How to offer epub on website question

[Kimberh]

Hi, I'm this question has been ask before but I can't seem to find the answer.

I have been able to convert the book into files formats epub and opf using
Calibre. I want to put a link on my web site offering the free book.

How if I just offer the epub file as a download then the file will not open correct for others. I assume they need the opf file also. How do I convert or set up the book so it can be offered as a download on my web site.

Thank you very much for any help
Kimberly

[theducks]

Originally Posted by Kimberh

Hi, I'm this question has been ask before but I can't seem to find the answer.

I have been able to convert the book into files formats epub and opf using
Calibre. I want to put a link on my web site offering the free book.

How if I just offer the epub file as a download then the file will not open correct for others. I assume they need the opf file also. How do I convert or set up the book so it can be offered as a download on my web site.

Thank you very much for any help
Kimberly

This is not really a Calibre question

EPUB is the book
If it will not open with an EPUB viewer, the book is not a valid EPUB.

Is the question 'How to flag a file as a Download' vs 'open in place'?
(Your Webmaster should know how to do this as a download)

[arjaybe]

The opf file is metadata for Calibre, isn't it? It doesn't need to be provided along with the epub for download.

[phossler]

Originally Posted by Kimberh

Hi, I'm this question has been ask before but I can't seem to find the answer.

I have been able to convert the book into files formats epub and opf using
Calibre. I want to put a link on my web site offering the free book.

How if I just offer the epub file as a download then the file will not open correct for others. I assume they need the opf file also. How do I convert or set up the book so it can be offered as a download on my web site.

Thank you very much for any help
Kimberly

The 'BookName.epub' is a zip file so if you rename the .epub part to .zip you can look at the 'innards'

The metadata.opf file is actually one of the files that is zipped into a single epub file so it's already there.

I understand that there can be differences between the OPF in the caliber folder and the OPF in the epub. I think it has to do with editing the metadata with Calibre and as opposed to actually editing the book (at least that's my experience, but I'm sure the more experienced members will jump in with a better explanation)

There is a very nice plugin called 'Modify epub' that will actually incorporate the Calibre cover and metadata into the epub file, as well as make other changes an cleanups.

[BetterRed]

@phossler - AFAIK the metadata.opf file in a book folder only serves one purpose - as a backup of the what's in the metadata.db database. My understanding is that it's only read by the Library Maintenance->Restore database function.

Any similarities between its content and similarly named components inside an ePub are coincidental. The book editor can be used independently without the presence of any calibre libraries.

Mentally, I rename the metadata.opf files in the book folders to calibre.metabak, and turn on the Hidden and Read only attributes

BR

[phossler]

I'm really don't know the ins and outs of Calibre or epub-ing so I'll gladly defer to the more knowledgeable members

I was only saying I thought there could be a difference between the metadata in the folder's OPF file and the OPF file in the epub based on what I read in the help file for the Modify ePub plug in:

Update metadata

Updates the ePub metadata in the manifest (such as title, description, authors etc). In some limited circumstances it will also update the cover as well, however you should instead also check the “Insert or replace cover” option for a more reliable cover replacement option.

Use this option to update the title/author/description internal metadata for your ePub to get it “up to date” for use in the calibre ebook viewer.

[eschwartz]

@BetterRed, not strictly true. It will also be read by the Adding books function, if using the option that treats each directory as a separate book, and possibly the other recursive adding as well.

@phossler, that refers to the EPUB manifest. It is true that Polish will update the manifest with the same data as the external opf, but that is a coincidence, a byproduct of the fact that that external opf is a backup copy of the metadata in the database. In other words, Polish does not read from the external opf. Nothing ever reads from the external opf, with the exception of Restore database and things like Adding books.

IMHO it distracts from the issue to discuss the differences between the metadata in calibre and in the EPUB itself.
That does NOT touch upon the OP's concern, which is that the EPUB might not open.

[PeterT]

Do you also have to ensure the correct mime-type for the .epub file?

[BetterRed]

Originally Posted by phossler

I'm really don't know the ins and outs of Calibre or epub-ing so I'll gladly defer to the more knowledgeable members

I was only saying I thought there could be a difference between the metadata in the folder's OPF file and the OPF file in the epub based on what I read in the help file for the Modify ePub plug in:

The Modify PI, and Polish, Embed Metadata, Conversion etc, take the metadata they write to output file (ePub or otherwise) from the database (metadata.db) not from the metadata.opf files in the book folders. The latter may not even be up to date if you just did a bulk update, and that includes correcting a misspelt Author or Publisher name or a Tag value.

Rewrites of the metadata.opf files occur in the background, depending on the number of books affected by a given change that can take a long time - as in hours.

@eschwartz - I had a suspicion that one or more of the Add books options might use it, but I wasn't sure under what circumstances - I add all books via a shell Send To->Autoadd.

Originally Posted by eschwartz

IMHO it distracts from the issue to discuss the differences between ...

Would that include digressions on the relative merits of chocolate v strawberry ice cream with your bête noire perennial protagonist

BR

[dwig]

Originally Posted by Kimberh

...
How if I just offer the epub file as a download then the file will not open correct for others.

It should open fine. If it doesn't then one of the following:

• it wasn't a properly formated ePub to start with
• it was corrupted when uploaded to the web site
• it was corrupted when it was downloaded from the web site.

Corruption can be severe or very minor. Frequently the source is a mis-configured web site that doesn't associate the proper MIME-type with the ePub file format. This can lead the downloading app/browser to make a mistake.

I assume they need the opf file also. ...

As others that discussed at length, no they don't need the OPF.

To avoid confusion, most users should disable/uncheck the "Save metadata in a separate OPF file" in the Prefs>Save to Disk panel. Then, when you use Save to Disk to extract an eBook for use outside of calibre you don't get the extra file. Checking the "Save cover separately" option, though, can be a handy way to get a cover image for use on the web site. One should always use Save to Disk rather than probing into the calibre's library folder tree manually.

[eschwartz]

Originally Posted by BetterRed

Would that include digressions on the relative merits of chocolate v strawberry ice cream with your bête noire perennial protagonist

BR

Well, distractions are one thing, confusions are another. So long as it is relatively easy to tell what is offtopic, well, I am as guilty as anyone.

[Kimberh]

Thanks to everyone for your help. I learned a lot.