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Re: CIF-JSON new draft

  • Subject: Re: CIF-JSON new draft
  • From: Marcin Wojdyr <wojdyr@xxxxxxxxx>
  • Date: Mon, 1 May 2017 10:11:36 +0100
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Hi James,thanks for refining the proposal.
I'd disagree with "CIF number values are represented as JSON stringvalues". While it makes the conversion easier, the JSON doesn't looknatural and is more difficult to use. It'd also make applications thatuse such JSON slower, and it looses information about type.

On 1 May 2017 at 02:25, James Hester <jamesrhester@gmail.com> wrote:> Dear CIF developers,>> I have redrafted the CIF-JSON proposal to take account of the comments over> the past few weeks.  In particular, I have removed discussion of "conversion> from a CIF file" and instead expressed the proposal as a JSON representation> of "CIF information".  I have also noted that this JSON format is not> suitable for high-fidelity conversion of CIF syntax files, and added a> pointer to "COD-JSON".  Given the choice of 'Metadata' and 'meta data' I> have opted for 'Metadata' but that is really a coin toss and we can allow> both if there is no agreement.>> The full diff listing is available from the following Github link:> https://github.com/COMCIFS/comcifs.github.io/commit/fe587d0c724eff97db4c31faaa8ebb09a808af1f#diff-fd4fbe8f7dc33b4a97fb39965f4e0243> and the latest draft is at> https://github.com/COMCIFS/comcifs.github.io/blob/master/cif-json.md>> I append the latest text below as well.>> Comments welcome. If we are generally satisfied, I will submit this to> COMCIFS for their approval.>> James.>>> # JSON representation of CIF information (DRAFT)>> ## Introduction>> The Crystallographic Information Framework (CIF) is a set of specifications> for describing> scientific information.  One or more *datavalues* are attached to> *datanames* to form> *dataitems*. Dataitems are collected together into *datablocks*.  Datablocks> are in turn> collected into *datafiles*.  Datanames, the possible values that can be> attached to> them, and dataname membership in *loops* (tabulations), are described in CIF> *dictionaries*. In the following standard, *CIF information* refers to any> scientific> information that can be defined and encapsulated using the above model.  The> CIF1 and CIF2> syntaxes describe closely related file formats for expressing CIF> information in a> form suitable for long-term archiving and transfer.>> JSON is a lightweight language for serialisation and transfer of data.> JSON is often used as a "pipeline" language to transfer information> between programs within a single system, and also as a way of> transferring information between internet applications.  JSON> libraries are widely available and therefore it is relatively simple> implement parsing and output of JSON.>> A standard way of expressing CIF information in JSON would allow> programs from different authors running within a single context (such> as a web browser or operating system) to interoperate with minimal work. The> following> CIF-JSON standard is intended to facilitate interoperability of such> software.>> ## The JSON representation of CIF information>> In the following, *name* refers to a JSON name and *value* to a JSON value.> A> JSON *object* is a collection of `name:value` pairs. CIF-related> datastructures> are described in the introduction.>> CIF information is represented in JSON as follows:>> 1. A CIF datafile is represented as a single JSON object> 1. The JSON file must conform to the i-JSON standard> [RFC7493](https://tools.ietf.org/html/rfc7493)> 1. A CIF datablock is represented by a JSON object within the top-level> object. This object is referred> to here as the *JSON datablock object*.  The name of this object must be in> Unicode case-normal form (which> means lower-case for Western scripts), and> conform to the characterset restrictions of the CIF2 syntax for datablock> names.> 1. A CIF dataname is a name in the JSON datablock object. The JSON name> is the CIF dataname, including the underscore.> 1. Datavalues are represented as follows:>    1. CIF string values are represented as JSON string values>    1. CIF number values are represented as JSON string values formatted> according to the>    `<Numeric>` production in International Tables>    for Crystallography, Volume G, Section paragraph 57. Note that>    this CIF `<Numeric>` production is identical to the JSON number format> with optional>    standard uncertainty appended in round brackets.>     3. The special CIF value `.` (null) is represented as the JSON `null`> value>     4. The special CIF value `?` (unknown) is represented as a JSON string> containing the single Unicode code point `0xFFFF`.>     5. (CIF2 only).  CIF2 list datavalues are represented as JSON lists. The> datavalues appearing>   in the list are represented in the same way as non-list datavalues.>     6. (CIF2 only).  CIF2 table datavalues are represented as JSON objects.> The names in the object>   are the same as the names in the CIF table. The values in the CIF table> are represented in the same>   way as other CIF datavalues>     7. (Looped values). The column of values corresponding to a looped>   CIF dataname is represented as a JSON list. This list becomes the value of>   the JSON name corresponding to that dataname. Each value in the list>   is represented as for unlooped datanames>> 6. A JSON datablock object may contain a special name: `loop tags`.  