wiki:GEMINI/Tutorial/GEC20/GENI_Desktop_and_GEMINI_data/RetrieveData

Version 7 (modified by mkeele@indiana.edu, 5 years ago) (diff)

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Retrieving data from periscope supporting backend

Overview

In the previous exercise, you may already have configured measurement probes via the GENI Desktop GUI. Here we are going to show you what happens in UNIS, the topology services that actually support and direct the measurements.


How Components Are Connected


The above diagram shows the components of GEMINI framework. When a user reserve a slice and the slivers on the slice, hosts are created and connections between the hosts are built as well. Next step is to initialize and instrumentize these raw resources, and during this procedure, several tools are installed to your machines. BLiPP, the probe agent is installed at each measurement points. One task that BLiPP carries out is to run various kinds of probes including ping, iperf, traceroute etc. An users can either let these agents run some default probe or manually start probes at selected times. here's the link https://github.com/periscope-ps/blipp to the BLiPP repo and wiki page where you can investigate more about using blipp for your special probes.


BLiPP generates Metadata and Data

BLiPP runs user probes, parses the command line output and eventually uploads the result data to the measurement storage (MS). The MS is running at the Global Node and collecting data for the slice. Because there could be many kinds of measurement data collected at different experiment period, and they all can be large. We separate the data into Metadata and Data. The metadata should describe which particular measurement event a real data set belongs to and the metadata is stored at UNIS as bookkeeping information. The real data, on the other hands will be stored at the Global Node on the slices, so it should not overwhelm UNIS service. Realizing that there are three UNIS objects involved in the business: the measurement, the metadata of the measurement and the data of the metadata.


  • The measurement object: a measurement object depict what probe the user want to use, and how to run this probe. It configures the probe command line arguments, user preference (e.g. how many times to repeat and what the interval is).
  • The metadata object: it is a handle stored at UNIS to retrieve the real data on the Global Node on each slice. It is also the key information users should specify if they need to access their raw data.
  • The data is the real output stored in the format of JSON


How to Access the Data through the RESTful API (step through)

step-by-step process of scanning the topology, looking for metadata, finding the eventTypes you are interested in (using unis_client.py or a browser), and then ms_plot.py as a simple graphing tool tht can be customized for whatever graphing the user needs


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