Incremental Delivery spec draft

cspell.yml

@@ -4,6 +4,7 @@ ignoreRegExpList:
   - /[a-z]{2,}'s/
 words:
   # Terms of art
+  - deprioritization
   - endianness
   - interoperation
   - monospace

spec/Section 3 -- Type System.md

@@ -794,8 +794,9 @@ And will yield the subset of each object type queried:
 When querying an Object, the resulting mapping of fields are conceptually
 ordered in the same order in which they were encountered during execution,
 excluding fragments for which the type does not apply and fields or fragments
-that are skipped via `@skip` or `@include` directives. This ordering is
-correctly produced when using the {CollectFields()} algorithm.
+that are skipped via `@skip` or `@include` directives or temporarily skipped via
+`@defer`. This ordering is correctly produced when using the {CollectFields()}
+algorithm.
 
 Response serialization formats capable of representing ordered maps should
 maintain this ordering. Serialization formats which can only represent unordered
@@ -1942,6 +1943,11 @@ by a validator, executor, or client tool such as a code generator.
 
 GraphQL implementations should provide the `@skip` and `@include` directives.
 
+GraphQL implementations are not required to implement the `@defer` and `@stream`
+directives. If either or both of these directives are implemented, they must be
+implemented according to this specification. GraphQL implementations that do not
+support these directives must not make them available via introspection.
+
 GraphQL implementations that support the type system definition language must
 provide the `@deprecated` directive if representing deprecated portions of the
 schema.
@@ -2162,3 +2168,99 @@ to the relevant IETF specification.
 ```graphql example
 scalar UUID @specifiedBy(url: "https://tools.ietf.org/html/rfc4122")
 ```
+
+### @defer
+
+```graphql
+directive @defer(
+  label: String
+  if: Boolean! = true
+) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+```
+
+The `@defer` directive may be provided for fragment spreads and inline fragments
+to inform the executor to delay the execution of the current fragment to
+indicate deprioritization of the current fragment. A query with `@defer`
+directive will cause the request to potentially return multiple responses, where
+non-deferred data is delivered in the initial response and data deferred is
+delivered in a subsequent response. `@include` and `@skip` take precedence over
+`@defer`.
+
+```graphql example
+query myQuery($shouldDefer: Boolean) {
+  user {
+    name
+    ...someFragment @defer(label: "someLabel", if: $shouldDefer)
+  }
+}
+fragment someFragment on User {
+  id
+  profile_picture {
+    uri
+  }
+}
+```
+
+#### @defer Arguments
+
+- `if: Boolean! = true` - When `true`, fragment _should_ be deferred (see
+  related note below). When `false`, fragment will not be deferred and data will
+  be included in the initial response. Defaults to `true` when omitted.
+- `label: String` - May be used by GraphQL clients to identify the data from
+  responses and associate it with the corresponding defer directive. If
+  provided, the GraphQL service must add it to the corresponding pending object
+  in the response. `label` must be unique label across all `@defer` and
+  `@stream` directives in a document. `label` must not be provided as a
+  variable.
+
+### @stream
+
+```graphql
+directive @stream(
+  label: String
+  if: Boolean! = true
+  initialCount: Int = 0
+) on FIELD
+```
+
+The `@stream` directive may be provided for a field of `List` type so that the
+backend can leverage technology such as asynchronous iterators to provide a
+partial list in the initial response, and additional list items in subsequent
+responses. `@include` and `@skip` take precedence over `@stream`.
+
+```graphql example
+query myQuery($shouldStream: Boolean) {
+  user {
+    friends(first: 10) {
+      nodes @stream(label: "friendsStream", initialCount: 5, if: $shouldStream)
+    }
+  }
+}
+```
+
+#### @stream Arguments
+
+- `if: Boolean! = true` - When `true`, field _should_ be streamed (see related
+  note below). When `false`, the field will not be streamed and all list items
+  will be included in the initial response. Defaults to `true` when omitted.
+- `label: String` - May be used by GraphQL clients to identify the data from
+  responses and associate it with the corresponding stream directive. If
+  provided, the GraphQL service must add it to the corresponding pending object
+  in the response. `label` must be unique label across all `@defer` and
+  `@stream` directives in a document. `label` must not be provided as a
+  variable.
+- `initialCount: Int` - The number of list items the service should return as
+  part of the initial response. If omitted, defaults to `0`. A field error will
+  be raised if the value of this argument is less than `0`.
+
+Note: The ability to defer and/or stream parts of a response can have a
+potentially significant impact on application performance. Developers generally
+need clear, predictable control over their application's performance. It is
+highly recommended that GraphQL services honor the `@defer` and `@stream`
+directives on each execution. However, the specification allows advanced use
+cases where the service can determine that it is more performant to not defer
+and/or stream. Therefore, GraphQL clients _must_ be able to process a response
+that ignores the `@defer` and/or `@stream` directives. This also applies to the
+`initialCount` argument on the `@stream` directive. Clients _must_ be able to
+process a streamed response that contains a different number of initial list
+items than what was specified in the `initialCount` argument.

