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 128 database schema make it possible to delete only the outdated top-level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