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\begin{document}
\paperID{D3} % bogus id since we need one
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\title{ESA ISO and XMM-Newton Archives Inter-Operability and VO services}
\titlemark{ISO and XMM-Newton VO Services}

%\author{David Bohlender}
%\affil{Canadian Astronomy Data Centre, Herzberg Institute of Astrophysics,
%5071 West Saanich Road, Victoria, BC, Canada V9E 2E7}

\author{Christophe Arviset, Pedro Osuna, Jesus Salgado}
\affil{RSSD Archive Development Team, ESA VILSPA, PO BOX 50727,
28080 Madrid, Spain}

\contact{Christophe Arviset}
\email{Christophe.Arviset@esa.int}

\paindex{Arviset, C.} 
\paindex{Osuna, P.} 
\paindex{Salgado, J.}

\authormark{Arviset, Osuna, Salgado}

\keywords{Infrared Space Observatory (ISO), XMM: Newton, archives, Virtual Observatory, SIAP, interoperability}

%-----------------------------------------------------------------------
%                              Abstract
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\begin{abstract}
The ISO Data Archive (IDA) and XMM-Newton Science Archive (XSA)
are usually accessed through a dedicated and powerful Java user
interface available from any browser. To allow the access to
external applications and expert or normal users that need to
retrieve data directly from the archive bypassing the Java User
Interface, an integrated Archive Inter Operability system (AIO)
has been developed for XSA and IDA. This paper describes the
general inter-operability services that this system provides as
well as the specific VO standards services like SIAP that are
already supported.
\end{abstract}

%-----------------------------------------------------------------------
%                             Main Body
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\section{Introduction}

Within the ESA's Science Operations and Data System Division, the
Archive Development Team in Villafranca, Spain is responsible of
developing and maintaining ESA Scientific Archives. For the ISO
Data Archive
(\htmladdnormallinkfoot{IDA}{http://www.iso.vilspa.esa.es/ida})
and the XMM-Newton Science Archive
(\htmladdnormallinkfoot{XSA}{http://xmm.vilspa.esa.es/xsa}), the
standard way to access to these ESA archives is through a powerful
Java User Interfaces.


To allow the access to external applications and expert or normal
users that need to retrieve data directly from the archive
bypassing the Java User Interface, an integrated Archive Inter
Operability system (AIO) has been developed for XSA and IDA.

The general AIO services are:
\begin{itemize}
\item Postcard Server (URL) \item Product Server (URL) \item
Product Server (Socket)
\end{itemize}



Later on, we have adapted our AIO inter-operability services to
comply to the new VO standards, in particular to SIAP (Simple
Image Access Prototype).

VO SIAP compatible AIO services are:
\begin{itemize}
\item Image Query \item Image Retrieval
\end{itemize}




\section{General AIO Services}
The IDA and XSA Archive Inter-Operability (AIO) systems allow
external applications or archives to access directly the ISO and
XMM-Newton data products bypassing the standard User Interfaces
which require interactions with a human being.

Full documentation about how to use these services can be found
at:
\begin{itemize}
\item ISO : http://pma.iso.vilspa.esa.es:8080/aio/doc \item
XMM-Newton : http://xsa.vilspa.esa.es:8080/aio/doc
\end{itemize}

\subsection{Postcard Server (URL)}
The Postcard Server is accessible via a URL for each observation
that returns an HTML page containing a quick-look view of the data
products for that observation together with links to relevant
documentation and links to the products themselves (via the
Product Server). Example of the Postcard Servers are given in
Figure~\ref{PostcardServers}.

The Postcard Server is already used by various archives such as
CDS, Aladin, IRSA, ADS, HEASARC.

\begin{figure}
\epsscale{0.6} \plotone{D3_1.eps} \caption{ISO and XMM-Newton
Postcard Servers.} \label{PostcardServers}
\end{figure}



\subsection{Product Server (URL)}
The Product Server is accessible via a URL that returns an HTML
page with the link to the FTP server where the requested data have
been put. After a few seconds, the data products download via FTP
is initiated. Alternatively, by setting an extra parameter, the
data products can be downloaded directly without going to the FTP
server. This is particularly interesting for applications like
Aladin who wants to request the products for future display.
Various parameters in the URL define the level of data products
that is requested by the user.

In combination with the Postcard Server which gives a quick view
of the available data, the Product Server allows the user to
download the real scientific products for his own analysis.



\subsection{Product Server (Socket)}
The Product Server can also run in the Socket mode in order from
any client or user to directly request ISO and XMM-Newton data
products without going through a URL.  This option is heavily used
by instrument experts who want to automatically retrieve data
products for automatic analysis.

Various parameters can be specified in the command line to define
the level of data products that is requested by the user. It can
return a single file or a conjunction of files in a tar format.
The Product Server also allows an XML file as input in order to
specify a more complex data products request.

An example of an AIO session in Socket Mode is given in
Figure~\ref{D3:AIOSocket}.

\begin{figure}
\epsscale{0.6} \plotone{D3_2.eps} \caption{AIO run in Socket Mode}
\label{D3:AIOSocket}
\end{figure}

\section{VO Compatible Services}
The ISO and XMM-Newton AIO systems have then been adapted to
support the VO standard SIAP (Simple Image Access Protocol) which
basically supports two modes, image query and image retrieval.

Details about the adaptation of the existing AIO system to the VO
standards can be found in Osuna et al. (2004).

\subsection{SIAP Image Query}
The SIAP defines various types of searches like cone search,
target search based on some already defined UCDs. The results of
such search can be in HTML or TEXT for human visualization but
also in VOTable (the standard VO format) for easier parsing and
later use into a VO client (e.g. Aladin). These SIAP Image Queries
re-use the existing search mechanisms already present in the ISO
Data Archive and XMM-Newton Science Archive. An example of the
SIAP cone search for XMM-Newton is given in
Figure~\ref{D3:SIAPConeSearch}.

\begin{figure}
\epsscale{0.6} \plotone{D3_3.eps} \caption{XMM-Newton SIAP Cone
Search, HTML and VOTABLE results} \label{D3:SIAPConeSearch}
\end{figure}


\subsection{SIAP Image Retrieval}
The AIO SIAP Image Retrieval is using the standard AIO product
server in a URL mode to pipe directly the standard data products
to the requesting client. The default data products to be returned
correspond to the highest level of automatically processed
products.


\section{Conclusions}
The ISO Data Archive and XMM-Newton Science Archive offer flexible
and powerful Inter-Operability services which allow to access
directly archive metadata and data products.

These services are already compliant to the recent VO standard
Simple Image Access Protocol and we have as well adapted them to
support Simple Spectra Access by using similar mechanism.

These services are already widely used by ESA instrument experts
and by external archives and applications and we foresee a more
extensive use in the coming era of the Virtual Observatory and
inter-operable archives.


\acknowledgements

The authors would like to acknowledge the rest of the ESA RSSD
VILSPA Archive Development Team who have participated in the IDA
and XSA development : John Dowson, Jose Hernandez, Inaki Ortiz,
Guillermo San Miguel and Vrata Venet as well as the ISO and
XMM-Newton Archive Scientists, Alberto Salama and Matteo
Guainazzi.

\begin{references}
\reference Arviset, C.\, 2003, \adassxii, \adassref{xii:O10-6}{47}
\reference Osuna, P.\, 2004, \adassxiii, \paperref{P2-3}
\end{references}


\end{document}