spec/Section 5 -- Validation.md

@@ -422,6 +422,7 @@ FieldsInSetCanMerge(set):
   {set} including visiting fragments and inline fragments.
 - Given each pair of members {fieldA} and {fieldB} in {fieldsForName}:
   - {SameResponseShape(fieldA, fieldB)} must be true.
+  - {SameStreamDirective(fieldA, fieldB)} must be true.
   - If the parent types of {fieldA} and {fieldB} are equal or if either is not
     an Object Type:
     - {fieldA} and {fieldB} must have identical field names.
@@ -456,6 +457,16 @@ SameResponseShape(fieldA, fieldB):
   - If {SameResponseShape(subfieldA, subfieldB)} is {false}, return {false}.
 - Return {true}.
 
+SameStreamDirective(fieldA, fieldB):
+
+- If neither {fieldA} nor {fieldB} has a directive named `stream`.
+  - Return {true}.
+- If both {fieldA} and {fieldB} have a directive named `stream`.
+  - Let {streamA} be the directive named `stream` on {fieldA}.
+  - Let {streamB} be the directive named `stream` on {fieldB}.
+  - If {streamA} and {streamB} have identical sets of arguments, return {true}.
+- Return {false}.
+
 Note: In prior versions of the spec the term "composite" was used to signal a
 type that is either an Object, Interface or Union type.
 
@@ -467,7 +478,7 @@ unambiguous. Therefore any two field selections which might both be encountered
 for the same object are only valid if they are equivalent.
 
 During execution, the simultaneous execution of fields with the same response
-name is accomplished by {MergeSelectionSets()} and {CollectFields()}.
+name is accomplished by {CollectSubfields()}.
 
