feat(planes): porting AEP-111 from AIP-111

No major changes, besides removing refrerences to AIPs.

aep/general/0111/aep.md

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+# Planes
+
+Resources and methods on an API can be divided into the _plane_ that they
+reside or perform operations upon. For the context of APIs, the following
+planes are defined:
+
+- Management plane: a uniform, resource-oriented API that primarily configures
+  and allows retrieval of resources.
+- Data plane: a heterogenous API (ideally resource-oriented) that reads and
+  write user data. Often connects to entities provisioned by the management
+  plane, such as virtual machines.
+
+The term "plane" was originally used in networking architecture. Although
+system and network architecture often defines additional planes (e.g. control
+plane or power planes), as the AEPs are focused on the interface, they are not
+defined in this AEP.
+
+## Guidance
+
+### Management Plane
+
+Management resources and methods exist primarily to provision, configure, and
+audit the resources that the data plane interfaces with.
+
+As an example, the following are considered management resources for a cloud
+provider:
+
+- virtual machines
+- virtual private networks
+- virtual disks
+- a blob store instance
+- a project or account
+
+### Data Plane
+
+Methods on the data plane operate on user data in a variety of data formats,
+and generally interface with a resource provisioned via a management plane API.
+Examples of data plane methods include:
+
+- writing and reading rows in a table
+- pushing to or pulling from a message queue
+- uploading blobs to or downloading blobs from a blob store instance
+
+Data plane APIs **may** be heterogenous across a larger API surface, due to
+requirements including high throughput, low latency, or the need to adhere to
+an existing interface specification (e.g. ANSI SQL).
+
+- For convenience, resources and methods that operate on the data plane **may**
+  expose themselves via resource-oriented management APIs. If so, those
+  resources and methods **must** adhere to the requirements of the management
+  plane as specified in the other AEPs.
+
+### Major distinctions between management and data plane
+
+- [Declarative clients][] operate on the management plane exclusively.
+- Data planes are often on the critical path of user-facing functionality, and
+  therefore:
+  - Have higher availabilty requirements than management planes.
+  - Are more peformance-sensitive than management planes.
+  - Require higher-throughput than management planes.
+
+[Declarative clients]: ./0003.md#declarative-clients
+
+## Changelog
+
+- **2024-01-27**: initial fork of this AEP from https://google.aip.dev/111.

aep/general/0111/aep.yaml

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+id: 111
+state: approved
+slug: planes
+created: 2024-01-27
+placement:
+  category: general