DIETAGENT(1)

NAME¶

dietAgent - DIET grid middleware agent

NAME¶

dietAgent - Main binary of the DIET Architecture for running DIET Agents (master and local agents)

SYNOPSYS¶

dietAgent [config file] ...

DESCRIPTION¶

The DietAgent is the main binary of the DIET distribution. It is used for both master and local agents of a DIET hierarchy.

DIET PLATFORM¶

A DIET platform is buildt upon Server Daemons (SeD). Requests are distributed amongst a hierarchy of agents. The scheduler can rely on resources availability informations collected from three different tools: NWS sensors which are placed on every node of the hierarchy, from the application-centric performance prediction tool FAST which relies on NWS informations or from CoRI Easy a module based on simple system calls and basic performance tests.

The different components of a DIET architecture are the following:

Client: A client is an application which uses DIET to solve computational problems. Clients could be web pages, PSE scripts like Matlab or Scilab or native program.
Master Agent (MA): A MA manages computation requests from clients. It chooses the best server available to handle the request based on performance informations collected from servers. Then, the reference of the chosen server is returned to the client.
Local Agent (LA): A LA transmits requests between MAs and servers. LAs store a list of services available in their subtree. For each service, LAs store a list of children (either agents or servers) providing the former. Depending on the underlying network topology, a hierarchy of LAs may exists between the MA and the appropriate servers, one of LAs tasks is to do a partial scheduling on its subtree, effectively reducing its MA workload.
Server Daemon (SeD): A SeD encapsulate a computational resource. FOr instance, it can be locate on the entry point of a parallel computer. SeD store a list of locally available data, available computational solvers and performance-related information (available memory amount or number or resources). During registration, SeD declare to its parent agent (LA or MA) every computational problem it can solve. SeD can send performance and hardware informations by using the CoRI module or performance predictions for some kinds of problems by using the FAST module.
Master Agent DAG (MA DAG): The Master Agent DAG (MADAG) provides DAG workflow scheduling. This agent serves as the entry point to the Diet Hierarchy for a client that wants to submit a workflow. The language supported by the MADAG is based on XML.

CORBA USAGE FOR DIET¶

DIET relies on the CORBA naming service for service discovery allowing every entity to interconnect. Reference to the omniORB naming service is written down in a CORBA configuration file whose path is given to omniORB through the environment variable OMNIORB_CONFIG.

The lines concerning the name server in the omniORB configuration file are built as follows:

InitRef  =  NameService=corbaname::<hostname>:<port>

The name server port is the port given as an argument to the -start option of omniNames. You also need to update your LD LIBRARY PATH to point to <install dir>/lib. So your LD LIBRARY PATH environment variable should now be :

LD LIBRARY PATH=<omniORB home>/lib:<install dir>/lib.

NB1: In order to avoid name collision, every agent must be assigned a different name in the name server; since they don’t have any children, SeDs do not need names assigned to them and they don’t register with the name server.

NB2: Each Diet hierarchy can use a different name server, or multiple hierarchies can share one name server (assuming all agents are assigned unique names). In a multi-MA environment, in order for multiple hierarchies to be able to cooperate it is necessary that they all share the same name server.

OPTIONS¶

config_file: Configuration file used by the agent to launch the DIET entity

DIET CONFIGURATION FILE¶

Every DIET entity requires a configuration file.

Please note that:

comments start with ’#’ and finish at the end of the current line,
meaningful lines have the format: keyword = value, following the format of configuration files for omniORB 4,
for options that accept 0 or 1, 0 means no and 1 means yes, and
keywords are case sensitive.

Depending on the type of DIET element, different kinds of keyword could be found. Here is a list of the possible keywords for a DIET Agent configuration file:

traceLevel

Integer value corresponding to the traceLevel for the DIET agent:

0: DIET do not print anything.
1: DIET prints only warnings and errors on the standard error output.
2: [default] DIET prints information on the main steps of a call.
5: DIET prints information on all internal steps too.
10: DIET prints all the communication structures too.
>10: (traceLevel - 10) is given to the ORB to print CORBA messages too.

0 Diet do not print anything, – 1 Diet prints only warnings and errors on the standard error output, – 2 [default] Diet prints information on the main steps of a call, – 5 Diet prints information on all internal steps too, – 10 Diet prints all the communication structures too, – > 10 (traceLevel - 10) is given to the ORB to print CORBA messages too.

agentType: three possible values

DIET MASTER AGENT (or MA) for a Master Agent
DIET LOCAL AGENT (or LA) for a Local Agent
DIET_MA_DAG for an MA DAG Agent

dietPort

Integer setting the listening port of the agent. If left empty, the ORB will get an open port from the system (if default 2809 is busy).

dietHostName

String setting the listening interface of the agent. If left empty, the ORB will use the system hostname (the first one if several are available).

name

String identifying the element. Clients and children nodes (LAs and SeDs) must point to the same CORBA Naming Service hosting the MA.

parentName

String identifying the parent agent.

[Remark: Only DIET Local Agents could use the parentName keyword]

fastUse

Boolean enabling/disabling FAST module. If set to 0, all LDAP and NWS parameters are ignored, and all requests to FAST are disabled (when Diet is compiled with FAST). This is useful while testing a DIET platform without having to deploy an LDAP base nor an NWS platform.