 For simple hand-written GraphQL, this rule is obviously a clear developer error,
 however nested fragments can make this difficult to detect manually.
@@ -1521,6 +1532,174 @@ query ($foo: Boolean = true, $bar: Boolean = false) {
 }
 ```
 
+### Defer And Stream Directives Are Used On Valid Root Field
+
+** Formal Specification **
+
+- For every {directive} in a document.
+- Let {directiveName} be the name of {directive}.
+- Let {mutationType} be the root Mutation type in {schema}.
+- Let {subscriptionType} be the root Subscription type in {schema}.
+- If {directiveName} is "defer" or "stream":
+  - The parent type of {directive} must not be {mutationType} or
+    {subscriptionType}.
+
+**Explanatory Text**
+
+The defer and stream directives are not allowed to be used on root fields of the
+mutation or subscription type.
+
+For example, the following document will not pass validation because `@defer`
+has been used on a root mutation field:
+
+```raw graphql counter-example
+mutation {
+  ... @defer {
+    mutationField
+  }
+}
+```
+
+### Defer And Stream Directives Are Used On Valid Operations
+
+** Formal Specification **
+
+- Let {subscriptionFragments} be the empty set.
+- For each {operation} in a document:
+  - If {operation} is a subscription operation:
+    - Let {fragments} be every fragment referenced by that {operation}
+      transitively.
+    - For each {fragment} in {fragments}:
+      - Let {fragmentName} be the name of {fragment}.
+      - Add {fragmentName} to {subscriptionFragments}.
+- For every {directive} in a document:
+  - If {directiveName} is not "defer" or "stream":
+    - Continue to the next {directive}.
+  - Let {ancestor} be the ancestor operation or fragment definition of
+    {directive}.
+  - If {ancestor} is a fragment definition:
+    - If the fragment name of {ancestor} is not present in
+      {subscriptionFragments}:
+      - Continue to the next {directive}.
+  - If {ancestor} is not a subscription operation:
+    - Continue to the next {directive}.
+  - Let {if} be the argument named "if" on {directive}.
+  - {if} must be defined.
+  - Let {argumentValue} be the value passed to {if}.
+  - {argumentValue} must be a variable, or the boolean value "false".
+
+**Explanatory Text**
+
+The defer and stream directives can not be used to defer or stream data in
+subscription operations. If these directives appear in a subscription operation
+they must be disabled using the "if" argument. This rule will not permit any
+defer or stream directives on a subscription operation that cannot be disabled
+using the "if" argument.
+
+For example, the following document will not pass validation because `@defer`
+has been used in a subscription operation with no "if" argument defined:
+
+```raw graphql counter-example
+subscription sub {
+  newMessage {
+    ... @defer {
+      body
+    }
+  }
+}
+```
+
+### Defer And Stream Directive Labels Are Unique
+
+** Formal Specification **
+
+- Let {labelValues} be an empty set.
+- For every {directive} in the document:
+  - Let {directiveName} be the name of {directive}.
+  - If {directiveName} is "defer" or "stream":
+    - For every {argument} in {directive}:
+      - Let {argumentName} be the name of {argument}.
+      - Let {argumentValue} be the value passed to {argument}.
+      - If {argumentName} is "label":
+        - {argumentValue} must not be a variable.
+        - {argumentValue} must not be present in {labelValues}.
+        - Append {argumentValue} to {labelValues}.
+
+**Explanatory Text**
+
+The `@defer` and `@stream` directives each accept an argument "label". This
+label may be used by GraphQL clients to uniquely identify response payloads. If
+a label is passed, it must not be a variable and it must be unique within all
+other `@defer` and `@stream` directives in the document.
+
+For example the following document is valid:
+
+```graphql example
+{
+  dog {
+    ...fragmentOne
+    ...fragmentTwo @defer(label: "dogDefer")
+  }
+  pets @stream(label: "petStream") {
+    name
+  }
+}
+
+fragment fragmentOne on Dog {
+  name
+}
+
+fragment fragmentTwo on Dog {
+  owner {
+    name
+  }
+}
+```
+
+For example, the following document will not pass validation because the same
+label is used in different `@defer` and `@stream` directives.:
+
+```raw graphql counter-example
+{
+  dog {
+    ...fragmentOne @defer(label: "MyLabel")
+  }
+  pets @stream(label: "MyLabel") {
+    name
+  }
+}
+
+fragment fragmentOne on Dog {
+  name
+}
+```
+
+### Stream Directives Are Used On List Fields
+
+**Formal Specification**
+
+- For every {directive} in a document.
+- Let {directiveName} be the name of {directive}.
+- If {directiveName} is "stream":
+  - Let {adjacent} be the AST node the directive affects.
+  - {adjacent} must be a List type.
+
+**Explanatory Text**
+
