Monday, 1 March 2010

The M-Word

There is one term that you really can't avoid in Grid computing - as much as you might want to.

It is the M-word - Middleware - a term that apparently dates back to the late 60s and has been gathering new definitions ever since.

As far as the current work of the NGS is concerned, Middleware is the software that you install on an existing computer system to hook it into the grid.

For sites associated with GridPP project, this software is gLite.

If you are outside GridPP and do not wish to use gLite, we currently recommend packages from the Virtual Data Toolkit (VDT). VDT is a project from the US Open Science Grid to collect together and package as much grid software as practical. There are more than enough packaged applications within VDT to get an NGS affiliate site on the grid.

Full NGS partners - who might need something gLite-like and capable of supporting many virtual organisations - can extend VDT with another set of seemingly random letters LCAS/LCMAPS (Local Centre Authorisation Service/ Local Credential Mapping Service).

To simplify the job of selecting the relevant packages from VDT, and building LCAS/LCMAPS - NGS staff have developed the 'NGS VDT Installer scripts'. These are maintained via the National eScience Centre's NeSCForge service (

The scripts started as a way of collating and documenting the knowledge of NGS operations staff.

Three years ago, the original NGS 'core' sites at RAL (STFC), Oxford, Manchester and Leeds had all deployed VDT but had set the service up independently.

So we got together, agreed on what packages were needed, how they should be configured and what local tweaks needed to make things work. Rather than simply documenting this information, we turned it into a set of executable scripts - the 'NGS VDT Installer' scripts - which could produce a consistent VDT-based service on a host.

The scripts can be thought of as runnable documentation. Someone who needed to reproduce a standard NGS installation could either run the script or read it as a guide to what to do.

More recently, following work done at Manchester, we scripted the process to building LCAS/LCMAPS. There is now a set of scripts that can take a site to full NGS partner status.

Maintaining and developing the installer scripts is one of the jobs of the NGS research and development group and we released the latest version last Friday.

Bug reports permitting, this will be the last of this generation of install scripts.

So where do we go from here?

That depends on what happens to the M-word over the next few months.

We do know VDT is still being developed. We also know there are plans to produce a pan-european Unified Middleware Distribution incorporating gLite.

Whatever happens, we'll be watching.

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