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 104 database schema make it possible to delete only the outdated top-level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