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Revision 1.29 by root, Thu Feb 19 01:13:46 2009 UTC vs.
Revision 1.34 by root, Thu Mar 11 17:36:09 2010 UTC

20 $perl_scalar = $coder->decode ($unicode_json_text); 20 $perl_scalar = $coder->decode ($unicode_json_text);
21 21
22 # Note that JSON version 2.0 and above will automatically use JSON::XS 22 # Note that JSON version 2.0 and above will automatically use JSON::XS
23 # if available, at virtually no speed overhead either, so you should 23 # if available, at virtually no speed overhead either, so you should
24 # be able to just: 24 # be able to just:
25 25
26 use JSON; 26 use JSON;
27 27
28 # and do the same things, except that you have a pure-perl fallback now. 28 # and do the same things, except that you have a pure-perl fallback now.
29 29
30DESCRIPTION 30DESCRIPTION
31 This module converts Perl data structures to JSON and vice versa. Its 31 This module converts Perl data structures to JSON and vice versa. Its
377 it is disabled, the same hash might be encoded differently even if 377 it is disabled, the same hash might be encoded differently even if
378 contains the same data, as key-value pairs have no inherent ordering 378 contains the same data, as key-value pairs have no inherent ordering
379 in Perl. 379 in Perl.
380 380
381 This setting has no effect when decoding JSON texts. 381 This setting has no effect when decoding JSON texts.
382
383 This setting has currently no effect on tied hashes.
382 384
383 $json = $json->allow_nonref ([$enable]) 385 $json = $json->allow_nonref ([$enable])
384 $enabled = $json->get_allow_nonref 386 $enabled = $json->get_allow_nonref
385 If $enable is true (or missing), then the "encode" method can 387 If $enable is true (or missing), then the "encode" method can
386 convert a non-reference into its corresponding string, number or 388 convert a non-reference into its corresponding string, number or
1151 my $yaml = $to_yaml->encode ($ref) . "\n"; 1153 my $yaml = $to_yaml->encode ($ref) . "\n";
1152 1154
1153 This will *usually* generate JSON texts that also parse as valid YAML. 1155 This will *usually* generate JSON texts that also parse as valid YAML.
1154 Please note that YAML has hardcoded limits on (simple) object key 1156 Please note that YAML has hardcoded limits on (simple) object key
1155 lengths that JSON doesn't have and also has different and incompatible 1157 lengths that JSON doesn't have and also has different and incompatible
1156 unicode handling, so you should make sure that your hash keys are 1158 unicode character escape syntax, so you should make sure that your hash
1157 noticeably shorter than the 1024 "stream characters" YAML allows and 1159 keys are noticeably shorter than the 1024 "stream characters" YAML
1158 that you do not have characters with codepoint values outside the 1160 allows and that you do not have characters with codepoint values outside
1159 Unicode BMP (basic multilingual page). YAML also does not allow "\/" 1161 the Unicode BMP (basic multilingual page). YAML also does not allow "\/"
1160 sequences in strings (which JSON::XS does not *currently* generate, but 1162 sequences in strings (which JSON::XS does not *currently* generate, but
1161 other JSON generators might). 1163 other JSON generators might).
1162 1164
1163 There might be other incompatibilities that I am not aware of (or the 1165 There might be other incompatibilities that I am not aware of (or the
1164 YAML specification has been changed yet again - it does so quite often). 1166 YAML specification has been changed yet again - it does so quite often).
1181 (which is not that difficult or long) and finally make YAML 1183 (which is not that difficult or long) and finally make YAML
1182 compatible to it, and educating users about the changes, instead of 1184 compatible to it, and educating users about the changes, instead of
1183 spreading lies about the real compatibility for many *years* and 1185 spreading lies about the real compatibility for many *years* and
1184 trying to silence people who point out that it isn't true. 1186 trying to silence people who point out that it isn't true.
1185 1187
1188 Addendum/2009: the YAML 1.2 spec is still incomaptible with JSON,
1189 even though the incompatibilities have been documented (and are
1190 known to Brian) for many years and the spec makes explicit claims
1191 that YAML is a superset of JSON. It would be so easy to fix, but
1192 apparently, bullying and corrupting userdata is so much easier.
1193
1186 SPEED 1194 SPEED
1187 It seems that JSON::XS is surprisingly fast, as shown in the following 1195 It seems that JSON::XS is surprisingly fast, as shown in the following
1188 tables. They have been generated with the help of the "eg/bench" program 1196 tables. They have been generated with the help of the "eg/bench" program
1189 in the JSON::XS distribution, to make it easy to compare on your own 1197 in the JSON::XS distribution, to make it easy to compare on your own
1190 system. 1198 system.
1193 single-line JSON string (also available at 1201 single-line JSON string (also available at
1194 <http://dist.schmorp.de/misc/json/short.json>). 1202 <http://dist.schmorp.de/misc/json/short.json>).
1195 1203
1196 {"method": "handleMessage", "params": ["user1", 1204 {"method": "handleMessage", "params": ["user1",
1197 "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7, 1205 "we were just talking"], "id": null, "array":[1,11,234,-5,1e5,1e7,
1198 true, false]} 1206 1, 0]}
1199 1207
1200 It shows the number of encodes/decodes per second (JSON::XS uses the 1208 It shows the number of encodes/decodes per second (JSON::XS uses the
1201 functional interface, while JSON::XS/2 uses the OO interface with 1209 functional interface, while JSON::XS/2 uses the OO interface with
1202 pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink). 1210 pretty-printing and hashkey sorting enabled, JSON::XS/3 enables shrink.
