4 htsn-import \- Import XML files from The Sports Network into an RDBMS.
8 \fBhtsn-import\fR [OPTIONS] [FILES]
12 The Sports Network <http://www.sportsnetwork.com/> offers an XML feed
13 containing various sports news and statistics. Our sister program
14 \fBhtsn\fR is capable of retrieving the feed and saving the individual
15 XML documents contained therein. But what to do with them?
17 The purpose of \fBhtsn-import\fR is to take these XML documents and
18 get them into something we can use, a relational database management
19 system (RDBMS), otherwise known as a SQL database. The structure of
20 relational database, is, well, relational, and the feed XML is not. So
21 there is some work to do before the data can be imported into the
24 First, we must parse the XML. Each supported document type (see below)
25 has a full pickle/unpickle implementation (\(dqpickle\(dq is simply a
26 synonym for serialize here). That means that we parse the entire
27 document into a data structure, and if we pickle (serialize) that data
28 structure, we get the exact same XML document tha we started with.
30 This is important for two reasons. First, it serves as a second level
31 of validation. The first validation is performed by the XML parser,
32 but if that succeeds and unpicking fails, we know that something is
33 fishy. Second, we don't ever want to be surprised by some new element
34 or attribute showing up in the XML. The fact that we can unpickle the
35 whole thing now means that we won't be surprised in the future.
37 The aforementioned feature is especially important because we
38 automatically migrate the database schema every time we import a
39 document. If you attempt to import a \(dqnewsxml.dtd\(dq document, all
40 database objects relating to the news will be created if they do not
41 exist. We don't want the schema to change out from under us without
42 warning, so it's important that no XML be parsed that would result in
43 a different schema than we had previously. Since we can
44 pickle/unpickle everything already, this should be impossible.
46 .SH SUPPORTED DOCUMENT TYPES
48 The XML document types obtained from the feed are uniquely identified
49 by their DTDs. We currently support documents with the following DTDs:
51 AutoRacingResultsXML.dtd
53 Auto_Racing_Schedule_XML.dtd
57 Injuries_Detail_XML.dtd
78 Matchup_NBA_NHL_XML.dtd
80 MLB_Gaming_Matchup_XML.dtd
90 NBA_Gaming_Matchup_XML.dtd
92 NBA_Playoff_Matchup_XML.dtd
98 NCAA_FB_Preview_XML.dtd
100 NFL_NCAA_FB_Matchup_XML.dtd
108 WorldBaseballPreviewXML.dtd
116 Cbask_All_Tourn_Teams_XML.dtd
124 Cbask_Conf_Standings_XML.dtd
126 Cbask_DivII_III_Indv_Stats_XML.dtd
128 Cbask_DivII_Team_Stats_XML.dtd
130 Cbask_DivIII_Team_Stats_XML.dtd
138 Cbask_Indv_Scoring_XML.dtd
144 CBASK_ReboundsXML.dtd
146 CBASK_ScoringLeadersXML.dtd
148 Cbask_Team_ThreePT_Made_XML.dtd
150 Cbask_Team_ThreePT_PCT_XML.dtd
152 Cbask_Team_Win_Pct_XML.dtd
154 Cbask_Top_Twenty_Five_XML.dtd
156 CBASK_TopTwentyFiveResult_XML.dtd
158 Cbask_Tourn_Awards_XML.dtd
160 Cbask_Tourn_Champs_XML.dtd
162 Cbask_Tourn_Indiv_XML.dtd
164 Cbask_Tourn_Leaders_XML.dtd
166 Cbask_Tourn_MVP_XML.dtd
168 Cbask_Tourn_Records_XML.dtd
170 LeagueScheduleXML.dtd
174 Minor_Baseball_League_Leaders_XML.dtd
177 The GameInfo and SportInfo types do not have their own top-level
178 tables in the database. Instead, their raw XML is stored in either the
179 \(dqgame_info\(dq or \(dqsport_info\(dq table respectively.
183 At the top level (with two notable exceptions), we have one table for
184 each of the XML document types that we import. For example, the
185 documents corresponding to \fInewsxml.dtd\fR will have a table called
186 \(dqnews\(dq. All top-level tables contain two important fields,
187 \(dqxml_file_id\(dq and \(dqtime_stamp\(dq. The former is unique and
188 prevents us from inserting the same data twice. The time stamp on the
189 other hand lets us know when the data is old and can be removed. The
190 database schema make it possible to delete only the outdated top-level
191 records; all transient children should be removed by triggers.
193 These top-level tables will often have children. For example, each
194 news item has zero or more locations associated with it. The child
195 table will be named <parent>_<children>, which in this case
196 corresponds to \(dqnews_locations\(dq.
198 To relate the two, a third table may exist with name
199 <parent>__<child>. Note the two underscores. This prevents ambiguity
200 when the child table itself contains underscores. The table joining
201 \(dqnews\(dq with \(dqnews_locations\(dq is thus called
202 \(dqnews__news_locations\(dq. This is necessary when the child table
203 has a unique constraint; we don't want to blindly insert duplicate
204 records keyed to the parent. Instead we'd like to use the third table
205 to map an existing child to the new parent.
