doc/man1/htsn-import.1

   1 .TH htsn-import 1
   2
   3 .SH NAME
   4 htsn-import \- Import XML files from The Sports Network into an RDBMS.
   5
   6 .SH SYNOPSIS
   7
   8 \fBhtsn-import\fR [OPTIONS] [FILES]
   9
  10 .SH DESCRIPTION
  11 .P
  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?
  16 .P
  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
  22 database.
  23 .P
  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.
  29 .P
  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.
  36 .P
  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.
  45
  46 .SH SUPPORTED DOCUMENT TYPES
  47 .P
  48 The XML document types obtained from the feed are uniquely identified
  49 by their DTDs. We currently support documents with the following DTDs:
  50 .IP \[bu] 2
  51 AutoRacingResultsXML.dtd
  52 .IP \[bu]
  53 Auto_Racing_Schedule_XML.dtd
  54 .IP \[bu]
  55 Heartbeat.dtd
  56 .IP \[bu]
  57 Injuries_Detail_XML.dtd
  58 .IP \[bu]
  59 injuriesxml.dtd
  60 .IP \[bu]
  61 newsxml.dtd
  62 .IP \[bu]
  63 Odds_XML.dtd
  64 .IP \[bu]
  65 scoresxml.dtd
  66 .IP \[bu]
  67 weatherxml.dtd
  68 .IP \[bu]
  69 GameInfo
  70 .RS
  71 .IP \[bu]
  72 CBASK_Lineup_XML.dtd
  73 .IP \[bu]
  74 cbaskpreviewxml.dtd
  75 .IP \[bu]
  76 cflpreviewxml.dtd
  77 .IP \[bu]
  78 Matchup_NBA_NHL_XML.dtd
  79 .IP \[bu]
  80 MLB_Gaming_Matchup_XML.dtd
  81 .IP \[bu]
  82 MLB_Lineup_XML.dtd
  83 .IP \[bu]
  84 MLB_Matchup_XML.dtd
  85 .IP \[bu]
  86 MLS_Preview_XML.dtd
  87 .IP \[bu]
  88 mlbpreviewxml.dtd
  89 .IP \[bu]
  90 NBA_Gaming_Matchup_XML.dtd
  91 .IP \[bu]
  92 NBA_Playoff_Matchup_XML.dtd
  93 .IP \[bu]
  94 NBALineupXML.dtd
  95 .IP \[bu]
  96 nbapreviewxml.dtd
  97 .IP \[bu]
  98 NCAA_FB_Preview_XML.dtd
  99 .IP \[bu]
 100 NFL_NCAA_FB_Matchup_XML.dtd
 101 .IP \[bu]
 102 nflpreviewxml.dtd
 103 .IP \[bu]
 104 nhlpreviewxml.dtd
 105 .IP \[bu]
 106 recapxml.dtd
 107 .IP \[bu]
 108 WorldBaseballPreviewXML.dtd
 109 .RE
 110 .IP \[bu]
 111 SportInfo
 112 .RS
 113 .IP \[bu]
 114 CBASK_3PPctXML.dtd
 115 .IP \[bu]
 116 Cbask_All_Tourn_Teams_XML.dtd
 117 .IP \[bu]
 118 CBASK_AssistsXML.dtd
 119 .IP \[bu]
 120 Cbask_Awards_XML.dtd
 121 .IP \[bu]
 122 CBASK_BlocksXML.dtd
 123 .IP \[bu]
 124 Cbask_Conf_Standings_XML.dtd
 125 .RE
 126 .P
 127 The GameInfo and SportInfo types do not have their own top-level
 128 tables in the database. Instead, their raw XML is stored in either the
 129 \(dqgame_info\(dq or \(dqsport_info\(dq table respectively.