+GraphQL directive locations do not provide enough granularity to distinguish the
+type of fields used in a GraphQL document. Since the stream directive is only
+valid on list fields, an additional validation rule must be used to ensure it is
+used correctly.
+
+For example, the following document will only pass validation if `field` is
+defined as a List type in the associated schema.
+
+```graphql counter-example
+query {
+  field @stream(initialCount: 0)
+}
+```
+
 ## Variables
 
 ### Variable Uniqueness

spec/Section 7 -- Response.md

@@ -10,7 +10,12 @@ the case that any _field error_ was raised on a field and was replaced with
 
 ## Response Format
 
-A response to a GraphQL request must be a map.
+A response to a GraphQL request must be a map or a stream of incrementally
+delivered results. The response will be a stream of incrementally delivered
+results when the GraphQL service has deferred or streamed data as a result of
+the `@defer` or `@stream` directives. When the response of the GraphQL operation
+contains incrementally delivered results, the first value will be an initial
+payload, followed by one or more subsequent payloads.
 
 If the request raised any errors, the response map must contain an entry with
 key `errors`. The value of this entry is described in the "Errors" section. If
@@ -22,14 +27,31 @@ key `data`. The value of this entry is described in the "Data" section. If the
 request failed before execution, due to a syntax error, missing information, or
 validation error, this entry must not be present.
 
+When the response of the GraphQL operation contains incrementally delivered
+results, both the initial payload and all subsequent payloads must contain an
+entry with key `hasNext`. The value of this entry must be {true} for all but the
+last response in the stream. The value of this entry must be {false} for the
+last response of the stream. This entry must not be present for GraphQL
+operations that return a single response map.
+
+When the response of the GraphQL operation contains incrementally delivered
+results, both the initial payload and any subsequent payloads may contain
+entries with the keys `pending`, `incremental`, and/or `completed`. The value of
+these entries are described in the "Pending", "Incremental", and "Completed"
+sections below.
+
 The response map may also contain an entry with key `extensions`. This entry, if
 set, must have a map as its value. This entry is reserved for implementers to
 extend the protocol however they see fit, and hence there are no additional
-restrictions on its contents.
+restrictions on its contents. When the response of the GraphQL operation is a
+response stream, the initial payload and any subsequent payloads may contain an
+entry with the key `extensions`, also reserved for implementers to extend the
+protocol however they see fit. Additionally, implementers may send subsequent
+payloads containing only `hasNext` and `extensions` entries.
 
 To ensure future changes to the protocol do not break existing services and
 clients, the top level response map must not contain any entries other than the
-three described above.
+entries described above.
 
 Note: When `errors` is present in the response, it may be helpful for it to
 appear first when serialized to make it more clear when errors are present in a
@@ -48,6 +70,10 @@ present in the result.
 If an error was raised during the execution that prevented a valid response, the
 `data` entry in the response should be `null`.
 
+When the response of the GraphQL operation contains incrementally delivered
+results, `data` may only be present in the initial payload. `data` must not be
+present in any subsequent payloads.
+
 ### Errors
 
 The `errors` entry in the response is a non-empty list of errors raised during
@@ -107,14 +133,8 @@ syntax element.
 If an error can be associated to a particular field in the GraphQL result, it
 must contain an entry with the key `path` that details the path of the response
 field which experienced the error. This allows clients to identify whether a
-`null` result is intentional or caused by a runtime error.
-
-If present, this field must be a list of path segments starting at the root of
-the response and ending with the field associated with the error. Path segments
-that represent fields must be strings, and path segments that represent list
-indices must be 0-indexed integers. If the error happens in an aliased field,
-the path to the error must use the aliased name, since it represents a path in
-the response, not in the request.
+`null` result is intentional or caused by a runtime error. The value of this
+field is described in the [Path](#sec-Path) section.
 
 For example, if fetching one of the friends' names fails in the following
 operation:
@@ -244,6 +264,366 @@ discouraged.
 }
 ```
 
