Metacat

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Metacat: XML Metadata Database

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                           http://bugzilla.ecoinformatics.org

              Chad Berkley (berkley@nceas.ucsb.edu)

              Dan Higgins (higgins@nceas.ucsb.edu)

              Duane Costa (dcosta@lternet.edu)

XML document, therefore allowing storage of XML documents with arbitrary

schemas. Metacat supports several databases on the back-end, including Oracle,

PostgreSQL and SQL Server (limited).  The server supports XML document

database to other metacat instances for backup and load balancing purposes.

Metacat currently uses an LDAP database for authenticating users, but was

written to accomodate other authentication services as well.

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See the file "docs/user/metacatinstall.html" for detailed instructions.

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This release comes with performace improvement, user interface enhancements

and bug fixes. Below is the list of bug fixes and performance improvements.

Bug Fixes:

* Modify property values of harvester registration servlets to match the

  servlet-mapping URL values in web.xml. The old values used the servlet

  class names. This worked in Tomcat 4 but seems to break in Tomcat 5 on

  Windows. The new values use the servlet-mapping URL values. This should

  work in both Tomcat 4 and Tomcat 5. (Bug 162)

* Re-implement logic to prune old log entries from the HARVEST_LOG and

  HARVEST_DETAIL_LOG tables. The old logic caused integrity constraint

  violations in the database because it tried to delete parent records from

  HARVEST_LOG prior to deleting child records from

  HARVEST_DETAIL_LOG. (Bug 162)

* In data registry, minor bugs fixed like the error page shows the link back

  to the form when error page was generated because of a document read

  request from search results page,  the successful delete button leading

  to a blank screen and the old ACL overwritten by the registry.

  (Bugs 1307, 1310, 1322, 1344, 1551)

* Changed the code to support insertion of following characters: ', `,

  charcters in the Numeric Character Reference format (&#xyz;) and

  characters like µ. Characters like µ will be converted to and stored in

  Numeric Character Reference format(&#xyz;). They will also be returned

  in Numeric Character Reference and it is upto the client to convert them

  and display them accordingly in the application. Partial fix provided by

  Johnoel Ancheta. (Bug 1538,1711)

* Spatial search failed on Oracle because of invalid entries made by

  some documents in the nodedata column of xml_nodes for paths involving

  'eastBoundingCoordinate', 'westBoundingCoordinate',

  'northBoundingCoordinate', 'southBoundingCoordinate'. A new column

  nodedatanumerical was added to xml_nodes table such that all the numerical

  nodedata is stored in this column and this column is now used for spatial

  search. (Bug 1703, 1718)

* In the default skin, clicking on the keywords on the home page did not

  result is a search being done. Fix provided by Owen Jones. (Bug 1768)

* Metacat generated a success message even when a document which didnt

  exsist was requested for deletion. This has been fixed. (Bug 1850)

* "packagetype" in xml-relation table was entered as eml200 namespace when

  an eml201 document was inserted. This is fixed now so that "packagetype"

  in xml-relation table points to eml201 namespace. (Bug 1979)

* System_id in xml_catalog pointed to http://knb.ecoinformatics.org/knb/

  earlier. Fixed such that it points to the locally installed metacat url.

  (Bug 1986)

* Changes to the Query subsystem fix bugs that prevented attributes from

  being expressed solely in the xpath query statement and the returnfield

  values. For instance, a query URL may now include search strings like

  '@packageId=sbclter%25' and return strings like 'returnfield=@packageId'.

  Previously, the attribute had to be appended to an element:

  '/eml/@packageId=sbclter%25'. These fixes change DBQuery.java,

  QuerySpecification.java, and QueryTerm.java (Bug 2052)

* Search query failed in case of Oracle if number of documents in the result

  were more than 1000. This has been fixed. (Bug 2000)

* Removed any occurence of enum which is now a keyword in Java 1.5

Enhancements:

* Major improvements done in user interface for the data registeries and

  various other skins. Improvements done based on suggestions from Mark

  Stromberg, Laura Downey and others. Improvements also done in resultset.xsl,

  the default skin and ldap templates. (Bug 1948)

* Coded added such that administrator can delete documents irrespective of

  who the document belongs to.

* Performance impovement done in searching of datasets. A part of the search

  time was taken up because of generation of resultset after the search had be

  done. So this was the sequence of events in earlier metacat

  1) Search for the given text

  2) A list of docids generated

  3) For each of the docids

     3a) Use xml_index and xml_nodes table to generate the string descibing

         the document including the returnfields requested in the search

  4) Add all the strings from step 3a to send back the resultant document.                                                                 Here a decent amount of time was being taken by step 3a. The algorithm is

  now modified by addition of two tables xml_queryresult and xml_returnfields

  and a user defined parameter xml_returnfield_count. The new algorithm works

  as follows

  1) Search for the given text

  2) A list of docids generated

  3) For the given set of return fields generate a unique string and check

     if that string exists in xml_returnfields

     3a) If string does not exist in xml_returnfield, then enter a new

         record usage_count as 1 and returnfield_string as the unique string

         generated above.

     3b) Else if the string exists, increment usage_count

  4) Given the docids from step 2 and the id of the returnfield record from

     step 3, query for any docids that already exist in xml_queryresult.

     For the docids that do exist, get the queryresult_string.

