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JSON Specification

General Conventions

The API uses JSON throughout; the Content-Type for all requests and responses is application/json.

As is general practice with REST, clients should not make assumptions about the server’s URL space. Clients are expected to discover all URL’s by navigating the API. To keep this document readable, we still mention specific URL’s, generally in the form of an absolute path. Clients should not use these, or assume that the actual URL structure follows these examples, and instead use discovered URL’s. Any client should start its discovery with the API entry point, here denoted with /api.


Basic types

The following are basic data types and type combinators that are used throughout:

Name Explanation Example serialization

Integer

Integer value

{ "id" : 10 }

String

JSON string

{ "state" : "running" }

URL

Absolute URL

{ "href" : "http://SERVER/vms/1/start" }

Timestamp

Timestamp in ISO8601 format

{ "created" : "2013-12-05T08:15:30Z" }

Array[T]

Array where each entry has type T

{ "vms" : [ { "id" : 1 }, { "id" : 2 }] }

Ref[T]

A reference to a T, used to model relations, the T is a valid Resource identifier

{ "vm" : { "href" : URL } }

Collection

Array[T] where T represents a Ref[T], this might allow actions to be executed on all members as a single unit

{ "vms" : { "count" : 2, "resources" : [ { "href" : URL}, { "href" : URL } ], "actions" : [] }

Struct

A structure with sub-attributes

"power_state": {"state" : "ON", "last_boot_time" : "2013-05-29T15:28Z", "state_change_time" : "2013-05-29T15:28Z"}

Common Attributes and Actions

The following describes attributes and actions that are shared by all resources and collections defined in this API.

Attributes

Attribute Type Description

id

Integer

An integer identifier for the referenced resource

href

Ref(self)

A unique self reference

name

String

A human name of the resource

{
  "id" : 10,
  "href" : "http://localhost:3000/api/vms/10",
  "name" : "first_vm"
}

Actions

Action HTTP method Description

create

POST

Create new resource in the collection

edit

PUT/PATCH/POST

Edit attributes in resource

delete

DELETE

Delete resource

About permissions and security:

Advertising of the common actions depends purely on the role and permissions of that the current API user does have for the particular resource.

Collections

Resources can be grouped into collections. Each collection is homogeneous so that it contains only one type of resource, and unordered. Resources can also exist outside any collection. In this case, we refer to these resources as singleton resources. Collections are themselves resources as well.

Collections can exist globally, at the top level of an API, but can also be contained inside a single resource. In the latter case, we refer to these collections as sub-collections. Sub-collections are usually used to express some kind of “contained in” relationship

Collections are serialized in JSON in the following way:

{
  "name" : String,
  "count": Integer,
  "subcount": Integer,
  "resources": [ ... ],
  "actions": [ ... ]
}

Where the name attribute is the collection name. The count attribute in a collection always denotes the total number of items in the collection, not the number of items returned. subcount attribute in a collection depicts the number of items returned. Then the resources attribute is an Array[T] where T might be a list of references to the T or, if expanded a list of resources with all attributes. The actions then contains an Array of actions that can be performed against the collection resources.

Action Specification

The representation of each resource will only contain an action and its URL if the current user is presently allowed to perform that action against that resource. Actions will be contained in the actions attribute of a resource; that attribute contains an array of action definition, where each action definition has a rel, method and a href attribute.

  • name attribute contains the action name

  • method attribute states the HTTP method that must be used in a client HTTP request in order to perform the given action (eg. GET, POST, PUT, DELETE)

  • href attribute contains the absolute URL that the HTTP request should be performed against

  • form an optional attribute that references a JSON document which describes the resource attributes that can be provided in the message body when performing this action. This description will indicate which of those attributes are mandatory and which are optional.

Collection actions

The actions performed against a collection of resources, are in most cases batch operations against multiple resources. The action request must include an HTTP body with the action name and the list of resource representations that the action will be performed against.

The resource representation might include the resource attributes as they can change the way how the action is actually performed. In the example below, the first service is retired immediately, versus the second being retired at a later date with a retirement warning of 3 days.

Sample JSON request body for collection action:

POST /api/services
{
  "action": "retire",
  "resources" : [
    { "href" : "http://localhost:3000/api/services/101" },
    { "href" : "http://localhost:3000/api/services/102",
      "date" : "10/30/2015",
      "warn" : 3
    }
  ]
}

Actions in collection:

{
  "name" : String,
  "count": Integer,
  "resources": [ ... ],
  "actions": [
    {
      "name"   : "start",
      "method" : "post",
      "href"   : URL
    },
    {
      "name"   : "stop",
      "method" : "post",
      "href"   : URL
    },
    {
      "name"   : "suspend",
      "method" : "post",
      "href"   : URL
    },
    {
      "name"    : "edit",
      "method" : "post",
      "href"   : URL
    },
    {
      "name"    : "delete",
      "method" : "post",
      "href"   : URL
    },
    {
      "name"   : "delete",
      "method" : "delete",
      "href"   : URL
    }
  ]
}

Resource actions

An action performed against a given resource is always described in the body of the HTTP request. The HTTP body could contain a list of resource attributes that dictate how the state of the receiving resource is to be changed once the action is performed. At minimum the JSON document in the message body must contain the name of the action to be performed.

In cases where no attributes are required to perform an action the HTTP body will contain an empty JSON document, in which case default values will be assigned to the corresponding attributes.

Sample JSON request body for resource action:

POST /api/services/101
{
  "action"   : "retire",
  "resource" : { "date" : "10/30/2015", "warn" : 5 }
}
POST /api/vms/321
{
  "action"   : "start",
  "resource" : {}
}

or Simply:

{
  "action"   : "start"
}

Actions in a resource:

{
  "id"    : Integer,
  "href"  : Ref(self),
  "name"  : "resource human name",
  "actions" : [
    {
      "name"   : "edit",
      "method" : "post",
      "href"   : URL
    }
  ]
}

Action Responses

When performing actions on resources, there are two types of responses that one is to expect.

  1. For actions that operate on the resource itself like a create or edit, the response is usually the updated resource. This includes creation of Provision or Automate requests where the created /api/provision_requests and /api/automation_requests gets returned.

  2. For others like a start or stop action, the response includes an action result for each targetted resource. An action result has the following construct in the response:

{
  "results" : [
    {
      "success" : true | false,
      "message" : String,
      "href" : Ref[resource],
      "result" : Struct,
      "task_id" : Id,
      "task_href" : Ref[task]
    },
    ...
  ]
}

results being an array of action results as one or more resources could be targeted in a request.

NOTE: * success and message are always there. * result is optional and would exist when an action results in data, i.e. policy resolve. * href is populated for the resource being targeted by the action * task_id and task_href are optional. They are defined when actions are run asynchronously and a task is created, i.e. http://localhost:3000/api/tasks/:id which can be monitored for action completion.

Other action specific attributes could also be returned in the the action result.

For tagging actions:

{
  "tag_category" : String,
  "tag_name" : String,
  "tag_href" : Ref[tags]
}

When executing actions on subcollections, like policies, policy_profiles and service_templates, the following is also provided in the action result:

{
  "<subcollection>_id" : Id,
  "<subcollection>_href" : Ref[subcollection]
}