Difference between revisions of "Repository"
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# The [[#EXPath Packaging|EXPath Packaging]] system provides a generic mechanism for adding XQuery modules to query processors. A package is defined as a {{Code|.xar}} archive, which encapsulates one or more extension libraries. | # The [[#EXPath Packaging|EXPath Packaging]] system provides a generic mechanism for adding XQuery modules to query processors. A package is defined as a {{Code|.xar}} archive, which encapsulates one or more extension libraries. | ||
− | =Accessing Modules= | + | ==Accessing Modules== |
− | Library modules can be imported with the {{Code|import module}} statement, | + | Library modules can be imported with the {{Code|import module}} statement, followed by a freely choosable prefix and the namespace of the target module. The specified location may be absolute or relative; in the latter case, it is resolved against the location (i.e., ''static base URI'') of the calling module. Import module statements must be placed at the beginning of a module: |
− | followed by a freely choosable prefix and the namespace of the target module. | ||
− | The specified location may be absolute or relative; in the latter case, it is resolved | ||
− | against the location (i.e., ''static base URI'') of the calling module. | ||
− | Import module statements must be placed at the beginning of a module: | ||
− | '''Main Module''' <code> | + | '''Main Module''' <code>hello-universe.xq</code>: |
− | < | + | <syntaxhighlight lang="xquery"> |
− | import module namespace m = 'http://basex.org/modules/ | + | import module namespace m = 'http://basex.org/modules/hello' at 'hello-world.xqm'; |
m:hello("Universe") | m:hello("Universe") | ||
− | </ | + | </syntaxhighlight> |
− | '''Library Module''' <code> | + | '''Library Module''' <code>hello-world.xqm</code> (in the same directory): |
− | < | + | <syntaxhighlight lang="xquery"> |
module namespace m = 'http://basex.org/modules/Hello'; | module namespace m = 'http://basex.org/modules/Hello'; | ||
declare function m:hello($world) { | declare function m:hello($world) { | ||
'Hello ' || $world | 'Hello ' || $world | ||
}; | }; | ||
− | </ | + | </syntaxhighlight> |
− | Repository modules are stored in | + | If no location is supplied, modules will be looked up in the repository. Repository modules are stored in the {{Code|repo}} directory, which resides in your [[Configuration#Home Directory|home directory]]. XQuery modules can be manually copied to the repository directory or installed and deleted via [[#Commands|commands]]. |
− | + | The following example calls a function from the FunctX module in the repository: | |
− | < | + | <syntaxhighlight lang="xquery"> |
import module namespace functx = 'http://www.functx.com'; | import module namespace functx = 'http://www.functx.com'; | ||
functx:capitalize-first('test') | functx:capitalize-first('test') | ||
− | </ | + | </syntaxhighlight> |
=Commands= | =Commands= | ||
− | There are various ways to | + | There are various ways to organize your packages: |
* Execute BaseX REPO commands (listed below) | * Execute BaseX REPO commands (listed below) | ||
Line 53: | Line 49: | ||
* Use the GUI (''Options'' → ''Packages'') | * Use the GUI (''Options'' → ''Packages'') | ||
− | You can even manually add and remove packages in the repository directory; all changes will automatically be detected by | + | You can even manually add and remove packages in the repository directory; all changes will automatically be detected by BaseX. |
==Installation== | ==Installation== | ||
Line 66: | Line 62: | ||
==Listing== | ==Listing== | ||
− | All currently installed packages can be listed with {{Command|REPO LIST}}. | + | All currently installed packages can be listed with {{Command|REPO LIST}}. The names of all packages are listed, along with their version, their package type, and the repository path: |
− | + | Name Version Type Path | |
− | ------------------------------------------------------- | + | ----------------------------------------------------------------- |
− | <nowiki>http://www.functx.com</nowiki> 1.0 http-www.functx.com-1.0 | + | <nowiki>http://www.functx.com</nowiki> 1.0 EXPath http-www.functx.com-1.0 |