  5) For rest of the docids from step2 which were not found in step 4, do

     the following for each of the documents:

     5a) Use xml_index and xml_nodes table to generate the string descibing

         the document including the returnfields requested in the search

     5b) If usage_count of the record from step is more than

         xml_returnfield_count set in metacat.properties, then store the

         string in xml_queryresult as a record which has the returnfield_id

         representing the set of returnfields, docid representing the

         document and the string as queryresult_string.

  6) Add all the strings from step 4 and step 5a to send back the resultant

     document

  So the results from step 3a in previous algorithm are effectively cached

  and hence same computation is not done again and again for each search.

  When a document is deleted, all the entries for that document in

  xml_queryresult table are also deleted. When a document is updated, all

  the entries for that document in xml_queryresult table are deleted. This

  works fine because those entries will be generated and cached again the

  next time the document is part of a search is requested.

* Performance impovement done for % search.

* Following new functions added to metacat client API: a method to set access

  on an xml document and a method to get newest version for a given document.

* Implement a new HarvesterServlet for running Harvester as a servlet. This

  eliminates the need to run Harvester in a terminal window. By default, the

  HarvesterServlet is commented out in lib/web.xml.tomcat(3,4,5). The user

  documentation will be modified to instruct Harvester administrators to

  uncomment the HarvesterServlet entry.

* Minor enhancement to support multiple email addresses for harvester

  administrator and site contact. Each address is separated by a comma or

  semicolon.

* Increase number of rows in Harvest List Editor from 300 to 1200.

* Changed default maxHarvests value to 0. Added logic to ignore maxHarvests

  value when it is set to 0 or a negative number. This allows Harvester to

  run indefinitely without shutting down after reaching a maximum number of

  harvests. The previous default value of 30 would cause Harvester to

  terminate after 30 harvests.

Details of all changes can be found in the bug database here:

http://bugzilla.ecoinformatics.org/buglist.cgi?product=Metacat&target_milestone=1.5

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This is a major release, and is the first to introduce many new features to

Metacat.  Some of the major new features in this version of Metacat include:

* Added a new 'Harvester' that allows documents to be periodically pulled

  from distributed sources into metacat, useful for interfacing with other

  system types. See the Metacat Tour for details.

* Added new 'skins' capability to allow the GUI for the metacat web interface

  to be more easily customized to fit into site needs.  The skin is based on

  a flexible mix of XSLT, CSS, and Javascript.

  is integrated with the 'skins' system for the main metacat interface.  The

  registry subsystem is written in Perl, and can simultaneously be used to

  present multiple 'registry' interfaces.

* A new 'client API' has been developed and implemented in Java and in Perl

  so that metacat functions can be accessed from any program in those

  languages.  The client API supports the major metacat servlet actions,

  including login(), logout(), query(), insert(), update(), delete(), and

  upload(). See the Metacat Tour for details.

* Added a new 'getlog' action that produces a usage history for all major

  events.  So now an XML report can be generated for document reads, inserts,

  deletes, etc.  See the new section in the Metacat Tour.

* Added a new 'buildindex' action that can rebuild the index entries for any

  document in the database.

* The configuration file for metacat (metacat.properties) has been moved out

  of the jar file and into the WEB-INF directory, allowing far easier changes

  to the configuration parameters.

  (configurable)

* Many bugs were fixed.

Details of all changes can be found in the bug database here:

http://bugzilla.ecoinformatics.org/buglist.cgi?product=Metacat&target_milestone=1.4

include:

    Java 1.3 and Java 1.4. Currently, Metacat 1.3.1 will work in both Java 1.3

    and Java 1.4.

Release Notes for 1.3.0

In 1.3.0 release, the structure of the xml_access table was changed and a new

installed Metacat, you should run a script file to updated the table structure

before installation.

For Oracle user: At the SQLPLUS prompt type the following -

@src/reviseformetacat13.sql

For Postgresql user: At install directory prompt type the following -

psql exp < src/reviseformetacat13_postgres.sql

(where 'exp' is the database name).

schema in xml_catalog table.

If you are a new Metacat user, this step is unneeded.

         it will cause potential replication issues.

      2) Delete the xercesImpl.jar and xmlParserAPIs.jar files

         which are in $CATALINA_HOME/common/endorsed. They are old version and

         don't support XML schema validation.

  1) Partialy support EML2 document. User can store, query, read and write

     EML2 documents. However, Metacat only support access control in resource

     level. The subtree level access control will be ignored.

  2) Support other xml document base on namespace/schema.

  3) Support query for attribute value

  4) Assign MIME type to data file base on metadata when user try to read it.

  5) Owner can assign access rules to a document which does not have access

     document to apply it.

  6) Support exporting single file, not only whole package

Fixes in 1.3.0:

  1) Couldn't finish delta T replication for large set of documents.

  2) Couldn't create access control during delta T replication.

  3) Eorr will be written to a seperated log file if some documents

     were failed in replication.

  4) Decrease the time to create access rules during insert or update

     a package.

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Contributions to this work are welcome.  Please see the above web site

for details on how to contribute.

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our bug tracking system (http://bugzilla.ecoinformatics.org). There is a

list of currently unimplemented features in Bugzilla that we are working on

for the next release.

Legalese

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and the National Center for Ecological Analysis and Synthesis

and licensed under the GNU GPL; see the 'LICENSE' file for

details.

0225676.  Any opinions, findings and conclusions or recomendations expressed

in this material are those of the author(s) and do not necessarily reflect

for details.