Hi Eugen,
is JSR 374 going to support any json values as root element? In that case
JSON Binding should aso support it.
Martin
On Thu, Mar 5, 2015 at 11:14 PM, Eugen Cepoi <cepoi.eugen_at_gmail.com> wrote:
>
>
> 2015-03-05 12:31 GMT-08:00 Martin Vojtek <voytoo_at_gmail.com>:
>
>> Hi Olena and Kiev UA JUG,
>>
>> thank you very much for your feedback.
>>
>> ad 1)
>>
>> there are several specifications related to JSON and they are not
>> consistent in the definition of JSON.
>>
>> According to RF4627 (http://www.ietf.org/rfc/rfc4627.txt):
>>
>> A JSON text is a serialized object or array.
>>
>> There are also several online JSON validators, which supports the idea,
>> e.g. http://jsonlint.com/
>> There are also several JSON validators, which are supporting all JSON
>> values, not only object or array.
>>
>> On the other hand, there is also newer proposed standard RFC 7159, which
>> relaxes this https://datatracker.ietf.org/doc/rfc7159
>>
>> A JSON text is a sequence of tokens. The set of tokens includes six
>> structural characters, strings, numbers, and three literal names.
>>
>> A JSON text is a serialized value. Note that certain previous
>> specifications of JSON constrained a JSON text to be an object or an
>>
>> array. Implementations that generate only objects or arrays where a
>> JSON text is called for will be interoperable in the sense that all
>> implementations will accept these as conforming JSON texts.
>>
>> I have to confess, that my first non-public proposal was accepting also
>> JSON values.
>>
>
> And you were right IMO :)
>
>
>>
>> I see the following advantages supporting only objects and arrays as JSON
>> text:
>>
>> 1. JSR 353: JavaTM API for JSON Processing (
>> https://jcp.org/en/jsr/detail?id=353)
>> JsonReader and JsonParser support only objects and arrays.
>>
>
> Not the next update. The new JSR will also support any json values as root
> element.
>
>
>>
>> JsonReader jsonReader = Json.createReader(new StringReader("1"));
>> System.out.println(jsonReader.read()); //javax.json.JsonException: Empty
>> stream
>>
>> There is no event emitted:
>> JsonParser parser = Json.createParser(new StringReader("1"));
>> while (parser.hasNext()) {
>> JsonParser.Event event = parser.next();
>> System.out.println("event="+event); //never happens
>> }
>>
>> JSON Binding should be compatible with JSR 353, and it is expected, that
>> JSON Binding RI will use JSON Processing RI.
>>
>> 2. Interoperability as stated in RFC 7159
>>
>> 3. I don't see much value added supporting this use case
>>
>>
> Maybe allowing to ser/de a root null object...or a root byte array ser/de
> using base64 encoded string.
> But I don't see either a reason to restrict it.
>
>
>> *I definitely want to hear some other opinions on this topic. *
>>
>> ad 2)
>>
>> It is clear that escaping must be supported. I will add some explicit
>> examples to express this.
>>
>> ad 3)
>>
>> The intention of these examples was to express, that default
>> implementation of Map should be LinkedHashMap<String, Object>.
>> Key/value pairs in JSON objects are not ordered, but it is very practical
>> to have these pairs ordered.
>>
>> From my point of view, the most reasonable implementation for JSON array
>> is ArrayList<Object>.
>>
>> If I specify default implementation for JSON object, it makes sense to
>> specify also default implementation for JSON array (at least for
>> consistency).
>>
>> Other advantage is predictability from the user of this API. If we don't
>> specify this, this will be probably implemented differently by different
>> implementations.
>> I can imagine that different fields could have different implementations
>> like Arrays.asList(...), Collections.EMPTY_LIST and so on.
>> This can be problematic in some use cases.
>> Specifying default implementations (for default mapping) will improve
>> operability and provide some sensible defaults for the user of the API.
>>
>>
> *I definitely want to hear some other opinions on this topic too. *
>>
>> MartinV
>>
>>
>> On Thu, Mar 5, 2015 at 5:58 PM, Olena Syrota <sirotae_at_gmail.com> wrote:
>>
>>> Hi guys,
>>>
>>> More feedback from Kiev UA JUG (with Oleg Tsal-Tsalko and Andrii
>>> Rodionov).
