Changes between Version 33 and Version 34 of orca-introduction

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Timestamp:
04/27/11 17:33:04 (8 years ago)
Author:
ibaldin (IP: 152.54.9.21)
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  • orca-introduction

    v33 v34  
    5959== Implementation == 
    6060 
    61 ORCA is implemented as a webapp intended to run inside a Tomcat Java servlet engine. A webapp implements a ''container'' in which one or more ORCA actors run. Actors can communicate with other actors across multiple containers. Actors digitally sign their communications using self-signed certificates (using certificates issued by a commercial CA is also possible). SSL is not used. We believe that state-changing commands or actions must be signed so that actions are non-repudiable and actors can be made accountable for their actions. SSL alone is not sufficient for this purpose. Given that we are concerned with message integrity and authenticity, and not privacy, SSL is not necessary either.  
     61ORCA is implemented as a webapp intended to run inside a Tomcat Java servlet engine. A webapp is packaged as a [http://en.wikipedia.org/wiki/WAR_file_format_(Sun) webapp WAR file]. Internally the webapp implements a ''container'' in which one or more ORCA actors run. Actors can communicate with other actors across multiple containers. Actors digitally sign their communications using self-signed certificates (using certificates issued by a commercial CA is also possible). SSL is not used. We believe that state-changing commands or actions must be signed so that actions are non-repudiable and actors can be made accountable for their actions. SSL alone is not sufficient for this purpose. Given that we are concerned with message integrity and authenticity, and not privacy, SSL is not necessary either.  
    6262 
    6363ORCA currently uses a slightly modified version of Tomcat 5.5 [source:/software/tomcat.tar.gz avaiable here]. Off-the-shelf Tomcat or other servlet engine (like Jetty) will not work.  
     
    6969== Configuration == 
    7070 
    71 Configuring ORCA requires creating a container.properties file which defines the basic properties of the entire container and an XML file which contains the configuration for the actors that will run inside this container. The container.properties file is read at webapp startup (either when the webapp is deployed into Tomcat engine, or when the Tomcat engine is restarted) and therefore can be modified at any time without affecting other parts of ORCA. The actor configuration XML file must be included into the [http://en.wikipedia.org/wiki/WAR_file_format_(Sun) webapp WAR file] and therefore any time this file is changed, the ORCA war file must be repackaged and the webapp must be redeployed to take effect. 
     71Configuring ORCA requires creating two configuration files: 
    7272 
    73 The actor configuration XML file defines the actors in a given container (their types, properties and plugins used by them; for authority actors it defines what resources are available to this actor and how to control them via handlers). It also defines how actors in this container communicate between each other and actors in other containers (i.e. ''actor topology'') 
     73 * container.properties file which defines the basic properties of the entire container. A sample file is available [source:orca/trunk/webapp/config/container.properties here] 
     74 * an XML file which contains the configuration for the actors that will run inside this container.  
     75 
     76The container.properties file is stored outside the webapp and is read at webapp startup (either when the webapp is deployed into a running Tomcat engine, or when the Tomcat engine is restarted) and therefore can be modified at any time without affecting other parts of ORCA.  
     77 
     78A [source:orca/trunk/webapp/actor_configs/config.xml default actor configuration XML file] is included with the binary distribution of the webbapp and the source code. This file starts a single-container emulation of three basic ORCA actors - an authority, a broker and a service manager. Emulation refers to the fact that ORCA does not operate on real substrate and only goes through the motions of managing reservations. An alternative configuration XML file can be created and placed outside of ORCA, in which case the default file will be ignored. Also, if you are rebuilding ORCA from source, you can package it with your own version of the actor configuration XML file. 
    7479 
    7580A relatively new feature of ORCA is an [http://geni.renci.org:11080/registry/actors.jsp ORCA actor registry] - a separate component that is run as a service for all ORCA users. If desired actors in any container can register with this registry and thus automatically become visible to all other publicly available actors. This feature allows for a much simpler configuration process, especially the actor topology part. In many cases using the ORCA Actor Registry makes the actor topology definition unnecessary.