Introduction

This page describes the http api of the ox drive module.

The module drive is used to synchronize files and folders between server and client, using a server-centric approach to allow an easy implementation on the client-side.

The synchronization is based on checksums for files and folders, differences between the server- and client-side are determined using a three-way comparison of server, client and previously acknowledged file- and directory-versions. The synchronization logic is performed by the server, who instructs the client with a set of actions that should be executed in order to come to a synchronized state.

Therefore, the client takes a snapshot of it's local files and directories, calculates their checksums, and sends them as a list to the server, along with a list of previously acknowledged checksums. The server takes a similar snapshot of the files and directories on the underlying file storages and evaluates which further actions are necessary for synchronization. After executing the server-side actions, the client receives a list of actions that should be executed on the client-side. These steps are repeated until the server-state matches the client-state.

Key concept is that the synchronization works stateless, i.e. it can be interrupted and restarted at any time, following the eventual consistency model.

Entry point for the synchronization is the syncfolders request, where the directories are compared, and further actions are determined by the server, amongst others actions to synchronize the files in a specific directory using the syncfiles request. After executing the actions, the client should send another syncfolders request to the server and execute the returned actions (if present), or finish the synchronization if there are no more actions to execute. In pseudo-code, the synchronization routine could be implemented as follows:

WHILE TRUE
{
  response = SYNCFOLDERS()
  IF 0 == response.actions.length
    BREAK
  ELSE
    EXECUTE(response.actions)
}

Basically, it's up to the client how often such a synchronization cycle is initiated. For example, he could start a new synchronization cycle after a fixed interval, if he recognizes that the client directories have changed, or if he is informed that something has changed on the server by an event. It's also up to the client to interrupt the synchronization cycle at any time during execution of the actions and continue later on, however, it's recommended to start a new synchronization cycle each time to avoid possibly outdated actions.

API

As part of the HTTP API, the basic conventions for exchanging messages described there are also valid for this case, especially the HTTP API (low level protocol) and HTTP API (error handling). Each request against the Drive API assumes a valid server session that is uniquely identified by the session id and the corresponding cookies and are sent with each request. A new session can be created via the HTTP API (login module).

The root folder plays another important role for the message exchange. The root folder has a unique identifier. It is the parent server folder for the synchronization. All path details for directories and files are relative to this folder. This folder's id is sent with each request. To select the root folder during initial client configuration, the client may get a list of synchronizable folders with the subfolders action.

Subsequently all transferred objects and all possible actions are listed.

File Version

A file in a directory is uniquely identified by its filename and the checksum of its content.

Name	Type	Value
name	String	The name of the file, including its extension, e.g. `test.doc`.
checksum	String	The MD5 hash of the file, expressed as a lowercase hexadecimal number string, 32 characters long, e.g. f8cacac95379527cd4fa15f0cb782a09.

Directory Version

A directory is uniquely identified by its full path, relative to the root folder, and the checksum of its content.

Name	Type	Value
path	String	The path of the directory, including the directory's name, relative to the root folder, e.g. `/sub/test/letters`.
checksum	String	The MD5 hash of the directory, expressed as a lowercase hexadecimal number string, 32 characters long, e.g. `f8cacac95379527cd4fa15f0cb782a09`.\|

Note: the checksum of a directory is calculated based on its contents in the following algorithm:

Build a list containing each file in the directory (not including subfolders or files in subfolders)
Ensure a lexicographically order in the following way:
- Normalize the filename using the NFC normalization form (canonical decomposition, followed by canonical composition) - see http://www.unicode.org/reports/tr15/tr15-23.html for details
- Encode the filename to an array of UTF-8 unsigned bytes (array of codepoints)
- Compare the filename (encoded as byte array "fn1") to another one "fn2" using the following comparator algorithm:
```
min_length = MIN(LENGTH(fn1), LENGTH(fn2))
FOR i = 0; i < min_length; i++
{
  result = fn1[i] - fn2[i]
  IF 0 != result RETURN result
}
RETURN LENGTH(fn1) - LENGTH(fn2)
```
Calculate the aggregated MD5 checksum for the directory based on each file in the ordered list:
- Append the file's NFC-normalized (see above) name, encoded as UTF-8 bytes
- Append the file's MD5 checksum string, encoded as UTF-8 bytes

Actions

All actions are encoded in the following format. Depending on the action type, not all properties may be present.

Name	Type	Value
action	String	The type of action to execute, currently one of `acknowledge`, `edit`, `download`, `upload`, `remove`, `sync`, `error`.
version	Object	The (original) file- or directory-version referenced by the action.
newVersion	Object	The (new) file- or directory-version referenced by the action.
path	String	The path to the synchronized folder, relative to the root folder.
root	String	The corresponding root folder identifier (optional, available since API version 5).
offset	Number	The requested start offset in bytes for file uploads.
totalLength	Number	The total length in bytes for file downloads.
contentType	String	The file's content type for downloads (deprecated, available until API version 2).
created	Timestamp	The file's creation time (always UTC, not translated into user time).
modified	Timestamp	The file's last modification time (always UTC, not translated into user time).
error	Object	The error object in case of synchronization errors.
quarantine	Boolean	The flag to indicate whether versions need to be excluded from synchronization.
reset	Boolean	The flag to indicate whether locally stored checksums should be invalidated.
stop	Boolean	The flag to signal that the client should stop the current synchronization cycle.
acknowledge	Boolean	The flag to signal if the client should not update it's stored checksums when performing an `EDIT` action.
thumbnailLink	String	A direct link to a small thumbnail image of the file if available (deprecated, available until API version 2).
previewLink	String	A direct link to a medium-sized preview image of the file if available (deprecated, available until API version 2).
directLink	String	A direct link to the detail view of the file in the web interface (deprecated, available until API version 2).
directLinkFragments	String	The fragments part of the direct link (deprecated, available until API version 2).

