GNDMS Architecture Primer

This is the GNDMS Architecture Primer. It is developer-level documentation that gives a general overview of the different layers of GNDMS, how they inter-operate with Globus Toolkit, as well as important concepts, components and classes. It is incomplete at this point.

The Layers of the Software Stack

The running GNDMS software stack roughly looks like this:

< Service Clients ------------------------------------------------------ >
[ services: DSpace, GORFX ---------------------------------------------- ]    
[ gritserv-------------------------------------------------------------- ]
|                 [ infra ---------------------------------------------- ]
|                 [ logic ---------------------------------------------- ]
|                 |                                    < Configuration > |
|                 |                                    < Monitor Shell > |
|                 [ kit ------------------------------------------------ ]
|                 |                                                      |    
|                 |               [ model --------------------]          |
|                 |               |                           |          |    
|                 |               [ stuff -------- ]          |          |      
|                 |               |                |          |          |
[ Service Stubs ]-[ GT4 Container ]                [ Open-JPA ]-[ Groovy ]
|                                                  [ Derby    ]-[ Jetty  ]
|                                                                        |    
[ Additional External Libraries ---------------------------------------- ]

Legend:

[ Module ]        # Software Module
                  # -- modules higher in the Stack
                  # -- depend on modules below them
	      
< Tool   >        # Software Tool
                  # -- what is below is needed to run

For the gndmc client, an additional layer is required:

< gndmc client --------------------------------------------------------- >
[ gndmc ---------------------------------------------------------------- ]
[ services: DSpace, GORFX ---------------------------------------------- ]    
..........................................................................

The software stack for building, installing, deployment and configuration of GNDMS roughly looks like this:

< buildr --------------------------------------------------------------- >
[ Build ---------------------------------------------------------------- ]
[ Buildr 1.4 ----------------------------------------------------------- ] 
|             [ introduce ------------ ]                                 |
[ JRuby 1.5 ] [ Ant ]                    < Configuration --------------- >    
[ Java 2 SDK 1.6 --------------------- ] < Monitor Shell --------------- >
< local UNIX tools ----------------------------------------------------- >

Components

Component Categories

There are several kinds of components that make up the GNDMS service stack. They can be grouped into various categories

Main
GNDMS source code to be found below a top-level diretory and directly built to a jar (Java)
Service
Located below services and compiled with introduce (XSD, WSDL, Java)
Client
Located below services and compiled with introduce (Part of service build process, consists of XSD, WSDL, and Java)
External
downloaded from the Internet during installation.
Globus
part of your local installation of Globus Toolkit 4.
Build
All code needed to build and install the software (Ruby and Shell). Of primary relevance are the Buildfile in $GNDMS_SOURCE and everything in $GNDMS_SOURCE/buildr.
Config
All code needed to configure GNDMS from the outside (Shell and possibly Groovy)

Components

Service Clients (Client)
Any program that accesses GNDMS via WSRF.
GORFX (Service)
The GORFX service provides the negotiation and execution of data management activites (like Staging and File Transfer) according to a co-scheduling protocol (located below $GNDMS_SOURCE/services/GORFX).
DSpace (Service)
The DSpace service provides management of storage resources (located below $GNDMS_SOURCE/services/DSpace).
gritserv (Main)
Service-level code that is shared between different grid services, like e.g. XSD type conversion (located below $GNDMS_SOURCE/gritserv).
infra (Main)
Main infrastructure code that ties the service code to GNDMS main classes. Configuration, Database setup, Dependency injection (located below $GNDMS_SOURCE/infra).
logic (Main)
All ‘Business’ logic of GNDMS that can be implemented outside of the actual service classes (located below $GNDMS_SOURCE/logic).
Configuration (Config)
Configuration scripts below $GNDMS_SOURCE scripts are executing during installation in order to configure a GNDMS instance for its purpose in a given community grid (located below $GNDMS_SOURCE/scrips).
Monitor Shell and Utilities (Config)
The monitor shell (client) allows access to the monitor shell implemented kit (located below $GNDMS_SOURCE/bin).
kit (Main)
Utility classes that depend on some functionality from Globus Toolkit and/or model. Kit contains the implementation of the GNDMS monitor shell and GridFTP auxiliaries (located below $GNDMS_SOURCE/kit).
model (Main)
Database model classes (located below $GNDMS_SOURCE/model)
stuff (Main)
Various utility classes (located below $GNDMS_SOURCE/stuff)
Service Stubs (Service)
Stub code needed to communicate with the Grid WSRF Services of GNDMS (located inside services).
GT4 Container (Globus)
The Globus Toolkit 4 WSRF Service Container.
Open JPA (External)
GNDMS uses Apache OpenJPA 2.0 as its Object Relational Mapper (ORM).
Derby (External)
GNDMS uses Apache Derby 1.5 as its underlying embedded database.
Groovy (External)
GNDMS provides support to access the system at runtime by means of executing groovy script code via the monitor shell.
Jetty (External)
The monitor shell is implemented atop a stripped-down version of jetty.
Additional External Libraries (External)
GNDMS uses a large selection of 3rd party libraries. Please either consult the Buildfile or $GNDMS_SOURCE/lib/gndms-depencies[.xml] (post-install) to find out more details. Consult $GNDMS_SOURCE/doc/licensing for licensing conditions of 3rd party components.
Build (Build)
Build scripts are written in ruby and placed in $GNDMS_SOURCE/Buildfile and $GNDMS_SOURCE/buildr/*.
Buildr 1.4 (Build)
GNDMS relies on Apache Buildr for build, installation, and deployment.
introduce (Build)
The Introduce Tool from the CAGrid project was used to generate service skeletons below $GNDMS_SOURCE/services.
JRuby 1.5 (Build)
Buildr needs this.
Java 2 SDK 1.6 (All)
GNDMS has been written in Java.
Documentation
Documentation is generated using Javadoc and Jekyll (has been installed in the included JRuby distribution)

GNDMS distribution packages contain a version of JRuby with preinstalled buildr and Jekyll. This is not a part of GNDMS (You could always fallback to your local installation of these tools) and provided for convenience only.

Suggested Code Walkthrough

  • Read the available documentation before entering the code, it will give you a rough idea of how everything is connected
  • Get to know the model classes
  • Read the action framework (Everything that inherits from de.zib.gndms.logic.action.Action)
  • Checkout infra/src/de/zib/gndms/infra/system/EMTools.java to understand how actions and the database are connected
  • Checkout Ext*ResourceHome in DSpace to see how resources are persisted.
  • Read the *ServiceImpl classes to see the actual workflow that is triggered by incoming requests. Follow down to code in logic as you see fit.
  • Read infra/src/de/zib/gndms/infra/system/GNDMSystem.java and infra/src/de/zib/gndms/infra/system/GNDMSystemDirectory.java to understand how GNDMS is bootstrapped and wired
  • The monitor is in kit in case you need to touch it