− | |||
− | |||
==Removal== | ==Removal== | ||
Line 78: | Line 72: | ||
A package can be deleted with {{Command|REPO DELETE}} and an additional argument, containing its name or the name suffixed with a hyphen and the package version: | A package can be deleted with {{Command|REPO DELETE}} and an additional argument, containing its name or the name suffixed with a hyphen and the package version: | ||
− | REPO DELETE <nowiki>http://www.functx.com</nowiki> | + | REPO DELETE <nowiki>http://www.functx.com</nowiki> |
REPO DELETE <nowiki>http://www.functx.com-1.0</nowiki> | REPO DELETE <nowiki>http://www.functx.com-1.0</nowiki> | ||
Line 85: | Line 79: | ||
==XQuery== | ==XQuery== | ||
− | If an XQuery file is specified as input for the install command, it will be parsed as XQuery library module. If the file can successfully be parsed, the module URI will be [[#URI Rewriting|rewritten]] to a file path and attached with the {{Code|.xqm}} file suffix, and the original file will possibly be renamed and copied to that path into the repository. | + | If an XQuery file is specified as input for the install command, it will be parsed as XQuery library module. If the file can successfully be parsed, the module URI will be [[Java Bindings#URI Rewriting|rewritten]] to a file path and attached with the {{Code|.xqm}} file suffix, and the original file will possibly be renamed and copied to that path into the repository. |
'''Example:''' | '''Example:''' | ||
Line 95: | Line 89: | ||
Importing the repository module: | Importing the repository module: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
import module namespace m = 'http://basex.org/modules/Hello'; | import module namespace m = 'http://basex.org/modules/Hello'; | ||
m:hello("Universe") | m:hello("Universe") | ||
− | </ | + | </syntaxhighlight> |
==Java== | ==Java== | ||
Line 106: | Line 100: | ||
Java archives (JARs) may contain one or more class files. One of them will be chosen as main class, which must be specified in a {{Code|Main-Class}} entry in the manifest file ({{Code|META-INF/MANIFEST.MF}}). This fully qualified Java class name will be rewritten to a file path by replacing the dots with slashes and attaching the {{Code|.jar}} file suffix, and the original file will be renamed and copied to that path into the repository. | Java archives (JARs) may contain one or more class files. One of them will be chosen as main class, which must be specified in a {{Code|Main-Class}} entry in the manifest file ({{Code|META-INF/MANIFEST.MF}}). This fully qualified Java class name will be rewritten to a file path by replacing the dots with slashes and attaching the {{Code|.jar}} file suffix, and the original file will be renamed and copied to that path into the repository. | ||
− | If the class will be imported in the prolog of the XQuery module, an instance of it will be created, and its public functions can then be addressed from XQuery. A class may extend the {{Code|QueryModule}} class to get access to the current query context and to be enriched by some helpful annotations (see [[Java_Bindings# | + | If the class will be imported in the prolog of the XQuery module, an instance of it will be created, and its public functions can then be addressed from XQuery. A class may extend the {{Code|QueryModule}} class to get access to the current query context and to be enriched by some helpful annotations (see [[Java_Bindings#Annotations|Annotations]]). |
'''Example:''' | '''Example:''' | ||
− | Structure of the <code>[ | + | Structure of the <code>[https://files.basex.org/modules/org/basex/modules/Hello/HelloWorld.jar HelloWorld.jar]</code> archive: |
META-INF/ | META-INF/ | ||
Line 124: | Line 118: | ||
Contents of the file {{Code|Hello.java}} (comments removed): | Contents of the file {{Code|Hello.java}} (comments removed): | ||
− | < | + | <syntaxhighlight lang="java"> |
package org.basex.modules; | package org.basex.modules; | ||
public class Hello { | public class Hello { | ||
Line 131: | Line 125: | ||
} | } | ||
} | } | ||
− | </ | + | </syntaxhighlight> |