 130
 131 .SH DATABASE SCHEMA
 132 .P
 133 At the top level (with two notable exceptions), we have one table for
 134 each of the XML document types that we import. For example, the
 135 documents corresponding to \fInewsxml.dtd\fR will have a table called
 136 \(dqnews\(dq. All top-level tables contain two important fields,
 137 \(dqxml_file_id\(dq and \(dqtime_stamp\(dq. The former is unique and
 138 prevents us from inserting the same data twice. The time stamp on the
 139 other hand lets us know when the data is old and can be removed. The
 140 database schema make it possible to delete only the outdated top-level
 141 records; all transient children should be removed by triggers.
 142 .P
 143 These top-level tables will often have children. For example, each
 144 news item has zero or more locations associated with it. The child
 145 table will be named <parent>_<children>, which in this case
 146 corresponds to \(dqnews_locations\(dq.
 147 .P
 148 To relate the two, a third table may exist with name
 149 <parent>__<child>. Note the two underscores. This prevents ambiguity
 150 when the child table itself contains underscores. The table joining
 151 \(dqnews\(dq with \(dqnews_locations\(dq is thus called
 152 \(dqnews__news_locations\(dq. This is necessary when the child table
 153 has a unique constraint; we don't want to blindly insert duplicate
 154 records keyed to the parent. Instead we'd like to use the third table
 155 to map an existing child to the new parent.
 156 .P
 157 Where it makes sense, children are kept unique to prevent pointless
 158 duplication. This slows down inserts, and speeds up reads (which are
 159 much more frequent). There is a tradeoff to be made, however. For a
 160 table with a small, fixed upper bound on the number of rows (like
 161 \(dqodds_casinos\(dq), there is great benefit to de-duplication. The
 162 total number of rows stays small, so inserts are still quick, and many
 163 duplicate rows are eliminated.
 164 .P
 165 But, with a table like \(dqodds_games\(dq, the number of games grows
 166 quickly and without bound. It is therefore more beneficial to be able
 167 to delete the old games (through an ON DELETE CASCADE, tied to
 168 \(dqodds\(dq) than it is to eliminate duplication. A table like
 169 \(dqnews_locations\(dq is somewhere in-between. It is hoped that the
 170 unique constraint in the top-level table's \(dqxml_file_id\(dq will
 171 prevent duplication in this case anyway.
 172 .P
 173 The aforementioned exceptions are the \(dqgame_info\(dq and
 174 \(dqsport_info\(dq tables. These tables contain the raw XML for a
 175 number of DTDs that are not handled individually. This is partially
 176 for backwards-compatibility with a legacy implementation, but is
 177 mostly a stopgap due to a lack of resources at the moment. These two
 178 tables (game_info and sport_info) still possess timestamps that allow
 179 us to prune old data.
 180 .P
 181 UML diagrams of the resulting database schema for each XML document
 182 type are provided with the \fBhtsn-import\fR documentation.
 183
 184 .SH XML Schema Oddities
 185 .P
 186 There are a number of problems with the XML on the wire. Even if we
 187 construct the DTDs ourselves, the results are sometimes
 188 inconsistent. Here we document a few of them.
 189
 190 .IP \[bu] 2
 191 Odds_XML.dtd
 192
 193 The <Notes> elements here are supposed to be associated with a set of
 194 <Game> elements, but since the pair
 195 (<Notes>...</Notes><Game>...</Game>) can appear zero or more times,
 196 this leads to ambiguity in parsing. We therefore ignore the notes
 197 entirely (although a hack is employed to facilitate parsing).
 198
 199 .IP \[bu]
 200 weatherxml.dtd
 201
 202 There appear to be two types of weather documents; the first has
 203 <listing> contained within <forecast> and the second has <forecast>
 204 contained within <listing>. While it would be possible to parse both,
 205 it would greatly complicate things. The first form is more common, so
 206 that's all we support for now.
 207
 208 .SH OPTIONS
 209
 210 .IP \fB\-\-backend\fR,\ \fB\-b\fR
 211 The RDBMS backend to use. Valid choices are \fISqlite\fR and
 212 \fIPostgres\fR. Capitalization is important, sorry.
