GET'> PUT'> POST'> DELETE'> '> '> ]> The &APIv2; is a ReSTful HTTP service that uses all aspects of the HTTP protocol including methods, URIs, media types, response codes, and so on. Providers can use existing features of the protocol including caching, persistent connections, and content compression. For example, providers who employ a caching layer can respond with a 203 code instead of a 200 code when a request is served from the cache. Additionally, providers can offer support for conditional &GET; requests by using ETags, or they may send a redirect in response to a &GET; request. Create clients so that these differences are accounted for.

The &APIv2; uses the Keystone Identity Service as the default authentication service. When Keystone is enabled, users that submit requests to the OpenStack Networking service must provide an authentication token in X-Auth-Token request header. You obtain the token by authenticating to the Keystone endpoint. For more information about Keystone, see the OpenStack Identity Service API v2.0 Reference. When Keystone is enabled, the tenant_id attribute is not required in create requests because the tenant ID is derived from the authentication token. The default authorization settings allow only administrative users to create resources on behalf of a different tenant. OpenStack Networking uses information received from Keystone to authorize user requests. OpenStack Networking handles the following types of authorization policies: Operation-based policies specify access criteria for specific operations, possibly with fine-grained control over specific attributes. Resource-based policies access a specific resource. Permissions might or might not be granted depending on the permissions configured for the resource. Currently available for only the network resource. The actual authorization policies enforced in OpenStack Networking might vary from deployment to deployment.

The &APIv2; supports both JSON and XML data serialization request and response formats.

Use the Content-Type request header to specify the request format. This header is required for operations that have a request body. The syntax for the Content-Type header is: Content-Type: application/FORMAT Where FORMAT is either json or xml.

Use one of the following methods to specify the response format: Accept header The syntax for the Accept header is: Accept: application/FORMAT Where FORMAT is either json or xml. The default format is json. Query extension Add an .xml or .json extension to the request URI. For example, the .xml extension in the following list networks URI request specifies that the response body is to be returned in XML format: &GET; publicURL/networks.xml If you do not specify a response format, JSON is the default. If the Accept header and the query extension specify conflicting formats, the format specified in the query extension takes precedence. For example, if the query extension is .xml and the Accept header specifies application/json, the response is returned in XML format. You can serialize a response in a different format from the request format.

The &APIv2; supports filtering based on all top level attributes of a resource. Filters are applicable to all list requests. For example, the following request returns all networks named foobar: GET /v2.0/networks?name=foobar When you specify multiple filters, the &APIv2; returns only objects that meet all filtering criteria. The operation applies an AND condition among the filters. OpenStack Networking does not offer an OR mechanism for filters. Alternatively, you can issue a distinct request for each filter and build a response set from the received responses on the client-side. By default, OpenStack Networking returns all attributes for any show or list call. The &APIv2; has a mechanism to limit the set of attributes returned. For example, return id. You can use the fields query parameter to control the attributes returned from the &APIv2;. For example, the following request returns only id and name for each network: GET /v2.0/networks.json?fields=id&fields=name

The &APIv2; presents a logical model of network connectivity consisting of networks, ports, and subnets. It is up to the OpenStack Networking plug-in to communicate with the underlying infrastructure to ensure packet forwarding is consistent with the logical model. A plug-in might perform these operations asynchronously. When an API client modifies the logical model by issuing an HTTP &POST;, &PUT;, or &DELETE; request, the API call might return before the plug-in modifies underlying virtual and physical switching devices. However, an API client is guaranteed that all subsequent API calls properly reflect the changed logical model. For example, if a client issues an HTTP &PUT; request to set the attachment for a port, there is no guarantee that packets sent by the interface named in the attachment are forwarded immediately when the HTTP call returns. However, it is guaranteed that a subsequent HTTP &GET; request to view the attachment on that port returns the new attachment value. You can use the status attribute with the network and port resources to determine whether the OpenStack Networking plug-in has successfully completed the configuration of the resource.

The &APIv2; enables you to create several objects of the same type in the same API request. Bulk create operations use exactly the same API syntax as single create operations except that you specify a list of objects rather than a single object in the request body. Bulk operations are always performed atomically, meaning that either all or none of the objects in the request body are created. If a particular plug-in does not support atomic operations, the &APIv2; emulates the atomic behavior so that users can expect the same behavior regardless of the particular plug-in running in the background. OpenStack Networking might be deployed without support for bulk operations and when the client attempts a bulk create operation, a 400 Bad request error is returned.