Installation (the file will be copied to {{Code|org/basex/modules/Hello.jar}}): | Installation (the file will be copied to {{Code|org/basex/modules/Hello.jar}}): | ||
Line 137: | Line 131: | ||
REPO INSTALL HelloWorld.jar | REPO INSTALL HelloWorld.jar | ||
− | XQuery file <code>[ | + | XQuery file <code>[https://files.basex.org/modules/org/basex/modules/Hello/HelloUniverse.xq HelloUniverse.xq]</code> (same as above): |
− | < | + | <syntaxhighlight lang="xquery"> |
import module namespace m = 'http://basex.org/modules/Hello'; | import module namespace m = 'http://basex.org/modules/Hello'; | ||
m:hello("Universe") | m:hello("Universe") | ||
− | </ | + | </syntaxhighlight> |
− | After having installed the module, all of the following URIs can be used in XQuery to import this module or call its functions (see [[#URI Rewriting|URI Rewriting]] for more information): | + | After having installed the module, all of the following URIs can be used in XQuery to import this module or call its functions (see [[Java Bindings#URI Rewriting|URI Rewriting]] for more information): |
<nowiki>http://basex.org/modules/Hello</nowiki> | <nowiki>http://basex.org/modules/Hello</nowiki> | ||
org/basex/modules/Hello | org/basex/modules/Hello | ||
org.basex.modules.Hello | org.basex.modules.Hello | ||
+ | |||
+ | ===Additional Libraries=== | ||
+ | |||
+ | A Java class may depend on additional libraries. The dependencies can be resolved by creating a fat JAR file, i.e., extracting all files of the library archives and producing a single, flat JAR package. | ||
+ | |||
+ | Another solution is to copy the libraries into a {{Code|lib}} directory of the JAR package. If the package will be installed, the additional library archives will be extracted and copied to a hidden sub-directory in the repository. If the package will be deleted, the hidden sub-directory will be removed as well. | ||
+ | |||
+ | ; Examplary contents of {{Code|Image.jar}} | ||
+ | |||
+ | lib/ | ||
+ | Images.jar | ||
+ | META-INF/ | ||
+ | MANIFEST.MF | ||
+ | org/basex/modules/ | ||
+ | Image.class | ||
+ | |||
+ | ; Directory structure of the repository directory after installing the package | ||
+ | |||
+ | org/basex/modules/ | ||
+ | Image.class | ||
+ | .Images/ | ||
+ | Images.jar | ||
==Combined== | ==Combined== | ||
− | |||
− | |||
It makes sense to combine the advantages of XQuery and Java packages: | It makes sense to combine the advantages of XQuery and Java packages: | ||
Line 171: | Line 185: | ||
; Main Module {{Code|hello-universe.xq}}: | ; Main Module {{Code|hello-universe.xq}}: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
import module namespace m = 'http://basex.org/modules/Hello'; | import module namespace m = 'http://basex.org/modules/Hello'; | ||
m:hello("Universe") | m:hello("Universe") | ||
− | </ | + | </syntaxhighlight> |
; Wrapper Module {{Code|Hello.xqm}}: | ; Wrapper Module {{Code|Hello.xqm}}: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
module namespace hello = 'http://basex.org/modules/Hello'; | module namespace hello = 'http://basex.org/modules/Hello'; | ||
Line 194: | Line 208: | ||
java:hello($world) | java:hello($world) | ||
}; | }; | ||
− | </ | + | </syntaxhighlight> |
; Java class {{Code|Hello.java}}: | ; Java class {{Code|Hello.java}}: | ||
− | < | + | <syntaxhighlight lang="java"> |
package org.basex.modules; | package org.basex.modules; | ||
Line 206: | Line 220: | ||
} | } | ||
} | } | ||
− | </ | + | </syntaxhighlight> |
− | If the JAR file | + | If the JAR file is installed, {{Code|Combined}} will be displayed as type: |
REPO INSTALL http://files.basex.org/modules/org/basex/modules/Hello.jar | REPO INSTALL http://files.basex.org/modules/org/basex/modules/Hello.jar | ||
REPO LIST | REPO LIST | ||
− | + | ||
Name Version Type Path | Name Version Type Path | ||
− | + | ----------------------------------------------------------------------- | |
org.basex.modules.Hello - Combined org/basex/modules/Hello.xqm | org.basex.modules.Hello - Combined org/basex/modules/Hello.xqm | ||
Line 223: | Line 237: | ||
==XQuery== | ==XQuery== | ||
