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 132 database schema make it possible to delete only the outdated top-level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