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Hosting and Accessing Objects via Persistent Web Services

Hosting and Accessing Objects via Persistent Web Services. Daniel J Grose Centre for E-Science Lancaster University. Overview. Brief introduction to GROWL and SABRE SABRE user requirements Taxonomy of GRID users Hosting Legacy Interfaces – the need for a client programmers API

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Hosting and Accessing Objects via Persistent Web Services

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  1. Hosting and Accessing Objects via Persistent Web Services Daniel J GroseCentre for E-ScienceLancaster University

  2. Overview • Brief introduction to GROWL and SABRE • SABRE user requirements • Taxonomy of GRID users • Hosting Legacy Interfaces – the need for a client programmers API • Client/Server Architecture • Conclusions

  3. SABRESoftware for the Analysis of Binary Recurrent Events SABRE is designed to model recurrent events for a collection of individuals or cases and many other types of repeated measures data with binary, ordinal or count responses. It fits both standard models and various mixture models which allow for residual heterogeneity. It can be used to fit the following univariate statistical models : • binary data with logit, probit or complementary log-log link • ordinal response data using a probit link • count response data using a log-linear Poisson model • continuous response using identity link SABRE employs reweighted least squares (standard homogenous models) and Newton-Raphson maximumlikelihood (random effects binary models) algorithms.

  4. SABRE Development History • Single threaded application with simple shell based user interface. • C++ wrapper to SABRE. • Single threaded extension to R (one model per session) employing C++ wrapper. • Multi-threaded extension to R (>= one model per session) • Parallel implementation using (MPI) running in batch mode • How to provide R interface to parallel implementation in employed remotely on HPC ?

  5. >library(sabreR) # load the sabreR library > sabre0<-sabre.session(); # create a new sabre model > trade.union<-read.table(``./TradeUnion.table'') # read the data into a data frame > names(trade.union) # show the variates [1] "CASE" "YEAR" "AGE" "EVNO" "SUPR" "HRS" "NOEM" "SEX1" "TU" "PROM" [11] "SC80" > sabre.data(sabre0,trade.union) > sabre.display.variates() Name Levels Type ________________________________ cons 1 X case 1 X year 1 X age 1 X evno 1 X supr 1 X hrs 1 X noem 1 X sex1 1 X tu 1 YVAR prom 1 X sc80 1 X fnoem 5 X fsc80 6 X > plot(trade.union) # plot the data

  6. > sabre.fit(sabre0,''year'',''age'',''fnoem'',''fsc80'') > # NB returns control to user immediatley even though analysis is still running > sabre.display.estimates(sabre0) *** Sabre analysis still in progress *** > # ... some time later ... > sabre.display.iterations(sabre0) Initial Homogeneous Fit: Iteration Log. lik. Difference __________________________________________ 1 -1131.9093 2 -1073.2798 58.63 3 -1073.0111 .2687 4 -1073.0110 0.1204E-03 5 -1073.0110 0.4700E-09 Iteration Log. lik. Step End-points Orthogonality length 0 1 criterion ________________________________________________________________________ 1 -917.86146 1.0000 fixed fixed 6.5174 2 -878.33512 1.0000 fixed fixed 19.983 3 -868.98256 1.0000 fixed fixed 4.6722 4 -867.52529 1.0000 fixed fixed 5.2621 5 -867.20337 1.0000 fixed fixed 11.115 > # ... user can be doing other things within R whilst sabre analysis takes place ... > sabre.display.estimates(sabre0)

  7. > nwg<-grid.resource(``~/smith.pem'',''~/ca.pem'', + ''growl.lancs.ac.uk:50000'',''~/smith.passwd'') > sabre0<-sabre.session(nwg) # this time create a sabre session with a grid resource ..... exactly the same session as before !! ...... What Extra is Required to Run a GRID SABRE Session ?

  8. The Problem – A Missing Layer * Adapted from Foster and Kesselman

  9. The Problem – A Missing Layer

  10. #ifndef ___ACCUMULATOR_H___ #define ___ACCUMULATOR_H___ class Accumulator { private: unsigned int m_nValue; public: Accumulator(); unsigned int NextValue(); }; Example.Local Interface and Implementation include "Accumulator.h" Accumulator::Accumulator() : m_nValue(0) {} unsigned int Accumulator::NextValue() { return m_nValue++; }

  11. #include <iostream> #include "Accumlulator.h" int main() { Accumaulator Acc; std::cout << Acc.NextValue() << std::endl; std::cout << Acc.NextValue() << std::endl; std::cout << Acc.NextValue() << std::endl; return 0; } Client Invoking Local Service

  12. Session Manager WSDL Agent Library + + + “IDL” Source *.c *.cpp *.f *.jav *.h *.f *.jav MAKE Server Library Client Library

  13. #include <iostream> #include "GROWL_Accumlulator.h" int main() { GROWL_Accumaulator Acc; // additional code required for invoking remote instance Acc.SetClientParams("~/smith.pem", "~/ca.pem", "growl.lancs.ac.uk:50000", "~/smith.passwd"); std::cout << Acc.NextValue() << std::endl; std::cout << Acc.NextValue() << std::endl; std::cout << Acc.NextValue() << std::endl; return 0; } Client Invoking Remote Service

  14. Configuration Certificate Certificate XML Session Manager Client Application LIB Agent Factory LIB LIB gSOAP server libraries

  15. Configuration DN Service Certificate GridResource Certificate XML XML Library Session Manager Client Application LIB Agent LIB Agent ID Socket Numbers Agent Factory LIB LIB gSOAP server libraries

  16. Configuration DN Agent ID Certificate Certificate XML XML Socket Number Session Manager Client Application LIB Agent LIB Globus Condor Agent Factory Other Certificate LIB LIB gSOAP server libraries

  17. Configuration Certificate Certificate XML XML Session Manager Client Application LIB Agent LIB Agent Factory LIB LIB gSOAP server libraries

  18. Agent Architecture

  19. Conclusions • Existing GRID users (the early adopters) are predominantly GRID middleware users. However, the large majority of potential grid users are not. • To capture the latter, client side developers require simple API's to program against legacy interfaces that can be integrated easily into existing client environments (ostensibly as if they were local services). The API's must offer multiple language mappings. • A potential risk is that development effort is too focused on creating user interfaces for interacting with middleware rather than developing the client programmers API. • The lifetime of the service does not usually correspond to the lifetime of the client. • These requirements imply extensible secure severs that can host multiple implementations via a common interface ... • ... and all of the implementation state must be on the server side. • What the client gets is what they have subscribed to !! The service provider is responsible for deciding how this is done. Importantly, the client side interface does not change when the user decides to change service provider !!

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