The following list gives an overview about the used action types:

acknowledge

Acknowledges the successful synchronization of a file- or directory version, i.e., the client should treat the version as synchronized by updating the corresponding entry in its metadata store and including this updated information in all following originalVersions arrays of the syncfiles / syncfolders actions. Depending on the version and newVersion parameters of the action, the following acknowledge operations should be executed (exemplarily for directory versions, file versions are acknowledged in the same way):

Example 1: Acknowledge a first time synchronized directory
The server sends an acknowledge action where the newly synchronized directory version is encoded in the newVersion parameter. The client should store the version in his local checksum store and send this version in the originalVersions array in upcoming syncfolders requests.

{
  "action" : "acknowledge",
  "newVersion" : {
      "path" : "/",
      "checksum" : "d41d8cd98f00b204e9800998ecf8427e"
  }
}

Example 2: Acknowledge a synchronized directory after updates
The server sends an acknowledge action where the previous directory version is encoded in the version, and the newly synchronized directory in the newVersion parameter. The client should replace any previously stored entries of the directory version in his local checksum store with the updated version, and send this version in the originalVersions array in upcoming syncfolders requests.

{
  "action" : "acknowledge",
  "newVersion" : {
    "path" : "/",
    "checksum" : "7bb1f1a550e9b9ab4be8a12246f9d5fb"
  },
  "version" : {
    "path" : "/",
    "checksum" : "d41d8cd98f00b204e9800998ecf8427e"
  }
}

Example 3: Acknowledge the deletion of a previously synchronized directory
The server sends an acknowledge where the newVersion parameter is set to null to acknowledge the deletion of the previously synchronized directory version as found in the version parameter. The client should remove any stored entries for this directory from his local checksum store, and no longer send this version in the originalVersions array in upcoming syncfolders requests. Note that an acknowledged deletion of a directory implicitly acknowledges the deletion of all contained files and subfolders, too, so the client should also remove those originalVersions from his local checksum store.

{
  "action" : "acknowledge",
  "version" : {
    "path" : "/test",
    "checksum" : "3525d6f28eb8cb30eb61ab7932367c35"
  }
}

edit

Instructs the client to edit a file- or directory version. This is used for move/rename operations. The version parameter is set to the version as sent in the clientVersions array of the preceding syncfiles/syncfolders action. The newVersion contains the new name/path the client should use. Unless the optional boolean parameter acknowledge is set to false an edit action implies that the client updates its known versions store accordingly, i.e. removes the previous entry for version and adds a new entry for newVersion. When editing a directory version, the client should implicitly take care to create any not existing subdirectories in the path of the newVersion parameter. A concurrent client-side modification of the file/directory version can be detected by the client by comparing the current checksum against the one in the passed newVersion parameter.

Example 1: Rename a file
The server sends an edit action where the source file is encoded in the version, and the target file in the newVersion parameter. The client should rename the file identified by the version parameter to the name found in the newVersion parameter. Doing so, the stored checksum entry for the file in version should be updated, too, to reflect the changes.

{
  "path" : "/",
  "action" : "edit",
  "newVersion" : {
    "name" : "test_1.txt",
    "checksum" : "03395a94b57eef069d248d90a9410650"
  },
  "version" : {
    "name" : "test.txt",
    "checksum" : "03395a94b57eef069d248d90a9410650"
  }
}

Example 2: Move a directory
The server sends an edit action where the source directory is encoded in the version, and the target directory in the newVersion parameter. The client should move the directory identified by the version parameter to the path found in the newVersion parameter. Doing so, the stored checksum entry for the directory in version should be updated, too, to reflect the changes.

{
  "action" : "edit",
  "newVersion" : {
    "path" : "/test2",
    "checksum" : "3addd6de801f4a8650c5e089769bdb62"
  },
  "version" : {
    "path" : "/test1/test2",
    "checksum" : "3addd6de801f4a8650c5e089769bdb62"
  }
}

Example 3: Rename a conflicting file
The server sends an edit action where the original client file is encoded in the version, and the target filename in the newVersion parameter. The client should rename the file identified by the version parameter to the new filename found in the newVersion parameter. If the acknowledge parameter is set to true or is not set, the stored checksum entry for the file in version should be updated, too, to reflect the changes, otherwise, as in this example, no changes should be done to the stored checksums.

{
  "action" : "edit",
  "version" : {
    "checksum" : "fade32203220752f1fa0e168889cf289",
    "name" : "test.txt"
  },
  "newVersion" : {
    "checksum" : "fade32203220752f1fa0e168889cf289",
    "name" : "test (TestDrive).txt"
  },
  "acknowledge" : false,
  "path" : "/"
}

download

Contains information about a file version the client should download. For updates of existing files, the previous client version is supplied in the version parameter. For new files, the version parameter is omitted. The newVersion holds the target file version, i.e. filename and checksum, and should be used for the following download request. The totalLength parameter is set to the file size in bytes, allowing the client to recognize when a download is finished. Given the supplied checksum, the client may decide on its own if the target file needs to be downloaded from the server, or can be created by copying a file with the same checksum to the target location, e.g. from a trash folder. The file's content type can be retrieved from the contentType parameter, similar to the file's creation and modification times that are available in the created and modified parameters.

Example 1: Download a new file
The server sends a download action where the file version to download is encoded in the newVersion paramter. The client should download and save the file as indicated by the name property of the newVersion in the directory identified by the supplied path. After downloading, the newVersion should be added to the client's known file versions database.

{
  "totalLength" : 536453,
  "path" : "/",
  "action" : "download",
  "newVersion" : {
    "name" : "test.pdf",
    "checksum" : "3e0d7541b37d332c42a9c3adbe34aca2"
  },
  "contentType" : "application/pdf",
  "created" : 1375276738232,
  "modified" : 1375343720985
}

Example 2: Download an updated file
The server sends a download action where the previous file version is encoded in the version, and the file version to download in the newVersion parameter. The client should download and save the file as indicated by the name property of the newVersion in the directory identified by the supplied path, replacing the previous file. After downloading, the newVersion should be added to the client's known file versions database, replacing an existing entry for the previous version.

