This one's a little trickier than it probably should be.
Your options are as follows.
If the zip files you want to read are fixed, you can you/should use a Reader/Feature Reader. These can decrypt the zip file automatically.
You may also be interested in this Community Answer which covers the structure of zip files: http://fmepedia.safe.com/AnswersQuestionDetail?id=906a0000000cl94AAA
If you must use a HttpFetcher, you will need to write the contents of the response to your disk before unzipping it. You do this with an AttributeFileWriter. Then there are various options for unzipping:
- a FeatureReader, as above (optimal)
- some Python (i.e.:
exec unzip -oq @Value(_ZipFileName)) followed by a FeatureReader (suboptimal)
For more information on the process see:
http://fmepedia.safe.com/articles/How_To/Read-Zip-File-from-URL-as-Source-Data-for-Workspace ; However, Note that this is dated 2011, so doesn't account for the fact that FME as of 2013 supports native ZIP file reading with Readers.