+### Path
+
+A `path` field allows for the association to a particular field in a GraphQL
+result. This field should be a list of path segments starting at the root of the
+response and ending with the field to be associated with. Path segments that
+represent fields should be strings, and path segments that represent list
+indices should be 0-indexed integers. If the path is associated to an aliased
+field, the path should use the aliased name, since it represents a path in the
+response, not in the request.
+
+When the `path` field is present on an "Error result", it indicates the response
+field which experienced the error.
+
+### Pending
+
+The `pending` entry in the response is a non-empty list of Pending Results. If
+the response of the GraphQL operation contains incrementally delivered results,
+this field may appear on both the initial and subsequent payloads. If present,
+the `pending` entry must contain at least one Pending Result.
+
+Each Pending Result corresponds to either a `@defer` or `@stream` directive
+located at a specific path in the response data. The Pending Result is used to
+communicate that the GraphQL service has chosen to incrementally deliver the
+data associated with this `@defer` or `@stream` directive and clients should
+expect the associated data in either the current payload, or one of the
+following payloads.
+
+**Pending Result Format**
+
+Every Pending Result must contain an entry with the key `id` with a string
+value. This `id` should be used by clients to correlate Pending Results with
+Completed Results. The `id` value must be unique for the entire response stream.
+There must not be any other Pending Result in any payload that contains the same
+`id`.
+
+Every Pending Result must contain an entry with the key `path`. When the Pending
+Result is associated with a `@stream` directive, it indicates the response list
+field that is not known to be complete. Clients should expect the GraphQL
+Service to incrementally deliver the remainder of indicated list field. When the
+Pending Result is associated with a `@defer` directive, it indicates that the
+response fields contained in the deferred fragment are not known to be complete.
+Clients should expect the the GraphQL Service to incrementally deliver the
+remainder of the fields contained in the deferred fragment.
+
+If the associated `@defer` or `@stream` directive contains a `label` argument,
+the Pending Result must contain an entry `label` with the value of this
+argument.
+
+If a Pending Result is not returned for a `@defer` or `@stream` directive,
+clients must assume that the GraphQL service chose not to incrementally deliver
+this data, and the data can be found either in the `data` entry in the initial
+payload, or one of the Incremental Results in a prior payload.
+
+### Incremental
+
+The `incremental` entry in the response is a non-empty list of Incremental
+Results. If the response of the GraphQL operation contains incrementally
+delivered results, this field may appear on both the initial and subsequent
+values. If present, the `incremental` entry must contain at least one
+Incremental Result.
+
+The Incremental Result is used to deliver data that the GraphQL service has
+chosen to incrementally deliver. An Incremental Result may be ether an
+Incremental List Result or an Incremental Object Result.
+
+An Incremental List Result is used to deliver additional list items for a list
+field with a `@stream` directive.
+
+An Incremental Object Result is used to deliver additional response fields that
+were contained in one or more fragments with a `@defer` directive.
+
+**Incremental Result Format**
+
+Every Incremental Result must contain an entry with the key `id` with a string
+value. This `id` must match the `id` that was returned in a prior Pending
+Result.
+
+Additionally, Incremental List Results and Incremental Object Results have
+further requirements.
+
+**Incremental List Result Format**
+
+An Incremental List Result's `id` entry must match the `id` that was returned in
+a prior Pending Result. This Pending Result must be associated with a `@stream`
+directive.
+
+The Incremental List Result's `path` can be determined using the prior Pending
+Result with the same `id` as this Incremental Result. The Incremental List
+Result's `path` is the same as the Pending Result's `path`.
+
+Every Incremental List Result must contain an `items` entry. The `items` entry
+must contain a list of additional list items for the response field at the