{
  "totalLength" : 1599431,
  "path" : "/",
  "action" : "download",
  "newVersion" : {
    "name" : "test.pdf",
    "checksum" : "bb198790904f5a1785d7402b0d8c390e"
  },
  "contentType" : "application/pdf",
  "version" : {
    "name" : "test.pdf",
    "checksum" : "3e0d7541b37d332c42a9c3adbe34aca2"
  },
  "created" : 1375276738232,
  "modified" : 1375343720985
}

upload

Instructs the client to upload a file to the server. For updates of existing files, the previous server version is supplied in the version parameter, and should be used for the following upload request. For new files, the version parameter is omitted. The newVersion holds the target file version, i.e. filename and checksum, and should be used for the following upload request. When resuming a previously partly completed upload, the offset parameter contains the offset in bytes from which the file version should be uploaded by the client. If possible, the client should set the contentType parameter for the uploaded file, otherwise, the content type falls back to application/octet-stream.

remove

Instructs the client to delete a file or directory version. The version parameter contains the version to delete. A deletion also implies a removal of the corresponding entry in the client's known versions store. A concurrent client-side modification of the file/directory version can be detected by comparing the current checksum against the one in the passed version parameter.

Example 1: Remove a file
The server sends a remove action where the file to be removed is encoded as version parameter. The newVersion parameter is not set in the action. The client should delete the file identified by the version parameter. A stored checksum entry for the file in version should be removed, too, to reflect the changes. The newVersion parameter is not set in the action.

{
  "path" : "/test2",
  "action" : "remove",
  "version" : {
    "name" : "test.txt",
    "checksum" : "03395a94b57eef069d248d90a9410650"
  }
}

Example 2: Remove a directory
The server sends a remove action where the directory to be removed is encoded as version parameter. The newVersion parameter is not set in the action. The client should delete the directory identified by the version parameter. A stored checksum entry for the directory in version should be removed, too, to reflect the changes.

{
  "action" : "remove",
  "version" : {
    "path" : "/test1",
    "checksum" : "d41d8cd98f00b204e9800998ecf8427e"
  }
}

sync

The client should trigger a synchronization of the files in the directory supplied in the version parameter using the syncfiles request. A sync action implies the client-side creation of the referenced directory if it not yet exists, in case of a new directory on the server.

If the version parameter is not specified, a synchronization of all folders using the syncfolders request should be initiated by the client.

If the reset flag in the SYNC action is set to true, the client should reset his local state before synchronizing the files in the directory. This may happen when the server detects a synchronization cycle, or believes something else is going wrong. Reset means that the client should invalidate any stored original checksums for the directory itself and any contained files, so that they get re-calculated upon the next synchronization. If the reset flag is set in a SYNC action without a specific directory version, the client should invalidate any stored checksums, so that all file- and directory-versions get re-calculated during the following synchronizations.

Example 1: Synchronize folder
The server sends a sync action with a version. The client should trigger a syncfiles request for the specified folder.

{
  "action": "sync",
  "version": {
    "path": "<folder>",
    "checksum": "<md5>"
  }
}

Example 2: Synchronize all folders
The server sends a sync action without version (or version is //null//). The client should trigger a syncfolder request, i.e. the client should synchronize all folders.

{
  "action": "sync",
  "version": null
}

error

With the error action, file- or directory versions causing a synchronization problem can be identified. The root cause of the error is encoded in the error parameter as described at the HTTP API (error handling).

Basically, there are two scenarios where either the errorneous version affects the synchronization state or not. For example, a file that was deleted at the client without sufficient permissions on the server can just be downloaded again by the client, and afterwards, client and server are in-sync again. On the other hand, e.g. when creating a new file at the client and this file can't be uploaded to the server due to missing permissions, the client is out of sync as long as the file is present. Therefore, the boolean parameter quarantine instructs the client whether the file or directory version must be excluded from the synchronization or not. If it is set to true, the client should exclude the version from the clientVersions array, and indicate the issue to the enduser. However, if the synchronization itself is not affected and the quarantine flag is set to false, the client may still indicate the issue once to the user in the background, e.g. as a balloontip notification.

The client may reset it's quarantined versions on it's own, e.g. if the user decides to "try again", or automatically after a configurable interval.

The server may also decide that further synchronization should be suspended, e.g. in case of repeated synchronization problems. Such a situation is indicated with the parameter stop set to true. In this case, the client should at least cancel the current synchronization cycle. If appropriate, the client should also be put into a 'paused' mode, and the user should be informed accordingly.

There may also be situations where a error or warning is sent to the client, independently of a file- or directory version, e.g. when the client version is outdated and a newer version is available for download.

The most common examples for errors are insufficient permissions or exceeded quota restrictions, see examples below.

Example 1: Create a file in a read-only folder
The server sends an error action where the errorneous file is encoded in the newVersion parameter and the quarantine flag is set to true. The client should exclude the version from the clientVersions array in upcoming syncFiles requests so that it doesn't affect the synchronization algorithm. The error message and further details are encoded in the error object of the action.

{
  "error" : {
    "category" : 3,
    "error_params" : ["/test"],
    "error" : "You are not allowed to create files at \"/test\"",
    "error_id" : "1358320776-69",
    "categories" : "PERMISSION_DENIED",
    "code" : "DRV-0012"
  },
  "path" : "/test",
  "quarantine" : true,
  "action" : "error",
  "newVersion" : {
    "name" : "test.txt",
    "checksum" : "3f978a5a54cef77fa3a4d3fe9a7047d2"
  }
}

Example 2: Delete a file without sufficient permissions
Besides a new download action to restore the locally deleted file again, the server sends an error action where the errorneous file is encoded in the version parameter and the quarantine flag is set to false. Further synchronizations are not affected, but the client may still inform the user about the rejected operation. The error message and further details are encoded in the error object of the action.

