should be considered a bug if they are incorrect. The diagrams are
created using the pgModeler <http://www.pgmodeler.com.br/> tool.
+.SH DATABASE SCHEMA COMPROMISES
+
+There are a few places that the database schema isn't exactly how we'd
+like it to be:
+
+.IP \[bu] 2
+\fIearlylineXML.dtd\fR
+
+The database representations for earlylineXML.dtd and
+MLB_earlylineXML.dtd are the same; that is, they share the same
+tables. The two document types represent team names in different
+ways. In order to accomodate both types with one parser, we had to
+make both ways optional, and then merge the two together before
+converting to the database representation.
+
+Unfortunately, when we merge two optional things together, we get
+another optional thing back. There's no way to say that \(dqat least
+one is not optional.\(dq So the team names in the database schema are
+optional as well, even though they should always be present.
+
+.SH NULL POLICY
+.P
+Normally in a database one makes a distinction between fields that
+simply don't exist, and those fields that are
+\(dqempty\(dq. Translating from XML, there is a natural way to
+determine which one should be used: if an element is present in the
+XML document but its contents are empty, then an empty string should
+be inserted into the corresponding field. If on the other hand the
+element is missing entirely, the corresponding database entry should
+be NULL to indicate that fact.
+.P
+This sounds well and good, but the XML must be consistent for the
+database consumer to make any sense of what he sees. The feed XML uses
+optional and blank elements interchangeably, and without any
+discernable pattern. To propagate this pattern into the database would
+only cause confusion.
+.P
+As a result, a policy was adopted: both optional elements and elements
+whose contents can be empty will be considered nullable in the
+database. If the element is missing, the corresponding field is
+NULL. Likewise if the content is simply missing. That means there
+should never be a (completely) empty string in a database column.
+
.SH XML SCHEMA GENERATION
.P
In order to parse XML, you need to know the structure of your
Processed 1 document(s) total.
.fi
.P
-At this point, the database schema matches the old documents, i.e. the
-ones without \fIAStarter\fR and \fIHStarter\fR. If we use a new
+At this point, the database schema matches the old documents, that is,
+the ones without \fIAStarter\fR and \fIHStarter\fR. If we use a new
version of \fBhtsn-import\fR, supporting the new fields, the migration
is handled gracefully:
.P
inconsistent. Here we document a few of them.
.IP \[bu] 2
+\fInewsxml.dtd\fR
+
+The TSN DTD for news (and almost all XML on the wire) suggests that
+there is a exactly one (possibly-empty) <SMS> element present in each
+message. However, we have seen an example (XML_File_ID 21232353) where
+an empty <SMS> followed a non-empty one:
+
+.fi
+<SMS>Odd Man Rush: Snow under pressure to improve Isles quickly</SMS>
+<SMS></SMS>
+.nf
+
+We don't parse this case at the moment, but we do recognize it and report
+it as unsupported so that offending documents can be removed. An example
+is provided as test/xml/newsxml-multiple-sms.xml.
+
+.IP \[bu]
+\fIMLB_earlylineXML.dtd\fR
+
+Unlike earlylineXML.dtd, this document type has more than one <game>
+associated with each <date>. Moreover, each <date> has a bunch of
+<note> children that are supposed to be associated with the <game>s,
+but the document structure indicates no explicit relationship. For
+example,
+
+.nf
+<date>
+ <note>...</note>
+ <game>...</game>
+ <game>...</game>
+ <note>...</note>
+ <game>...</game>
+</date>
+.fi
+
+Here the first <note> is inferred to apply to the two <game>s that
+follow it, and the second <note> applies to the single <game> that
+follows it. But this is very fragile to parse. Instead, we use a hack
+to facilitate (un)pickling, and then drop the notes entirely during
+the database conversion.
+
+A similar workaround is implemented for Odds_XML.dtd.
+
+.IP \[bu]
\fIOdds_XML.dtd\fR
The <Notes> elements here are supposed to be associated with a set of
contained within <listing>. While it would be possible to parse both,
it would greatly complicate things. The first form is more common, so
that's all we support for now. An example is provided as
-schemagen/weatherxml/20143655.xml.
+test/xml/weatherxml-type2.xml.