− | Apart from the package descriptor, a {{Code|.xar}} archive contains a directory which includes the actual XQuery modules. For example, the [ | + | Apart from the package descriptor, a {{Code|.xar}} archive contains a directory which includes the actual XQuery modules. For example, the [https://files.basex.org/modules/expath/functx-1.0.xar FunctX XAR archive] is packaged as follows: |
− | < | + | <syntaxhighlight> |
expath-pkg.xml | expath-pkg.xml | ||
functx/ | functx/ | ||
functx.xql | functx.xql | ||
functx.xsl | functx.xsl | ||
− | </ | + | </syntaxhighlight> |
==Java== | ==Java== | ||
Line 238: | Line 252: | ||
* Apart from the package descriptor <code>expath-pkg.xml</code>, the package has to contain a descriptor file at its root, defining the included jars and the binary names of their public classes. It must be named <code>basex.xml</code> and must conform to the following structure: | * Apart from the package descriptor <code>expath-pkg.xml</code>, the package has to contain a descriptor file at its root, defining the included jars and the binary names of their public classes. It must be named <code>basex.xml</code> and must conform to the following structure: | ||
− | < | + | <syntaxhighlight lang="xml"> |
<package xmlns="http://expath.org/ns/pkg"> | <package xmlns="http://expath.org/ns/pkg"> | ||
<jar>...</jar> | <jar>...</jar> | ||
Line 246: | Line 260: | ||
.... | .... | ||
</package> | </package> | ||
− | </ | + | </syntaxhighlight> |
* The jar file itself along with an XQuery file defining wrapper functions around the java methods has to reside in the module directory. The following example illustrates how java methods are wrapped with XQuery functions: | * The jar file itself along with an XQuery file defining wrapper functions around the java methods has to reside in the module directory. The following example illustrates how java methods are wrapped with XQuery functions: | ||
Line 252: | Line 266: | ||
'''Example:'''<br>Suppose we have a simple class <code>Printer</code> having just one public method <code>print()</code>: | '''Example:'''<br>Suppose we have a simple class <code>Printer</code> having just one public method <code>print()</code>: | ||
− | < | + | <syntaxhighlight lang="java"> |
package test; | package test; | ||
Line 260: | Line 274: | ||
} | } | ||
} | } | ||
− | </ | + | </syntaxhighlight> |
We want to extend BaseX with this class and use its method. In order to make this possible we have to define an XQuery function which wraps the <code>print</code> method of our class. This can be done in the following way: | We want to extend BaseX with this class and use its method. In order to make this possible we have to define an XQuery function which wraps the <code>print</code> method of our class. This can be done in the following way: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
import module namespace j="http://basex.org/lib/testJar"; | import module namespace j="http://basex.org/lib/testJar"; | ||
Line 273: | Line 287: | ||
return p:print($printer, $str) | return p:print($printer, $str) | ||
}; | }; | ||
− | </ | + | </syntaxhighlight> |
As it can be seen, the class {{Code|Printer}} is declared with its binary name as a namespace prefixed with "java" and the XQuery function is implemented using the [http://docs.basex.org/wiki/Java_Bindings Java Bindings] offered by BaseX. | As it can be seen, the class {{Code|Printer}} is declared with its binary name as a namespace prefixed with "java" and the XQuery function is implemented using the [http://docs.basex.org/wiki/Java_Bindings Java Bindings] offered by BaseX. | ||
− | On our [ | + | On our [https://files.basex.org/modules/ file server], you can find some example libraries packaged as XML archives (xar files). You can use them to try our packaging API or just as a reference for creating your own packages. |
− | = | + | =Performance= |
− | + | Importing XQuery modules that are located in the repository is just as fast as importing any other modules. Modules that are imported several times in a project will only be compiled once. | |