{
  "error" : {
    "category" : 3,
    "error_params" : ["test.png", "/test"],
    "error" : "You are not allowed to delete the file \"test.png\" at \"/test\"",
    "error_id" : "1358320776-74",
    "categories" : "PERMISSION_DENIED",
    "code" : "DRV-0011"
  },
  "path" : "/test",
  "quarantine" : false,
  "action" : "error",
  "newVersion" : {
    "name" : "test.png",
    "checksum" : "438f06398ce968afdbb7f4db425aff09"
  }
}

Example 3: Upload a file that exceeds the quota
The server sends an error action where the errorneous file is encoded in the newVersion parameter and the quarantine flag is set to true. The client should exclude the version from the clientVersions array in upcoming syncFiles requests so that it doesn't affect the synchronization algorithm. The error message and further details are encoded in the error object of the action.

{
  "error" : {
    "category" : 3,
    "error_params" : [],
    "error" : "The allowed Quota is reached",
    "error_id" : "-485491844-918",
    "categories" : "PERMISSION_DENIED",
    "code" : "DRV-0016"
  },
  "path" : "/",
  "quarantine" : true,
  "action" : "error",
  "newVersion" : {
    "name" : "test.txt",
    "checksum" : "0ca6033e2a9c2bea1586a2984bf111e6"
  }
}

Example 4: Synchronize with a client where the version is no longer supported.
The server sends an error action with code DRV-0028 and an appropriate error message. The stop flag is set to true to interrupt the synchronization cycle.

{
  "stop" : true,
  "error" : {
    "category" : 13,
    "error_params" : [],
    "error" : "The client application you're using is outdated and no longer supported - please upgrade to a newer version.",
    "error_id" : "103394512-13",
    "categories" : "WARNING",
    "code" : "DRV-0028",
    "error_desc" : "Client outdated - current: \"0.9.2\", required: \"0.9.10\""
  },
  "quarantine" : false,
  "action" : "error"
}

Example 5: Synchronize with a client where a new version of the client application is available.
The server sends an error action with code DRV-0029 and an appropriate error message. The stop flag is set to false to indicate that the synchronization can continue.

{
  "stop" : false,
  "error" : {
    "category" : 13,
    "error_params" : [],
    "error" : "A newer version of your client application is available for download.",
    "error_id" : "103394512-29",
    "categories" : "WARNING",
    "code" : "DRV-0029",
    "error_desc" : "Client update available - current: \"0.9.10\", available: \"0.9.12\""
  },
  "quarantine" : false,
  "action" : "error"
}

File- and Directory Name Restrictions

Regarding the case sensitivity of file and directory names, OX Drive works in a case-insensitive, but case-preserving way. That means that there cannot be two files with an equal name ignoring case in the same directory, but it's still possible to synchronize the names in a case-sensitive manner, as well as it's possible to change only the case of file- and directory names.

The same applies to equally named files and directories on the same level in the folder hierarchy, i.e. it's not possible to create a new file in a directory where an equally (ignoring case) named subdirectory already exists and vice versa.

There is a similar restriction regarding file and directory names in the same directory having different unicode normalization forms, yet the same textual representation. OX Drive requires uniqueness regarding this textual representaion of potentially different encoded unicode strings. So, in case the client tries to synchronize two textually equal files or directories, he is instructed to put one of them into quarantine. Internally the server performs an equals-check of the "NFC" normalization forms of the strings, i.e. an unicode string is normalized using full canonical decomposition, followed by the replacement of sequences with their primary composites, if possible. Details regarding unicode normalization can be found at http://www.unicode.org/reports/tr15/tr15-23.html .

Invalid and ignored Filenames

There are some filenames that are invalid or ignored and therefore not synchronized. This means that files with these names should not be taken into account when sending the directory contents to the server, or when calculating the directory checksum (see below). The following list describes when a filename is considered invalid:

If it contains one of the following reserved characters:

Character	Description
<	less than
>	greater than
:	colon
"	double quote
/	forward slash
\	backslash
\|	vertical bar or pipe
?	question mark
*	asterisk

It contains a character whose integer representations is in the range from 0 through 31
The last character is a . (dot) or ' ' (space)
It's case-invariant name without an optional extension matches one of the reserved names CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, or LPT9
It consists solely of whitespace characters

The following list gives an overview about the ignored filenames:

desktop.ini
Thumbs.db
.DS_Store
icon
Any filename ending with .drivepart
Any filename starting with .msngr_hstr_data_ and ending with .log

Nevertheless, if the client still insists to send a file version with an invalid or ignored filename, the file creation on the server is refused with a corresponding error action (see below).

Invalid and ignored Directory Names

There are also similar restrictions regarding invalid directory names. Any try to include them in the list of directory versions will be responded with a corresponding error action for the directory version. The following list describes when a path is considered invalid:

If it contains one or of the following reserved characters:

Character	Description
<	less than
>	greater than
:	colon
"	double quote
\	backslash
\|	vertical bar or pipe
?	question mark
*	asterisk

It contains a character whose integer representations is in the range from 0 through 31
The last character of any subpath (i.e. the last part of the whole path or the part preceding the spearator character /) is a . (dot) or ' ' (space)
It consists solely of whitespace characters
It not equals the root path /, but ends with a / (forward slash) character
It contains two or more consecutive / (forward slash) characters

The following list gives an overview about the ignored directory names:

/.drive
Any directory whose path ends with /.msngr_hstr_data

Length Restrictions

The maximum allowed length for path segments, i.e. the parts between forawrd slashes (/) in directory and filenames, is restricted to 255 characters. Synchronizing a file or directory version that contains path segments longer than this limit leads to those versions being put into quarantine.