+Incremental List Result's `path`. This output will be a list of the same type of
+the response field at this path.
+
+If any field errors were raised during the execution of the results in `items`
+and these errors bubbled to a path higher than the Incremental List Result's
+path, The Incremental List Result is considered failed and should not be
+included in the response stream. The errors that caused this failure will be
+included in a Completed Result.
+
+If any field errors were raised during the execution of the results in `items`
+and these errors did not bubble to a path higher than the Incremental List
+Result's path, the Incremental List Result must contain an entry with key
+`errors` containing these field errors. The value of this entry is described in
+the "Errors" section.
+
+**Incremental Object Result Format**
+
+An Incremental List Result's `id` entry must match the `id` that was returned in
+a prior Pending Result. This Pending Result must be associated with a `@defer`
+directive.
+
+The Incremental Object Result's `path` can be determined using the prior Pending
+Result with the same `id` as this Incremental Result. The Incremental Object
+Result may contain a `subPath` entry. If the `subPath` entry is present, The
+Incremental Object Record's path can be determined by concatenating the Pending
+Result's `path` with this `subPath`. If no `subPath` entry is present, the path
+is the same as the Pending Result's `path`.
+
+Every Incremental Object Result must contain an `data` entry. The `data` entry
+must contain a map of additional response fields. The `data` entry in an
+Incremental Object Result will be of the type of a particular field in the
+GraphQL result. The Incremental Object Result's `path` will contain the path
+segments of the field this data is associated with.
+
+An Incremental Object Result's data may contain response fields that were
+contained in more than one deferred fragments. In that case, the `id` of the
+Incremental Object Result must point to the Pending Result that results in the
+shortest `subPath`.
+
+If any field errors were raised during the execution of the results in `data`
+and these errors bubbled to a path higher than the Incremental Object Result's
+path, The Incremental Object Result is considered failed and should not be
+included in the response stream. The errors that caused this failure will be
+included in a Completed Result.
+
+If any field errors were raised during the execution of the results in `data`
+and these errors did not bubble to a path higher than the Incremental Object
+Result's path, the Incremental Object Result must contain an entry with key
+`errors` containing these field errors. The value of this entry is described in
+the "Errors" section.
+
+### Completed
+
+The `completed` entry in the response is a non-empty list of Completed Results.
+If the response of the GraphQL operation contains incrementally delivered
+results, this field may appear on both the initial and subsequent payloads. If
+present, the `completed` entry must contain at least one Completed Result.
+
+Each Completed Result corresponds to a prior Pending Result. The Completed
+Result is used to communicate that the GraphQL service has completed the
+incremental delivery of the data associated with the corresponding Pending
+Result. The associated data must have been completed in the current payload.
+
+**Completed Result Format**
+
+Every Completed Result must contain an entry with the key `id` with a string
+value. The `id` entry must match the `id` that was returned in a prior Pending
+Result.
+
+A Completed Result may contain an `errors` entry. When the `errors` entry is
+present, it informs clients that the delivery of the data associated with the
+corresponding Pending Result has failed, due to an error bubbling to a path
+higher than the Incremental Data Result's path. The `errors` entry must contain
+these field errors. The value of this entry is described in the "Errors"
+section.
+
+### Examples
+
+#### A query containing both defer and stream:
+
+```graphql example
+query {
+  person(id: "cGVvcGxlOjE=") {
+    ...HomeWorldFragment @defer(label: "homeWorldDefer")
+    name
+    films @stream(initialCount: 1, label: "filmsStream") {
+      title
+    }
+  }
+}
+fragment HomeWorldFragment on Person {
+  homeWorld {
+    name
+  }
+}
+```
+
+The response stream might look like:
+
+Payload 1, the initial response does not contain any deferred or streamed
