Hi Joe, I follow your reasoning on the semantics of "media". One might argue that media files are a case of "document" or that a document is a case of "media".
I'm not proposing filters for the mode of processing, I'm proposing a flag/enum with 3 values: A) extract metadata only; B) extract content only and place it into the flowfile content; C) extract both metadata and content. I think the default should be C, to extract both. At least in my experience most flows I've dealt with were interested in extracting both. I don't see how this mode would benefit from being expression driven - ? I think we can add this enum mode and have the basic use case covered. Additionally, further down the line, I was thinking we could ponder the following (these have been essential in search engine ingestion): 1. Extraction from compressed files/archives. How would UnpackContent work with ExtractMediaAttributes? Use-case being, we've got a zip file as input and want to crack it open and unravel it recursively; it may have other, nested zips inside, along with other documents. One way to handle this is to treat the whole archive as one document and merge all attributes into one FlowFile. The other way would be to treat each archive entry as its own flow file and keep a pointer back at the parent archive. Yet another case is when the user might want to only extract the 'leaf' entries and discard any parent container archives. 2. Attachments and embeddings. Users may want to treat any attached or embedded files as separate flowfiles with perhaps pointers back to the parent files. This definitely warrants a filter. Oftentimes Office documents have 'media' embeddings which are often not of interest, especially for the case of ingesting into a search engine. 3. PDF. For PDF's, we can do OCR. This is important for the 'image'/scanned PDF's for which Tika won't extract text. I'd like to understand how much of this is already supported in NiFi and if not I'd volunteer/collaborate to implement some of this. - Dmitry On Wed, Mar 30, 2016 at 9:03 AM, Joe Skora <[email protected]> wrote: > Dmitry, > > Are you proposing separate filters that determine the mode of processing, > metadata/content/metadataAndContent? I was thinking of one selection > filters and a static mode switch at the processor instance level, to make > configuration more obvious such that one instance of the processor will > handle a known set of files regardless of the processing mode. > > I was thinking it would be useful for the mode switch to support expression > language, but I'm not sure about that since the selection filters will > control what files get processed and it would be harder to configure if the > output flow file could vary between source format and extracted text. So, > while it might be easy to do, and occasionally useful, I think in normal > use I'd never have a varying mode but would more likely have multiple > processor instances with some routing or selection going on further > upstream. > > I wrestled with the naming issue too. I went with "ExtractMediaAttributes" > over "ExtractDocumentAttributes" because it seemed to represent the broader > context better. In reality, media files and documents and documents are > media files, but in the end it's all just semantics. > > I don't think I would change the NAR bundle name, because I think > "nifi-media-nar" establishes it as a place to collect this and other media > related processors in the future. > > Regards, > Joe > > On Tue, Mar 29, 2016 at 3:09 PM, Dmitry Goldenberg < > [email protected] > > wrote: > > > Hi Joe, > > > > Thanks for all the details. > > > > I wanted to propose that I do some of this work so as to go through the > > full cycle of developing a processor and committing it. > > > > Once your changes are merged, I could extend your 'ExtractMediaMetadata' > > processor to handle the content, in addition to the metadata. > > > > We could keep the FILENAME_FILTER and MIMETYPE_FILTER but add a mode > with 3 > > values: metadataOnly, contentOnly, metadataAndContent. > > > > One thing that looks to be a design issue right now is, your changes and > > the 'nomenclature' seem media-oriented ("nifi-media-nar" etc.) > > > > Would it make sense to have a generic processor > > ExtractDocumentMetadataAndContent? Are there enough specifics in the > > image/video processing stuff to warrant that to be a separate layer; > > perhaps a subclass of ExtractDocumentMetadataAndContent ? Might it make > > sense to rename nifi-media-nar into nifi-text-extract-nar ? > > > > Thanks, > > - Dmitry > > > > > > > > On Tue, Mar 29, 2016 at 2:36 PM, Joe Skora <[email protected]> wrote: > > > > > Dmitry, > > > > > > Yeah, I agree, Tika is pretty impressive. The original ticket, > NIFI-615 > > > <https://issues.apache.org/jira/browse/NIFI-615>, wanted extraction of > > > metadata from WAV files, but as I got into it I found Tika so for the > > same > > > effort it supports the 1,000+ file formats Tika understands. That new > > > processor called "ExtractMediaMetadata", you can pull that pull PR-252 > > > <https://github.com/apache/nifi/pull/252> from GitHub if you want to > > give > > > it a try before it's merged. > > > > > > Extraction content for those 1,000+ formats would be a valuable > addition. > > > I see two possible approaches, 1) create a new "ExtractMediaContent" > > > processor that would put the document content in a new flow file, and > 2) > > > extend the new "ExtractMediaMetadata" processor so it can extract > > metadata, > > > content, or both. One combined processor makes sense if it can > provide a > > > performance gain, otherwise two complementary processors may make usage > > > easier. > > > > > > I'm glad to help if you want to take a cut at the processor yourself, > or > > I > > > can take a crack at it myself if you'd prefer. > > > > > > Don't hesitate to ask questions or share comments and feedback > regarding > > > the ExtractMediaMetadata processor or the addition of content handling. > > > > > > Regards, > > > Joe Skora > > > > > > On Thu, Mar 24, 2016 at 11:40 AM, Dmitry Goldenberg < > > > [email protected]> wrote: > > > > > > > Thanks, Joe! > > > > > > > > Hi Joe S. - I'm definitely up for discussing and contributing. > > > > > > > > While building search-related ingestion systems, I've seen metadata > and > > > > text extraction being done all the time; it's always there and always > > has > > > > to be done for building search indexes. Beyond that, OCR-related > > > > capabilities are often requested, and the advantage of Tika is that > it > > > > supports OCR out of the box. > > > > > > > > - Dmitry > > > > > > > > On Thu, Mar 24, 2016 at 11:36 AM, Joe Witt <[email protected]> > wrote: > > > > > > > > > Dmitry, > > > > > > > > > > Another community member (Joe Skora) has a PR outstanding for > > > > > extracting metadata from media files using Tika. Perhaps it makes > > > > > sense to broaden that to in general extract what Tika can find. > Joe > > - > > > > > perhaps you can discuss your ideas with Dmitry and see if > broadening > > > > > is a good idea or if rather domain specific ones make more sense. > > > > > > > > > > This concept of extracting metadata from documents/text files, > etc.. > > > > > using something like Tika is certainly useful as that then can > drive > > > > > nice automated routing decisions. > > > > > > > > > > Thanks > > > > > Joe > > > > > > > > > > On Thu, Mar 24, 2016 at 9:28 AM, Dmitry Goldenberg > > > > > <[email protected]> wrote: > > > > > > Hi, > > > > > > > > > > > > I see that the ExtractText processor extracts text using regex. > > > > > > > > > > > > What about a processor that extracts text and metadata from > > incoming > > > > > > files? That doesn't seem to exist - but perhaps I didn't quite > > look > > > in > > > > > the > > > > > > right spots. > > > > > > > > > > > > If that doesn't exist I'd like to implement and commit it, using > > > Apache > > > > > > Tika. There may also be a couple of related processors to that. > > > > > > > > > > > > Thoughts? > > > > > > > > > > > > Thanks, > > > > > > - Dmitry > > > > > > > > > > > > > > >
