catalog

chain

A general container for xchain commands. Children of a chain are executed, in order, until one of them returns true or throws an exception.

If one of the chain's children returns true , then each child that was executed will have its post process executed and then the chain will return true .

If one of the chain's children throws an exception, then each children that was executed, including the command that threw the exception, will have its post process executed with the exception that was thrown. If none of the children's post process returns true , then the exception will be rethrown by this chain. If any of the childrens post process returns true , then this chain will return false and its next sibling will execute.

<xchain:chain xmlns:xchain="http://www.xchain.org/core/1.0">
   ...
 </xchain:chain>

choose

The choose command allows the execution of one chain based on tested conditions. Only when and otherwise commands can be direct children of the choose command. Each when command has a test attribute. The first when command whose test attribute evaluates to true will be executed and no other child when or otherwise commands will be executed or have their test condition evaluated. otherwise commands will always be executed if encountered.

<xchain:choose xmlns:xchain="http://www.xchain.org/core/1.0">
   <xchain:when test="/some/xpath">
     ...
   </xchain:when>
   <xchain:when test="/some/other/xpath">
     ...
   </xchain:when>
   <xchain:otherwise>
     ...
   </xchain:otherwise>
 </xchain:choose>

debug-message

eval

The eval command will evaluate an xpath expression.

<xchain:eval xmlns:xchain="http://www.xchain.org/core/1.0" expression="/some/xpath"/>

execute

The execute command can execute another command chain. The command can be in the current catalog or in a different catalog. The command chain will continue if and only if the referenced command would continue the command chain.

<xchain:chain xmlns:xchain="http://www.xchain.org/core/1.0">
   ...
   <xchain:execute system-id="$myCatalog" name="$myCommand">
   ...
 </xchain:choose>

filter-chain

A general container for xchain commands. Children of a chain are executed, in order, until one of them returns true or throws an exception.

If one of the chain's children returns true , then each child that was executed will have its post process executed and then the chain will return true .

If one of the chain's children throws an exception, then each children that was executed, including the command that threw the exception, will have its post process executed with the exception that was thrown. If none of the children's post process returns true , then the exception will be rethrown by this chain. If any of the children's post process returns true , then this chain will return false and its next sibling will execute.

If post process is run on this chain then the post process will be run on it's children in reverse order of their original execution.

<xchain:filter-chain xmlns:xchain="http://www.xchain.org/core/1.0">
   ...
 </xchain:filter-chain>

filter-choose

The choose command implemented as a filter. This command allows the execution of one chain based on tested conditions. Only when and otherwise commands can be direct children of the choose command. Each when command has a test attribute. The first when command whose test attribute evaluates to true will be executed and no other child when or otherwise commands will be executed or have their test condition evaluated. otherwise commands will always be executed if encountered.

<xchain:filter-choose xmlns:xchain="http://www.xchain.org/core/1.0">
   <xchain:when test="/some/xpath">
     ...
   </xchain:when>
   <xchain:when test="/some/other/xpath">
     ...
   </xchain:when>
   <xchain:otherwise>
     ...
   </xchain:otherwise>
 </xchain:filter-choose>

filter-if

The if command implemented as a filter. This command will execute its child commands if the test attribute evaluates to true .

<xchain:filter-if xmlns:xchain="http://www.xchain.org/core/1.0" test="/some/xpath">
   ...
 </xchain:filter-if>

filter-variable

The variable command implemented as a filter. The filter-variable will declare and set a variable in the context. The name attribute is the QName of the variable. The select , select-nodes , or select-single-node attribute will be the value of the variable. The scope attribute will determine the scope of the variable. A 'chain' scope variable will only exist in the current context. A 'request' scope variable will exist for every context. A request scope is assumed if no scope attribute is provided.

During post process the original value at the QName will be restored. If no value existed at the QName then the variable will be undeclared.

for-each

<xchain:for-each xmlns:xchain="http://www.xchain.org/core/1.0" select="/some/xpath">
   ...
 </xchain:for-each>

<xchain:for-each xmlns:xchain="http://www.xchain.org/core/1.0" select-nodes="/some/xpath">
   ...
 </xchain:for-each>

handled

A command that can stop the execution of an xchain by reporting that it handled the request. The command will return true when its test condition is true.

  <xchain:chain xmlns:xchain="http://www.xchain.org/core/1.0">
     <xchain:handled test="true()"/>
     <-- A command here will never execute -->
   </xchain:chain>

if

<xchain:if xmlns:xchain="http://www.xchain.org/core/1.0" test="/some/xpath">
   ...
 </xchain:if>

iterate

<xchain:iterate xmlns:xchain="http://www.xchain.org/core/1.0" select="/some/xpath" variable="name">
   ...
 </xchain:iterate>

throw

trace

variable

The variable command will declare and set a variable in the context. The name attribute is the QName of the variable. The select , select-nodes , or select-single-node attribute will be the value of the variable. The scope attribute will determine the scope of the variable. A 'chain' scope variable will only exist if the current context. A 'request' scope variable will exist for every context. A request scope is assumed if no scope attribute is provided.

<xchain:variable xmlns:xchain="http://www.xchain.org/core/1.0" name="/some/xpath" select="/some/xpath"/ scope="chain"/>

with

The with command will execute its child commands with the selected element as the root context.

<xchain:with xmlns:xchain="http://www.xchain.org/core/1.0" select="/some/xpath">
   ...
 </xchain:with>