Changes between Initial Version and Version 1 of Overview

Timestamp:

09/21/05 11:57:55 (20 years ago)

Author:

joe

Comment:

--

Overview

@@ +1 @@
+= The Virtual Solar Observatory Overview =
+
+This document will explain the general structure of the Virtual Solar
+Observatory's architecture, the goals and objectives that influenced
+that architecture, and the terms and abbreviations used in this and
+other supporting documentation.
+
+== Goals and Objectives ==
+
+For a detailed explaination of the design influences for the VSO,
+please see 
+[http://virtualsolar.org/docs/VSO_strawman_20021125.pdf The Virtual Solar Observatory Design Proposal, 2002 November].
+Relevent excerpts are contained below.
+
+=== Principal Features ===
+
+
+  * the ability to search all participating data sources with a common interface,
+  * the use of existing data query facilities at the current data sources,
+  * the use of industry-standard protocols such as eXtensible Markup Language (XML) in its internals,
+  * access through a Web browser interface to a remote VSO server, an Application Programming Interface (API), or via a VSO instance on a local computer, and
+  * extensibility to multiple additional features, including the registration of searches to enable other solar physicists to, for instance, attempt to reproduce the results of published literature.
+
+=== Original Prototype ===
+
+The original VSO prototype, which is occassionally refered to as
+version 0.5, contained the following features:
+
+  * virtualization of data search, data discovery, and query refinement,
+  * multiple interfaces (browsers, application programming interface),
+  * leveraging of existing data services (rather than creating e.g. new metadata standards),
+  * direct user access to data (without the VSO as an intermediary), and
+  * the ability to expand to several more data sources in the implementation and maintenance phases of the VSO (FY04 and beyond).
+
+The prototype specifically did not include the following:
+
+  * a central catalog,
+  * grid computing
+  * any fetures that limit or restrict access to data or software (authentication).
+
+Planned features for later implementation included the following:
+
+  * catalog caching (to speed queries),
+  * multiple instances of the VSO (to make the VSO truly virtual, it could run on local machines instead of on a small number of remote servers), and
+  * logging of searches (without identifyng the party who carried out the original search).
+
+This reference implementation imparted the following ideas into the
+project:
+
+
+  First, it is not a monolitic server with a database that stores
+  metadata.  Instead, it is an agile, lightweight application program
+  that accepts input (user queries) and provides output (data location
+  and access).  We store XML descriptions of data providers as a data
+  structure (it can reside in memory) instead of static files or
+  records.
+  
+  Second, we treat each user input and query not only as a transaction
+  but as a real-time computation.  By doing so, we are able to view VSOs
+  inner-parts as instantiated objects and perform operations or
+  manipulate them by applying methods.
+  
+  Finally, the deployment of VSO may be fully distributed with the
+  ability to have multiple, fully customizable VSOs running on user
+  desktops.
+
+=== VSO 0.5 Architecture ===
+
+{{{
+ UI  --> VSO --> WS --> DP
+
+UI  : User Interface
+VSO : VSO 'Core' Application
+WS  : Web Service
+DP  : Data Provider
+}}}
+
+
+== VSO 0.6 ==
+
+With VSO 0.6, the inidividual objects were simplified and attempts
+were made so that each one could function autonomously.  The system
+was modeled as additional objects, while still using the basic overall
+concepts from 0.5:
+
+{{{
+              Registry
+                 ^
+                 |
+ UI --> UQI --> VSO --> DQI --> DP
+
+UQI : User Query Interface
+DQI : Data Query Interface
+}}}
+
+=== Improvements in 0.6 ===
+
+The changes from 0.5 to 0.6 were refinements of the VSO architecture
+to assist with later maintenance of the VSO.  In addition, the data
+model signicantly changed with this revision.  The following additional
+objectives were realized:
+
+  * the addition of new data providers should not require the modification of existing code,
+  * the modification of the VSO data model should not require significant changes to the VSO Core, and
+  * the modification of the VSO data model should not require immediate action by VSO Data Providers.
+
+To deal with the implications of these new objectives, there
