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Apache Wink provides the "SimpleSymphonyApplicationSimpleWinkApplication" class in order to support the loading of resources and providers through a simple text file that contains a list of fully qualified class names of the resource and provider classes. Each line contains a single fully qualified class name that is either a resource or a provider. Empty lines and lines that begin with a number sign (#) are permitted and ignored.
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The path to a simple application file is configured via the symphony. applicationConfigLocation init-param in the web.xml file. It is possible to specify multiple files by separating them with a semicolon.
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<servlet> <servlet-name>restSdkService</servlet-name> <servlet-class> comorg.hpapache.symphonywink.server.internal.servlet.RestServlet </servlet-class> <init-param> <param-name>symphony.applicationConfigLocation<name>applicationConfigLocation</param-name> <param-value>/WEB-INF/providers;/WEB-INF/resources</param-value> </init-param> </servletservlet> |
Apache Wink Application
Apache Wink extends the javax.ws.rs.core.Application class with the comorg.hpapache.symphonywink.common.SymphonyApplication WinkApplication class in order to provide the Dynamic Resources and the Priorities functionality.
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title | Reference |
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Refer to sections TBD and TBD for more information on Dynamic Resources and Priorities.
An application may provide an instance of the Apache Wink Application to the Apache Wink runtime as specified by the JAX-RS specification.
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A Dynamic Resource is useful for situations where a resource class must be bound to multiple paths, for example, a sorting resource:
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xml | xml |
public class SortingResource<E extends Comparable<? super E>> {
private List<E> list;
@POST
public void sort() {
Collections.sort(list);
}
public void setList(List<E> list) {
this.list = list;
}
public List<E> getList() {
return list;
}
}
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Explanation
In this the following example, the SortingResource class can sort any list. If the application manages a library of books and exposes the following resource paths, then the SortingResource class can be used for the implementation of all these resource paths, assuming that it could be bound to more than one path.
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A Dynamic Resource is a resource class that implements the comorg.hpapache.symphonywink.server.DynamicResource interface or extends the comorg.hpapache.symphonywink.server.AbstractDynamicResource convenience class.
A Dynamic Resource is not registered in Apache Wink through the Application#getClasses() method or the Application#getSignletons() method, since the same class can be used for multiple resources.
In order to register Dynamic Resources in the system, the SymphonyApplication#getInstancesWinkApplication#getInstances()method must be used.
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Refer to section TBD for more information about Registration.
Scope
The scope of a Dynamic Resource is limited to "singleton" as it is initialized prior to its registration, and the system does not have enough information to create it in runtime. This limitation is irrelevant when working with Spring. Refer to chapter 0 for more information on Spring integration.
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Although JAX-RS defines the algorithm for searching for resources and providers, Apache Wink enables to extend this algorithm by allowing the specification of priorities for them.
Apache Wink extends the JAX-RS search algorithms by providing the ability to specify priorities on the resources and providers. This is achieved by enabling the registration of multiple Application instances with different priorities, rendering the order of their registration irrelevant as long as they have different priorities.
In order to register a prioritized Application, it is necessary to register an instance of a Apache WinkApplication class.
Priority values range between 0 and 1. In the event that the priority was not specified, a default priority of 0.5 is used.
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Priorities on resources are useful for situations where an application registers core resources bound to paths, and allows extensions to register resources on the same paths in order to override the core resources.
The Apache Wink runtime first sorts the resources based on their priority and then based on the JAX-RS specification, thus if two resources have the same path, the one with higher priority is invoked.
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JAX-RS requires that application-provided providers be used in preference to implementation pre-packaged providers. Apache Wink extends this requirement by allowing applications to specify a priority for providers.
The Apache Wink runtime initially sorts the matching providers according to the JAX-RS specification, and uses the priority as the last sorting key for providers of equal standing.
If two providers have the same priority, the order in which they are registered determines their priority such that the latest addition receives the highest priority.
In order to meet the JAX-RS requirements, the pre-packages providers are registered using a priority of 0.1.