>>>
>>> 1. JSON value formatting. Let me propose to follow The JSON Data
>>> Interchange Format (
>>> http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf).
>>> Due to this document JSON value is printed without square brackets "[...]".
>>> Square brakets are used for JSON array.
>>>
>>> e.g.
>>>
>>> - jsonb.fromJson("1", Byte.class)
>>>
>>> instead of
>>>
>>> - jsonb.fromJson("[1]", Byte.class), etc.
>>>
>>>
>>> 2. More cases for String mapping should be considered. Due to
>>> http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf,
>>> page 5, we should add mapping cases for \", /, \\, \r, \n, \t, \f, \b,
>>> \uXXXX.
>>> See
>>> https://github.com/sirotae/jsonb-spec-ua-adopt/tree/master/examples/src/test/java/jug/ua/jsonb/examples/default_mapping,
>>> file StringMapping.java
>>>
>>> 3. Structure Mapping from Json.
>>> Case 1. Instead of
>>>
>>> - Collection<Object> collection =
>>> (ArrayList<Object>)jsonb.fromJson("[{\"value\":\"first\"},
>>> {\"value\":\"second\"}]", Object.class);
>>>
>>>
>>> Let me propose:
>>>
>>> - List<Object> act = (List)jsonb.fromJson("[{\"value\":\"first\"},
>>> {\"value\":\"second\"}]", Object.class);
>>>
>>>
>>> Case 2. Instead of
>>>
>>> - Map<String, Object> map =
>>> (LinkedHashMap<String,Object>)jsonb.fromJson("{\"name\":\"unknown
>>> object\"}", Object.class);
>>>
>>>
>>> let me propose
>>>
>>> - Map<String, Object> map = (Map)jsonb.fromJson("{\"name\":\"unknown
>>> object\"}", Object.class);
>>>
>>>
>>>
>>> Thank you
>>> Olena
>>>
>>> 2015-03-04 0:05 GMT+02:00 Eugen Cepoi <cepoi.eugen_at_gmail.com>:
>>>
>>>> The way byte arrays are being ser/de can be a config. option.
>>>> The advantage of base64 is that it produces much smaller json than
>>>> using an array.
>>>> I didn't benchmark ser/de speed when using one or the other but I guess
>>>> the difference is probably not so big.
>>>>
>>>> Eugen
>>>>
>>>> 2015-03-03 13:47 GMT-08:00 Hendrik Dev <hendrikdev22_at_gmail.com>:
>>>>
>>>> Hi all,
>>>>>
>>>>> what about byte[] serialization and deserialization to/from base64?
>>>>> For me its natural (like proposed by MartinV) so ser/deser into a
>>>>> array of bytes like [3,-1,33,-11] but some json binding frameworks out
>>>>> there ser/deser byte[] to/from a base64 encoded string by default.
>>>>> To make the spec compatible with them maybe we should consider to
>>>>> support both?
>>>>>
>>>>> Wdyt?
>>>>>
>>>>> Thanks
>>>>> Hendrik
>>>>>
>>>>>
>>>>> On Fri, Feb 27, 2015 at 5:45 PM, Martin Grebac <
>>>>> martin.grebac_at_oracle.com> wrote:
>>>>> >
>>>>> > Please ignore the last point - bad example. Will provide multiple
>>>>> examples
>>>>> > within the generics topic.
>>>>> > MartiNG
>>>>> >
>>>>> >
>>>>> > On 27.02.15 10:03, Martin Grebac wrote:
>>>>> >>
>>>>> >> On 25.02.15 20:29, Przemyslaw Bielicki wrote:
>>>>> >>>
>>>>> >>>
>>>>> >>> Yes exactly like this.
>>>>> >>>
>>>>> >> Not sure exactly like what - are you suggesting both scenarios?
>>>>> Root level
>>>>> >> as well as nested?
>>>>> >>
>>>>> >>> Without typetoken it could be difficult as Optional is a final
>>>>> class thus
>>>>> >>> we cannot make custom classes like OptionalFoo extends
>>>>> Optional<Foo>
>>>>> >>>
>>>>> >>> 25 lut 2015 19:35 "Eugen Cepoi" <cepoi.eugen_at_gmail.com
>>>>> >>> <mailto:cepoi.eugen_at_gmail.com>> napisał(a):
>>>>> >>>
>>>>> >>> If it is about Optional at the mapping level I am not sure
>>>>> there
>>>>> >>> is a need to make it appear in the spec.
