RESTful Service Description Language
 | This article needs more links to other articles to help integrate it into the encyclopedia. (November 2013) |
RSDL (RESTful Service Description Language) is a machine and human readable XML description of HTTP-based web applications (typically REST web services). It models the resource(s) provided by a service, the relationships between them, and the parameters that has to be supplied for the certain operation; specifies if parameters have to be mandated; and describes possible overloads as parameters sets. RSDL is intended to simplify the reuse of web services that are based on the HTTP architecture of the web. It is platform and language independent and aims to promote reuse of applications beyond the basic use in a web browser by both humans and machines.
Unlike WADL, it concentrates in describing URIs as stand-alone entry points in to the application which can be invoked in different ways, does not require traversing over URI components to figure out URI structure, and supports URI/Headers/body parameters overloads. This makes it human-readable and easily consumed by both humans and machines.
Concept
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Self descriptive
RSDL represents different URIs as stand-alone entry points into the application. Following resource URIs, one can figure out which methods are available for the given resources and how those resources can be consumed.
Machine-readable
Each URI in RSDL contains all the necessary information to generate an HTTP request from it, which can be easily consumed by accessing the URI internals.
Human-readable
Each URI in RSDL contains "rel" and "description" attributes describing the meaning of the given operation on that URI. Humans can easily fetch all available operations for a given collection/resource simply by locating different descriptors within the same URI.
Format
<?xml version="1.0" encoding="utf-8"?>
<rsdl rel="rsdl" href="/api?rsdl">
<description />
<version revision="0" build="0" minor="0" major="0" />
<schema rel="schema" href="/api?schema">
<name>api.xsd</name>
<description />
</schema>
<general rel="*" href="/*">
<request>
<headers>
<header required="true|false">
<name />
<description />
<value />
</header>
</headers>
<url>
<parameters_set>
<parameter context="query|matrix" type="xs:string"
required="true|false">
<name />
<value />
</parameter>
</parameters_set>
</url>
</request>
<name />
<description />
</general>
<links>
<link rel="get|..." href="/api/xxx">
<request>
<http_method>GET|POST|PUT|DELETE|...</http_method>
<headers>
<header required="true|false">
<name />
<value />
</header>
</headers>
<url>
<parameters_set>
<parameter context="query|matrix" type=""
required="true|false">
<name />
<value />
</parameter>
</parameters_set>
</url>
<body>
<type>...</type>
<parameters_set>
<parameter type="" required="true|false">
<name>FQ-name-to-parameter</name>
</parameter>
</parameters_set>
</body>
</request>
<response>
<type />
</response>
</link>
</links>
</rsdl>
Components
URI
<links>
<link rel="get|..." href="/api/xxx">
Request
<request>
<http_method>GET|POST|PUT|DELETE|...</http_method>
<headers>
<header required="true|false">
<name></name>
<value></value>
</header>
...
</headers>
<url>
<parameters_set>
<parameter context="query|matrix" type="" required="true|false">
<name></name>
<value></value>
</parameter>
...
</parameters_set>
...
</url>
<body>
<type>...</type>
<parameters_set>
<parameter type="" required="true|false">
<name>FQ-name-to-parameter</name>
</parameter>
...
</parameters_set>
...
</body>
</request>
Response
<response>
<type></type>
...