+were some minor changes 
+
+
+=== VSO 0.7 ===
+
+With VSO 0.7, we attempted to move specifics of individual Data Providers
+out of the User Interface.  To meet these goals, we did the
+the following:
+
+  * the ability to request the necessary data provider information to generate query forms, and
+  * the ability to determine the proper procedure to download data from a particular data provider.
+
+These changes have resulted in the need for an additional component, the
+Central Server.  The Central Server contains the authoritative records
+for various information that the VSO Core instances and User Interfaces
+may require to provide a consistent experience with the addition of new
+data providers.  To maintain the virtual aspects of the system,
+provisions have been made for multiple Central Server mirrors, and for
+the possibilty of no Central Servers being available.
+
+VSO 0.7 was never released to the public, due to flaws in the
+logic for ordering data, specifically in the cases of a 'partial success' situation.
+
+
+=== VSO 0.8 ===
+
+To solve the logic errors present in 0.7, modifications were made to the
+ordering mechanims within VSO.  The following changes were made:
+
+  * Data Providers returned enough information for a User Interface to repeat the query, without having maintained records of what the original query was.
+
+=== VSO 1.0 ===
+
+The 1.0 release was a series of small, but subtle refinements to VSO,
+to move it to the point where solar researchers could use it for regular
+tasks.
+
+The following modifications were made:
+
+  * Data Serialization was improved to support the possibility of communicating with components written in strictly-typed languages, and
+  * Mechanisms were added to permit Data Providers to extend the messages to send additional information.
+
+More obvious to the general public, however, was a revamping of the 
+default web-based User Interface, which included the following:
+
+  * Customizable search form generation,
+  * improved searching by 'nicknames',
+  * thumbnail previews of data products when available, and
+  * improved data product ordering capabilities.
+
+=== VSO 1.2 ===
+
+The 1.2 release encorporated refinements suggested by the solar physics
+community, and attempted to make the overall system easier to maintain.
+
+The following modifications were made:
+
+  * Created a system to browse the VSO Registry,
+  * Populated additional information in the VSO Registry, including 'data layout',
+  * Provided a mechanism to allow a provider matching to work for providers with multiple web services,
+  * Improved handling of unit conversions in spectral ranges searches, and
+
+
+Significant changes were made to the web-based User Interface, with
+the result of removing all data provider specific code from the User
+Interface.
+
+Modifications to the web-based User Interface included the following:
+
+  * Introduced the 'catalog search' interface, to allow the time parameter to be derived from solar event catalogs,
+  * provided online help for search terms,
+  * added a 'drill down' interface as an alternative to select instruments,
+  * added a system to allow VSO Cart IDs to be used to reload the results saved from past searches,
+  * added a mechanism to turn the browse images for VSO data products into a slideshow, and
+  * provided a mechanism to pass arguments into the search form to pre-select items.
+
+
+== What VSO isn't ==
+
+VSO's primary goal is to discover and facilitate the retrieval of data
+products.  Although later VSO User Interfaces may automate the retrieval
+process, or post processing of data products, this is outside of the
+scope of VSO's primary objectives, and may not be present through all
+VSO User Interfaces.
+
+VSO is a lightweight, virtualized system.  It provides a framework for
+finding data products, but does not maintain an itemized list of data
+products available.  The VSO Registry maintains generalized information
+about the product offerings from each data provider, which may be made
+more specific in the future to assist in optimization efforts.
+
+== Future Plans ==
+
+The Virtual Solar Observatory project will work with other similar and
+complementary projects to make data products and services more widely
+available to the solar physics community.  Data providers will be added
+to provide additional data products. User interfaces will be added to
+provide for both general and niche purposes.  Features will be added and
+refinements made to assist solar researchers in finding data products
+that may be of interest.