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 122 database schema make it possible to delete only the outdated top-level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