1203 Higher is better: 1211 JSON::DWIW/DS uses the deserialise function, while JSON::DWIW::FJ uses
1212 the from_json method). Higher is better:
1204 1213
1205 module | encode | decode | 1214 module | encode | decode |
1206 -----------|------------|------------| 1215 --------------|------------|------------|
1207 JSON 1.x | 4990.842 | 4088.813 | 1216 JSON::DWIW/DS | 86302.551 | 102300.098 |
1208 JSON::DWIW | 51653.990 | 71575.154 | 1217 JSON::DWIW/FJ | 86302.551 | 75983.768 |
1209 JSON::PC | 65948.176 | 74631.744 | 1218 JSON::PP | 15827.562 | 6638.658 |
1210 JSON::PP | 8931.652 | 3817.168 | 1219 JSON::Syck | 63358.066 | 47662.545 |
1211 JSON::Syck | 24877.248 | 27776.848 | 1220 JSON::XS | 511500.488 | 511500.488 |
1212 JSON::XS | 388361.481 | 227951.304 | 1221 JSON::XS/2 | 291271.111 | 388361.481 |
1213 JSON::XS/2 | 227951.304 | 218453.333 | 1222 JSON::XS/3 | 361577.931 | 361577.931 |
1214 JSON::XS/3 | 338250.323 | 218453.333 | 1223 Storable | 66788.280 | 265462.278 |
1215 Storable | 16500.016 | 135300.129 |
1216 -----------+------------+------------+ 1224 --------------+------------+------------+
1217 1225
1218 That is, JSON::XS is about five times faster than JSON::DWIW on 1226 That is, JSON::XS is almost six times faster than JSON::DWIW on
1219 encoding, about three times faster on decoding, and over forty times 1227 encoding, about five times faster on decoding, and over thirty to
1220 faster than JSON, even with pretty-printing and key sorting. It also 1228 seventy times faster than JSON's pure perl implementation. It also
1221 compares favourably to Storable for small amounts of data. 1229 compares favourably to Storable for small amounts of data.
1222 1230
1223 Using a longer test string (roughly 18KB, generated from Yahoo! Locals 1231 Using a longer test string (roughly 18KB, generated from Yahoo! Locals
1224 search API (<http://dist.schmorp.de/misc/json/long.json>). 1232 search API (<http://dist.schmorp.de/misc/json/long.json>).
1225 1233
1226 module | encode | decode | 1234 module | encode | decode |
1227 -----------|------------|------------| 1235 --------------|------------|------------|
1228 JSON 1.x | 55.260 | 34.971 | 1236 JSON::DWIW/DS | 1647.927 | 2673.916 |
1229 JSON::DWIW | 825.228 | 1082.513 | 1237 JSON::DWIW/FJ | 1630.249 | 2596.128 |
1230 JSON::PC | 3571.444 | 2394.829 |
1231 JSON::PP | 210.987 | 32.574 | 1238 JSON::PP | 400.640 | 62.311 |
1232 JSON::Syck | 552.551 | 787.544 | 1239 JSON::Syck | 1481.040 | 1524.869 |
1233 JSON::XS | 5780.463 | 4854.519 | 1240 JSON::XS | 20661.596 | 9541.183 |
1234 JSON::XS/2 | 3869.998 | 4798.975 | 1241 JSON::XS/2 | 10683.403 | 9416.938 |
1235 JSON::XS/3 | 5862.880 | 4798.975 | 1242 JSON::XS/3 | 20661.596 | 9400.054 |
1236 Storable | 4445.002 | 5235.027 | 1243 Storable | 19765.806 | 10000.725 |
1237 -----------+------------+------------+ 1244 --------------+------------+------------+
1238 1245
1239 Again, JSON::XS leads by far (except for Storable which non-surprisingly 1246 Again, JSON::XS leads by far (except for Storable which non-surprisingly
1240 decodes faster). 1247 decodes a bit faster).
1241 1248
1242 On large strings containing lots of high Unicode characters, some 1249 On large strings containing lots of high Unicode characters, some
1243 modules (such as JSON::PC) seem to decode faster than JSON::XS, but the 1250 modules (such as JSON::PC) seem to decode faster than JSON::XS, but the
1244 result will be broken due to missing (or wrong) Unicode handling. Others 1251 result will be broken due to missing (or wrong) Unicode handling. Others
1245 refuse to decode or encode properly, so it was impossible to prepare a 1252 refuse to decode or encode properly, so it was impossible to prepare a
1280 information you might want to make sure that exceptions thrown by 1287 information you might want to make sure that exceptions thrown by
1281 JSON::XS will not end up in front of untrusted eyes. 1288 JSON::XS will not end up in front of untrusted eyes.
1282 1289
1283 If you are using JSON::XS to return packets to consumption by JavaScript 1290 If you are using JSON::XS to return packets to consumption by JavaScript
1284 scripts in a browser you should have a look at 1291 scripts in a browser you should have a look at
1285 <http://jpsykes.com/47/practical-csrf-and-json-security> to see whether 1292 <http://blog.archive.jpsykes.com/47/practical-csrf-and-json-security/>
1286 you are vulnerable to some common attack vectors (which really are 1293 to see whether you are vulnerable to some common attack vectors (which
1287 browser design bugs, but it is still you who will have to deal with it, 1294 really are browser design bugs, but it is still you who will have to
1288 as major browser developers care only for features, not about getting 1295 deal with it, as major browser developers care only for features, not
1289 security right). 1296 about getting security right).
1290 1297
1291THREADS 1298THREADS
1292 This module is *not* guaranteed to be thread safe and there are no plans 1299 This module is *not* guaranteed to be thread safe and there are no plans
1293 to change this until Perl gets thread support (as opposed to the 1300 to change this until Perl gets thread support (as opposed to the
1294 horribly slow so-called "threads" which are simply slow and bloated 1301 horribly slow so-called "threads" which are simply slow and bloated

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