High level api

[gernot-h]

@tngraf, we discussed about this proposal already Siemens-internal a while ago. I still use and love it in a number of places, especially for interactive API usage, so here's the public PR. :)

Several times, I found myself writing project-specific JSON parsing code (especially to parse ['_embedded']['sw360:releases'] and friends). So I started with first basic classes and made some important attributes and especially relations available in an OO fashion.

My code tries to be a thin and maintenable extension to the mostly direct API access we have now, only adding OO abstractions where they provide real benefit. To avoid the need to closely follow each SW360 api change, I only make important attributes available, the rest is available as the usual JSON data in the details attribute.

Example session:

>>> debian10 = sw360.get_project("123")
>>> debian10 = sw360.Project(debian10)
>>> debian10
Project(name='Debian_Buster', version='10', project_id='365275b1c92aae35d49f4a9c012dd7e9')
>>> debian10.releases                                                                                                                                  
{'334': Release(name='strace', version='4.26-0.2.debian', release_id='334'),
 'cd4': Release(name='usbutils', version='010-3.debian', release_id='cd4'),
 '7f5': Release(name='Linux Kernel', version='4.19.98-1.debian', release_id='7f5'),
[...]
>>> for release_id, release in debian10.releases.items(): 
...     print(release.name, release.version)
strace 4.26-0.2.debian
usbutils 010-3.debian
[...]
>>> release = debian10.releases['334']
>>> release.attachments
{}
>>> release.get(sw360_api)  # you will only get basic data within SW360 project, get full release data now
>>> release.attachments                                                                                                                                    
{'ed4': Attachment(attachment_type='CLEARING_REPORT', filename='strace_4.26-0.2_report.docx', attachment_id='ed4'),
 '659': Attachment(attachment_type='SOURCE_SELF', filename='strace_4.26-0.2.tar.bz2', attachment_id='659')}

Main open points:

• For now, this only allows read access to SW360, code to push changes to the instances back to SW360 needs to be added, e.g. to_json() methods.
• How to create high-level objects without breaking / duplicating low-level API? Currently, there are two ways: rel = Release(sw360.get_release("1234")), rel = Release().get(sw360, "1234")
• Use SW360 names for attributes or Python-style ones? (attachment_type vs. attachmentType)

[gernot-h]

@heliocastro, as you already contributed some valuable refactoring code, perhaps you're interested in reviewing my proposal for an OO API extension here? I would love to hear your opinion...

[gernot-h]

Agreed with @tngraf to proceed with the MR, open topics before merge:

• clearly state in documentation that low-level API is the official, maintained one where the other is just best-effort, also verify that this statement is rendered on https://sw360.github.io/sw360python/
• probably add objects for new Package feature

[heliocastro]

Just FIY, we're in full mode towards next SW360 release, where we we kicked away liferay and whole authentication methods changed and extended API calls will exist, so some refactoring will be needed on sw360python as well.
( Yes, i'm willing to help as well )