+
+We are however able to identify the second type. When one is
+encountered, an informational message (that it is unsupported) will be
+printed. If the \fI\-\-remove\fR flag is used, the file will be
+deleted. This prevents documents that we know we can't import from
+building up.
+
+Another problem that comes up occasionally is that the home and away
+team elements appear in the reverse order. As in the other case, we
+report these as unsupported and then \(dqsucceed\(dq so that the
+offending document can be removed if desired. An example is provided
+as test/xml/weatherxml-backwards-teams.xml.
+
+.SH DATE/TIME ISSUES
+
+Dates and times appear in a number of places on the feed. The date
+portions are usually, fine, but the times often lack important
+information such as the time zone, or whether \(dq8 o'clock\(dq means
+a.m. or p.m.
+
+The most pervasive issue occurs with the timestamps that are included
+in every message. A typical timestamp looks like,
+
+.nf
+<time_stamp> May 24, 2014, at 04:18 PM ET </time_stamp>
+.fi
+
+The \(dqtime zone\(dq is given as \(dqET\(dq, but unfortunately
+\(dqET\(dq is not a valid time zone. It stands for \(dqEastern
+Time\(dq, which can belong to either of two time zones, EST or EDT,
+based on the time of the year (that is, whether or not daylight
+savings time is in effect) and one's location (for example, Arizona
+doesn't observe daylight savings time). It's not much more useful to
+be off by one hour than it is to be off by five hours, and since we
+can't determine the true offset from the timestamp, we always parse
+and store these as UTC.
+
+Here's a list of the ones that may cause surprises:
+
+.IP \[bu] 2
+\fIAutoRacingResultsXML.dtd\fR
+
+The <RaceDate> elements contain a full date and time, but no time zone
+information:
+
+.nf
+<RaceDate>5/24/2014 2:45:00 PM</RaceDate>
+.fi
+
+We parse them as UTC, which will be wrong when stored,
+but \(dqcorrect\(dq if the new UTC time zone is ignored.
+
+.IP \[bu]
+\fIAuto_Racing_Schedule_XML.dtd\fR
+
+The <Race_Date> and <Race_Time> elements are combined into on field in
+the database, but no time zone information is given. For example,
+
+.nf
+<Race_Date>02/16/2013</Race_Date>
+<Race_Time>08:10 PM</Race_Time>
+.fi
+
+As a result, we parse and store the times as UTC. The race times are
+not always present in the database, but when they are missing, they
+are presented as \(dqTBA\(dq (to be announced):
+
+.nf
+<Race_Time>TBA</Race_Time>
+.fi
+
+Since the dates do not appear to be optional, we store only the race
+date in that case.
+
+.IP \[bu]
+\fIearlylineXML.dtd\fR
+
+The <time> elements in the early lines contain neither a time zone nor
+an am/pm identifier:
+
+.nf
+<time>8:30</time>
+.fi
+
+The times are parsed and stored as UTC, since we
+don't have any other information upon which to base a guess. Even if
+one ignores the UTC time zone, the time can possibly be off by 12
+hours (due to the a.m./p.m. issue).
+
+The game <time> elements can also be empty. Since we store the
+combined game date/time in one field, these games will appear to begin
+at midnight on the day they occur.
+
+.IP \[bu]
+\fIjfilexml.dtd\fR
+
+The <Game_Date> and <Game_Time> elements are combined into on field in
+the database, but no time zone information is given. For example,
+
+.nf
+<Game_Date>06/15/2014</Game_Date>
+<Game_Time>08:00 PM</Game_Time>
+.fi
+
+As a result, we parse and store the times as UTC.
+
+The <CurrentTimestamp> elements suffer a similar problem, sans the
+date:
+
+.nf
+<CurrentTimeStamp>11:30 A.M.</CurrentTimeStamp>
+.fi
+
+They are also stored as UTC.
+
+.IP \[bu]
+\fIMLB_earlylineXML.dtd\fR
+
+See earlylineXML.dtd.
+
+.IP \[bu]
+\fIOdds_XML.dtd\fR
+
+The <Game_Date> and <Game_Time> elements are combined into on field in
+the database, but no time zone information is given. For example,
+
+.nf
+<Game_Date>01/04/2014</Game_Date>
+<Game_Time>04:35 PM</Game_Time>
+.fi
+
+As a result, we parse and store the times as UTC.