− | + | Imported Java archives will be dynamically added to the classpath and unregistered after query execution. This requires some constant overhead and may lead to unexpected effects in scenarios with highly concurrent read operations. If you want to get optimal performance, it is recommendable to move your JAR files into the {{Code|lib/custom}} directory of BaseX. This way, the archive will be added to the classpath if BaseX is started. If you have installed a [[#Combined|Combined Package]], you can simply keep your XQuery module in the repository, and the Java classes will be automatically detected. | |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | If | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
=Changelog= | =Changelog= | ||
Line 304: | Line 304: | ||
* Added: [[#Combined|Combined]] XQuery and Java packages | * Added: [[#Combined|Combined]] XQuery and Java packages | ||
− | + | * Added: [[#Additional Libraries|Additional Libraries]] | |
− | |||
− | |||
− | * Added: [[# | ||
;Version 7.2.1 | ;Version 7.2.1 | ||
Line 313: | Line 310: | ||
* Updated: [[#Installation|Installation]]: existing packages will be replaced without raising an error | * Updated: [[#Installation|Installation]]: existing packages will be replaced without raising an error | ||
* Updated: [[#Removal|Removal]]: remove specific version of a package | * Updated: [[#Removal|Removal]]: remove specific version of a package | ||
− | |||
;Version 7.1 | ;Version 7.1 |
Revision as of 12:45, 2 July 2020
This article is part of the XQuery Portal. It describes how external XQuery modules and Java code can be installed in the XQuery module repository, and how new packages are built and deployed.
Contents
Introduction
One of the things that makes languages successful is the availability of external libraries. As XQuery comes with only 150 pre-defined functions, which cannot meet all requirements, additional library modules exist – such as FunctX – which extend the language with new features.
BaseX offers the following mechanisms to make external modules accessible to the XQuery processor:
- The internal Packaging mechanism will install single XQuery and JAR modules in the repository.
- The EXPath Packaging system provides a generic mechanism for adding XQuery modules to query processors. A package is defined as a
.xar
archive, which encapsulates one or more extension libraries.
Accessing Modules
Library modules can be imported with the import module
statement, followed by a freely choosable prefix and the namespace of the target module. The specified location may be absolute or relative; in the latter case, it is resolved against the location (i.e., static base URI) of the calling module. Import module statements must be placed at the beginning of a module:
Main Module hello-universe.xq
:
<syntaxhighlight lang="xquery"> import module namespace m = 'http://basex.org/modules/hello' at 'hello-world.xqm'; m:hello("Universe") </syntaxhighlight>
Library Module hello-world.xqm
(in the same directory):
<syntaxhighlight lang="xquery"> module namespace m = 'http://basex.org/modules/Hello'; declare function m:hello($world) {
'Hello ' || $world
}; </syntaxhighlight>
If no location is supplied, modules will be looked up in the repository. Repository modules are stored in the repo
directory, which resides in your home directory. XQuery modules can be manually copied to the repository directory or installed and deleted via commands.
The following example calls a function from the FunctX module in the repository:
<syntaxhighlight lang="xquery"> import module namespace functx = 'http://www.functx.com'; functx:capitalize-first('test') </syntaxhighlight>
Commands
There are various ways to organize your packages:
- Execute BaseX REPO commands (listed below)
- Call XQuery functions of the Repository Module
- Use the GUI (Options → Packages)
You can even manually add and remove packages in the repository directory; all changes will automatically be detected by BaseX.
Installation
A module or package can be installed with REPO INSTALL
. The path to the file has to be given as a parameter:
REPO INSTALL http://files.basex.org/modules/expath/functx-1.0.xar REPO INSTALL hello-world.xqm
The installation will only succeed if the specified file conforms to the constraints described below. If you know that your input is valid, you may as well copy the files directly to the repository directory, or edit its contents in the repository without deleting and reinstalling them.
