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 110 database schema make it possible to delete only the outdated top-level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