3.1.urn:ietf:params:jmap:blob

The presence of the capabilityurn:ietf:params:jmap:blob in theaccountCapabilities property of an account represents support for additionalAPI methods on the Blob datatype. Servers that include the capability in oneor more accountCapabilities propertiesMUST also include theproperty in the capabilities property.¶

The value of this property in the JMAP Session capabilitiespropertyMUST be an empty object.¶

The value of this property in an account's accountCapabilitiesproperty is an object thatMUST contain the following informationon server capabilities and permissions for that account:¶

• maxSizeBlobSet: "UnsignedInt|null"¶

  The maximum size of the blob (in octets) that the server will allow to be created (including blobs created by concatenating multiple data sources together).¶

  ClientsMUST NOT attempt to create blobs larger than this size.¶

  If this value isnull, then clients are not required to limit the size of the blob they try to create, though servers can always reject creation of blobs regardless of size, e.g., due to lack of disk space or per-user rate limits.¶

• maxDataSources: "UnsignedInt"¶

  The maximum number of DataSourceObjects allowed per creation in a Blob/upload.¶

  ServersMUST allow at least 64 DataSourceObjects per creation.¶

• supportedTypeNames: "String[]"¶

  An array of data type names that are supported forBlob/lookup. If the server does not support lookups, then this will be the empty list.¶

  Note that the supportedTypeNames list may include private types that are not in the "JMAP Data Types" registry defined by this document. ClientsMUST ignore type names they do not recognise.¶

• supportedDigestAlgorithms: "String[]"¶

  An array of supported digest algorithms that are supported forBlob/get. If the server does not support calculating blob digests, then this will be the empty list. Algorithms in this listMUST be present in the "HTTP Digest Algorithm Values" registry defined by[RFC3230]; however, in JMAP, they must be lowercased, e.g., "md5" rather than "MD5".¶

  ClientsSHOULD prefer algorithms listed earlier in this list.¶

{  "capabilities": {    ...,    "urn:ietf:params:jmap:blob": {}  },  "accounts": {    "A13842": {      ...      "accountCapabilities": {        "urn:ietf:params:jmap:blob": {          "maxSizeBlobSet": 50000000,          "maxDataSources": 100,          "supportedTypeNames" : [            "Mailbox",            "Thread",            "Email"          ],          "supportedDigestAlgorithms" : [            "sha",            "sha-256"          ]        }      }    }  }}

4.1.Blob/upload

This is similar to a Foo/set in[RFC8620] in someways. However, blobs cannot be updated or deleted, so onlycreate isallowed in the method call. Also, blobs do not have state, so there is nostate field present in the method response.¶

Parameters¶

• accountId: "Id"¶

  The id of the account in which the blobs will be created.¶

• create: "Id[UploadObject]"¶

  A map of creation id to UploadObjects.¶

Result¶

The result is the same as for Foo/set in[RFC8620], withcreated andnotCreated objectsmapping from the creation id.¶

Thecreated objects contain:¶

• id: "Id"¶

  The blobId that was created.¶

• type: "String|null"¶

  The media type as given in the creation (if any). If not provided, the serverMAY perform content analysis and return one of the following: the calculated value, "application/octet-string", or null.¶

• size: "UnsignedInt"¶

  As per[RFC8620], the size of the created blob in octets.¶

The created objects will also contain any other properties identical to those that would be returned in the JSON response of the upload endpoint described in[RFC8620]. This may be extended in the future; in this document, it is anticipated that implementations will extend both the upload endpoint and the Blob/upload responses in the same way.¶

If there is a problem with a creation, then the server will return anotCreated response with a map from the failed creation id to aSetError object.¶

For each successful upload, serversMUST add an entry to thecreatedIds map ([RFC8620],Section 3.3) for the request; even if the caller did not explicitly pass acreatedIds, the value must be available to later methods defined in the sameRequest Object. This allows the blobId to be used via back-reference insubsequent method calls.¶

The created blob will have the same lifetime and same expiry semantics asany other binary object created via the mechanism specified in[RFC8620],Section 6.¶

Uploads using this mechanism will be restricted by the maxUploadSize limitfor JMAP requests specified by the server, and clientsSHOULDconsider using the upload mechanism defined by[RFC8620] for blobs larger than a megabyte.¶

UploadObject¶

• data: "DataSourceObject[]"¶

  An array of zero or more octet sources in order (zero to create an empty blob). The result of each of these sources is concatenated in order to create the blob.¶

