Stream RO-Crate Zip

CITATION.cff

@@ -1,6 +1,9 @@
 cff-version: 1.1.0
 message: "Cite as"
-authors:
+author:
+  - family-names: Bauer
+    given-names: Daniel
+    orcid: https://orcid.org/0000-0001-9447-460X
   - family-names: Chadwick
     given-names: Eli
     orcid: https://orcid.org/0000-0002-0035-6475

README.md

@@ -451,6 +451,7 @@ Options:
 * Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 * Copyright 2024 Data Centre, SciLifeLab, SE
 * Copyright 2024 National Institute of Informatics (NII), JP
+* Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 
 Licensed under the
 Apache License, version 2.0 <https://www.apache.org/licenses/LICENSE-2.0>,

examples/fastapi/main.py

@@ -0,0 +1,64 @@
+# Copyright 2019-2024 The University of Manchester, UK
+# Copyright 2020-2024 Vlaams Instituut voor Biotechnologie (VIB), BE
+# Copyright 2020-2024 Barcelona Supercomputing Center (BSC), ES
+# Copyright 2020-2024 Center for Advanced Studies, Research and Development in Sardinia (CRS4), IT
+# Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
+# Copyright 2024 Data Centre, SciLifeLab, SE
+# Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Streaming RO-Crates from a web server
+
+This example demonstrates how to create an RO-Crate on-the-fly
+and stream the result to the client.
+By using `stream_zip`, the RO-Crate is not written to disk and remote
+data is only fetched on the fly.
+
+To run: `fastapi dev main.py`, then visit http://localhost:8000/crate
+"""
+
+from fastapi import FastAPI
+from fastapi.responses import StreamingResponse
+from rocrate.rocrate import ROCrate
+from io import StringIO
+
+app = FastAPI()
+
+
+@app.get("/crate")
+async def get():
+    crate = ROCrate()
+
+    # Add a remote file
+    crate.add_file(
+        "https://raw.githubusercontent.com/ResearchObject/ro-crate-py/refs/heads/master/test/test-data/sample_file.txt",
+        fetch_remote=True
+    )
+
+    # Add a file containing a string to the crate
+    crate.add_file(
+        source=StringIO("Hello, World!"),
+        dest_path="test-data/hello.txt"
+    )
+
+    # Stream crate to client as a zip file
+    return StreamingResponse(
+        crate.stream_zip(),
+        media_type="application/rocrate+zip",
+        headers={
+            "Content-Disposition": "attachment; filename=crate.zip",
+        }
+    )

examples/fastapi/requirements.txt

@@ -0,0 +1,3 @@
+../../
+fastapi
+fastapi-cli

examples/read_test_metadata.py

@@ -5,6 +5,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/__init__.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -30,6 +31,7 @@
 """
 
 __author__ = ", ".join((
+    'Daniel Bauer',
     'Eli Chadwick',
     'Paul De Geest',
     'Bert Droesbeke',
@@ -52,6 +54,7 @@
 Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 Copyright 2024 Data Centre, SciLifeLab, SE
 Copyright 2024 National Institute of Informatics (NII), JP
+Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 """
 __license__ = ("Apache License, version 2.0 "
                "<https://www.apache.org/licenses/LICENSE-2.0>")

rocrate/cli.py

@@ -5,6 +5,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/memory_buffer.py

@@ -0,0 +1,52 @@
+# Copyright 2019-2024 The University of Manchester, UK
+# Copyright 2020-2024 Vlaams Instituut voor Biotechnologie (VIB), BE
+# Copyright 2020-2024 Barcelona Supercomputing Center (BSC), ES
+# Copyright 2020-2024 Center for Advanced Studies, Research and Development in Sardinia (CRS4), IT
+# Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
+# Copyright 2024 Data Centre, SciLifeLab, SE
+# Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from io import RawIOBase
+
+
+class MemoryBuffer(RawIOBase):
+    """
+    A buffer class that supports reading and writing binary data.
+    The buffer automatically resets upon reading to make sure all data is read only once.
+    """
+
+    def __init__(self):
+        self._buffer = b''
+
+    def write(self, data):
+        if self.closed:
+            raise ValueError('write to closed file')
+        self._buffer += data
+        return len(data)
+
+    def read(self, size=-1):
+        if self.closed:
+            raise ValueError('read from closed file')
+        if size < 0:
+            data = self._buffer
+            self._buffer = b''
+        else:
+            data = self._buffer[:size]
+            self._buffer = self._buffer[size:]
+        return data
+
+    def __len__(self):
+        return len(self._buffer)

rocrate/metadata.py

@@ -5,6 +5,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/__init__.py

@@ -5,6 +5,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/computationalworkflow.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/computerlanguage.py

@@ -5,6 +5,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/contextentity.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/creativework.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

rocrate/model/data_entity.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -28,3 +29,14 @@ class DataEntity(Entity):
 
     def write(self, base_path):
         pass
+
+    def stream(self, chunk_size=8192):
+        """ Stream the data from the source. Each chunk of the content is yielded as a tuple
+        containing the name of the destination file relative to the crate and the chunk of data.
+        The destination file name is required because a DataEntity can be a file or a
+        collection of files (Dataset) and the caller need to know to which file a chunk belongs.
+        For collection of files, the caller can assume that files are streamed one after another,
+        meaning once the destination name changes, a file can be closed and the next one can be
+        openend.
+        """
+        yield from ()

rocrate/model/dataset.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -22,7 +23,7 @@
 
 import errno
 import os
-import shutil
+import warnings
 from pathlib import Path
 from urllib.request import urlopen
 
