Read/download the BLOB

Motivation

Retrieve the BLOB from the field of a document or record, using API

Functional design

GET /api/v2/apps/{owner}/{app}/workspaces/{wsid}/docs/{pkg}.{table}/{id}/blobs/{fieldName}

Headers / Cookies

Authorization is supported via Bearer token. The token can be passed in the Authorization header or as a cookie. The token is obtained during the authentication process.

Key	Value	Description
Authorization	Bearer {PrincipalToken}	The token obtained during the authentication process

Parameters

Parameter	Type	Description
owner	string	name of a user who owns the application
app	string	name of an application
wsid	int64	the ID of workspace
pkg, table	string	identifies a table (document or record)
id	int64	ID of a document or record
fieldName	string	name of the field containing the BLOB

Response Headers

Key	Value	Description
Content-Type	BLOB metadata	Returns the originally provided metadata
Blob-Name	BLOB name	Returns the originally provided name
Content-Length	BLOB size	Returns the BLOB size in bytes

Result

Code	Description	Body
200	OK	BLOB binary data
400	Bad Request	error object
401	Unauthorized	error object
403	Forbidden	error object
404	Not Found	error object
429	Too Many Requests	error object
500	Internal Server Error	error object
503	Service Unavailable	error object

Technical design

Schema

Components

• pkg/router

  • API v2 URL path handler ~cmp.routerBlobsReadPathHandler~covrd¹✅:

• pkg/processors/blobber

  • BLOB request handler :
    • interface ~cmp.blobber.IRequestHandler~covrd²✅
    • implementation: read handler for APIv2, sends messages to the bus ~cmp.blobber.implIRequestHandler_Read2~covrd³✅
  • Provide BLOB processor, which handles read and write operations for BLOBs ~cmp.blobber.ProvideService~covrd⁴✅
  • Sync Pipeline of the BLOB processor ~cmp.blobber.ServicePipeline~covrd⁵✅
    • operator getBLOBMessageRead ~cmp.blobber.ServicePipeline_getBLOBMessageRead~covrd⁶✅
    • operator getBLOBIDFromOwner ~cmp.blobber.ServicePipeline_getBLOBIDFromOwner~covrd⁷✅
      • for APIv2: gets BLOB ID from the owner by fieldname by sending request to QPv2 to bus and verifies the access rights
    • operator getBLOBKeyRead ~cmp.blobber.ServicePipeline_getBLOBKeyRead~covrd⁸✅
      • creates BLOB key for reading
    • queryBLOBState ~cmp.blobber.ServicePipeline_queryBLOBState~covrd⁹✅
      • reads and verifies BLOB state from iblobstoragestg
    • downloadBLOBHelper ~cmp.blobber.ServicePipeline_downloadBLOBHelper~covrd¹⁰✅
      • for APIv1: verifies token by executing q.sys.DownloadBLOBAuthnz
    • initResponse ~cmp.blobber.ServicePipeline_initResponse~covrd¹¹✅
      • init response with BLOB name and content type
    • readBLOB ~cmp.blobber.ServicePipeline_readBLOB~covrd¹²✅
      • reads BLOB from iblobstoragestg and writes it to the response
    • catchReadError ~cmp.blobber.ServicePipeline_catchReadError~covrd¹³✅
      • handles errors

• pkg/sys/it

  • integration test for reading BLOBs
    • ~it.TestBlobsRead~covrd¹⁴✅

Footnotes

1. [~server.apiv2.blobs/cmp.routerBlobsReadPathHandler~impl] pkg/router/impl_apiv2.go:134:impl ↩

2. [~server.apiv2.blobs/cmp.blobber.IRequestHandler~impl] pkg/processors/blobber/interface.go:19:impl ↩

3. [~server.apiv2.blobs/cmp.blobber.implIRequestHandler_Read2~impl] pkg/processors/blobber/impl_requesthandler.go:38:impl ↩

4. [~server.apiv2.blobs/cmp.blobber.ProvideService~impl] pkg/processors/blobber/provide.go:17:impl ↩

5. [~server.apiv2.blobs/cmp.blobber.ServicePipeline~impl] pkg/processors/blobber/impl.go:15:impl ↩

6. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_getBLOBMessageRead~impl] pkg/processors/blobber/impl.go:21:impl, pkg/processors/blobber/impl_read.go:164:impl ↩

7. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_getBLOBIDFromOwner~impl] pkg/processors/blobber/impl.go:22:impl, pkg/processors/blobber/impl_read.go:122:impl ↩

8. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_getBLOBKeyRead~impl] pkg/processors/blobber/impl.go:23:impl, pkg/processors/blobber/impl_read.go:26:impl ↩

9. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_queryBLOBState~impl] pkg/processors/blobber/impl.go:24:impl, pkg/processors/blobber/impl_read.go:64:impl ↩

10. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_downloadBLOBHelper~impl] pkg/processors/blobber/impl.go:25:impl, pkg/processors/blobber/impl_read.go:85:impl ↩

11. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_initResponse~impl] pkg/processors/blobber/impl.go:26:impl, pkg/processors/blobber/impl_read.go:54:impl ↩

12. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_readBLOB~impl] pkg/processors/blobber/impl.go:27:impl, pkg/processors/blobber/impl_read.go:109:impl ↩

13. [~server.apiv2.blobs/cmp.blobber.ServicePipeline_catchReadError~impl] pkg/processors/blobber/impl.go:28:impl, pkg/processors/blobber/types.go:93:impl ↩

14. [~server.apiv2.blobs/it.TestBlobsRead~impl] pkg/sys/it/impl_blob_test.go:73:impl ↩