• type: "String|null" (default: null)¶

  A hint for media type of the data.¶

DataSourceObject¶

Exactly one of:¶

• data:asText: "String|null" (raw octets, must be UTF-8)¶

• data:asBase64: "String|null" (base64 representation of octets)¶

or a blobId source:¶

• blobId: "Id"¶

• offset: "UnsignedInt|null" (MAY be zero)¶

• length: "UnsignedInt|null" (MAY be zero)¶

Ifnull, then offset is assumed to be zero.¶

Ifnull, then length is the remaining octets in the blob.¶

If the range cannot be fully satisfied (i.e., it begins or extends pastthe end of the data in the blob), then the DataSourceObject is invalidand results in a notCreated response for this creation id.¶

If the data properties have any invalid references or invalid datacontained in them, the serverMUST NOT guess the user's intentandMUST reject the creation and return a notCreated response for thatcreation id.¶

Likewise, invalid characters in the base64 of data:asBase64 or invalidUTF-8 in data:asTextMUST result in a notCreated response.¶

It is envisaged that the definition for DataSourceObject might beextended in the future, for example, to fetch external content.¶

A serverMUST accept at least 64 DataSourceObjects per create, asdescribed inSection 3.1 of this document.¶

[ "Blob/upload", {  "accountId": "account1",  "create": {   "1": {    "data" : [    {     "data:asBase64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKA                       AAAA1BMVEX/AAAZ4gk3AAAAAXRSTlN/gFy0ywAAAApJRE                       FUeJxjYgAAAAYAAzY3fKgAAAAASUVORK5CYII="    }   ],   "type": "image/png"   }  } }, "R1"]

[  "Blob/upload",  {    "accountId" : "account1",    "created" : {      "1": {        "id" : "G4c6751edf9dd6903ff54b792e432fba781271beb",        "type" : "image/png",        "size" : 95      }    }  },  "R1"]

[ [  "Blob/upload",  {   "create": {    "b4": {     "data": [      {       "data:asText": "The quick brown fox jumped over the lazy dog."      }    ]   }  } }, "S4"],[  "Blob/upload",  {   "create": {     "cat": {       "data": [         {           "data:asText": "How"         },         {           "blobId": "#b4",           "length": 7,           "offset": 3         },         {           "data:asText": "was t"         },         {           "blobId": "#b4",           "length": 1,           "offset": 1         },         {           "data:asBase64": "YXQ/"         }       ]     }   }  },  "CAT"],[  "Blob/get",  {   "properties": [     "data:asText",     "size"   ],   "ids": [     "#cat"   ]  },  "G4" ]]

[  [    "Blob/upload",    {      "oldState": null,      "created": {        "b4": {          "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e",          "size": 45,          "type": "application/octet-stream"        }      },      "notCreated": null,      "accountId": "account1"    },    "S4"  ],  [    "Blob/upload",    {      "oldState": null,      "created": {        "cat": {          "id": "Gcc60576f036321ae6e8037ffc56bdee589bd3e23",          "size": 19,          "type": "application/octet-stream"        }      },      "notCreated": null,      "accountId": "account1"    },    "CAT"  ],  [    "Blob/get",    {      "list": [        {          "id": "Gcc60576f036321ae6e8037ffc56bdee589bd3e23",          "data:asText": "How quick was that?",          "size": 19        }      ],      "notFound": [],      "accountId": "account1"    },    "G4"  ]]

4.2.Blob/get

A standard JMAP get, with two additional optional parameters:¶

• offset: "UnsignedInt|null"¶

  Start this many octets into the blob data. If null or unspecified, this defaults to zero.¶

• length: "UnsignedInt|null"¶

  Return at most this many octets of the blob data. If null or unspecified, then all remaining octets in the blob are returned. This can be considered equivalent to an infinitely large length value, except that the isTruncated warning is not given unless the start offset is past the end of the blob.¶

Request Properties:¶

Any of:¶

• data:asText¶
• data:asBase64¶
• data (returns data:asText if the selected octets are valid UTF-8 or data:asBase64)¶
• digest:<algorithm> (where <algorithm> is one of the named algorithms in thesupportedDigestAlgorithms capability)¶
• size¶

If not given, the properties default todata andsize.¶

Result Properties:¶

• data:asText: "String|null"¶

  The raw octets of the selected range if they are valid UTF-8; otherwise, null.¶

• data:asBase64: "String"¶

  The base64 encoding of the octets in the selected range.¶

• digest:<algorithm>: "String"¶

  The base64 encoding of the digest of the octets in the selected range, calculated using the named algorithm.¶