</response>
XML schema
<xs:element name="detailedLinks" type="DetailedLinks"/>
<xs:complexType name="DetailedLinks">
<xs:sequence>
<xs:annotation>
<xs:appinfo>
<jaxb:property name="links"/>
</xs:appinfo>
</xs:annotation>
<xs:element type="DetailedLink" name="link" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:element name="link" type="Link"/>
<xs:complexType name="Link">
<xs:attribute name="href" type="xs:string"/>
<xs:attribute name="rel" type="xs:string"/>
</xs:complexType>
<xs:element name="url" type="Url"/>
<xs:complexType name="Url">
<xs:sequence>
<xs:element ref="parameters_set" maxOccurs="unbounded" minOccurs="0">
<xs:annotation>
<xs:appinfo>
<jaxb:property name="ParametersSets"/>
</xs:appinfo>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element name="body" type="Body"/>
<xs:complexType name="Body">
<xs:sequence>
<xs:element name="type" type="xs:string" minOccurs="1" maxOccurs="1"/>
<xs:element ref="parameters_set" maxOccurs="unbounded" minOccurs="0">
<xs:annotation>
<xs:appinfo>
<jaxb:property name="ParametersSets"/>
</xs:appinfo>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:attribute name="required" type="xs:boolean">
<xs:annotation>
<xs:appinfo>
<jaxb:property generateIsSetMethod="false"/>
</xs:appinfo>
</xs:annotation>
</xs:attribute>
</xs:complexType>
<xs:element name="request" type="Request"/>
<xs:complexType name="Request">
<xs:sequence>
<xs:element name="http_method" type="HttpMethod" minOccurs="1" maxOccurs="1"/>
<xs:element ref="headers" minOccurs="0" maxOccurs="1"/>
<xs:element ref="url" minOccurs="0" maxOccurs="1"/>
<xs:element ref="body" minOccurs="0" maxOccurs="1"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="HttpMethod">
<xs:restriction base="xs:string">
<xs:enumeration value="GET"/>
<xs:enumeration value="POST"/>
<xs:enumeration value="PUT"/>
<xs:enumeration value="DELETE"/>
<xs:enumeration value="OPTIONS"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="response" type="Response"/>
<xs:complexType name="Response">
<xs:sequence>
<xs:element name="type" type="xs:string" minOccurs="1" maxOccurs="1"/>
</xs:sequence>
</xs:complexType>
<xs:element name="parameter" type="Parameter"/>
<xs:complexType name="Parameter">
<xs:complexContent>
<xs:extension base="BaseResource">
<xs:sequence>
<xs:element name="value" type="xs:string" minOccurs="1" maxOccurs="1"/>
<xs:element ref="parameters_set" minOccurs="0" maxOccurs="1"/>
</xs:sequence>
<xs:attribute name="required" type="xs:boolean">
<xs:annotation>
<xs:appinfo>
<jaxb:property generateIsSetMethod="false"/>
</xs:appinfo>
</xs:annotation>
</xs:attribute>
<xs:attribute name="type" type="xs:string"/>
<xs:attribute name="context" type="xs:string"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="header" type="Header"/>
<xs:complexType name="Header">
<xs:complexContent>
<xs:extension base="BaseResource">
<xs:sequence>
<xs:element name="value" type="xs:string" minOccurs="1" maxOccurs="1"/>
</xs:sequence>
<xs:attribute name="required" type="xs:boolean">
<xs:annotation>
<xs:appinfo>
<jaxb:property generateIsSetMethod="false"/>
</xs:appinfo>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="headers" type="Headers"/>
<xs:complexType name="Headers">
<xs:sequence>
<xs:element ref="header" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<jaxb:property name="Headers"/>
</xs:appinfo>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element name="parameters_set" type="ParametersSet"/>
<xs:complexType name="ParametersSet">
<xs:sequence>
<xs:element ref="parameter" maxOccurs="unbounded" minOccurs="0">
<xs:annotation>
<xs:appinfo>
<jaxb:property name="Parameters"/>
</xs:appinfo>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element name="schema" type="Schema"/>
<xs:complexType name="Schema">
<xs:complexContent>
<xs:extension base="Link">
<xs:sequence>
<xs:element name="name" type="xs:string" minOccurs="0" maxOccurs="1"/>
<xs:element name="description" type="xs:string" minOccurs="0" maxOccurs="1"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="general_metadata" type="GeneralMetadata"/>
<xs:complexType name="GeneralMetadata">
<xs:complexContent>
<xs:extension base="DetailedLink">
<xs:sequence>
<xs:element name="name" type="xs:string" minOccurs="0" maxOccurs="1"/>
<xs:element name="description" type="xs:string" minOccurs="0" maxOccurs="1"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="rsdl" type="RSDL"/>
<xs:complexType name="RSDL">
<xs:sequence>
<xs:element name="description" type="xs:string" minOccurs="0"/>
<xs:element type="Version" name="version" minOccurs="0" maxOccurs="1" />
<xs:element ref="schema" minOccurs="0" maxOccurs="1" />
<xs:element type="GeneralMetadata" name="general" minOccurs="0" maxOccurs="1"/>
