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 112 database schema make it possible to delete only the outdated top-level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