or by telling Ant where to look for them. Removing

  349. the central management of defined task names allows tasks libraries to be

  350. developed and maintained independently of Ant much more easily.

  351. </p>

  352. 

  353. <p>

  354. Once centralised management of the task namespace is removed, there is,

  355. however, the possibility of name collision. A mechanism is required to allow a

  356. build file  writer to select which particular tasks are assigned to which

  357. tasknames.

  358. </p>

  359. 

  360.                     </td>

  361.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  362.       </tr>

  363.       <tr>

  364.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  365.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  366.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  367.       </tr>

  368.     </table>

  369.   </div>

  370.                     </blockquote>

  371.     </td></tr>

  372.   </table>

  373.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  374.     <tr><td bgcolor="#828DA6">

  375.       <font color="#ffffff" face="arial,helvetica,sanserif">

  376.         <a name="Top level tasks"><strong>Top level tasks</strong></a>

  377.       </font>

  378.     </td></tr>

  379.     <tr><td>

  380.       <blockquote>

  381.                         <p>

  382. In Ant1 certain tasks may appear outside of any target. This is implemented as a

  383. set of hardcoded conditions in the XML parsing phase. The execution and

  384. configuration of these tasks does not involve the use of RuntimeConfigurable and

  385. UnknownElement.

  386. </p>

  387.                                 <p>

  388. This hardcoding is not very inituitive. It is confusing to users who do not

  389. know why only some tasks may be run outside of a target. Also as the list of

  390. tasks that may be useful as a top-level task grows, further special cases must

  391. be added to the code making the code harder to maintain.

  392. </p>

  393.                                   <div align="left">

  394.     <table cellspacing="4" cellpadding="0" border="0">

  395.       <tr>

  396.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  397.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  398.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  399.       </tr>

  400.       <tr>

  401.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  402.         <td bgcolor="#ffffff">

  403.                           

  404. <p>

  405. The number of special names should be kept to a minimum. Special cases should

  406. be avoided as they are not inituitive.

  407. </p>

  408. 

  409.                     </td>

  410.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  411.       </tr>

  412.       <tr>

  413.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  414.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  415.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  416.       </tr>

  417.     </table>

  418.   </div>

  419.                     </blockquote>

  420.     </td></tr>

  421.   </table>

  422.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  423.     <tr><td bgcolor="#828DA6">

  424.       <font color="#ffffff" face="arial,helvetica,sanserif">

  425.         <a name="Build file inclusion is cumbersome"><strong>Build file inclusion is cumbersome</strong></a>

  426.       </font>

  427.     </td></tr>

  428.     <tr><td>

  429.       <blockquote>

  430.                         <p>

  431. In Ant1, the inclusion of a set of build file definitions or targets is achieved

  432. through the use of XML entities. This is just cumbersome.

  433. </p>

  434.                                   <div align="left">

  435.     <table cellspacing="4" cellpadding="0" border="0">

  436.       <tr>

  437.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  438.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  439.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  440.       </tr>

  441.       <tr>

  442.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  443.         <td bgcolor="#ffffff">

  444.                           

  445. <p>

  446. A simplified include mechanism is required to replace the entity based

  447. inclusion of Ant1.

  448. </p>

  449. 

  450.                     </td>

  451.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  452.       </tr>

  453.       <tr>

  454.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  455.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  456.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  457.       </tr>

  458.     </table>

  459.   </div>

  460.                     </blockquote>

  461.     </td></tr>

  462.   </table>

  463.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  464.     <tr><td bgcolor="#828DA6">

  465.       <font color="#ffffff" face="arial,helvetica,sanserif">

  466.         <a name="Classpath management"><strong>Classpath management</strong></a>

  467.       </font>

  468.     </td></tr>

  469.     <tr><td>

  470.       <blockquote>

  471.                         <p>

  472. Probably the greatest issue facing Ant1 today involves the management of the

  473. classpath and the associated visibility of classes. Most optional tasks in Ant1

  474. require the supporting classes for the task to be available on the system

  475. classpath. For example, the JUnit task is only usable if the JUnit jar is on

  476. the classpath. If it is not, Ant will complain about being unable to create the

  477. junit task.

  478. </p>

  479.                                 <p>

  480. The usual solution when a user runs into this problem is to put the required jar

  481. into the ANT_HOME/lib directory. This just adds the required jar to the system

  482. classpath prior to starting Ant albeit without requiring the user to explicitly

  483. set the classpath.

