add support for 0006-flat-omit-prefix-storage-layout

README.md

@@ -19,6 +19,7 @@ them easy to interact with in a unix-like way.
 - [0004-hashed-n-tuple-storage-layout](https://ocfl.github.io/extensions/0004-hashed-n-tuple-storage-layout.html)
 - [0005-mutable-head](https://ocfl.github.io/extensions/0005-mutable-head.html):
   Only read is supported; not write.
+- [0006-flat-omit-prefix-storage-layout](https://ocfl.github.io/extensions/0006-flat-omit-prefix-storage-layout.html)
 
 Additionally, it uses the following extensions for write support that
 have not been specified:

resources/main/specs/0006-flat-omit-prefix-storage-layout.md

@@ -0,0 +1,141 @@
+# OCFL Community Extension 0006: Flat Omit Prefix Storage Layout
+
+* **Extension Name:** 0006-flat-omit-prefix-storage-layout
+* **Authors:** Andrew Woods
+* **Minimum OCFL Version:** 1.0
+* **OCFL Community Extensions Version:** 1.0
+* **Obsoletes:** n/a
+* **Obsoleted by:** n/a
+
+## Overview
+
+This storage root extension describes a flat OCFL storage layout. The OCFL object directories are direct children of
+the OCFL storage root directory.
+The OCFL object identifiers are expected to contain prefixes which are removed in the mapping to directory names. The
+OCFL object identifier prefix is defined as all characters before and including a configurable delimiter.
+
+The limitations of this layout are filesystem dependent, but are generally as follows:
+
+* The size of object identifiers, minus the length of the prefix, cannot exceed the maximum allowed directory name size
+  (eg. 255 characters)
+* Object identifiers cannot include characters that are illegal in directory names
+* Performance may degrade as the size of a repository increases because every object is a direct child of the storage root
+
+## Parameters
+
+### Summary
+
+* **Name:** `delimiter`
+    * **Description:** The case-insensitive, delimiter marking the end of the OCFL object identifier prefix; MUST consist
+      of a character string of length one or greater. If the delimiter is found multiple times in the OCFL object
+      identifier, its last occurence (right-most) will be used to select the termination of the prefix.
+    * **Type:** string
+    * **Constraints:** Must not be empty
+    * **Default:**
+
+## Examples
+
+### Example 1
+
+This example demonstrates mappings where the single-character delimiter is found one or more times in the OCFL object
+identifier.
+
+#### Parameters
+
+There is no default configuration; therefore, configuration parameters must be provided.
+
+```json
+{
+    "extensionName": "0006-flat-omit-prefix-storage-layout",
+    "delimiter": ":"
+}
+```
+
+#### Mappings
+
+| Object ID | Object Root Path |
+| --- | --- |
+| namespace:12887296 | `12887296` |
+| urn:uuid:6e8bc430-9c3a-11d9-9669-0800200c9a66 | `6e8bc430-9c3a-11d9-9669-0800200c9a66` |
+
+#### Storage Hierarchy
+
+```
+[storage_root]/
+├── 0=ocfl_1.0
+├── ocfl_layout.json
+├── 12887296/
+│   ├── 0=ocfl_object_1.0
+│   ├── inventory.json
+│   ├── inventory.json.sha512
+│   └── v1 [...]
+└── 6e8bc430-9c3a-11d9-9669-0800200c9a66/
+    ├── 0=ocfl_object_1.0
+    ├── inventory.json
+    ├── inventory.json.sha512
+    └── v1 [...]
+```
+
+### Example 2
+
+This example demonstrates mappings where the multi-character delimiter is found one or more times in the OCFL object
+identifier.
+
+#### Parameters
+
+There is no default configuration; therefore, configuration parameters must be provided.
+
+```json
+{
+    "extensionName": "0006-flat-omit-prefix-storage-layout",
+    "delimiter": "edu/"
+}
+```
+
+#### Mappings
+
+| Object ID | Object Root Path |
+| --- | --- |
+| https://institution.edu/3448793 | `3448793` |
+| https://institution.edu/abc/edu/f8.05v | `f8.05v` |
+
+#### Storage Hierarchy
+
+```
+[storage_root]/
+├── 0=ocfl_1.0
+├── ocfl_layout.json
+├── 3448793/
+│   ├── 0=ocfl_object_1.0
+│   ├── inventory.json
+│   ├── inventory.json.sha512
+│   └── v1 [...]
+└── f8.05v/
+    ├── 0=ocfl_object_1.0
+    ├── inventory.json
+    ├── inventory.json.sha512
+    └── v1 [...]
+```
+
+### Example 3
+
+This example demonstrates mappings that produce directory names that are invalid on unix filesystems; therefore this
+layout cannot be used in a repository that needs to be able to store objects with identifiers like these.
+
+#### Parameters
+
+There is no default configuration; therefore, configuration parameters must be provided.
+
+```json
+{
+    "extensionName": "0006-flat-omit-prefix-storage-layout",
+    "delimiter": "info:"
+}
+```
+
+#### Mappings
+
+| Object ID | Object Root Path |
+| --- | --- |
+| info:fedora/object-01 | `fedora/object-01` |
+| https://example.org/info:/12345/x54xz321/s3/f8.05v | `/12345/x54xz321/s3/f8.05v` |