Listing
All currently installed packages can be listed with REPO LIST
. The names of all packages are listed, along with their version, their package type, and the repository path:
Name Version Type Path ----------------------------------------------------------------- http://www.functx.com 1.0 EXPath http-www.functx.com-1.0
Removal
A package can be deleted with REPO DELETE
and an additional argument, containing its name or the name suffixed with a hyphen and the package version:
REPO DELETE http://www.functx.com REPO DELETE http://www.functx.com-1.0
Packaging
XQuery
If an XQuery file is specified as input for the install command, it will be parsed as XQuery library module. If the file can successfully be parsed, the module URI will be rewritten to a file path and attached with the .xqm
file suffix, and the original file will possibly be renamed and copied to that path into the repository.
Example:
Installation (the original file will be copied to the org/basex/modules/Hello
sub-directory of the repository):
REPO INSTALL http://files.basex.org/modules/org/basex/modules/Hello/HelloWorld.xqm
Importing the repository module:
<syntaxhighlight lang="xquery"> import module namespace m = 'http://basex.org/modules/Hello'; m:hello("Universe") </syntaxhighlight>
Java
For general notes on importing Java classes, please read the Java Bindings article on Module Imports.
Java archives (JARs) may contain one or more class files. One of them will be chosen as main class, which must be specified in a Main-Class
entry in the manifest file (META-INF/MANIFEST.MF
). This fully qualified Java class name will be rewritten to a file path by replacing the dots with slashes and attaching the .jar
file suffix, and the original file will be renamed and copied to that path into the repository.
If the class will be imported in the prolog of the XQuery module, an instance of it will be created, and its public functions can then be addressed from XQuery. A class may extend the QueryModule
class to get access to the current query context and to be enriched by some helpful annotations (see Annotations).
Example:
Structure of the HelloWorld.jar
archive:
META-INF/ MANIFEST.MF org/basex/modules/ Hello.class
Contents of the file MANIFEST.mf
(the whitespaces are obligatory):
Manifest-Version: 1.0 Main-Class: org.basex.modules.Hello
Contents of the file Hello.java
(comments removed):
<syntaxhighlight lang="java"> package org.basex.modules; public class Hello {
public String hello(final String world) { return "Hello " + world; }
} </syntaxhighlight>
Installation (the file will be copied to org/basex/modules/Hello.jar
):
REPO INSTALL HelloWorld.jar
XQuery file HelloUniverse.xq
(same as above):
<syntaxhighlight lang="xquery"> import module namespace m = 'http://basex.org/modules/Hello'; m:hello("Universe") </syntaxhighlight>
After having installed the module, all of the following URIs can be used in XQuery to import this module or call its functions (see URI Rewriting for more information):
http://basex.org/modules/Hello org/basex/modules/Hello org.basex.modules.Hello
Additional Libraries
A Java class may depend on additional libraries. The dependencies can be resolved by creating a fat JAR file, i.e., extracting all files of the library archives and producing a single, flat JAR package.
Another solution is to copy the libraries into a lib
directory of the JAR package. If the package will be installed, the additional library archives will be extracted and copied to a hidden sub-directory in the repository. If the package will be deleted, the hidden sub-directory will be removed as well.
- Examplary contents of
Image.jar
lib/ Images.jar META-INF/ MANIFEST.MF org/basex/modules/ Image.class
- Directory structure of the repository directory after installing the package
org/basex/modules/ Image.class .Images/ Images.jar
Combined
It makes sense to combine the advantages of XQuery and Java packages:
- Instead of directly calling Java code, a wrapper module can be provided. This module contains functions that invoke the Java functions.
- These functions can be strictly typed. This reduces the danger of erroneous or unexpected conversions between XQuery and Java code.
- In addition, the entry functions can have properly maintained XQuery comments.
XQuery and Java can be combined as follows:
- First, a JAR package is created (as described above).
- A new XQuery wrapper module is created, which is named identically to the Java main class.
- The URL of the
import module
statement in the wrapper module must start with thejava:
prefix. - The finalized XQuery module must be copied into the JAR file, and placed in the same directory as the Java main class.
If the resulting JAR file is installed, the embedded XQuery module will be extracted, and will be called first if the module will be imported.
