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 130 database schema make it possible to delete only the outdated top-level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