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 Heartbeat.dtd
  54 .IP \[bu]
  55 Injuries_Detail_XML.dtd
  56 .IP \[bu]
  57 injuriesxml.dtd
  58 .IP \[bu]
  59 newsxml.dtd
  60 .IP \[bu]
  61 Odds_XML.dtd
  62 .IP \[bu]
  63 scoresxml.dtd
  64 .IP \[bu]
  65 weatherxml.dtd
  66 .IP \[bu]
  67 GameInfo
  68 .RS
  69 .IP \[bu]
  70 CBASK_Lineup_XML.dtd
  71 .IP \[bu]
  72 cbaskpreviewxml.dtd
  73 .IP \[bu]
  74 cflpreviewxml.dtd
  75 .IP \[bu]
  76 Matchup_NBA_NHL_XML.dtd
  77 .IP \[bu]
  78 MLB_Gaming_Matchup_XML.dtd
  79 .IP \[bu]
  80 MLB_Lineup_XML.dtd
  81 .IP \[bu]
  82 MLB_Matchup_XML.dtd
  83 .IP \[bu]
  84 MLS_Preview_XML.dtd
  85 .IP \[bu]
  86 mlbpreviewxml.dtd
  87 .IP \[bu]
  88 NBA_Gaming_Matchup_XML.dtd
  89 .IP \[bu]
  90 NBA_Playoff_Matchup_XML.dtd
  91 .IP \[bu]
  92 NBALineupXML.dtd
  93 .IP \[bu]
  94 nbapreviewxml.dtd
  95 .IP \[bu]
  96 NCAA_FB_Preview_XML.dtd
  97 .IP \[bu]
  98 nflpreviewxml.dtd
  99 .IP \[bu]
 100 nhlpreviewxml.dtd
 101 .IP \[bu]
 102 recapxml.dtd
 103 .RE
 104 .P
 105 The GameInfo and SportsInfo types do not have their own top-level
 106 tables in the database. Instead, their raw XML is stored in either the
 107 \(dqgame_info\(dq or \(dqsports_info\(dq table respectively.
 108
 109 .SH DATABASE SCHEMA
 110 .P
 111 At the top level (with two notable exceptions), we have one table for
 112 each of the XML document types that we import. For example, the
 113 documents corresponding to \fInewsxml.dtd\fR will have a table called
 114 \(dqnews\(dq. All top-level tables contain two important fields,
 115 \(dqxml_file_id\(dq and \(dqtime_stamp\(dq. The former is unique and
 116 prevents us from inserting the same data twice. The time stamp on the
 117 other hand lets us know when the data is old and can be removed. The
 118 database schema make it possible to delete only the outdated top-level
 119 records; all transient children should be removed by triggers.
 120 .P
 121 These top-level tables will often have children. For example, each
 122 news item has zero or more locations associated with it. The child
 123 table will be named <parent>_<children>, which in this case
 124 corresponds to \(dqnews_locations\(dq.
 125 .P
 126 To relate the two, a third table may exist with name
 127 <parent>__<child>. Note the two underscores. This prevents ambiguity
 128 when the child table itself contains underscores. The table joining
 129 \(dqnews\(dq with \(dqnews_locations\(dq is thus called
 130 \(dqnews__news_locations\(dq. This is necessary when the child table
 131 has a unique constraint; we don't want to blindly insert duplicate
 132 records keyed to the parent. Instead we'd like to use the third table
 133 to map an existing child to the new parent.
 134 .P
 135 Where it makes sense, children are kept unique to prevent pointless
 136 duplication. This slows down inserts, and speeds up reads (which are
 137 much more frequent). There is a tradeoff to be made, however. For a
 138 table with a small, fixed upper bound on the number of rows (like
 139 \(dqodds_casinos\(dq), there is great benefit to de-duplication. The
 140 total number of rows stays small, so inserts are still quick, and many
 141 duplicate rows are eliminated.
 142 .P
 143 But, with a table like \(dqodds_games\(dq, the number of games grows
 144 quickly and without bound. It is therefore more beneficial to be able
 145 to delete the old games (through an ON DELETE CASCADE, tied to
 146 \(dqodds\(dq) than it is to eliminate duplication. A table like
 147 \(dqnews_locations\(dq is somewhere in-between. It is hoped that the
 148 unique constraint in the top-level table's \(dqxml_file_id\(dq will
 149 prevent duplication in this case anyway.
 150 .P
 151 The aforementioned exceptions are the \(dqgame_info\(dq and
 152 \(dqsports_info\(dq tables. These tables contain the raw XML for a
 153 number of DTDs that are not handled individually. This is partially
 154 for backwards-compatibility with a legacy implementation, but is
 155 mostly a stopgap due to a lack of resources at the moment. These two
 156 tables (game_info and sports_info) still possess timestamps that allow
 157 us to prune old data.
 158 .P
 159 UML diagrams of the resulting database schema for each XML document
 160 type are provided with the \fBhtsn-import\fR documentation.