@@ -43,37 +44,84 @@ def _empty(self):
     def format_id(self, identifier):
         return identifier.rstrip("/") + "/"
 
+    def _write_from_url(self, base_path):
+        if self.validate_url and not self.fetch_remote:
+            with urlopen(self.source) as _:
+                self._jsonld['sdDatePublished'] = iso_now()
+        if self.fetch_remote:
+            out_file_path, out_file = None, None
+            for rel_path, chunk in self._stream_folder_from_url():
+                path = base_path / rel_path
+                if path != out_file_path:
+                    if out_file:
+                        out_file.close()
+                    out_file_path = Path(path)
+                    out_file_path.parent.mkdir(parents=True, exist_ok=True)
+                    out_file = open(out_file_path, 'wb')
+                out_file.write(chunk)
+            if out_file:
+                out_file.close()
+
+    def _copy_folder(self, base_path):
+        abs_out_path = base_path / self.id
+        if self.source is None:
+            abs_out_path.mkdir(parents=True, exist_ok=True)
+        else:
+            if not Path(self.source).exists():
+                raise FileNotFoundError(
+                    errno.ENOENT, os.strerror(errno.ENOENT), str(self.source)
+                )
+            abs_out_path.mkdir(parents=True, exist_ok=True)
+            if not self.crate.source:
+                self.crate._copy_unlisted(self.source, abs_out_path)
+
     def write(self, base_path):
-        out_path = Path(base_path) / self.id
+        base_path = Path(base_path)
         if is_url(str(self.source)):
-            if self.validate_url and not self.fetch_remote:
+            self._write_from_url(base_path)
+        else:
+            self._copy_folder(base_path)
+
+    def stream(self, chunk_size=8192):
+        if self.source is None:
+            return
+        elif is_url(str(self.source)):
+            yield from self._stream_folder_from_url(chunk_size)
+        else:
+            yield from self._stream_folder_from_path(chunk_size)
+
+    def _stream_folder_from_path(self, chunk_size=8192):
+        if not Path(str(self.source)).exists():
+            raise FileNotFoundError(
+                errno.ENOENT, os.strerror(errno.ENOENT), str(self.source)
+            )
+        if not self.crate.source:
+            for root, _, files in os.walk(self.source):
+                root = Path(root)
+                for name in files:
+                    source = root / name
+                    dest = source.relative_to(Path(self.source).parent)
+                    with open(source, 'rb') as f:
+                        while chunk := f.read(chunk_size):
+                            yield str(dest), chunk
+
+    def _stream_folder_from_url(self, chunk_size=8192):
+        if not self.fetch_remote:
+            if self.validate_url:
                 with urlopen(self.source) as _:
                     self._jsonld['sdDatePublished'] = iso_now()
-            if self.fetch_remote:
-                self.__get_parts(out_path)
         else:
-            if self.source is None:
-                out_path.mkdir(parents=True, exist_ok=True)
-            else:
-                if not Path(self.source).exists():
-                    raise FileNotFoundError(
-                        errno.ENOENT, os.strerror(errno.ENOENT), str(self.source)
-                    )
-                out_path.mkdir(parents=True, exist_ok=True)
-                if not self.crate.source:
-                    self.crate._copy_unlisted(self.source, out_path)
+            base = self.source.rstrip("/")
+            for entry in self._jsonld.get("hasPart", []):
+                try:
+                    part = entry["@id"]
+                    if is_url(part) or part.startswith("/"):
+                        raise RuntimeError(f"'{self.source}': part '{part}' is not a relative path")
+                    part_uri = f"{base}/{part}"
+                    rel_out_path = Path(self.id) / part
 
-    def __get_parts(self, out_path):
-        out_path.mkdir(parents=True, exist_ok=True)
-        base = self.source.rstrip("/")
-        for entry in self._jsonld.get("hasPart", []):
-            try:
-                part = entry["@id"]
-            except KeyError:
-                continue
-            if is_url(part) or part.startswith("/"):
-                raise RuntimeError(f"'{self.source}': part '{part}' is not a relative path")
-            part_uri = f"{base}/{part}"
-            part_out_path = out_path / part
-            with urlopen(part_uri) as r, open(part_out_path, 'wb') as f:
-                shutil.copyfileobj(r, f)
+                    with urlopen(part_uri) as response:
+                        while chunk := response.read(chunk_size):
+                            yield str(rel_out_path), chunk
+                except KeyError:
+                    warnings.warn(f"'hasPart' entry in {self.id} is missing '@id'. Skipping.")

rocrate/model/entity.py

@@ -7,6 +7,7 @@
 # Copyright 2022-2024 École Polytechnique Fédérale de Lausanne, CH
 # Copyright 2024 Data Centre, SciLifeLab, SE
 # Copyright 2024 National Institute of Informatics (NII), JP
+# Copyright 2025 Senckenberg Society for Nature Research (SGN), DE
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.