>>>>> >>>
>>>>> >> In spec we have to define (or decide to not to define) the
>>>>> behaviour for
>>>>> >> Optional within default mapping at least to not cause portability
>>>>> problems.
>>>>> >>
>>>>> >>> The use case I would see with optional at root level is when
>>>>> the
>>>>> >>> root value it self is null... with typetoken could look like (I
>>>>> >>> don't know how you plan to handle generics):
>>>>> >>>
>>>>> >>> Optional<Foo> optFoo = jsonb.fromJson(json, new
>>>>> >>> TypeToken<Optional<Foo>>() {})
>>>>> >>>
>>>>> >> What is the value that this support brings to JSON Binding? Does
>>>>> this have
>>>>> >> value for further work with optFoo?
>>>>> >> The call requires constructing the specific type, requires us to
>>>>> remove
>>>>> >> type checking from the method signature which is useful in
>>>>> non-generic
>>>>> >> cases, and I'm not sure about the value or problem it actually
>>>>> solves.
>>>>> >>
>>>>> >>> But the most common would be to have optional nested in Pojo
>>>>> like
>>>>> >>> structures. In that case it would be handled directly by impls.
>>>>> >>>
>>>>> >> We're again inherently discussing generics here with Optional, too.
>>>>> And
>>>>> >> the same as above applies - we need portable behaviour. So, let's
>>>>> say we
>>>>> >> have
>>>>> >>
>>>>> >> public class B {
>>>>> >> Optional<C> c;
>>>>> >> }
>>>>> >> public class C {
>>>>> >> Optional<List<Optional<String>>> s;
>>>>> >> OptionalInt i;
>>>>> >> D<String,Long> d;
>>>>> >> }
>>>>> >> public class D<T1,T2> {
>>>>> >> List<T1> l1;
>>>>> >> Optional<T2> t2;
>>>>> >> }
>>>>> >>
>>>>> >> And you want to be marshalling / unmarshalling from / into this
>>>>> structure.
>>>>> >> How would the implementation at runtime be able to defer and create
>>>>> proper
>>>>> >> types for the individual properties?
>>>>> >>
>>>>> >> MartiNG
>>>>> >>
>>>>> >>> 2015-02-25 5:27 GMT-08:00 Martin Grebac <
>>>>> martin.grebac_at_oracle.com
>>>>> >>> <mailto:martin.grebac_at_oracle.com>>:
>>>>> >>>
>>>>> >>> On 25.02.15 8:44, Przemyslaw Bielicki wrote:
>>>>> >>>
>>>>> >>> The trouble with Optional is that it is typed, and
>>>>> as
>>>>> >>> such its use is too complex within the api methods
>>>>> we
>>>>> >>> have now compared to the minimal benefit it brings.
>>>>> >>>
>>>>> >>> Anyway I think it should be impl specific feature -
>>>>> sorry
>>>>> >>> for the noise.
>>>>> >>>
>>>>> >>> After re-reading I think I may have been too fast and
>>>>> >>> misunderstood the usecase. Before I jump into my rant on
>>>>> >>> Optional :) , would you please give some examples of the
>>>>> >>> expected outcomes, say based on MartinV's default mapping
>>>>> >>> examples?
>>>>> >>>
>>>>> >>> I think it makes sense to get some clarity into this and
>>>>> make
>>>>> >>> decisions whether the support for Optional should be in the
>>>>> >>> spec, whether it should be default, and whether it should
>>>>> be
>>>>> >>> spec defined configuration, mostly because Optional has
>>>>> value
>>>>> >>> wrt lambdas. Thus I also expect the reasoning will likely
>>>>> have
>>>>> >>> to include the expected stream use? I don't find Optional
>>>>> >>> bringing any significant value outside of streams.
>>>>> >>>
>>>>> >>> MartiNG
>>>>> >>>
>>>>> >
>>>>> > --
>>>>> > Martin Grebac, SW Engineering Manager
>>>>> > Oracle Czech, Prague
>>>>> >
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Hendrik Saly (salyh, hendrikdev22)
>>>>> @hendrikdev22
>>>>> PGP: 0x22D7F6EC
>>>>>
>>>>
>>>>
>>>
>>
>