 161
 162 .SH XML Schema Oddities
 163 .P
 164 There are a number of problems with the XML on the wire. Even if we
 165 construct the DTDs ourselves, the results are sometimes
 166 inconsistent. Here we document a few of them.
 167
 168 .IP \[bu] 2
 169 Odds_XML.dtd
 170
 171 The <Notes> elements here are supposed to be associated with a set of
 172 <Game> elements, but since the pair
 173 (<Notes>...</Notes><Game>...</Game>) can appear zero or more times,
 174 this leads to ambiguity in parsing. We therefore ignore the notes
 175 entirely (although a hack is employed to facilitate parsing).
 176
 177 .IP \[bu]
 178 weatherxml.dtd
 179
 180 There appear to be two types of weather documents; the first has
 181 <listing> contained within <forecast> and the second has <forecast>
 182 contained within <listing>. While it would be possible to parse both,
 183 it would greatly complicate things. The first form is more common, so
 184 that's all we support for now.
 185
 186 .SH OPTIONS
 187
 188 .IP \fB\-\-backend\fR,\ \fB\-b\fR
 189 The RDBMS backend to use. Valid choices are \fISqlite\fR and
 190 \fIPostgres\fR. Capitalization is important, sorry.
 191
 192 Default: Sqlite
 193
 194 .IP \fB\-\-connection-string\fR,\ \fB\-c\fR
 195 The connection string used for connecting to the database backend
 196 given by the \fB\-\-backend\fR option. The default is appropriate for
 197 the \fISqlite\fR backend.
 198
 199 Default: \(dq:memory:\(dq
 200
 201 .IP \fB\-\-log-file\fR
 202 If you specify a file here, logs will be written to it (possibly in
 203 addition to syslog). Can be either a relative or absolute path. It
 204 will not be auto-rotated; use something like logrotate for that.
 205
 206 Default: none
 207
 208 .IP \fB\-\-log-level\fR
 209 How verbose should the logs be? We log notifications at four levels:
 210 DEBUG, INFO, WARN, and ERROR. Specify the \(dqmost boring\(dq level of
 211 notifications you would like to receive (in all-caps); more
 212 interesting notifications will be logged as well. The debug output is
 213 extremely verbose and will not be written to syslog even if you try.
 214
 215 Default: INFO
 216
 217 .IP \fB\-\-remove\fR,\ \fB\-r\fR
 218 Remove successfully processed files. If you enable this, you can see
 219 at a glance which XML files are not being processed, because they're
 220 all that should be left.
 221
 222 Default: disabled
 223
 224 .IP \fB\-\-syslog\fR,\ \fB\-s\fR
 225 Enable logging to syslog. On Windows this will attempt to communicate
 226 (over UDP) with a syslog daemon on localhost, which will most likely
 227 not work.
 228
 229 Default: disabled
 230
 231 .SH CONFIGURATION FILE
 232 .P
 233 Any of the command-line options mentioned above can be specified in a
 234 configuration file instead. We first look for \(dqhtsn-importrc\(dq in
 235 the system configuration directory. We then look for a file named
 236 \(dq.htsn-importrc\(dq in the user's home directory. The latter will
 237 override the former.
 238 .P
 239 The user's home directory is simply $HOME on Unix; on Windows it's
 240 wherever %APPDATA% points. The system configuration directory is
 241 determined by Cabal; the \(dqsysconfdir\(dq parameter during the
 242 \(dqconfigure\(dq step is used.
 243 .P
 244 The file's syntax is given by examples in the htsn-importrc.example file
 245 (included with \fBhtsn-import\fR).
 246 .P
 247 Options specified on the command-line override those in either
 248 configuration file.
 249
 250 .SH EXAMPLES
 251 .IP \[bu] 2
 252 Import newsxml.xml into a preexisting sqlite database named \(dqfoo.sqlite3\(dq:
 253
 254 .nf
 255 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
 256 .I "              test/xml/newsxml.xml"
 257 Successfully imported test/xml/newsxml.xml.
 258 Imported 1 document(s) total.
 259 .fi
 260 .IP \[bu]
 261 Repeat the previous example, but delete newsxml.xml afterwards:
 262
 263 .nf
 264 .I $ htsn-import --connection-string='foo.sqlite3' \\\\
 265 .I "              --remove test/xml/newsxml.xml"
 266 Successfully imported test/xml/newsxml.xml.
 267 Imported 1 document(s) total.
 268 Removed processed file test/xml/newsxml.xml.
 269 .fi
 270 .IP \[bu]
 271 Use a Postgres database instead of the default Sqlite. This assumes
 272 that you have a database named \(dqhtsn\(dq accessible to user
 273 \(dqpostgres\(dq locally:
 274
 275 .nf
 276 .I $ htsn-import --connection-string='dbname=htsn user=postgres' \\\\
 277 .I "              --backend=Postgres test/xml/newsxml.xml"
 278 Successfully imported test/xml/newsxml.xml.
 279 Imported 1 document(s) total.
 280 .fi
 281
 282 .SH BUGS
 283
 284 .P
 285 Send bugs to michael@orlitzky.com.