207 Where it makes sense, children are kept unique to prevent pointless
208 duplication. This slows down inserts, and speeds up reads (which are
209 much more frequent). There is a tradeoff to be made, however. For a
210 table with a small, fixed upper bound on the number of rows (like
211 \(dqodds_casinos\(dq), there is great benefit to de-duplication. The
212 total number of rows stays small, so inserts are still quick, and many
213 duplicate rows are eliminated.
215 But, with a table like \(dqodds_games\(dq, the number of games grows
216 quickly and without bound. It is therefore more beneficial to be able
217 to delete the old games (through an ON DELETE CASCADE, tied to
218 \(dqodds\(dq) than it is to eliminate duplication. A table like
219 \(dqnews_locations\(dq is somewhere in-between. It is hoped that the
220 unique constraint in the top-level table's \(dqxml_file_id\(dq will
221 prevent duplication in this case anyway.
223 The aforementioned exceptions are the \(dqgame_info\(dq and
224 \(dqsport_info\(dq tables. These tables contain the raw XML for a
225 number of DTDs that are not handled individually. This is partially
226 for backwards-compatibility with a legacy implementation, but is
227 mostly a stopgap due to a lack of resources at the moment. These two
228 tables (game_info and sport_info) still possess timestamps that allow
229 us to prune old data.
231 UML diagrams of the resulting database schema for each XML document
232 type are provided with the \fBhtsn-import\fR documentation.
234 .SH XML Schema Oddities
236 There are a number of problems with the XML on the wire. Even if we
237 construct the DTDs ourselves, the results are sometimes
238 inconsistent. Here we document a few of them.
243 The <Notes> elements here are supposed to be associated with a set of
244 <Game> elements, but since the pair
245 (<Notes>...</Notes><Game>...</Game>) can appear zero or more times,
246 this leads to ambiguity in parsing. We therefore ignore the notes
247 entirely (although a hack is employed to facilitate parsing).
252 There appear to be two types of weather documents; the first has
253 <listing> contained within <forecast> and the second has <forecast>
254 contained within <listing>. While it would be possible to parse both,
255 it would greatly complicate things. The first form is more common, so
256 that's all we support for now.
260 .IP \fB\-\-backend\fR,\ \fB\-b\fR
261 The RDBMS backend to use. Valid choices are \fISqlite\fR and
262 \fIPostgres\fR. Capitalization is important, sorry.
266 .IP \fB\-\-connection-string\fR,\ \fB\-c\fR
267 The connection string used for connecting to the database backend
268 given by the \fB\-\-backend\fR option. The default is appropriate for
269 the \fISqlite\fR backend.
271 Default: \(dq:memory:\(dq
273 .IP \fB\-\-log-file\fR
274 If you specify a file here, logs will be written to it (possibly in
275 addition to syslog). Can be either a relative or absolute path. It
276 will not be auto-rotated; use something like logrotate for that.
280 .IP \fB\-\-log-level\fR
281 How verbose should the logs be? We log notifications at four levels:
282 DEBUG, INFO, WARN, and ERROR. Specify the \(dqmost boring\(dq level of
283 notifications you would like to receive (in all-caps); more
284 interesting notifications will be logged as well. The debug output is
285 extremely verbose and will not be written to syslog even if you try.
289 .IP \fB\-\-remove\fR,\ \fB\-r\fR
290 Remove successfully processed files. If you enable this, you can see
291 at a glance which XML files are not being processed, because they're
292 all that should be left.
296 .IP \fB\-\-syslog\fR,\ \fB\-s\fR
297 Enable logging to syslog. On Windows this will attempt to communicate
298 (over UDP) with a syslog daemon on localhost, which will most likely
303 .SH CONFIGURATION FILE
305 Any of the command-line options mentioned above can be specified in a
306 configuration file instead. We first look for \(dqhtsn-importrc\(dq in
307 the system configuration directory. We then look for a file named
308 \(dq.htsn-importrc\(dq in the user's home directory. The latter will
311 The user's home directory is simply $HOME on Unix; on Windows it's
312 wherever %APPDATA% points. The system configuration directory is
313 determined by Cabal; the \(dqsysconfdir\(dq parameter during the
314 \(dqconfigure\(dq step is used.
316 The file's syntax is given by examples in the htsn-importrc.example file
317 (included with \fBhtsn-import\fR).
319 Options specified on the command-line override those in either
324 Import newsxml.xml into a preexisting sqlite database named \(dqfoo.sqlite3\(dq:
327 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
328 .I " test/xml/newsxml.xml"
329 Successfully imported test/xml/newsxml.xml.
330 Imported 1 document(s) total.
333 Repeat the previous example, but delete newsxml.xml afterwards:
336 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
337 .I " --remove test/xml/newsxml.xml"
338 Successfully imported test/xml/newsxml.xml.
339 Imported 1 document(s) total.
340 Removed processed file test/xml/newsxml.xml.
343 Use a Postgres database instead of the default Sqlite. This assumes
344 that you have a database named \(dqhtsn\(dq accessible to user
345 \(dqpostgres\(dq locally:
348 .I $ htsn-import --connection-string='dbname=htsn user=postgres' \\\\
349 .I " --backend=Postgres test/xml/newsxml.xml"
350 Successfully imported test/xml/newsxml.xml.
351 Imported 1 document(s) total.
357 Send bugs to michael@orlitzky.com.