<xs:element type="DetailedLinks" name="links" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="href" type="xs:string"/>
<xs:attribute name="rel" type="xs:string"/>
</xs:complexType>
Usage
| This section is empty. You can help by adding to it. (June 2013) |
Examples
List resources
<link rel="get" href="/api/clusters">
<request>
<http_method>GET</http_method>
<headers>
<header required="false">
<name>Filter</name>
<value>true|false</value>
</header>
</headers>
<url>
<parameters_set>
<parameter context="query" type="xs:string" required="false">
<name>search</name>
<value>search query</value>
</parameter>
<parameter context="matrix" type="xs:boolean" required="false">
<name>case_sensitive</name>
<value>true|false</value>
</parameter>
<parameter context="matrix" type="xs:int" required="false">
<name>max</name>
<value>max results</value>
</parameter>
</parameters_set>
</url>
<body/>
</request>
<response>
<type>Clusters</type>
</response>
</link>
Get resource
<link rel="get" href="/api/clusters/{cluster:id}">
<request>
<http_method>GET</http_method>
<headers>
<header required="false">
<name>Filter</name>
<value>true|false</value>
</header>
</headers>
<body/>
</request>
<response>
<type>Cluster</type>
</response>
</link>
Update resource
<link rel="update" href="/api/clusters/{cluster:id}">
<request>
<http_method>PUT</http_method>
<headers>
<header required="true">
<name>Content-Type</name>
<value>application/xml|json</value>
</header>
<header required="false">
<name>Correlation-Id</name>
<value>any string</value>
</header>
</headers>
<body>
<type>Cluster</type>
<parameters_set>
<parameter type="xs:string" required="false">
<name>cluster.name</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.description</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.cpu.id</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.version.major</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.version.minor</name>
</parameter>
<parameter type="xs:double" required="false">
<name>cluster.memory_policy.overcommit.percent</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.memory_policy.transparent_hugepages.enabled
</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.scheduling_policy.policy</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.low</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.high</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.duration</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.error_handling.on_error</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.virt_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.gluster_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.threads_as_cores</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.tunnel_migration</name>
</parameter>
</parameters_set>
</body>
</request>
<response>
<type>Cluster</type>
</response>
</link>
Create resource
<link rel="add" href="/api/clusters">
<request>
<http_method>POST</http_method>
<headers>
<header required="true">
<name>Content-Type</name>
<value>application/xml|json</value>
</header>
<header required="false">
<name>Expect</name>
<value>201-created</value>
</header>
<header required="false">
<name>Correlation-Id</name>
<value>any string</value>
</header>
</headers>
<body>
<type>Cluster</type>
<parameters_set>
<parameter type="xs:string" required="true">
<name>cluster.data_center.id|name</name>
</parameter>
<parameter type="xs:string" required="true">
<name>cluster.name</name>
</parameter>
<parameter type="xs:int" required="true">
<name>cluster.version.major</name>
</parameter>
<parameter type="xs:int" required="true">
<name>cluster.version.minor</name>
</parameter>
<parameter type="xs:string" required="true">
<name>cluster.cpu.id</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.description</name>
</parameter>
<parameter type="xs:double" required="false">
<name>cluster.memory_policy.overcommit.percent</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.memory_policy.transparent_hugepages.enabled</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.scheduling_policy.policy</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.low</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.high</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.duration</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.error_handling.on_error</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.virt_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.gluster_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.threads_as_cores</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.tunnel_migration</name>
</parameter>
</parameters_set>
</body>
</request>
<response>
<type>Cluster</type>
</response>
</link>
