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i am quite noobie about OpenStack components and role, and i am having trouble understanding how each component works and when they operate; Suppose that i have a certain image in my openStack storage and a client uses it and complete some operation(like saving files); how is the interaction between the components to perform this operation?( i would like to know how and which conponents work from the creation of volumes to the changements saved; Thank you very much.

Rotom92
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    If you go through some openstack tutorials and read some of the respective books I think you will find your answer. – Athafoud Apr 01 '15 at 17:01
  • @Athafoud maybe is because i ve read but i did not understand that i am doing a question here. – Rotom92 Apr 01 '15 at 22:13

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Openstack follows Service Oriented Architecture. It uses WSGI and django framework. So, every component exposes few REST APIs.

You can find these APIs in api folder. For example (https://github.com/openstack/cinder/tree/master/cinder/api).

Internally, these API calls make call to manager. manager.py is the file which handles main logic. (https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py).

It calls underlying driver classes and co-ordinate with other openstack services through their APIs.

SaurabhJinturkar
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  • i asked to explain how the components interact (example how glance use the image, what cinder does with volumes, what is the role of swift). – Rotom92 Apr 04 '15 at 08:27
  • Glance stores image, swift is similar to S3 is Amazon web services. They interact through APIs provided. If you have any specific question please ask. – SaurabhJinturkar Apr 04 '15 at 08:36
  • thank you for the answer. What is the role of cinder in my example? it just creates the volumes where i can attach the instances of nova or what? does it save the images in phisical disks? please help me know the difference between swift role and cinder role and i'll put accept answer on the answer u gave me. Thank you for your availability. – Rotom92 Apr 04 '15 at 08:47
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    Cinder is a block storage provision service. So using cinder you can allocated drives for your computing resources. It can store varied range of data in block memory. Consider it as hard disk of your machine. While swift is object storage system. It can storage large objects such as system images and other object structures. Glance is image management service. So it will help to manage images which user can use to boot their compute resources. – SaurabhJinturkar Apr 04 '15 at 09:16
  • Ok i understood. So i use cinder for example for applications where an hard drive is needed (for example a db management or something like this) instead of swift that allows to save objects like media and so on.Thank you very much.Very kind. – Rotom92 Apr 04 '15 at 09:29