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Property Name | Description | Default Value | |
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wink.http.uri | URI that is used by the Link Builders in case of HTTP | Use the URI from the request | Chapter TBD |
wink.https.uri | URI used by the Link Builders in case of HTTPS | Use the URI from the request | Chapter TBD |
wink.context.uri | Context path used by the Link Builders | Use the context path from the request | Chapter TBD |
wink.defaultUrisRelative | Indicates if URIs generated by the Link Builders are absolute or relative, valid values: true or false | true - links are relative | |
wink.addAltParam | Indicates if the "alt" query parameter should be added to URIs generated by the Link Builders. Valid values are: true, false | true - add the alt query parameter | Chapter TBD |
wink.searchPolicyContinuedSearch search | Indicates if continues search is enabled. Valid values: true, false | true - continued search is enabled | |
wink.rootResource | ndicates Indicates if a root resource with Service Document generation capabilities should be added. | atom+html --atom and html Service Document generation capabilities | |
wink.serviceDocumentCssPath | Defines path to a css file that is used in the html Service Document generation. Relevant only if html Service Document is defined | No css file defined | |
wink.handlersFactoryClass | Defines a org.apache.wink.server | No user handlers defined | |
wink.mediaType | Defines a org.apache.wink.server.handlers | No media type mappers defined | |
wink.loadApplications | Loads providers defined | True, automatically load all wink-application specified classes Chapter TBD |
Custom Properties File Definition
In order to provide a custom properties file, the application should define the symphony. propertiesLocation init-param in the Apache Wink Servlet definition.
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# Providers <servlet> <servlet-name>restSdkService</servlet-name> <servlet-class> comorg.hpapache.symphonywink.server.internal.servlet.RestServlet </servlet-class> <init-param> <param-name>symphony.propertiesLocation<name>propertiesLocation</param-name> <param-value>/WEB-INF/configuration.properties</param-value> </init-param> <init-param> <param-name>symphonyApplicationConfigLocation<name>winkApplicationConfigLocation</param-name> <param-value>/WEB-INF/application</param-value> </init-param> <load-on-startup>0</load-on-startup> </servlet> |
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RegistrationApache Wink provides several APIs for Runtime Registration. The APIs appear in the comorg.hpapache.symphonywink.server.utils.RegistrationUtils class. The most important method is the one that registers an instance of the javax.ws.rs.core.Application class
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# Providers static void registerApplication(Application application, ServletContext servletContext) |
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Registration is ignored and a warning is printed to the log if the instance was previously registered |
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It is sometimes necessary to override the Content-Type response header based on the client user agent. For example, the Firefox browser cannot handle the application/atom+xml media type for Atom content, unless it is defined as a text/xml.
Apache Wink provides a set of predefined Media-Type mappings for use in such cases by supplying the MediaTypeMapper class. Applications may extend or override the MediaTypeMapper class to define additional mappings.
Predefined Mapping Table
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User Agent
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Content Type
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Map To
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application/atom+xml text/xml
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text/xml
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Mozilla/
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application/atomsvc+xml text/xml
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text/xml
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Mozilla/
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pplication/opensearchdescription+xml
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text/xml
Customizing Mappings
In order to customize these mappings the application should create a instance of a comorg.hpapache.symphonywink.server.internalhandlers.MediaTypeMapper MediaTypeMapperFactory class and set it on the DeploymentConfiguration instancein a customized Wink properties file.
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Refer to section TBD 5.1 Registration and Configuration for more information on Customizing the Default Deployment Properties Configuration. |
Alternative Shortcuts
Clients specify the requested media type by setting the Http Accept header. Apache Wink provides an alternate method for specifying the requested media type via use of the "alt" request parameter. This functionality is useful for situation where the client has little affect on the accept header, for example when requesting a resource using a browser.
For example, a request to /entry?alt=application/xml specifies that the requested response media type is application/xml.
Apache Wink provides a shortcut mechanism for specifying the media type of the alt query parameter and provides a predefined set of shortcuts for common media types.
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Refer to chapter 0 section 2 Apache Wink Building Blocks for more information about on Customizing the Default Deployment Configuration. |