• isEncodingProblem: "Boolean" (default: false)¶

• isTruncated: "Boolean" (default: false)¶

• size: "UnsignedInt"¶

  The number of octets in the entire blob.¶

The size valueMUST always be the number of octets in the underlying blob,regardless of offset and length.¶

The data fields contain a representation of the octets within the selectedrange that are present in the blob. If the octets selected are not validUTF-8 (including truncating in the middle of a multi-octet sequence)anddata ordata:asText was requested, then the keyisEncodingProblemMUST be set totrue, and thedata:asText response valueMUST benull.In the case wheredata was requested and the data is not valid UTF-8,thendata:asBase64MUST be returned.¶

If the selected range requests data outside the blob (i.e., theoffset+length is larger than the blob), then the result is either just theoctets from the offset to the end of the blob or an empty string if theoffset is past the end of the blob. Either way, the isTruncatedproperty in the resultMUST be set totrue to tell theclient that the requested range could not be fully satisfied. If digest wasrequested, anydigest is calculated on the octets that would bereturned for adata field.¶

ServersSHOULD store the size for blobs in a format that isefficient to read, and clientsSHOULD limit their request tojust the size parameter if that is all they need, as fetching blob contentcould be significantly more expensive and slower for the server.¶

[  [    "Blob/get",    {      "accountId" : "account1",      "ids" : [        "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e",        "not-a-blob"      ],      "properties" : [        "data:asText",        "digest:sha",        "size"      ]    },    "R1"  ],  [    "Blob/get",    {      "accountId" : "account1",      "ids" : [        "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e"      ],      "properties" : [        "data:asText",        "digest:sha",        "digest:sha-256",        "size"      ],      "offset" : 4,      "length" : 9    },    "R2"  ]]

[ [  "Blob/get",  {   "accountId": "account1",   "list": [    {     "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e",     "data:asText": "The quick brown fox jumped over the lazy dog.",     "digest:sha": "wIVPufsDxBzOOALLDSIFKebu+U4=",     "size": 45    }  ],  "notFound": [   "not-a-blob"  ] }, "R1"],[ "Blob/get", {  "accountId": "account1",  "list": [   {    "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e",    "data:asText": "quick bro",    "digest:sha": "QiRAPtfyX8K6tm1iOAtZ87Xj3Ww=",    "digest:sha-256": "gdg9INW7lwHK6OQ9u0dwDz2ZY/gubi0En0xlFpKt0OA=",    "size": 45    }   ]  },  "R2" ]]

[  [    "Blob/upload",    {      "create": {        "b1": {          "data": [            {              "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW                                Qgb3ZlciB0aGUggYEgZG9nLg=="            }          ]        },        "b2": {          "data": [            {              "data:asText": "hello world"            }          ],          "type" : "text/plain"        }      }    },    "S1"  ],  [    "Blob/get",    {      "ids": [        "#b1",        "#b2"      ]    },    "G1"  ],  [    "Blob/get",    {      "ids": [        "#b1",        "#b2"      ],      "properties": [        "data:asText",        "size"      ]    },    "G2"  ],  [    "Blob/get",    {      "ids": [        "#b1",        "#b2"      ],      "properties": [        "data:asBase64",        "size"      ]    },    "G3"  ],  [    "Blob/get",    {      "offset": 0,      "length": 5,      "ids": [        "#b1",        "#b2"      ]    },    "G4"  ],  [    "Blob/get",    {      "offset": 20,      "length": 100,      "ids": [        "#b1",        "#b2"      ]    },    "G5"  ]]

[  [    "Blob/upload",    {      "oldState": null,      "created": {        "b2": {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "size": 11,          "type": "application/octet-stream"        },        "b1": {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "size": 43,          "type": "text/plain"        }      },      "updated": null,      "destroyed": null,      "notCreated": null,      "notUpdated": null,      "notDestroyed": null,      "accountId": "account1"    },    "S1"  ],  [    "Blob/get",    {      "list": [        {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "isEncodingProblem": true,          "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW                            Qgb3ZlciB0aGUggYEgZG9nLg==",          "size": 43        },        {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "data:asText": "hello world",          "size": 11        }      ],      "notFound": [],      "accountId": "account1"    },    "G1"  ],  [    "Blob/get",    {      "list": [        {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "isEncodingProblem": true,          "size": 43        },        {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "data:asText": "hello world",          "size": 11        }      ],      "notFound": [],      "accountId": "account1"    },    "G2"  ],  [    "Blob/get",    {      "list": [        {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW                            Qgb3ZlciB0aGUggYEgZG9nLg==",          "size": 43        },        {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "data:asBase64": "aGVsbG8gd29ybGQ=",          "size": 11        }      ],      "notFound": [],      "accountId": "account1"    },    "G3"  ],  [    "Blob/get",    {      "list": [        {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "data:asText": "The q",          "size": 43        },        {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "data:asText": "hello",          "size": 11        }      ],      "notFound": [],      "accountId": "account1"    },    "G4"  ],  [    "Blob/get",    {      "list": [        {          "id": "G72cfa4804194563685d9a4b695f7ba20e7739576",          "isTruncated": true,          "isEncodingProblem": true,          "data:asBase64": "anVtcGVkIG92ZXIgdGhlIIGBIGRvZy4=",          "size": 43        },        {          "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",          "isTruncated": true,          "data:asText": "",          "size": 11        }      ],      "notFound": [],      "accountId": "account1"    },    "G5"  ]]

