[jira] [Updated] (DAFFODIL-2254) BLOB support for scanning for end of blob

["Steve Lawrence (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DAFFODIL-2254?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steve Lawrence updated DAFFODIL-2254:
-------------------------------------
    Priority: Minor  (was: Major)

> BLOB support for scanning for end of blob
> -----------------------------------------
>
>                 Key: DAFFODIL-2254
>                 URL: https://issues.apache.org/jira/browse/DAFFODIL-2254
>             Project: Daffodil
>          Issue Type: New Feature
>          Components: Back End
>    Affects Versions: 2.5.0
>            Reporter: Steve Lawrence
>            Priority: Minor
>
> To keep the initial BLOB imlementation relatively simple, it only supports lengthKind="explicit". However, some formats may need a scanning mechanism to find the end of the BLOB. One example of this is RPM, which has a compressed payload at the end of the file, and the length is just everything from one point to the end of the file. We ideally want to treat this payload as a blob, but since there is no explicit length for it, some sort of scanning must occurr.
> Some initial thoughts for potential solutions:
> 1. lengthKind="delimited" allows for the end of the data stream to be a delimiter. So we could just make changes to delimiter scanning to support outputting the field to a blob file rather than somewhere in internal memory. This would allow for supporting delimited blobs in cases more than just end of stream, but could be some what challenging of a change.
> 2. Support endOfParent for blobs, or perhaps a new lengthKind, or a blob specific property that can be used for end of data. The logic here would likely be much simpleer than delimier scanning, but is pretty single purpose. 



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