📝 Add op submission lifecycle to middleware docs

Author: alecgibson

docs/api/backend.md

@@ -115,7 +115,7 @@ Optional
 
 ### `MIDDLEWARE_ACTIONS` -- Object
 
-> Map of available [middleware actions]({{ site.baseurl }}{% link middleware/index.md %}#actions)
+> Map of available [middleware actions]({{ site.baseurl }}{% link middleware/actions.md %})
 
 ## Methods
 

docs/middleware/actions.md

@@ -0,0 +1,223 @@
+---
+title: Actions
+nav_order: 2
+layout: default
+parent: Middleware
+
+copy:
+  submit_request_props: |-
+    `collection` -- string
+    > The collection of the op
+
+    `id` -- string
+    > The document ID
+
+    `op` -- Object
+    > The submitted op
+
+    `snapshot` -- [`Snapshot`]({{ site.baseurl }}{% link api/snapshot.md %})
+    > The snapshot
+
+    `extra` -- Object
+    > `extra.source` -- Object
+    >> The submitted source when [`doc.submitSource`]({{ site.baseurl }}{% link api/doc.md %}http://localhost:4000/api/doc#submitsource--boolean) is set to `true`
+
+    `saveMilestoneSnapshot` -- boolean
+    > Flag to control [saving a milestone snapshot]({{ site.baseurl }}{% link adapters/milestone.md#requesting-snapshots %})
+
+    `suppressPublish` -- boolean
+    > Flag to prevent broadcasting over [pub/sub]({{ site.baseurl }}{% link pub-sub.md %})
+
+    `retries` -- number
+    > The number of times the op has attempted to submit
+
+    `maxRetries` -- number
+    > The maximum number of times to retry submitting the op
+
+    `channels` -- string[]
+    > The [pub/sub]({{ site.baseurl }}{% link pub-sub.md %}) channels the op will publish to
+
+---
+
+# Middleware actions
+{: .no_toc }
+
+1. TOC
+{:toc}
+
+The actions represent different stages of information flow through the server. These hooks are also available on [`backend.MIDDLEWARE_ACTIONS`]({{ site.baseurl }}{% link api/backend.md %}#middleware_actions--object).
+
+All of the actions will have these `context` properties:
+
+`action` -- string
+
+> The triggered middleware action
+
+`agent` -- [Agent]({{ site.baseurl }}{% link api/agent.md %})
+
+> The [`Agent`]({{ site.baseurl }}{% link api/agent.md %}) communicating with the client
+
+`backend` -- [Backend]({{ site.baseurl }}{% link api/backend.md %})
+
+> The [`Backend`]({{ site.baseurl }}{% link api/backend.md %}) handling the request
+
+## `'connect'`
+
+A new client connected to the server.
+
+This action has these additional `context` properties:
+
+`stream` -- [Stream](https://nodejs.org/api/stream.html)
+
+> The [`Stream`](https://nodejs.org/api/stream.html) that connected
+
+`req` -- Object
+
+> The `request` argument provided to [`backend.listen()`]({{ site.baseurl }}{% link api/backend.md %}#listen)
+
+## `'receive'`
+
+The server received a message from a client.
+
+This action has these additional `context` properties:
+
+`data` -- Object
+
+> The received data
+
+## `'reply'`
+
+The server is about to send a non-error reply to a client message.
+
+This action has these additional `context` properties:
+
+`request` -- Object
+
+> The client's received request
+
+`reply` -- Object
+
+> The reply about to be sent
+
+## `'sendPresence'`
+
+Presence information is about to be sent to a client.
+
+This action has these additional `context` properties:
+
+`collection` -- string
+
+> The collection the presence is associated with
+
+`presence` -- Object
+
+> The presence object being sent. Its shape depends on its [type]({{ site.baseurl }}{% link types/index.md %})
+
+## `'query'`
+
+A new query request is about to be submitted to the database
+
+This action has these additional `context` properties:
+
+`index` -- string
+
+> The name of the query's collection or [projection]({{ site.baseurl }}{% link projections.md %})
+
+`collection` -- string
+
+> The name of the query's target collection
+
+`projection` -- string
+
+> The name of the query's [projection]({{ site.baseurl }}{% link projections.md %})
+
+`fields` -- Object
+
+> The query's projection [fields]({{ site.baseurl }}{% link api/backend.md %}#addprojection)
+
+`channel` -- string
+
+> The [Pub/Sub]({{ site.baseurl }}{% link adapters/pub-sub.md %}) channel the query will subscribe to. Defaults to its collection channel.
+
+`query` -- Object
+
+> The query being submitted to the database adapter
+
+`options` -- Object
+
+> The query [options]({{ site.baseurl }}{% link api/connection.md %}#createfetchquery)
+
+`db` -- [DB]({{ site.baseurl }}{% link adapters/database.md %})
+
+> The database the query will be run against
+
+## `'readSnapshots'`
+
+One or more snapshots were loaded from the database for a fetch or subscribe.
+
+This action has these additional `context` properties:
+
+`collection` -- string
+
+> The collection the snapshots belong to
+
+`snapshots` -- [Snapshot[]]({{ site.baseurl }}{% link api/snapshot.md %})
+
+> The [`Snapshot`]({{ site.baseurl }}{% link api/snapshot.md %})s being read
+
+`snapshotType` -- string
+
+> One of:
+> - `current` -- the snapshots are the latest version
+> - `byVersion` -- the snapshots are being fetched by version
+> - `byTimestamp` -- the snapshots are being fetched by timestamp
+
+## `'op'`
+
+An operation was loaded from the database.
+
+This action has these additional `context` properties:
+
+`collection` -- string
+
+> The collection of the op
+
+`id` -- string
+
+> The document ID
+
+`op` -- Object
+
+> The op being read
+
+## `'submit'`
+
+An operation has been submitted to the server.
+
+This action has these additional `context` properties:
+
+{{ page.copy.submit_request_props }}
+
+## `'apply'`
+
+An operation is about to be applied to a snapshot, before committing.
+
+This action has these additional `context` properties:
+
+{{ page.copy.submit_request_props }}
+
+## `'commit'`
+
+An operation was applied to a snapshot, and is about to be committed to the database.
+
+This action has these additional `context` properties:
+
+{{ page.copy.submit_request_props }}
+
+## `'afterWrite'`
+
+An operation and its updated snapshot were successfully written to the database.
+
+This action has these additional `context` properties:
+
+{{ page.copy.submit_request_props }}