  484. </p>

  485.                                 <p>

  486. There are a number of issues with this approach. The classes on the

  487. classpath share the same classloader as Ant's classes and Ant's support

  488. libraries - particularly the XML parser. If a task wishes to use a specific XML

  489. parser, it may conflict with Ant's own parser. If two tasks require different

  490. versions of a supporting jar, these will conflict.

  491. </p>

  492.                                 <p>

  493. Many tasks make use of factory objects (dynamic class instantiation, dynamic

  494. resource loading, etc). When the factory is in the system classpath it will not

  495. be able to load resources available in a taskdef'd task's custom classpath due

  496. to the delegating nature of classloaders. Such errors can be very confusing to

  497. users. More recent code is likely to attempt use of a context classloader but

  498. this is not set by Ant1 currently.

  499. </p>

  500.                                   <div align="left">

  501.     <table cellspacing="4" cellpadding="0" border="0">

  502.       <tr>

  503.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  504.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  505.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  506.       </tr>

  507.       <tr>

  508.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  509.         <td bgcolor="#ffffff">

  510.                           

  511. <p>

  512. Do not require jars to be added to ANT_HOME/lib to enable tasks. Allow users to

  513. specify the location of support jars on a per-library basis.

  514. </p>

  515. 

  516.                     </td>

  517.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  518.       </tr>

  519.       <tr>

  520.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  521.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  522.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  523.       </tr>

  524.     </table>

  525.   </div>

  526.                     </blockquote>

  527.     </td></tr>

  528.   </table>

  529.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  530.     <tr><td bgcolor="#828DA6">

  531.       <font color="#ffffff" face="arial,helvetica,sanserif">

  532.         <a name="Extensibility"><strong>Extensibility</strong></a>

  533.       </font>

  534.     </td></tr>

  535.     <tr><td>

  536.       <blockquote>

  537.                         <p>

  538. The earliest versions Ant1 did not explicitly support any datatypes. The only

  539. datatype, property, was actually created as a side-effect of running the

  540. <code>&lt;property&gt;</code> task. If it were to be implemented today, property

  541. would probably be known as a string datatype, perhaps associated with a

  542. <code>&lt;load-properties&gt;</code> task. This is also the reason property

  543. is one of those tasks which is allowed to exist outside of a target.

  544. </p>

  545.                                 <p> As Ant1 evolved new types such as <code>&lt;path&gt;</code> and

  546. <code>&lt;fileset&gt;</code> were added. The concept of datatypes has continued

  547. to evolve to the point where users can now define new datatypes. It would be

  548. expected that in addition to new types there will be many sub-types created,

  549. such as new types of fileset. Ant1, however, does not strongly support such type

  550. extensibility. When a subtype is created by extending an existing type, Ant1

  551. requires it to be either used by reference or all tasks which accept the base

  552. type need to be modified to support the new type. Use by reference is not always

  553. possible. It will depend on whether the base type has been coded to support

  554. references. </p>

  555.                                   <div align="left">

  556.     <table cellspacing="4" cellpadding="0" border="0">

  557.       <tr>

  558.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  559.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  560.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  561.       </tr>

  562.       <tr>

  563.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  564.         <td bgcolor="#ffffff">

  565.                           

  566. <p>

  567. Support polymorphic behaviour, allowing a build file to pass a subtype to a

  568. task which is defined to accept the base type. Allow task interfaces to be

  569. defined in terms of interfaces.

  570. </p>

  571. 

  572. <p>

  573. Move reference processing to the core to make it more regular removing the

  574. burden of type developers to explicitly support references.

  575. </p>

  576. 

