1. Introduction
2. Basics
3. Overlapping and Hierarchichal Descriptions
4. Provenance Graph Definition
5. Timeless Formal Model
6. Inferences
7. Formal Model and Time Annotations
8. Time Constraints and Inferences
9. Support for Collections
10. Example of Representation
11. Conclusion
12. Best Practice on the Use of Agensts
13. References

Comments

Best Practice on the Use of Agents

With the defined notion of account, we now revisit the sky mosaic example. Instead of Figure~\repegasus:figur, a different description could encompass the steps the operating system (or the grid) goes through in order to execute a program (as in the PASS and ES3 approaches). Figure~\repegasus3b:figur illustrates some possible causal dependencies for a system-level description. Here, we see an explicit reference to the workflow script used by the enactor.

Figure 18: Overlapping Montage Provenance

Naturally, both descriptions can coexist in a same provenance graph, using the concept of overlapping descriptions, as depicted by Figure \repegasus3c-1:figur. While such a description is perfectly acceptable, it fails to tell us that the agent Pegasus/Condor Dagman is this executable, which itself was activated under the control of the operating system (or Grid).

Figure 19: Montage Provenance

In other circumstances, it is necessary to explain that multiple agents were all controlling a same process, but from different perspective. For the case present, the researcher who controlled the experiment, the enactment engine, and the funding institution are all potential causes of the experiment. We then obtain Figure~\repegasus4:figur, where we see three processes triggering the production of a mosaic. Further experience will the model will allow us to identify guidelines to promote inter-operability of systems.

Figure 20: Multiple Agents Controlling a Process

-- PaulGroth - 31 Jul 2008