To reduce load on the service, list operations will return a maximum number of items at a time. To navigate the collection, the parameters limit, marker and page_reverse can be set in the URI. For example: ?limit=100&marker=1234&page_reverse=False The marker parameter is the ID of the last item in the previous list. The limit parameter sets the page size. The page_reverse parameter sets the page direction. These parameters are optional. If the client requests a limit beyond the maximum limit configured by the deployment, the server returns the maximum limit number of items. For convenience, list responses contain atom "next" links and "previous" links. The last page in the list requested with 'page_reverse=False' will not contain "next" link, and the last page in the list requested with 'page_reverse=True' will not contain "previous" link. The following examples illustrate two pages with three items. The first page was retrieved through: &GET; http://127.0.0.1:9696/v2.0/networks.json?limit=2 Pagination is an optional feature of OpenStack Networking API, and it might be disabled. If pagination is disabled, the pagination parameters will be ignored and return all the items. If a particular plug-in does not support pagination operations, and pagination is enabled, the &APIv2; will emulate the pagination behavior so that users can expect the same behavior regardless of the particular plug-in running in the background. Unfortunately OpenStack Networking does not expose any mechanism to tell user if pagination is supported by particular plug-in or enabled. GET /v2.0/networks.json?limit=2 HTTP/1.1 Host: 127.0.0.1:9696 Content-Type: application/json Accept: application/json GET /v2.0/networks.xml?limit=2 HTTP/1.1 Host: 127.0.0.1:9696 Content-Type: application/xml Accept: application/xml The last page won't show the "next" links GET /v2.0/networks.json?limit=2&marker=71c1e68c-171a-4aa2-aca5-50ea153a3718 HTTP/1.1 Host: 127.0.0.1:9696 Content-Type: application/json Accept: application/json GET /v2.0/networks.xml?limit=2&marker=71c1e68c-171a-4aa2-aca5-50ea153a3718 HTTP/1.1 Host: 127.0.0.1:9696 Content-Type: application/xml Accept: application/xml

You can use the sort_key and sort_dir parameters to sort the results of list operations. Currently sorting does not work with extended attributes of resource. The sort_key and sort_dir can be repeated, and the number of sort_key and sort_dir provided must be same. The sort_dir parameter indicates in which direction to sort. Acceptable values are asc (ascending) and desc (descending). Sorting is optional feature of OpenStack Networking API, and it might be disabled. If sorting is disabled, the sorting parameters are ignored. If a particular plug-in does not support sorting operations and sorting is enabled, the &APIv2; emulates the sorting behavior so that users can expect the same behavior regardless of the particular plug-in that runs in the background. Unfortunately OpenStack Networking does not provide a mechanism to tell users if specific plug-ins support or have enabled sorting.

The &APIv2; is extensible. The purpose of &APIv2; extensions is to: Introduce new features in the API without requiring a version change. Introduce vendor-specific niche functionality. Act as a proving ground for experimental functionalities that might be included in a future version of the API. To programmatically determine which extensions are available, issue a &GET; request on the v2.0/extensions URI. To query extensions individually by unique alias, issue a &GET; request on the /v2.0/extensions/alias_name URI. Use this method to easily determine if an extension is available. If the extension is not available, a 404 Not Found response is returned. You can extend existing core API resources with new actions or extra attributes. Also, you can add new resources as extensions. Extensions usually have tags that prevent conflicts with other extensions that define attributes or resources with the same names, and with core resources and attributes. Because an extension might not be supported by all plug-ins, the availability of an extension varies with deployments and the specific plug-in in use. For information about specific extensions, see Networking API v2.0 extensions.

The &APIv2; returns an error response if a failure occurs while processing a request. OpenStack Networking uses only standard HTTP error codes. 4nn errors indicate problems in the particular request being sent from the client. Error Description 400 Bad request Malformed request URI or body requested admin state invalid Invalid values entered Bulk operations disallowed Validation failed Method not allowed for request body (such as trying to update attributes that can be specified at create-time only) 404 Not Found Non existent URI Resource not found 409 Conflict Port configured on network IP allocated on subnet Conflicting IP allocation pools for subnet 500 Internal server error Internal OpenStack Networking error 503 Service unavailable Failure in Mac address generation Users submitting requests to the &APIv2; might also receive the following errors: 401 Unauthorized - If invalid credentials are provided. 403 Forbidden - If the user cannot access a specific resource or perform the requested operation.