The core activity amongst all of the execution system team members is to develop, refine, and implement the notion of Virtual Grids (VGs).  This includes the VG abstraction itself, implementation technologies, and underlying statistical resource classification techniques.  To effectively support applications while achieving efficient resource selection and scheduling, VGs must enable applications to express simply their desired resource abstraction and preferences.  To develop these abstractions, we have studied several leading grid application efforts, abstracted their requirements, and evaluated the effectiveness of VG abstractions for each. We then implemented the VG abstractions deemed most useful in the Virtual Grid Execution System (vgES) and tested our evaluations. This abstraction-implementation-evaluation process continues today as we extend the vgES, notably the incorporation of support for time (slotted VGs) and reliability (fault tolerance) in new complex, adaptive workflow applications. We also continue to refine and improve implementation techniques for core vgES tasks, such as finding and binding (discovering and reserving) appropriate resources and monitoring execution status.

More details about VGs can be found on the dedicated Virtual Grid page.

The overall architecture of vgES is given on the vgES Design page.

Other pages listed at left describe activities that directly support the development and evaluation of VGs. In particular, they discuss

• Defining VGs through the Virtual Grid Description Language (vgDL)
• Characterizing resources for use in VGs through NWS measurements and statistical inference
  
• Allocating  VGs with appropriate attributes through the VGrADS Find-and-Bind mechanism
• Monitoring VG activity with the Mortar system
• Evaluating VG performance and scalability through grid modeling and simulation
  

• Advanced scheduling based on VGs
  
• A temporal resoning framework for understanding VG behaviors
  
• Fault tolerance techniques integrated with VGs
• Slotted VGs to incorporate availability information into VG selection