+
+.IP \[bu]
+\fISchedule_Changes_XML.dtd\fR
+
+The <Game_Date> and <Game_Time> elements are combined into on field in
+the database, but no time zone information is given. For example,
+
+.nf
+<Game_Date>06/06/2014</Game_Date>
+<Game_Time>04:00 PM</Game_Time>
+.fi
+
+As a result, we parse and store the times as UTC. The game times are
+not always present in the database, but when they are missing, they
+are presented as \(dqTBA\(dq (to be announced):
+
+.nf
+<Game_Time>TBA</Game_Time>
+.fi
+
+Since the dates do not appear to be optional, we store only the game
+date in that case.
+
+.SH DEPLOYMENT
+.P
+When deploying for the first time, the target database will most
+likely be empty. The schema will be migrated when a new document type
+is seen, but this has a downside: it can be months before every
+supported document type has been seen once. This can make it difficult
+to test the database permissions.
+.P
+Since all of the test XML documents have old timestamps, one easy
+workaround is the following: simply import all of the test XML
+documents, and then delete them using whatever script is used to prune
+old entries. This will force the migration of the schema, after which
+you can set and test the database permissions.
+.P
+Something as simple as,
+.P
+.nf
+.I $ find ./test/xml -iname '*.xml' | xargs htsn-import -c foo.sqlite
+.fi
+.P
+should do it.
.SH OPTIONS
.IP \[bu]
Auto_Racing_Schedule_XML.dtd
.IP \[bu]
+earlylineXML.dtd
+.IP \[bu]
Heartbeat.dtd
.IP \[bu]
Injuries_Detail_XML.dtd
.IP \[bu]
jfilexml.dtd
.IP \[bu]
+MLB_earlylineXML.dtd
+.IP \[bu]
newsxml.dtd
.IP \[bu]
Odds_XML.dtd
.IP \[bu]
+Schedule_Changes_XML.dtd
+.IP \[bu]
scoresxml.dtd
.IP \[bu]
weatherxml.dtd
.IP \[bu]
CBASK_FTPctXML.dtd
.IP \[bu]
+Cbask_Indv_No_Avg_XML
+.IP \[bu]
Cbask_Indv_Scoring_XML.dtd
.IP \[bu]
+Cbask_Indv_Shooting_XML.dtd
+.IP \[bu]
CBASK_MinutesXML.dtd
.IP \[bu]
Cbask_Polls_XML.dtd
.IP \[bu]
NFLGiveTakeXML.dtd
.IP \[bu]
+NFLGrassTurfDomeOutsideXML.dtd
+.IP \[bu]
NFLInside20XML.dtd
.IP \[bu]
+NFLInterceptionLeadersXML.dtd
+.IP \[bu]
NFLKickoffsXML.dtd
.IP \[bu]
NFLMondayNightXML.dtd
.IP \[bu]
+NFLPassingLeadersXML.dtd
+.IP \[bu]
NFLPassLeadXML.dtd
.IP \[bu]
NFLQBStartsXML.dtd
.IP \[bu]
+NFLReceivingLeadersXML.dtd
+.IP \[bu]
+NFLRushingLeadersXML.dtd
+.IP \[bu]
NFLSackLeadersXML.dtd
.IP \[bu]
nflstandxml.dtd
.IP \[bu]
+NFLTackleFFLeadersXML.dtd
+.IP \[bu]
NFLTeamRankingsXML.dtd
.IP \[bu]
+NFLTopKickoffReturnXML.dtd
+.IP \[bu]
NFLTopPerformanceXML.dtd
.IP \[bu]
+NFLTopPuntReturnXML.dtd
+.IP \[bu]
NFLTotalYardageXML.dtd
.IP \[bu]
+NFLYardsXML.dtd
+.IP \[bu]
NFL_KickingLeaders_XML.dtd
.IP \[bu]
NFL_NBA_Draft_XML.dtd
.IP \[bu]
+NFL_PuntingLeaders_XML.dtd
+.IP \[bu]
NFL_Roster_XML.dtd
.IP \[bu]
NFL_Team_Stats_XML.dtd
projects / dead / htsn-import.git / blobdiff