- Main Module
hello-universe.xq
<syntaxhighlight lang="xquery"> import module namespace m = 'http://basex.org/modules/Hello'; m:hello("Universe") </syntaxhighlight>
- Wrapper Module
Hello.xqm
<syntaxhighlight lang="xquery"> module namespace hello = 'http://basex.org/modules/Hello';
(: Import JAR file :) import module namespace java = 'java:org.basex.modules.Hello';
(:~
: Say hello to someone. : @param $world the one to be greeted : @return welcome string :)
declare function hello:hello(
$world as xs:string
) as xs:string {
java:hello($world)
}; </syntaxhighlight>
- Java class
Hello.java
<syntaxhighlight lang="java"> package org.basex.modules;
public class Hello {
public String hello(final String world) { return "Hello " + world; }
} </syntaxhighlight>
If the JAR file is installed, Combined
will be displayed as type:
REPO INSTALL http://files.basex.org/modules/org/basex/modules/Hello.jar REPO LIST Name Version Type Path ----------------------------------------------------------------------- org.basex.modules.Hello - Combined org/basex/modules/Hello.xqm
EXPath Packaging
The EXPath specification defines how the structure of a .xar archive shall look like. The package contains at its root a package descriptor named expath-pkg.xml
. This descriptor presents some meta data about the package as well as the libraries which it contains and their dependencies on other libraries or processors.
XQuery
Apart from the package descriptor, a .xar
archive contains a directory which includes the actual XQuery modules. For example, the FunctX XAR archive is packaged as follows:
<syntaxhighlight> expath-pkg.xml functx/
functx.xql functx.xsl
</syntaxhighlight>
Java
If you want to package an EXPath archive with Java code, some additional requirements have to be fulfilled:
- Apart from the package descriptor
expath-pkg.xml
, the package has to contain a descriptor file at its root, defining the included jars and the binary names of their public classes. It must be namedbasex.xml
and must conform to the following structure:
<syntaxhighlight lang="xml"> <package xmlns="http://expath.org/ns/pkg">
<jar>...</jar> .... <class>...</class> <class>...</class> ....
</package> </syntaxhighlight>
- The jar file itself along with an XQuery file defining wrapper functions around the java methods has to reside in the module directory. The following example illustrates how java methods are wrapped with XQuery functions:
Example:
Suppose we have a simple class Printer
having just one public method print()
:
<syntaxhighlight lang="java"> package test;
public final class Printer {
public String print(final String s) { return new Writer(s).write(); }
} </syntaxhighlight>
We want to extend BaseX with this class and use its method. In order to make this possible we have to define an XQuery function which wraps the print
method of our class. This can be done in the following way:
<syntaxhighlight lang="xquery"> import module namespace j="http://basex.org/lib/testJar";
declare namespace p="java:test.Printer";
declare function j:print($str as xs:string) as xs:string {
let $printer := p:new() return p:print($printer, $str)
}; </syntaxhighlight>
As it can be seen, the class Printer
is declared with its binary name as a namespace prefixed with "java" and the XQuery function is implemented using the Java Bindings offered by BaseX.
On our file server, you can find some example libraries packaged as XML archives (xar files). You can use them to try our packaging API or just as a reference for creating your own packages.
Performance
Importing XQuery modules that are located in the repository is just as fast as importing any other modules. Modules that are imported several times in a project will only be compiled once.
Imported Java archives will be dynamically added to the classpath and unregistered after query execution. This requires some constant overhead and may lead to unexpected effects in scenarios with highly concurrent read operations. If you want to get optimal performance, it is recommendable to move your JAR files into the lib/custom
directory of BaseX. This way, the archive will be added to the classpath if BaseX is started. If you have installed a Combined Package, you can simply keep your XQuery module in the repository, and the Java classes will be automatically detected.
Changelog
- Version 9.0
- Added: Combined XQuery and Java packages
- Added: Additional Libraries
- Version 7.2.1
- Updated: Installation: existing packages will be replaced without raising an error
- Updated: Removal: remove specific version of a package
- Version 7.1
- Added: Repository Module
- Version 7.0
- Added: EXPath Packaging