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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SIS-180) Place a crude JDBC driver over Dbase files
Date Tue, 14 Oct 2014 16:52:33 GMT

    [ https://issues.apache.org/jira/browse/SIS-180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14171208#comment-14171208
] 

Martin Desruisseaux commented on SIS-180:
-----------------------------------------

Committed on the JDK8 branch. But before to continue on JDBC support, would it be possible
to do some consolidation work?

I applied the following changes:

* Renamed package as {{org.apache.sis.internal.shapefile.jdbc}}, so those classes will be
hidden from public API.
* Renamed {{XXXUnimplementedFeature}} classes as {{AbstractXXX}}.
* Omitted {{DBaseJDBCDriverUnhandledOperationException}}. Used {{java.sql.SQLFeatureNotSupportedException}}
instead.
* Removed all {{throw new RuntimeException("Should not have been there")}} lines since they
were unnecessary (note: {{throw new AssertionError(...)}} would have been more accurate).
See the code for the simplification trick.
* Defined {{InvalidDbaseFileFormatException}} as a subtype of {{SQLNonTransientException}}
instead than {{SQLException}}.

Would you have a chance to apply the following proposed consolidation, if you agree?

* Please configure your IDE for using spaces rather than tabulations, since not all editors
have the same tabulation width.
* Remove the {{public}} modifier for every classes that do not need to be accessed from outside
the package.
* Replace star imports by explicit imports, unless there is really a lot of them (e.g. more
than 8 from the same package).
* Minor grammatical note: Javadoc convention asks us to use the third person in the first
sentence of method javadoc (e.g. "Format*s*" instead than "Format").
* Some classes have {{\@SuppressWarnings("unused")}} annotation in front of every arguments,
which make method signature very verbose. {{"unused"}} is not a value recognized by the Oracle
{{javac}} compiler (as of JDK8). I presume that this is an Eclipse-specific one? If this annotation
is really desired, I suggest to put it at the class level at least in {{AbstractFoo}} classes,
for avoiding to repeat it hundred of times.
* {{unsupportedOperation}} method excepts the source class and method in argument. But this
information is not complete at least in {{AbstractResultSet}}. We could complete them... but
given that this information duplicates the stack trace information, maybe it could also be
completely omitted.
* It may be worth to take a look at the Javadoc of all JDBC methods and see if some of them
are optional. I suspect that not all methods need to throws a {{SQLFeatureNotSupportedException}}.
* In the Javadoc, I guess that all the {{\@see the_implemented_JDBC_method}} were inserted
by Eclipse? Since the Javadoc tool generates this information automatically in the "Specified
by" section, those automatically generated {{\@see}} tags are redundant and could be omitted.


> Place a crude JDBC driver over Dbase files
> ------------------------------------------
>
>                 Key: SIS-180
>                 URL: https://issues.apache.org/jira/browse/SIS-180
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>          Components: Storage
>    Affects Versions: 0.5
>            Reporter: M. Le Bihan
>            Assignee: Martin Desruisseaux
>            Priority: Minor
>             Fix For: 0.5
>
>         Attachments: src.zip
>
>
> It would be useful to be able to query DBF content through SQL.
> But there are no free drivers available for the old _Dbase 3_ format.
> The first step is to create short implementations of _Connection_, _Statement_, _ResultSet_,
_ResultSetMetadata_ interfaces for a JDBC using our _Database_ class as core binary loader
at the begining.
> The main difficulty is to respond to a SQL request, and first : being able to analyze
it to understand what is expected.
> The SQL request analysis is a very strong job, but I suggest to ease it a lot by relying
on _AntLR_ API for grammar analysis, associated with a BNF grammar file, maybe taken from
^1^ or from elsewhere (grammars are of public domain).
> The goal of this current JIRA is only to be able to perform a 
> _SELECT * FROM <shapefile layer name>_
> The WHERE clause or the selection of fields, will come later in other JIRA.
> No transactions, classic _Statement_ only.
> _PreparedStatement_ would be also implemented later (another JIRA).
> Of course, this improvment can be discarded if an open source or free driver is discovered,
that would allow us to execute SQL requests on DBase 3 easily.
> ^1^ For example, [http://www.savage.net.au/SQL/] has some BNF, but maybe elsewhere they
will more compliant with AntLR.



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