 213
 214 Default: Sqlite
 215
 216 .IP \fB\-\-connection-string\fR,\ \fB\-c\fR
 217 The connection string used for connecting to the database backend
 218 given by the \fB\-\-backend\fR option. The default is appropriate for
 219 the \fISqlite\fR backend.
 220
 221 Default: \(dq:memory:\(dq
 222
 223 .IP \fB\-\-log-file\fR
 224 If you specify a file here, logs will be written to it (possibly in
 225 addition to syslog). Can be either a relative or absolute path. It
 226 will not be auto-rotated; use something like logrotate for that.
 227
 228 Default: none
 229
 230 .IP \fB\-\-log-level\fR
 231 How verbose should the logs be? We log notifications at four levels:
 232 DEBUG, INFO, WARN, and ERROR. Specify the \(dqmost boring\(dq level of
 233 notifications you would like to receive (in all-caps); more
 234 interesting notifications will be logged as well. The debug output is
 235 extremely verbose and will not be written to syslog even if you try.
 236
 237 Default: INFO
 238
 239 .IP \fB\-\-remove\fR,\ \fB\-r\fR
 240 Remove successfully processed files. If you enable this, you can see
 241 at a glance which XML files are not being processed, because they're
 242 all that should be left.
 243
 244 Default: disabled
 245
 246 .IP \fB\-\-syslog\fR,\ \fB\-s\fR
 247 Enable logging to syslog. On Windows this will attempt to communicate
 248 (over UDP) with a syslog daemon on localhost, which will most likely
 249 not work.
 250
 251 Default: disabled
 252
 253 .SH CONFIGURATION FILE
 254 .P
 255 Any of the command-line options mentioned above can be specified in a
 256 configuration file instead. We first look for \(dqhtsn-importrc\(dq in
 257 the system configuration directory. We then look for a file named
 258 \(dq.htsn-importrc\(dq in the user's home directory. The latter will
 259 override the former.
 260 .P
 261 The user's home directory is simply $HOME on Unix; on Windows it's
 262 wherever %APPDATA% points. The system configuration directory is
 263 determined by Cabal; the \(dqsysconfdir\(dq parameter during the
 264 \(dqconfigure\(dq step is used.
 265 .P
 266 The file's syntax is given by examples in the htsn-importrc.example file
 267 (included with \fBhtsn-import\fR).
 268 .P
 269 Options specified on the command-line override those in either
 270 configuration file.
 271
 272 .SH EXAMPLES
 273 .IP \[bu] 2
 274 Import newsxml.xml into a preexisting sqlite database named \(dqfoo.sqlite3\(dq:
 275
 276 .nf
 277 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
 278 .I "              test/xml/newsxml.xml"
 279 Successfully imported test/xml/newsxml.xml.
 280 Imported 1 document(s) total.
 281 .fi
 282 .IP \[bu]
 283 Repeat the previous example, but delete newsxml.xml afterwards:
 284
 285 .nf
 286 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
 287 .I "              --remove test/xml/newsxml.xml"
 288 Successfully imported test/xml/newsxml.xml.
 289 Imported 1 document(s) total.
 290 Removed processed file test/xml/newsxml.xml.
 291 .fi
 292 .IP \[bu]
 293 Use a Postgres database instead of the default Sqlite. This assumes
 294 that you have a database named \(dqhtsn\(dq accessible to user
 295 \(dqpostgres\(dq locally:
 296
 297 .nf
 298 .I $ htsn-import --connection-string='dbname=htsn user=postgres' \\\\
 299 .I "              --backend=Postgres test/xml/newsxml.xml"
 300 Successfully imported test/xml/newsxml.xml.
 301 Imported 1 document(s) total.
 302 .fi
 303
 304 .SH BUGS
 305
 306 .P
 307 Send bugs to michael@orlitzky.com.