so…

ZIP files as XML Catalogs

Volume 5, Issue 19; 12 Aug 2021
Published by Norman Walsh

Schemas and other resources are often distributed in ZIP files. Now you can just point the resolver at them.

As I proposed a couple of weeks ago, I’ve implemented the feature whereby you can just put ZIP files on the catalog path.

TL;DR, you can try this out with the 3.1.0-SNAPSHOT release of XML Resolver:

  1. Create a ZIP file containing the resources you want to resolve.
  2. Add a catalog to it that resolves URIs for those resources relative to the catalog.
  3. Add the ZIP file to the catalog path.

ZIP files seem to come in two flavors, one that unzip files into the current directory: 

$ unzip -v sample
Archive:  sample.zip
 Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
--------  ------  ------- ---- ---------- ----- --------  ----
    1481  Defl:N      398  73% 07-11-2021 10:02 28c9c5bd  sample.xsd
     266  Defl:N      155  42% 07-11-2021 10:02 b499b6f3  blocks.rnc
    1129  Defl:N      273  76% 07-28-2021 17:29 22734814  catalog.xml
   …
     417  Defl:N      188  55% 07-11-2021 10:02 0d156a81  blocks.dtd
--------          -------  ---                            -------
   18972             5994  68%                            13 files

and ones that unzip files into a common subdirectory: 

$ unzip -v dir-sample.zip
Archive:  dir-sample.zip
 Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
--------  ------  ------- ---- ---------- ----- --------  ----
       0  Stored        0   0% 08-10-2021 16:27 00000000  directory-x.y/
    1481  Defl:N      398  73% 07-11-2021 10:02 28c9c5bd  directory-x.y/sample.xsd
     266  Defl:N      155  42% 07-11-2021 10:02 b499b6f3  directory-x.y/blocks.rnc
    1129  Defl:N      273  76% 07-28-2021 17:29 22734814  directory-x.y/catalog.xml
   …
     417  Defl:N      188  55% 07-11-2021 10:02 0d156a81  directory-x.y/blocks.dtd
--------          -------  ---                            -------
   18972             5994  68%                            14 files

If every entry in the ZIP file begins with the same directory name (e.g., directory-x.y/), then the resolver looks for directory-x.y/org/xmlresolver/catalog.xml and directory-x.y/catalog.xml. If it finds both, it uses the former.

If there are no leading directories, or if there are different leading directories, or if only some files are in directories, then the resolver looks for org/xmlresolver/catalog.xml and catalog.xml. Once again, if it finds both, it uses the former.

Feedback welcome.