  577.                     </td>

  578.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  579.       </tr>

  580.       <tr>

  581.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  582.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  583.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  584.       </tr>

  585.     </table>

  586.   </div>

  587.                     </blockquote>

  588.     </td></tr>

  589.   </table>

  590.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  591.     <tr><td bgcolor="#828DA6">

  592.       <font color="#ffffff" face="arial,helvetica,sanserif">

  593.         <a name="Project object does too much"><strong>Project object does too much</strong></a>

  594.       </font>

  595.     </td></tr>

  596.     <tr><td>

  597.       <blockquote>

  598.                         <p>

  599. In Ant1 the Project object takes on too many roles including all of the

  600. following:

  601. </p>

  602.                                 <ul>

  603. <li>Holds the project model built when parsing the build file</li>

  604. <li>Holds the run-time state of the build through the properties and current

  605. task definitions</li>

  606. <li>Provides context for task execution. All tasks have a reference to their

  607. project instance and use it to access core functions</li>

  608. <li>Provides the implementation of common task operations</li>

  609. <li>Build event management</li>

  610. <li>Message logging</li>

  611. <li>Global filter definitions</li>

  612. <li>Java Version</li>

  613. <li>Property replacement</li>

  614. <li>Message Levels</li>

  615. <li>Utility functions such as boolean conversion and path translation</li>

  616. <li>Integration point for embedding Ant</li>

  617. </ul>

  618.                                 <p> As a class, Project is not cohesive. Reuse of the Ant core functionality is

  619. difficulty as all of these concerns bring in many other support classes.

  620. </p>

  621.                                   <div align="left">

  622.     <table cellspacing="4" cellpadding="0" border="0">

  623.       <tr>

  624.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  625.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  626.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  627.       </tr>

  628.       <tr>

  629.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  630.         <td bgcolor="#ffffff">

  631.                           

  632. <p>

  633. Separate the various roles of Project into more cohesive classes.

  634. </p>

  635. 

  636.                     </td>

  637.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  638.       </tr>

  639.       <tr>

  640.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  641.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  642.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  643.       </tr>

  644.     </table>

  645.   </div>

  646.                     </blockquote>

  647.     </td></tr>

  648.   </table>

  649.                     </blockquote>

  650.     </td></tr>

  651.   </table>

  652.         <table border="0" cellspacing="0" cellpadding="2" width="100%">

  653.     <tr><td bgcolor="#525D76">

  654.       <font color="#ffffff" face="arial,helvetica,sanserif">

  655.         <a name="Other Goals"><strong>Other Goals</strong></a>

  656.       </font>

  657.     </td></tr>

  658.     <tr><td>

  659.       <blockquote>

  660.                         <p>

  661. In addition to the issues which arise from Ant1 limitations, there are a number

  662. of requirements which have emerged in the mailing list discussions about Ant2.

  663. This isn't a complete list - just the ones I picked up for Mutant.

  664. </p>

  665.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  666.     <tr><td bgcolor="#828DA6">

  667.       <font color="#ffffff" face="arial,helvetica,sanserif">

  668.         <a name="Limited project reuse"><strong>Limited project reuse</strong></a>

  669.       </font>

  670.     </td></tr>

  671.     <tr><td>

  672.       <blockquote>

  673.                         <p> In Ant1 the only way to reuse build file definitions is to use the

  674. <code>&lt;ant&gt;</code> task. While useful, it is relatively coarse-grained. It

  675. can also be tedious if you are trying to extend an existing project definition -

  676. that is, adding new targets while retaining a user's ability to access the

  677. existing targets. </p>

  678.                                 <p>

  679. In addition to the extension of projects, it should be possible to compose

  680. projects creating dependencies between the targets of the different projects,

  681. and to access the data and definitions of one project by a controlling project

  682. </p>

  683.                                   <div align="left">

  684.     <table cellspacing="4" cellpadding="0" border="0">

  685.       <tr>

  686.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  687.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  688.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  689.       </tr>

  690.       <tr>

  691.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  692.         <td bgcolor="#ffffff">

  693.                           

  694. <p>

  695. Allow a project to extend and control other projects

  696. </p>

  697. 

  698.                     </td>

  699.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  700.       </tr>

  701.       <tr>

  702.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  703.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  704.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  705.       </tr>

  706.     </table>

  707.   </div>

  708.                     </blockquote>

  709.     </td></tr>

  710.   </table>

  711.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  712.     <tr><td bgcolor="#828DA6">

  713.       <font color="#ffffff" face="arial,helvetica,sanserif">

  714.         <a name="Ant1 Compatibility - Zero Friction"><strong>Ant1 Compatibility - Zero Friction</strong></a>

  715.       </font>

  716.     </td></tr>

  717.     <tr><td>

  718.       <blockquote>

  719.                         <p>

  720. While it has always been accepted that there will be come backward compatibility

  721. breaks in moving from Ant1 to Ant2, these should be minimized. If the changeover

  722. from Ant1 to Ant2 is difficult, it may never happen. On the other hand, the

  723. openness of the Ant1 interface means that some tasks will not work as expected -

  724. the most difficult being the <code>&lt;script&gt;</code> task.