If this> name> appears, its value will be a list of lists.  For each loop in the CIF block,> a list of the datanames appearing in the loop will be included in the `loop> tags` value.> 7. It is not an error to omit the `loop tags` name, even when the CIF data> block contains> a loop. If the `loop tags` name appears, information on all loops in the> datablock must be> included.> 9. If the CIF data block includes save frames (currently only used in> dictionaries),> the JSON datablock object must contain the special name `frames`. The value> of this name> is a JSON object. Each name in this object is the name of a save frame> found in the datablock. The value for each of these names is a JSON> datablock object, represented> as for normal CIF data blocks.> 10. An optional object named `Metadata` may be present in the top-level> object. The object name> must begin with a capital 'M' to distinguish it from a normal datablock> name. The `Metadata` object contains> information that is useful for conversion of CIF-JSON objects to other> syntaxes> (for example, CIF syntax files) and information about the CIF-JSON version.> The following names are defined for the `Metadata` object:>     1. `cif-version`: the minimum CIF syntax version required to express the> contents of the object; currently `1.1` or `2.0` are available>     1. `schema-name`: always `CIF-JSON`>     1. `schema-version`: the version of the CIF-JSON schema that this JSON> object conforms to>     1. `schema-uri`: a URI for the CIF-JSON schema.>> ## Comments>> 1. A JSON list is used both for columns and CIF2 lists.  Where a> dataname is known to occur in a loop (either through the `loop tags` name> or as stated in the relevant CIF dictionary), the JSON parser may assume> that each entry in the outermost list level is the column entry.> 1. Any list-valued name that does not appear in a loop is a CIF2 list.> 1. This specification contains some features to allow straightforward> conversion to JSON from files in CIF syntax. However, round-tripping> through CIF-JSON will not preserve features of CIF syntax that are not> used by CIF dictionaries. In particular, block and dataname order, and> the type of delimiters used, if any, are not expressed in CIF-JSON. If> such high-fidelity transformation is required (for example, for CIF> syntax validation) the COD-JSON format used by the freely available> [COD tools](http://wiki.crystallography.net/cod-tools/) is> recommended.>> ## Example>> ### CIF syntax file:>>>     #\#CIF_2.0>     data_example>       _dataname.a   syzygy>       _flight.vector    [0.25 1.2(15) -0.01(12)]>       _dataname.table   {"save":222 "mode":full "url":"http:/bit.ly/2"}>       _flight.bearing  221.45(7)>       loop_>         _x.id>         _y>         _z>         _alpha>         1    4.23(14)     [a a a c]    1.5e-6(2)>         2   11.9(3)       [c a c a]    2.1e-6(11)>         3    0.2(4)       [b a a a]    0.0051(4)>         4     .              .             ?>>       loop_>         _q.key>         _q.access>         xxp     {"s":2  "k":-5}>         yyx     {"s":1  "k":-2}>>       _dataname.chapter   1.2>       _dataname.verylong>     ;<whatever>\\>     <whatever>This contains one very long line \>     <whatever>that we wrap around using the \>     <whatever>excellent CIF2 line expansion protocol.>     ;>>      data_another_block>        _abc    xyz>        save_internal>           _abc   yzx>           loop_>              _r.fruit>              _r.colour>              apple    red>              pear     green>        save_>> ### Equivalent CIF-JSON:>> ```json>     {"Metadata":{"cif-version":2.0,>                  "schema-name":"CIF-JSON",>                  "schema-version":"1.0",>> "schema-uri":"http://www.iucr.org/resources/cif/cif-json.txt">                  },>      "example":>         {"_dataname.a":"syzygy",>          "_flight.vector":["0.25","1.2(15)","-0.01(12)"],>          "_dataname.table":{"save":222, "mode":"full",> "url":"http:/bit.ly/2"},>          "_flight.bearing":"221.45(7)",>          "_x.id":["1","2","3","4"],>          "_y":["4.23(14)","11.9(3)","0.2(4)",null],>          "_z":[["a","a","a","c"],>                ["c","a","c","a"],>                ["b","a","a","a"],>                null],>          "_alpha":["1.5e-6(2)","2.1e-6(11)","5.1e-3(4)","\uFFFF"],>          "_q.key":["xxp","yyx"],>          "_q.access":[{"s":2,  "k":-5},{"s":1,  "k":-2}],>          "_dataname.chapter":"1.2",>          "_dataname.verylong":"This contains one very long line that we wrap> around using the excellent CIF2 line expansion protocol.",>          "loop tags":[["_x.id","_y","_z"],["_q.key","_q.access"]],>          },>      "another_block":{>         "_abc":"xyz",>         "frames":>            {"internal":{"_abc":"yzx",>                         "_r.fruit":["apple","pear"],>                         "_r.colour":["red","green"]}>                         }>            }>     }> ```>>> --> T +61 (02) 9717 9907> F +61 (02) 9717 3145> M +61 (04) 0249 4148>> _______________________________________________> cif-developers mailing list> cif-developers@iucr.org> http://mailman.iucr.org/cgi-bin/mailman/listinfo/cif-developers>_______________________________________________cif-developers mailing listcif-developers@iucr.orghttp://mailman.iucr.org/cgi-bin/mailman/listinfo/cif-developers

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