Client side filtering

OX Drive clients may define a user- and/or application-defined list of file- and directory name exclusions. Those exclusion filters are then taken into account during synchronization, i.e. files and directories matching a defined exclusion pattern are ignored when comparing the list of server-, client- and original versions. Also, the file exclusion lists are considered for the calculation of aggergated directory checksums.

The exclusion filters may be set, changed or unset at any time during synchronization, there are no additional requests needed to set them up. Instead, the list of excluded files and directories is simply sent along with each syncFolders, syncFiles and download request. The following tables show the JSON representation of file- and directory patterns that are used to build up the exlcusion lists:

Directory pattern

A directory pattern is defined by a pattern string and further attributes.

Name	Type	Value
type	String	The pattern type, currently one of `exact` or `glob`.
path	String	The path pattern, in a format depending on the pattern type.
caseSensitive	Boolean	Optional flag to enable case-sensitive matching, defaults to `false`

File pattern

A file pattern is defined by pattern strings for the filename and path, as well as further attributes.

Name	Type	Value
type	String	The pattern type, currently one of `exact` or `glob`.
path	String	The path pattern, in a format depending on the pattern type.
name	String	The filename pattern, in a format depending on the pattern type.
caseSensitive	Boolean	Optional flag to enable case-sensitive matching, defaults to `false`

Pattern types

A pattern currently may be defined in two formats: exact or glob.

exact
An exact pattern, matching the file- or directory version literally. For example, to exclude the file Backup.pst in the subfolder Mail below the root synchronization folder, an exact file pattern would look like: {"path":"/Mail","name":"Backup.pst","type":"exact"}, or, an exact directory pattern for the directory /Archive would be represented as {"path":"/Archive","type":"exact"}.
glob
A simple pattern allowing to use the common wildcards * and ? to match file- and directory versions. For example, to exclude all files ending with .tmp across all directories, the glob file pattern could be defined as {"path":"*","name":"*.tmp","type":"glob"}, or, to exclude the directory /Project/.git and all its subdirectories recursively, this would be expressed using a combination of the following two directory patterns: [{"path":"/Project/.git","type":"exact"},{"path":"/Project/.git*","type":"glob"}].

Further considerations

It's possible to exclude a (parent) directory with an appropriate pattern, while still subfolders below that directory being synchronized. This usually results in the excluded directory being created ob both client- and server side, but no file contents within the excluded directory being exchanged. If subfolders should be excluded, too, a wildcard should be used in the pattern to match any subdirectories.
If the client tries to synchronize a file- or directory version that is ignored, i.e. a version that would match any of the provided exclusion filters, the server behaves similarly to the handling of invalid and ignored file- and directory names (see above), i.e. the client would be instructed to put those versions into quarantine.
For the calculation of directory checksums, it's important that the server and client perform exactly the same matching for ignored filenames: A * character matches zero or more characters, a ? character matches exactly one character. All other characters are matched literally. Advanced glob flavors like braces to define subpattern alternatives or square brackets for character sets are not used.
Client-side filtering is available with API version 2. The API version that is supported by the server is included in the response of the Settings request.
Whenever there are active exclusion filters, the syncFolders request should contain all of both directory and file exclusion filter lists. For the syncFiles request, it's sufficient to include the list of file exclusions.

Metadata Synchronization

Previously, only the "raw" folders and files were synchronized between server and clients. While this is sufficient for basic synchronization, there are cases where the clients could benefit from additional data - "metadata" - that is already available on the server. For example, clients could display directories that have been shared or published to other people in a different way. Or, clients could consider folder permissions directly in case the user is performing a local change that would be rejected by the server in the next synchronization cycle anyway.

To supply the clients with those additional information without any influence on the existing synchronization protocol (!), .drive-meta files are introduced for each synchronized directory. Regarding synchronization, such files are treated like any other ordinary file. Especially, those files are taken into account when it comes to directory checksum calculation. Doing so, metadata updates result in a changed .drive-meta file, which in turn causes the parent directory checksum to change, hence synchronization is triggered.

However, some special handling applies for those files:

Clients are not allowed to change metadata, so modifications of metadata files or the deletion of them is rejected. Recovery is done via the protocol here, i.e. the client is instructed to re-download the file.
.drive-meta files are actually not stored physically on the file storage backend, but created on the fly based on the actual metadata of the directory.
Client applications may either store such files on the client file system, or evaluate and store the contained metadata information in a local database for later retrieval. If the file is not saved physically on the client (which is actually recommended), the client is responsible to consider the metadata file in a virtual way and include it's checksum for the directory checksum calculation - similar to the server's internal handling.

Note: Embedded metadata synchronization is enabled by default, but can be forcibly disabled by setting the driveMeta parameter to false in each request.

Metadata format

The metadata in .drive-meta files is serialized in JSON format to allow easy processing at the clients. The following shows an example of the contents:

