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 134 database schema make it possible to delete only the outdated top-level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