8.9 KiB
Request Blueprint
Request format
Basic requests
A request blueprint is a document containing a list of HTTP requests that a client can send to a server. Once the server receives the request blueprint, it MUST process all the HTTP requests in the blueprint to produce a single response containing the information of the responses to the blueprint requests.
The request that sends the request blueprint is referenced as the master request or the root request.
An example of a blueprint could look like this:
[
{
"requestId": "req-1",
"uri": "/restaurants/886e3b86-fa53-4bb3-b2c2-3ed544f1cd51?fields=title",
"action": "view",
"headers": {
"Accept": "application/json"
}
},
{
"requestId": "req-2",
"uri": "/deals?page[limit]=5",
"action": "view",
"headers": {
"Accept": "application/vnd.api+json"
}
},
{
"requestId": "req-3",
"uri": "/stats",
"action": "create",
"body": "{\"visitor\":\"anonymous\"}",
"headers": {
"Accept": "application/json",
"Content-Type": "application/json"
}
}
]
The blueprint above represents three different requests that may be run in parallel by the server. These requests could transform into the following parallel HTTP requests.
GET /restaurants/886e3b86-fa53-4bb3-b2c2-3ed544f1cd51 HTTP/1.1
Host: example.org
Accept: application/vnd.api+json
GET /restaurants/886e3b86-fa53-4bb3-b2c2-3ed544f1cd51 HTTP/1.1
Host: example.org
Accept: application/vnd.api+json
POST /stats HTTP/1.1
Host: example.org
Accept: application/json
Content-Type: application/json
{"visitor":"anonymous"}
Payload format
You MUST provide a Content-Type header when sending a request to the front
controller that processes the request blueprint. The content type header will
determine what format is used in the blueprint. All the examples in this
document assume application/json as the content type.
You MAY send the blueprint document as the payload in a POST request.
Alternatively, you MAY also send it in a GET request as a percent
encoded string in a query
string parameter with the name of query.
The blueprint document MUST be an array of subrequests. Each one of these subrequests SHOULD contain at least the following properties:
action: this indicates the type of action this subrequest will execute. Common values for this property areview,create,update,replace,delete,existsanddiscover.uri: the URI for the subrequest.
Additionally the payload for a subrequest MAY contain the following properties:
requestId: a unique identifier for the subrequest. This will be used to match the subrequest with one of the partial responses.body: the serialized content of the body for the subrequest.headers: an object of key value pairs. Each key MUST be interpreted as a header name for the subrequest, and the values as the header value.waitFor: contains the array of request IDs from another request. Indicates that the current subrequest depends on the other subrequest. When this property is present, the that particular subrequest cannot be processed until the referenced request has generated a response.
Sequential requests
Many times it is necessary to use the information of previous requests in order to build the correct request. That happens because a given request has a dependency some other requests to be resolved first. That use case is solved by request dependencies and by response pointers.
Request dependency
Any request can express a dependency on the response of a previous request. To
do so such request SHOULD express the dependency in the waitFor key. The
contents of this property WILL contain the request ID this request depends
on.
One subrequest CAN only indicate a dependency to one other subrequest. If a subrequest depends on a collection of subrequests at the same time, then the user MAY turn that collection into a request blueprint. That will to convert that collection into a single subrequest that can be waited for.
Response embedding
Some subrequests need information that is only made available when a previous subrequest has been processed and turned into a response. In that situation a subrequest CAN contain a replacement token that MUST be resolved from responses to previous subrequests in the same blueprint.
The format of the replacement token is:
{{/<request-id>.<location>@<json-path-expression>}}
The replacement data will be extracted from the response to the request indicated by the request ID in the replacement token. The specific data in that response to be embedded will be selected using a json path. If the JSON path expression resolves more than one result, then multiple responses will be generated for that single request.
A data pointer is a string that specifies what part of the referenced response should be embedded in place of the token. The embedded data SHOULD be serialized into a string according to the content type specified for the master request.
When the content type of the master request is set to application/json then
the data pointer SHOULD conform to the JSON pointer specification RFC
6901. If the content type is set to
application/xml then the data pointer SHOULD be an XPath 2.0 compatible
with the W3C specification.
Replacement tokens SHOULD NOT be used in the requestId or waitFor
properties.
Example
The following example shows how you can make use of the response embedding in the request blueprint to express dependencies.
[
{
"requestId": "req-1",
"uri": "/restaurants/886e3b86-fa53-4bb3-b2c2-3ed544f1cd51&fields=menus",
"action": "view",
"headers": {
"Accept": "application/json"
}
},
{
"requestId": "req-2",
"waitFor": ["req-1"],
"uri": "/menus/{{req-1.body@$.rels.meny.id}}",
"action": "view",
"headers": {
"Accept": "application/json"
}
},
{
"requestId": "req-3",
"waitFor": ["req-2"],
"uri": "/menus/{{req-1.body@$.rels.meny.id}}/courses/{{req-2.body@$.mainCourse.id}}",
"action": "view",
"headers": {
"Accept": "application/json"
}
}
]
This example shows how the request for the restaurant menu needs information in the body from the request to the response to req-1. It also shows that req-3 depends on both req-1 and req-2 to compose the request.
Response format
Once all the requests have been processed and the corresponding responses have been generated, the server MUST give a single response to the master request containing the responses to all subrequests.
The response MUST use the 207 response code for multiple status, since each partial response will specify the status for their requests.
HTML Response
The default response format is HTML.
HTML responses will use the multipart/related MIME type as specified in
RFC 2387:
Content-Type: multipart/related; boundary="e43889"; type=application/json
A response to the blueprint above could look like:
--e43889
Cache-Control: no-cache
Content-Id: <req-1>
Content-Type: application/json
Status: 200
{"attrs": {"name": "Foo restaurant"}, "rels": {"menu": {"id": "1234"}}}
--e43889
Cache-Control: no-cache
Content-Id: <req-2>
Content-Type: application/json
Status: 200
{"mainCourse": {"id": "meat-pie"}, "desert": {"id": "9876"}}
--e43889
Cache-Control: no-cache
Content-Id: <req-3>
Content-Type: application/vnd.api+json
Status: 200
{"ingredients": ["meat", "crust"]}
--e43889--
JSON Response
A JSON response can be requested by specifying the JSON format with
?_format=json.
The response will be a JSON object containing each subrequest response keyed by
the specified requestId.
A response to the blueprint above could look like:
{
"req-1": {
"headers": {
"cache-control": [
"no-cache"
],
"content-id": [
"<req-1>"
],
"content-type": [
"application/json"
],
"status": [
200
]
},
"body": "{\"attrs\": {\"name\": \"Foo restaurant\"}, \"rels\": {\"menu\":{\"id\":\"1234\"}}}"
},
"req-2": {
"headers": {
"cache-control": [
"no-cache"
],
"content-id": [
"<req-2>"
],
"content-type": [
"application/json"
],
"status": [
200
]
},
"body": "{\"mainCourse\": {\"id\": \"meat-pie\"}, \"desert\": {\"id\":\"9876\"}}"
},
"req-3": {
"headers": {
"cache-control": [
"no-cache"
],
"content-id": [
"<req-3>"
],
"content-type": [
"application/vnd.api+json"
],
"status": [
200
]
},
"body": "{\"ingredients\": [\"meat\", \"crust\"]}"
}
}