src/cmd/mod.rs

@@ -193,6 +193,10 @@ fn create_layout(layout_name: Layout, config_file: Option<&Path>) -> Result<Opti
             LayoutExtensionName::HashedNTupleObjectIdLayout,
             config_bytes.as_deref(),
         )?),
+        Layout::FlatOmitPrefix => Some(StorageLayout::new(
+            LayoutExtensionName::FlatOmitPrefixLayout,
+            config_bytes.as_deref(),
+        )?),
     };
 
     Ok(layout)

src/cmd/opts.rs

@@ -565,6 +565,8 @@ pub enum Layout {
     HashedNTuple,
     #[strum(serialize = "0003-hash-and-id-n-tuple-storage-layout")]
     HashedNTupleObjectId,
+    #[strum(serialize = "0006-flat-omit-prefix-storage-layout")]
+    FlatOmitPrefix,
 }
 
 arg_enum! {

src/ocfl/consts.rs

@@ -23,6 +23,7 @@ pub const HASHED_NTUPLE_OBJECT_ID_LAYOUT_EXTENSION: &str =
     "0003-hash-and-id-n-tuple-storage-layout";
 pub const HASHED_NTUPLE_LAYOUT_EXTENSION: &str = "0004-hashed-n-tuple-storage-layout";
 pub const MUTABLE_HEAD_EXTENSION: &str = "0005-mutable-head";
+pub const FLAT_OMIT_PREFIX_LAYOUT_EXTENSION: &str = "0006-flat-omit-prefix-storage-layout";
 pub const ROCFL_STAGING_EXTENSION: &str = "rocfl-staging";
 pub const ROCFL_LOCKS_EXTENSION: &str = "rocfl-locks";
 
@@ -32,6 +33,7 @@ pub static SUPPORTED_EXTENSIONS: Lazy<HashSet<&str>> = Lazy::new(|| {
     set.insert(HASHED_NTUPLE_OBJECT_ID_LAYOUT_EXTENSION);
     set.insert(HASHED_NTUPLE_LAYOUT_EXTENSION);
     set.insert(MUTABLE_HEAD_EXTENSION);
+    set.insert(FLAT_OMIT_PREFIX_LAYOUT_EXTENSION);
     set.insert(ROCFL_STAGING_EXTENSION);
     set.insert(ROCFL_LOCKS_EXTENSION);
     set

src/ocfl/specs.rs

@@ -5,3 +5,5 @@ pub const EXT_0003_SPEC: &str =
     include_str!("../../resources/main/specs/0003-hash-and-id-n-tuple-storage-layout.md");
 pub const EXT_0004_SPEC: &str =
     include_str!("../../resources/main/specs/0004-hashed-n-tuple-storage-layout.md");
+pub const EXT_0006_SPEC: &str =
+    include_str!("../../resources/main/specs/0006-flat-omit-prefix-storage-layout.md");

src/ocfl/store/fs.rs

@@ -1056,6 +1056,7 @@ fn write_layout_config(root: impl AsRef<Path>, layout: &StorageLayout) -> Result
         LayoutExtensionName::FlatDirectLayout => specs::EXT_0002_SPEC,
         LayoutExtensionName::HashedNTupleObjectIdLayout => specs::EXT_0003_SPEC,
         LayoutExtensionName::HashedNTupleLayout => specs::EXT_0004_SPEC,
+        LayoutExtensionName::FlatOmitPrefixLayout => specs::EXT_0006_SPEC,
     };
 
     write!(