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 120 database schema make it possible to delete only the outdated top-level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