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 106 database schema make it possible to delete only the outdated top-level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