{
  "path": "/",
  "localized_name": "Meine Dateien",
  "own_rights": 403710016,
  "permissions": [{
    "bits": 403710016,
    "group": false,
    "entity": 182,
    "display_name": "Mander, Jens",
    "email_address": "jens.mander@example.com",
    "guest": false
  }],
  "shareable": true,
  "jump": ["permissions"],
  "files": [{
    "name": "Koala.jpg",
    "created": 1418024190565,
    "modified": 1418026995663,
    "created_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "modified_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "preview": "http://192.168.32.191/ajax/files?action=document&folder=268931&id=268931/297620&version=1&delivery=download&scaleType=contain&width=800&height=800&rotate=true",
    "thumbnail": "http://192.168.32.191/ajax/files?action=document&folder=268931&id=268931/297620&version=1&delivery=download&scaleType=contain&width=100&height=100&rotate=true",
    "object_permissions": [{
      "bits": 1,
      "group": false,
      "entity": 10,
      "display_name": "Klaus Mander",
      "email_address": "klaus.mander@example.com",
      "guest": false
    },
    {
      "bits": 1,
      "group": false,
      "entity": 8338,
      "email_address": "horst@example.com",
      "guest": true
    }],
    "shareable": true,
    "shared": true,
    "number_of_versions": 1,
    "version": "1",
    "jump": ["preview",
    "permissions",
    "version_history"]
  },
  {
    "name": "test.txt",
    "created": 1418024198520,
    "modified": 1418027394897,
    "created_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "modified_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "preview": "http://192.168.32.191/ajax/files?action=document&format=preview_image&folder=268931&id=268931/297621&version=6&delivery=download&scaleType=contain&width=800&height=800",
    "thumbnail": "http://192.168.32.191/ajax/files?action=document&format=preview_image&folder=268931&id=268931/297621&version=6&delivery=download&scaleType=contain&width=100&height=100",
    "locked": true,
    "shareable": true,
    "number_of_versions": 4,
    "version": "6",
    "version_comment": "Uploaded with OX Drive (TestDrive)",
    "versions": [{
      "name": "test.txt",
      "file_size": 23,
      "created": 1418024198520,
      "modified": 1418024202878,
      "created_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "modified_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "version": "1",
      "version_comment": "Uploaded with OX Drive (TestDrive)"
    },
    {
      "name": "test.txt",
      "file_size": 54,
      "created": 1418024234782,
      "modified": 1418024231522,
      "created_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "modified_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "version": "2",
      "version_comment": "Uploaded with OX Drive (TestDrive)"
    },
    {
      "name": "test.txt",
      "file_size": 120,
      "created": 1418027349026,
      "modified": 1418027355957,
      "created_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "modified_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "version": "5"
    },
    {
      "name": "test.txt",
      "file_size": 127,
      "created": 1418027370051,
      "modified": 1418027366945,
      "created_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "modified_by": {
        "group": false,
        "entity": 182,
        "display_name": "Mander, Jens",
        "email_address": "jens.mander@example.com",
        "guest": false
      },
      "version": "6",
      "version_comment": "Uploaded with OX Drive (TestDrive)"
    }],
    "jump": ["preview",
    "edit",
    "permissions",
    "version_history"]
  },
  {
    "name": "Kalimba.mp3",
    "created": 1418026529047,
    "modified": 1247549551659,
    "created_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "modified_by": {
      "group": false,
      "entity": 182,
      "display_name": "Mander, Jens",
      "email_address": "jens.mander@example.com",
      "guest": false
    },
    "preview": "http://192.168.32.191/ajax/image/file/mp3Cover?folder=268931&id=268931/297623&version=1&delivery=download&scaleType=contain&width=800&height=800",
    "thumbnail": "http://192.168.32.191/ajax/image/file/mp3Cover?folder=268931&id=268931/297623&version=1&delivery=download&scaleType=contain&width=100&height=100",
    "shareable": true,
    "number_of_versions": 1,
    "version": "1",
    "version_comment": "Uploaded with OX Drive (TestDrive)",
    "jump": ["preview",
    "permissions",
    "version_history"]
  }]
}

The following objects describe the JSON structure of the metadata for a directory:

Directory Metadata

Name	Type	Value
id	String	The server-side unique identifier of the directory.
localized_name	String	The localized display name of the directory, if different from the physical name.
checksum	String	The directory's checksum. Only set if metadata is not retrieved through Metadata Synchronization.
own_rights	Number	Folder permissions which apply to the current user, as described in HTTP API (Permission Flags).
permissions	Array	All folder permissions, each element is an object as described in HTTP API (Permission Object).
extended_permissions	Array	All folder permissions including some additional information, each element is an object as described in HTTP API (Extended Permission Object).
default_folder	Boolean	`true` if the folder is a default folder, `false` or not set, otherwise.
has_subfolders	Boolean	`true` if the folder (potentially) has subfolders, `false` or not set, otherwise.
shared	Boolean	`true` if the folder is shared, `false` or not set, otherwise.
shareable	Boolean	`true` if the folder can be shared to others by the user, `false` or not set, otherwise.
not_synchronizable	Boolean	`true` if the folder is exluded from synchronization, `false` or not set, otherwise.
type	Number	The special folder type, or not set, if not available.
jump	Array	An array containing the names of possible jump methods to use for the folder.
files	Array	Metadata for the contained files, each element is an object as described in File Metadata. Only set if metadata is retrieved through Metadata Synchronization.

File Metadata

Name	Type	Value
name	String	The name of the file the metadata belongs to.
checksum	String	The file's checksum. Only set if metadata is not retrieved through Metadata Synchronization.
path	String	The path of the parent directory. Only set if metadata is not retrieved through Metadata Synchronization.
created	Timestamp	The file's last modification time (always UTC, not translated into user time).
modified	Timestamp	The file's last modification time (always UTC, not translated into user time).
created_by	Number	User ID of the user who created this object.
modified_by	Number	User ID of the user who last modified this object.
content_type	String	The content type of the file.
preview	String	A URL to a preview image for the file.
thumbnail	String	A URL to a thumbnail image for the file.
object_permissions	Array	All file permissions, each element is an object as described in HTTP API (Object Permission Object).
extended_object_permissions	Array	All file permissions including some additional information, each element is an object as described in HTTP API (Extended Object Permission Object).
shared	Boolean	`true` if the file is shared, `false` or not set, otherwise.
shareable	Boolean	`true` if the file can be shared to others by the user, `false` or not set, otherwise.
locked	Boolean	`true` if the file is locked, `false` or not set, otherwise.
jump	Array	An array containing the names of possible jump methods to use for the file.
number_of_versions	Number	The number of all versions of the file.
version	String	The current version identifier (usually, but not necessarily a numerical value) of the file.
version_comment	String	An additional comment for the file version.
versions	Array	Metadata for all versions of the file, each element is an object as described in File Version.

