Transcript Grid services

Interaction model of grid
services in mobile grid
environment
Ladislav Pesicka
[email protected]
University of West Bohemia
The main topics
Using mobile devices
– To access computation grid
– To be a part of the grid
Support of mobile agents
– Disconnected computing
– Migration
Content
Computation grids
– short overview
Mobile devices
– restrictions
The role of mobile agents
– how to help
– Interaction model
Grids
In mid. 1990s, most development in last
years –> web services, XML
Distributed computing infrastructure for
advanced science and engineering
Establish virtual organizations (VO)
Manage security, trust, privacy
Manage and monitor distributed resources
Virtual Organization (VO)
Real organizations
can participate in one or more VO
Resource sharing – conditional
(constraint given by resource owner)
when, where and what can be done
Member services
what resources able to access, the “quality”,
and the policies that govern access
Standards
OGSA (Open Grid Service Architecture)
defines what Grid services are, no technical
and detailed specifications
OGSI (Open Grid Service Infrastructure)
formal and technical specification
Globus Toolkit 3 (http://www.globus.org)
implementation of OGSI
Open Grid Services Infrastructure
(OGSI)
OGSI defines mechanisms for creating,
managing, and exchanging information among
entities called Grid services
Grid service - a Web service that conforms to
a set of conventions (interfaces and behaviors)
that define how a client interacts with
a Grid service
Grid service
Grid service factories concept
responsible for creating and destroying of objects
Client performs operations on the same instance of Gs
One instance – used mostly by one client
Service data elements – state of the service
Factory:
-Create instance
-Destroy instance
Grid service – naming
Distinguish among different instances
GSH (Grid Service Handler) - naming, URI
http://localhost:8080/ogsa/services/samples/counter/basic/
CounterFactoryService/hash-31889293-1079702176271
GSR (Grid Service Reference)
in the form of WSDL document
describes what the clients need to know
to be able to communicate with grid service
Globus Toolkit 3
Grid service middleware
Implementation of core grid services based on
OGSI – pure Java language, other services in
C language
Important services:
–
–
–
–
GRAM (Globus Resource Allocation Manager)
GridFTP (File Transfer Protocol, similar to FTP)
MDS3 (Monitoring and Discovery Service)
GSI (Grid Security Infrastructure)
Grid - resources
Provides list of available resources
together with its characteristics
These characteristics are given by
available SDE (Service Data Elements),
just its values can change - predefined
RSL (Resource Specification Language)
In the form of pair (Atribute, value)
Resource metric or configuration parameter
Used to specify requirements of the application
Executable, directory, stdin, stdout, …
Globusrun –r node –o “&(executable=/bin/ls)”
Resource allocation
Deep knowledge of
– Client demands
(computational and memory allocation demands)
– Offer of given resource
(speed, available memory)
Work with incomplete knowledge
missing or just estimated information
(computation power vs. supposed lifetime)
Do not know requirements of “future” clients
Mobile devices - restrictions
Host resources
(computation capability, memory, limited power sources)
Network resources
(narrow bandwidth, latency, lost of signal, costs)
Security issues
(security problems in wireless networks)
Interoperability
(different OS, HW and SW equipment)
Availability
(power-loss, switching off initiated by the user)
Mobile agent support
To obtain resource characteristics
(need to gain more information then SDEs)
To control the computation
instead of mobile device
(support for disconnected computing)
Perform some actions on the mobile device
(computation, searching)
(MD as computation resource)
System architecture
Home network, Foreign network
Grid environment – VO
Home base inside Home network
MA hosting environment available in
resource nodes of the foreign network
Stationary agent in MD – control
communication with home base
Home base
One node in the home network
(optionally visitors base in foreign network)
More nodes can be home base candidates
(against the failure), communicate together to
know which one servers the given mobile device
Mobile device – a priority list of IPs, or DNS
names of the candidates
Home base
Main tasks:
– Repository of agents owned by the users that
could be sent to the network
– Agent management system
– Messages queue to collect notices and logs
for the client (MD), at the time it is
disconnected
The model of interactions
Foreign network
Home network
2
Home base
(static IP)
3
1,4
The choice of most suitable resource
1 request, 2 MA sent, 3 MA returns, 4 response
Mobile device
(dynamic IP)
Control of the computation based on MA
Client sends request to the home base
Home base – agents repository, including:
– Agents to find proper resource node
– Agents capable to control comp. on the foreign node
(where they will be sent)
Feedback – agent communicates with home
base or directly with mobile node
Using certificates (VO agreement)
MD as computation resource
Mobile device as grid-enabled node
Mobile device includes environment to
host mobile agents
Lifetime management (power down)
Accounting – e.g. communication costs
(WiFi connection) in foreign network can be paid
in the form of computational cycles
(powerful notebooks)
Some problems and features
Availability of suitable J2ME (or J2SE)
environment for different kind of mobile devices
Availability and stability of mobile agents hosting
environment for the mobile devices
Take care about robustness, security,
communication overhead of the system
Conclusion
Mobile devices
– Demand for mobile access to the grids
– They are more and more powerful
(source of information, computation cycles)
Mobile agents
– Agent based grid
– Monitoring of grids
Mobile grids
– As energy outlets – just connected and obtain proper
computation power and resources anywhere anytime
Thank You for Your Attention
[email protected]