[GridSim-users] Flow Links - GridSimCore

[Jonathan M. <jon...@bs...>]

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Hi all,

Analyzing the code, I've found that my problem with new flow level network is
that there is a "pretty" static attribute in GridSimCore, which is initialized
to NET_PACKET_LEVEL by default...

[...]

/** Specifies which type of network to be used.
     * By default, the simulation uses the gridsim.net package or differentiated
     * network service. To change this default property, please use the
     * {@link gridsim.GridSim#initNetworkType(int)} method <b>before</b> the
     * simulation starts.
     * @see gridsim.GridSim#initNetworkType(int)
     * @see gridsim.GridSimTags#NET_PACKET_LEVEL
     * @see gridsim.GridSimTags#NET_FLOW_LEVEL
     * @see gridsim.GridSimTags#NET_BUFFER_PACKET_LEVEL
*/
protected static int NETWORK_TYPE = GridSimTags.NET_PACKET_LEVEL;

[...]


This implies that every creation of an entity based on GridSimCore (such as
users) initializes its Sim_ports in/out with Input/Output types... which are
incompatible with flow networking (that use FlowInput/FlowOutput).

To solve this...you can see the "note" in the javadoc of GridSimCore that tells
us how to change this attribute:

[...] use the gridsim.GridSim.initNetworkType(int) method before the
      simulation starts. [...]

But that is not completely true, because calling the method immediately before
GridSim.startGridSimulation is useless, since all the entities that are created
before starting the simulation would use the default NET_PACKET_LEVEL.

So eventually, the solution is using the method immediately after GridSim is
initialized (GridSim.init), instead of before starting the simulation.


Finally, my question to developers is, why do you use this static attribute
instead of taking the type of Link into account to know whether we want old
input/output or new flowinput/flowoutput?

Moreover, I think that you shouldn't expect that users find this note in
GridSimCore class documentation.


Thanks,


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Jonathan Martí Fraiz
Storage Systems Research Group  - Computer Sciences Department
Barcelona Supercomputing Center - Centro Nacional de Supercomputación
www   : http://www.bsc.es/StorageSystems
email : jonathan(dot)marti(at)bsc(dot)es
phone : (0034) 934054281
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