File Version

Name	Type	Value
name	String	The name of the file version.
file_size	Number	The file size of the version in bytes.
created	Timestamp	The file version's last modification time (always UTC, not translated into user time).
modified	Timestamp	The file version's last modification time (always UTC, not translated into user time).
created_by	Number	User ID of the user who created this object.
modified_by	Number	User ID of the user who last modified this object.
version	String	The version identifier (usually, but not necessarily a numerical value) of the file version.
version_comment	String	An additional comment for the file version.

Client-side implementation

In order to make use of the metadata, clients should roughly implement the following:

Include the apiVersion parameter in each request, and set it to at least 3 in order to include .drive-meta during synchronization
Evaluate .drive-meta files and store the information, as well as the file's checksums in a local database
Include this file in the calculation of the parent directory checksum, just like an ordinary file in that directory
Do something useful with the metadata information.

Additional notes

The metadata synchronization via .drive-meta files embedded into the synchronization protocol obsoletes the previously used methods to receive metadata information (fileMetadata and columns parameter in syncFiles).
Depending on the underlying file storage backend, the included metadata may vary, so each information should be treatened as optional.
Embedded metadata synchronization is enabled by default, but can be forcibly disabled by setting the driveMeta parameter to false in each request.

Possible use cases

For files where the locked property is true, display some kind of "lock" icon (-overlay) in the file list / explorer view
For files or folders where the shared property is true, display some kind of "cloud" icon (-overlay) in the file list / explorer view
For files or folders where the user is not allowed to perform an action with, don't offer such actions (e.g. if a file cannot be deleted or renamed by the user due to insufficient permissions, disable the corresponding options)
Use the URLs in preview and thumbnail to get a preview image for the files
Display the server creation / last modification timestamps of files and folders
Embed a version history for files with multiple versions
Show to which users a file or folder is currently shared
Offer appropriate "jump" actions to the groupware web interface for more advanced options (e.g. to directly edit an .xlsx file in the spreadsheet application of the web interface, or to manage a folder's permission

Synchronize files for multiple folders

Utilizing the multiple request, it is possible to execute multiple "syncfiles" requests in parallel. Especially during an initial synchronization and in combination with "inline" mode for .drive-meta files, this may reduce the number of necessary requests. Therefore, the parameters and file versions of each syncfiles request are serializied into a JSON array of the multiple-request body. In the same way, the response contains the resulting actions of each "syncfiles" result in an JSON array of the response.

The following shows an example of executing three syncfiles actions inside a single mutliple request:

==> PUT http://local.ox/ajax/multiple?session=0833ca06093a4bad826347a30bf7ace7&continue=true
  > Content:
    [{
      "module": "drive",
      "action": "syncfiles",
      "root": 33,
      "apiVersion": 4,
      "path": "/",
      "driveMeta": "inline",
      "data": {
        "clientVersions": [],
        "originalVersions": []
      }
    },
    {
      "module": "drive",
      "action": "syncfiles",
      "root": 33,
      "apiVersion": 4,
      "path": "/Pictures",
      "driveMeta": "inline",
      "data": {
        "clientVersions": [],
        "originalVersions": []
      }
    },
    {
      "module": "drive",
      "action": "syncfiles",
      "root": 33,
      "apiVersion": 4,
      "path": "/Music",
      "driveMeta": "inline",
      "data": {
        "clientVersions": [],
        "originalVersions": []
      }
    }]