  725. </p>

  726.                                   <div align="left">

  727.     <table cellspacing="4" cellpadding="0" border="0">

  728.       <tr>

  729.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  730.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  731.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  732.       </tr>

  733.       <tr>

  734.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  735.         <td bgcolor="#ffffff">

  736.                           

  737. <p>

  738. Achieve a practical level of compatability without degrading the integrity of

  739. the core's interfaces. A practical level of compatability is intentionally a

  740. vague measure but it would require the majority of projects in Gump to be built

  741. without noticeable differences from Ant1

  742. </p>

  743. 

  744.                     </td>

  745.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  746.       </tr>

  747.       <tr>

  748.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  749.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  750.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  751.       </tr>

  752.     </table>

  753.   </div>

  754.                     </blockquote>

  755.     </td></tr>

  756.   </table>

  757.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  758.     <tr><td bgcolor="#828DA6">

  759.       <font color="#ffffff" face="arial,helvetica,sanserif">

  760.         <a name="XML Configuration"><strong>XML Configuration</strong></a>

  761.       </font>

  762.     </td></tr>

  763.     <tr><td>

  764.       <blockquote>

  765.                         <p>

  766. In Ant1 configuration of Ant is achieved either through the execution of OS

  767. dependent scripts by the launcher scripts or though properties files which have

  768. the limited capability to set properties.

  769. </p>

  770.                                   <div align="left">

  771.     <table cellspacing="4" cellpadding="0" border="0">

  772.       <tr>

  773.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  774.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  775.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  776.       </tr>

  777.       <tr>

  778.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  779.         <td bgcolor="#ffffff">

  780.                           

  781. <p>

  782. Provide an XML based configuration system with rich capabilities to configure

  783. the operation of Ant.

  784. </p>

  785. 

  786.                     </td>

  787.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  788.       </tr>

  789.       <tr>

  790.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  791.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  792.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  793.       </tr>

  794.     </table>

  795.   </div>

  796.                     </blockquote>

  797.     </td></tr>

  798.   </table>

  799.                                   <table border="0" cellspacing="0" cellpadding="2" width="100%">

  800.     <tr><td bgcolor="#828DA6">

  801.       <font color="#ffffff" face="arial,helvetica,sanserif">

  802.         <a name="Aspects"><strong>Aspects</strong></a>

  803.       </font>

  804.     </td></tr>

  805.     <tr><td>

  806.       <blockquote>

  807.                         <p>

  808. In Ant1 there are many things which are common to a group of tasks but adding

  809. the capability to each task is repetitive and tedious. An example would be the

  810. failonerror attribute which controls whether a task will cause the build to stop

  811. when it fails. This started on just one task but has since been added to many

  812. other tasks as users want more fine control over when their builds stop. Aspects

  813. have been discussed as a mechanism for providing a single implementation of a

  814. concept or control that can then be applied to tasks independently.

  815. </p>

  816.                                   <div align="left">

  817.     <table cellspacing="4" cellpadding="0" border="0">

  818.       <tr>

  819.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  820.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  821.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  822.       </tr>

  823.       <tr>

  824.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  825.         <td bgcolor="#ffffff">

  826.                           

  827. <p>

  828. Investigate the use of an Aspect approach to provide common functionality

  829. across tasks with a single implementation

  830. </p>

  831. 

  832.                     </td>

  833.         <td bgcolor="#023264" width="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  834.       </tr>

  835.       <tr>

  836.         <td bgcolor="#023264" width="1" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

  837.         <td bgcolor="#023264" height="1"><img src="/images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0"/></td>

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Please read the following content carefully:

Dear OpenI User

Thank you for your continuous support to the Openl Qizhi Community AI Collaboration Platform. In order to protect your usage rights and ensure network security, we updated the Openl Qizhi Community AI Collaboration Platform Usage Agreement in January 2024. The updated agreement specifies that users are prohibited from using intranet penetration tools. After you click "Agree and continue", you can continue to use our services. Thank you for your cooperation and understanding.

For more agreement content, please refer to the《Openl Qizhi Community AI Collaboration Platform Usage Agreement》

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