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 108 database schema make it possible to delete only the outdated top-level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