<== HTTP 200 OK (92.2341 ms elapsed, 2058 bytes received)
<   Content:
    [{
      "data": [{
        "action": "download",
        "newVersion": {
          "checksum": "e9000b2444dfbc780f91df6586e24615",
          "name": ".drive-meta"
        },
        "totalLength": 1663,
        "data": {
          "id": "33",
          "default_folder": true,
          "has_subfolders": true,
          "own_rights": 403710016,
          "permissions": [{
            "bits": 403710016,
            "entity": 4,
            "group": false
          }],
          "extended_permissions": [{
            "entity": 4,
            "bits": 403710016,
            "type": "user",
            "display_name": "Jens Mander",
            "contact": {
              "email1": "jens@local.ox",
              "last_name": "Mander",
              "first_name": "Jens",
              "image1_url": "/ajax/image/user/picture?id=4&timestamp=1453992059223"
            }
          }],
          "jump": ["permissions"],
          "shareable": true,
          "files": [{
            "name": "versions.txt",
            "created": 1458723308686,
            "modified": 1458723332449,
            "created_by": 4,
            "modified_by": 4,
            "content_type": "text/plain",
            "preview": "http://local.ox/ajax/files?action=document&format=preview_image&folder=33&id=33/488915&version=1&context=1&user=4&delivery=download&scaleType=contain&width=1600&height=1600",
            "thumbnail": "http://local.ox/ajax/files?action=document&format=preview_image&folder=33&id=33/488915&version=1&context=1&user=4&delivery=download&scaleType=contain&width=200&height=150",
            "shareable": true,
            "number_of_versions": 4,
            "version": "1",
            "versions": [{
              "name": "versions.txt",
              "file_size": 1,
              "created": 1458723308686,
              "modified": 1458723308686,
              "created_by": 4,
              "modified_by": 4,
              "version": "1"
            },
            {
              "name": "versions.txt",
              "file_size": 3,
              "created": 1458723311033,
              "modified": 1458723311019,
              "created_by": 4,
              "modified_by": 4,
              "version": "2",
              "version_comment": ""
            },
            {
              "name": "versions.txt",
              "file_size": 5,
              "created": 1458723313260,
              "modified": 1458723332449,
              "created_by": 4,
              "modified_by": 4,
              "version": "3",
              "version_comment": ""
            },
            {
              "name": "versions.txt",
              "file_size": 8,
              "created": 1458723316567,
              "modified": 1458723316551,
              "created_by": 4,
              "modified_by": 4,
              "version": "4",
              "version_comment": ""
            }],
            "jump": ["preview",
            "edit",
            "permissions",
            "version_history"]
          }]
        },
        "path": "/",
        "modified": 1467622558800
      },
      {
        "action": "download",
        "newVersion": {
          "checksum": "c4ca4238a0b923820dcc509a6f75849b",
          "name": "versions.txt"
        },
        "totalLength": 1,
        "created": 1458723308686,
        "path": "/",
        "modified": 1458723332449
      }]
    },
    {
      "data": [{
        "action": "download",
        "newVersion": {
          "checksum": "46114c4a55ed74b836da0fd83809fb06",
          "name": ".drive-meta"
        },
        "totalLength": 2531,
        "data": {
          "id": "103432",
          "default_folder": true,
          "has_subfolders": true,
          "type": 20,
          "own_rights": 403710016,
          "permissions": [{
            "bits": 403710016,
            "entity": 4,
            "group": false
          },
          {
            "bits": 257,
            "entity": 192,
            "group": false
          }],
          "extended_permissions": [{
            "entity": 4,
            "bits": 403710016,
            "type": "user",
            "display_name": "Jens Mander",
            "contact": {
              "email1": "jens@local.ox",
              "last_name": "Mander",
              "first_name": "Jens",
              "image1_url": "/ajax/image/user/picture?id=4&timestamp=1453992059223"
            }
          },
          {
            "entity": 192,
            "bits": 257,
            "type": "guest",
            "display_name": "Otto Example",
            "contact": {
              "email1": "otto@example.com"
            }
          }],
          "jump": ["permissions"],
          "shared": true,
          "shareable": true,
          "files": [{
            "name": "Desert.jpg",
            "created": 1458717785226,
            "modified": 1458717785226,
            "created_by": 4,
            "modified_by": 4,
            "content_type": "image/jpeg",
            "preview": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/488906&version=1&context=1&user=4&delivery=download&scaleType=contain&width=1600&height=1600&shrinkOnly=true&rotate=true",
            "thumbnail": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/488906&version=1&context=1&user=4&delivery=download&scaleType=contain&width=200&height=150&shrinkOnly=true&rotate=true",
            "shareable": true,
            "number_of_versions": 1,
            "version": "1",
            "jump": ["preview",
            "permissions",
            "version_history"]
          },
          {
            "name": "Hydrangeas.jpg",
            "created": 1458717785374,
            "modified": 1458717785374,
            "created_by": 4,
            "modified_by": 4,
            "content_type": "image/jpeg",
            "preview": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/488907&version=1&context=1&user=4&delivery=download&scaleType=contain&width=1600&height=1600&shrinkOnly=true&rotate=true",
            "thumbnail": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/488907&version=1&context=1&user=4&delivery=download&scaleType=contain&width=200&height=150&shrinkOnly=true&rotate=true",
            "shareable": true,
            "number_of_versions": 1,
            "version": "1",
            "jump": ["preview",
            "permissions",
            "version_history"]
          },
          {
            "name": "2110.JPG",
            "created": 1460283874321,
            "modified": 1460443249927,
            "created_by": 4,
            "modified_by": 4,
            "content_type": "image/jpeg",
            "preview": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/494179&version=1&context=1&user=4&delivery=download&scaleType=contain&width=1600&height=1600&shrinkOnly=true&rotate=true",
            "thumbnail": "http://local.ox/ajax/files?action=document&folder=103432&id=103432/494179&version=1&context=1&user=4&delivery=download&scaleType=contain&width=200&height=150&shrinkOnly=true&rotate=true",
            "shareable": true,
            "number_of_versions": 1,
            "version": "1",
            "jump": ["preview",
            "permissions",
            "version_history"]
          }]
        },
        "path": "/Pictures",
        "modified": 1459842066104
      },
      {
        "action": "download",
        "newVersion": {
          "checksum": "7c1e3c12567f8279dff97faee04af9c2",
          "name": "2110.JPG"
        },
        "totalLength": 4421093,
        "created": 1460283874321,
        "path": "/Pictures",
        "modified": 1460443249927
      },
      {
        "action": "download",
        "newVersion": {
          "checksum": "ba45c8f60456a672e003a875e469d0eb",
          "name": "Desert.jpg"
        },
        "totalLength": 845941,
        "created": 1458717785226,
        "path": "/Pictures",
        "modified": 1458717785226
      },
      {
        "action": "download",
        "newVersion": {
          "checksum": "bdf3bf1da3405725be763540d6601144",
          "name": "Hydrangeas.jpg"
        },
        "totalLength": 595284,
        "created": 1458717785374,
        "path": "/Pictures",
        "modified": 1458717785374
      }]
    },
    {
      "data": [{
        "action": "download",
        "newVersion": {
          "checksum": "9829c1949b6347cec22467e34b0814dd",
          "name": ".drive-meta"
        },
        "totalLength": 438,
        "data": {
          "id": "103434",
          "default_folder": true,
          "type": 22,
          "own_rights": 403710016,
          "permissions": [{
            "bits": 403710016,
            "entity": 4,
            "group": false
          }],
          "extended_permissions": [{
            "entity": 4,
            "bits": 403710016,
            "type": "user",
            "display_name": "Jens Mander",
            "contact": {
              "email1": "jens@local.ox",
              "last_name": "Mander",
              "first_name": "Jens",
              "image1_url": "/ajax/image/user/picture?id=4&timestamp=1453992059223"
            }
          }],
          "jump": ["permissions"],
          "shareable": true,
          "files": []
        },
        "path": "/Music",
        "modified": 1465453273921
      }]
    }]

Table of Contents

Introduction

API

File Version

Directory Version

Actions

acknowledge

edit

download

upload

remove

sync

error

File- and Directory Name Restrictions

Invalid and ignored Filenames

Invalid and ignored Directory Names

Length Restrictions

Client side filtering

Directory pattern

File pattern

Pattern types

Further considerations

Metadata Synchronization

Metadata format

Directory Metadata

File Metadata

File Version

Client-side implementation

Additional notes

Possible use cases

Synchronize files for multiple folders