Delete resource
<link rel="delete" href="/api/clusters/{cluster:id}">
<request>
<http_method>DELETE</http_method>
<headers>
<header required="false">
<name>Correlation-Id</name>
<value>any string</value>
</header>
</headers>
<url>
<parameters_set>
<parameter context="matrix" type="xs:boolean" required="false">
<name>async</name>
<value>true|false</value>
</parameter>
</parameters_set>
</url>
<body/>
</request>
</link>
Code generation
RSDL URI descriptor
<link rel="add" href="/api/clusters">
<request>
<http_method>POST</http_method>
<headers>
<header required="true">
<name>Content-Type</name>
<value>application/xml|json</value>
</header>
<header required="false">
<name>Expect</name>
<value>201-created</value>
</header>
<header required="false">
<name>Correlation-Id</name>
<value>any string</value>
</header>
</headers>
<body>
<type>Cluster</type>
<parameters_set>
<parameter type="xs:string" required="true">
<name>cluster.data_center.id|name</name>
</parameter>
<parameter type="xs:string" required="true">
<name>cluster.name</name>
</parameter>
<parameter type="xs:int" required="true">
<name>cluster.version.major</name>
</parameter>
<parameter type="xs:int" required="true">
<name>cluster.version.minor</name>
</parameter>
<parameter type="xs:string" required="true">
<name>cluster.cpu.id</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.description</name>
</parameter>
<parameter type="xs:double" required="false">
<name>cluster.memory_policy.overcommit.percent</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.memory_policy.transparent_hugepages.enabled</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.scheduling_policy.policy</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.low</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.high</name>
</parameter>
<parameter type="xs:int" required="false">
<name>cluster.scheduling_policy.thresholds.duration</name>
</parameter>
<parameter type="xs:string" required="false">
<name>cluster.error_handling.on_error</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.virt_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.gluster_service</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.threads_as_cores</name>
</parameter>
<parameter type="xs:boolean" required="false">
<name>cluster.tunnel_migration</name>
</parameter>
</parameters_set>
</body>
</request>
<response>
<type>Cluster</type>
</response>
</link>
Generated code signature(s)
/**
* Adds Cluster object.
* @param cluster {@link org.ovirt.engine.sdk.entities.Cluster}
* cluster.data_center.id|name
* cluster.name
* cluster.version.major
* cluster.version.minor
* cluster.cpu.id
* [cluster.description]
* [cluster.memory_policy.overcommit.percent]
* [cluster.memory_policy.transparent_hugepages.enabled]
* [cluster.scheduling_policy.policy]
* [cluster.scheduling_policy.thresholds.low]
* [cluster.scheduling_policy.thresholds.high]
* [cluster.scheduling_policy.thresholds.duration]
* [cluster.error_handling.on_error]
* [cluster.virt_service]
* [cluster.gluster_service]
* [cluster.threads_as_cores]
* [cluster.tunnel_migration]
* @return
* {@link Cluster }
* @throws ClientProtocolException
* Signals that HTTP/S protocol error has occurred.
* @throws ServerException
* Signals that an oVirt api error has occurred.
* @throws IOException
* Signals that an I/O exception of some sort has occurred.
*/
public Cluster add(org.ovirt.engine.sdk.entities.Cluster cluster) throws
ClientProtocolException, ServerException, IOException {
....
}
/**
* Adds Cluster object.
* @param cluster {@link org.ovirt.engine.sdk.entities.Cluster}
* cluster.data_center.id|name
* cluster.name
* cluster.version.major
* cluster.version.minor
* cluster.cpu.id
* [cluster.description]
* [cluster.memory_policy.overcommit.percent]
* [cluster.memory_policy.transparent_hugepages.enabled]
* [cluster.scheduling_policy.policy]
* [cluster.scheduling_policy.thresholds.low]
* [cluster.scheduling_policy.thresholds.high]
* [cluster.scheduling_policy.thresholds.duration]
* [cluster.error_handling.on_error]
* [cluster.virt_service]
* [cluster.gluster_service]
* [cluster.threads_as_cores]
* [cluster.tunnel_migration]
* @param expect
* [201-created]
* @param correlationId
* [any string]
* @return
* {@link Cluster }
* @throws ClientProtocolException
* Signals that HTTP/S protocol error has occurred.
* @throws ServerException
* Signals that an oVirt api error has occurred.
* @throws IOException
* Signals that an I/O exception of some sort has occurred.
*/
public Cluster add(org.ovirt.engine.sdk.entities.Cluster cluster, String expect, String correlationId) throws
ClientProtocolException, ServerException, IOException {
....
}
Maintainer
Michael Pasternak: mpastern@redhat.com