4.3.Blob/lookup

Given a list of blobIds, this method does a reverse lookup in each ofthe provided type names to find the list of Ids within that data typethat reference the provided blob.¶

Since different datatypes will have different semantics of "contains",the definition of "reference" is somewhat loose but roughlymeans "you could discover this blobId by looking at this object orat other objects recursively contained within this object".¶

For example, with a server that supports[RFC8621], if a Mailbox references a blob and if any Emailswithin that Mailbox reference the blobId, then the Mailbox references thatblobId. For any Thread that references an Email that references a blobId, itcan be said that the Thread references the blobId.¶

However, this does not mean that if an Email references a Mailbox in itsmailboxIds property, then any blobId referenced by other Emails inthat Mailbox are also referenced by the initial Email.¶

Parameters¶

• accountId: "Id"¶

  The id of the account used for the call.¶

• typeNames: "String[]"¶

  A list of names from the "JMAP Data Types" registry or defined byprivate extensions that the client has requested. Only namesfor which "Can reference blobs" is true may be specified, and thecapability that defines each type must also be used by the overallJMAP request in which this method is called.¶

  If a type name is not known by the server, or the associated capabilityhas not been requested, then the server returns an "unknownDataType"error.¶

• ids: "Id[]"¶

  A list of blobId values to be looked for.¶

Response¶

• list: "BlobInfo[]"¶

  A list of BlobInfo objects.¶

BlobInfo Object¶

• id: "Id"¶

  The blobId.¶

• matchedIds: "String[Id[]]"¶

  A map from type name to a list of Ids of that data type (e.g., the name"Email" maps to a list of emailIds).¶

If a blob is not visible to a user or does not exist on the server at all,then the serverMUST still return an empty array for each typeas this doesn't leak any information about whether the blob is on the serverbut not visible to the requesting user.¶

[  "Blob/lookup",  {    "typeNames": [      "Mailbox",      "Thread",      "Email"    ],    "ids": [      "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",      "not-a-blob"    ]  },  "R1"]

[  "Blob/lookup",  {    "list": [      {        "id": "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",        "matchedIds": {          "Mailbox": [            "M54e97373",            "Mcbe6b662"          ],          "Thread": [            "T1530616e"          ],          "Email": [            "E16e70a73eb4",            "E84b0930cf16"          ]        }      }    ],    "notFound": [      "not-a-blob"    ]  },  "R1"]

6.1.JMAP Capability Registration for "blob"

IANA has registered the "blob" JMAP capability as follows:¶

Capability Name:

urn:ietf:params:jmap:blob¶

Specification document:

RFC 9404¶

Intended use:

common¶

Change Controller:

IETF¶

Security and privacy considerations:

RFC 9404,Section 5¶

6.2.JMAP Error Codes Registration for "unknownDataType"

IANA has registered the "unknownDataType" JMAP error code as follows:¶

JMAP Error Code:

unknownDataType¶

Intended use:

common¶

Change Controller:

IETF¶

Reference:

RFC 9404¶

Description:

The server does not recognise this data type, or the capability to enable it is not present in the current Request Object.¶

6.3.Creation of "JMAP Data Types" Registry

IANA has created a new registry called "JMAP Data Types".Table 1 shows the initial contents of thisnew registry.¶

The registration policy for this registry is "Specification Required"[RFC8126]. Either an RFC or a similarly stable reference document defines a JMAP Data Typeand associated capability.¶

IANA will appoint designated experts to review requests for additions to thisregistry, with guidance to allow any registration that provides a stable document describingthe capability and control over the URI namespace to which the capability URI points.¶