+results in the `data` entry. The initial response contains a `hasNext` entry,
+indicating that subsequent payloads will be delivered. There are two Pending
+Responses indicating that results for both the `@defer` and `@stream` in the
+query will be delivered in the subsequent payloads.
+
+```json example
+{
+  "data": {
+    "person": {
+      "name": "Luke Skywalker",
+      "films": [{ "title": "A New Hope" }]
+    }
+  },
+  "pending": [
+    { "id": "0", "path": ["person"], "label": "homeWorldDefer" },
+    { "id": "1", "path": ["person", "films"], "label": "filmsStream" }
+  ],
+  "hasNext": true
+}
+```
+
+Payload 2, contains the deferred data and the first streamed list item. There is
+one Completed Result, indicating that the deferred data has been completely
+delivered.
+
+```json example
+{
+  "incremental": [
+    {
+      "id": "0",
+      "data": { "homeWorld": { "name": "Tatooine" } }
+    },
+    {
+      "id": "1",
+      "items": [{ "title": "The Empire Strikes Back" }]
+    }
+  ],
+  "completed": [
+    {"id": "0"}
+  ]
+  "hasNext": true
+}
+```
+
+Payload 3, contains the final stream payload. In this example, the underlying
+iterator does not close synchronously so {hasNext} is set to {true}. If this
+iterator did close synchronously, {hasNext} would be set to {false} and this
+would be the final response.
+
+```json example
+{
+  "incremental": [
+    {
+      "id": "1",
+      "items": [{ "title": "Return of the Jedi" }]
+    }
+  ],
+  "hasNext": true
+}
+```
+
+Payload 4, contains no incremental data. {hasNext} set to {false} indicates the
+end of the response stream. This response is sent when the underlying iterator
+of the `films` field closes.
+
+```json example
+{
+  "hasNext": false
+}
+```
+
+### Examples
+
+#### A query containing overlapping defers:
+
+```graphql example
+query {
+  person(id: "cGVvcGxlOjE=") {
+    ...HomeWorldFragment @defer(label: "homeWorldDefer")
+    ...NameAndHomeWorldFragment @defer(label: "nameAndWorld")
+    firstName
+  }
+}
+fragment HomeWorldFragment on Person {
+  homeWorld {
+    name
+    terrain
+  }
+}
+
+fragment NameAndHomeWorldFragment on Person {
+  firstName
+  lastName
+  homeWorld {
+    name
+  }
+}
+```
+
+The response stream might look like:
+
+Payload 1, the initial response contains the results of the `firstName` field.
+Even though it is also present in the `HomeWorldFragment`, it must be returned
+in the initial payload because it is also defined outside of any fragments with
+the `@defer` directive. Additionally, There are two Pending Responses indicating
+that results for both `@defer`s in the query will be delivered in the subsequent
+payloads.
+
+```json example
+{
+  "data": {
+    "person": {
+      "firstName": "Luke"
+    }
+  },
+  "pending": [
+    { "id": "0", "path": ["person"], "label": "homeWorldDefer" },
+    { "id": "1", "path": ["person"], "label": "nameAndWorld" }
+  ],
+  "hasNext": true
+}
+```
+
+Payload 2, contains the deferred data from `HomeWorldFragment`. There is one
+Completed Result, indicating that `HomeWorldFragment` has been completely
+delivered. Because the `homeWorld` field is present in two separate `@defer`s,
+it is separated into its own Incremental Result.
+
+The second Incremental Result contains the data for the `terrain` field. This
+incremental result contains a `subPath` property to indicate to clients that the
+path of this result can be determined by concatenating the path from the Pending
+Result with id `"0"` and this `subPath` entry.
+
+```json example
+{
+  "incremental": [
+    {
+      "id": "0",
+      "data": { "homeWorld": { "name": "Tatooine" } }
+    },
+    {
+      "id": "0",
+      "subPath": ["homeWorld"],
+      "data": { "terrain": "desert" }
+    }
+  ],
+  "completed": [{ "id": "0" }],
+  "hasNext": true
+}
+```
+
+Payload 3, contains the remaining data from the `NameAndHomeWorldFragment`.
+`lastName` is the only remaining field that has not been delivered in a previous
+payload.
+
+```json example
+{
+  "incremental": [
+    {
+      "id": "1",
+      "data": { "lastName": "Skywalker" }]
+    }
+  ],
+  "completed": [{"id": "1"}],
+  "hasNext": false
+}
+```
+
 ## Serialization Format
 
 GraphQL does not require a specific serialization format. However, clients
@@ -320,3 +700,7 @@ encode the same value, they also have observably different property orderings.
 
 Note: This does not violate the JSON spec, as clients may still interpret
 objects in the response as unordered Maps and arrive at a valid value.
+
+```
+
+```