ReDaC Service Usage

Simple Tutorial for using ReDaC (Redeployment and Reconfiguration)

Prerequisite:

Before you proceed further, please read the step-by-step tutorial page first.

Note:

ReDaC is a middleware service provided by the DAnCE framework.
ReDaC service is used for redeployment and/or reconfiguration of your running component-based application on the fly without shutting down your application.
ReDaC currently works for CIAO QoS-enabled component middleware only.

Example Description

We will use the Hello example to illustrate how one could use ReDaC service to perform redeployment and reconfiguration.

Initial Deployment

Below steps are required for the initial deployment of your application, which is performed by DAnCE. The below steps are different from those presented in the step-by-step tutorial page in the sense that we pass different command line options to the Plan_Launcher client:

Go into the descriptors directory Start NodeManagers (NodeDameons) by running run_NodeDaemons.pl

This step is the same as the one presented in the step-by-step tutorial page.

Start the execution manager: $CIAO_ROOT/DAnCE/ExecutionManager/Execution_Manager -o EM.ior -i NodeManagerMap.dat

As one can see, we use the "NodeManagerMap.dat" file to instruct the Execution_Manager how to find the endpoint of each individual NodeManager (i.e., Node Daemon) where component(s) will be deployed.

This step is the same as the one presented in the step-by-step tutorial page.

Start the plan launcher: $CIAO_ROOT/DAnCE/Plan_Launcher/plan_launcher -p flattened_deploymentplan_without_ns.cdp -k file://EM.ior -o DAM.ior

After this, components should be deployed successfully.
This step is different from the one presented in the step-by-step tutorial page in the way that we added an additional "-o" option when running Plan_Launcher, which dumps an IOR file of DAnCE's DomainApplicationManager. With this option added, the plan_launcher will exit immediately after the application is deployed, instead of staying in the interactive mode. (As a normal user, you don't need to worry about the details of what exactly a DomainApplicationManager is.)

Redeployment and Reconfiguration

Basically, you could use ReDaC service in two ways.

Use ReDaC service directly through DAnCE's Plan_Launcher client
Use ReDaC service programmatically by writing your own client

This tutorial illustrates how exactly you could use ReDaC.

Use ReDaC service through Plan_Launcher of DAnCE:

As we've already mentioned, you should first deploy your Hello application with DAnCE, which is described in the above "Initial Deployment" section of this tutorial.
Use ReDaC service through Plan_Launcher's "-r" command line option to perform redeployment and reconfiguration.
Run the command $CIAO_ROOT/DAnCE/Plan_Launcher/plan_launcher -r flattened_deploymentplan_without_ns_add.cdpwill add additional components to the existing running assembly.
Run the command $CIAO_ROOT/DAnCE/Plan_Launcher/plan_launcher -r flattened_deploymentplan_without_ns_remove.cdpwill remove components from the existing running assembly.
Run the command $CIAO_ROOT/DAnCE/Plan_Launcher/plan_launcher -i file://DAM.ior will tear down your entire application completely.

NOTE: By using ReDaC through Plan_Launcher, as a user you must provide a new DeploymentPlan (.cdp) XML file, which captures the new deployment and configuration settings of your application, and the Plan_UUID of the new DeploymentPlan should be the same as the one of the old (running) DeploymentPlan. Otherwise, DAnCE will think you want to deploy a totally different deployment plan, instead of applying some changes to the existing plan. One could use CoSMIC MDD tool to create such a deployment plan XML file.

Use ReDaC service programmatically:

You could also use ReDaC service programmatically by writing your own client to invoke ReDaC service. Basically, to accomplish this, your client program needs to:

Obtain the ExecutionManager object reference, either through naming service or through IOR file.
Invoke the operation perform_redeployment on this interface by passing a single argument type called DeploymentPlan.

The IDL signature of this operation is as follows:




    void perform_redeployment (in DeploymentPlan new_plan)


      raises (PlanError,


              InstallationFailure,


              UnknownImplId,


              ImplEntryPointNotFound,


              InvalidConnection,


              InvalidProperty,


              ::Components::RemoveFailure);

In order to simplify the creation of a the "new_plan", we are implementing a utility class which allows a developer to easily manipulate a deployment plan data structure.

Email:

ciao-users@cse.wustl.edu