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From Marshall Schor <...@schor.com>
Subject Re: opinion on degree of backwards compatibility for Uima V3 experiment
Date Fri, 02 Sep 2016 13:10:13 GMT
yes, good idea :-)  I'll change this in v3, so the id is more likely to
correspond to the v2 one.  I suspect the performance impact will be unnoticable.


On 9/2/2016 8:17 AM, Burn Lewis wrote:
> Could the id assigned in V3 be the same as the V2 address, as if the offset
> in a heap?  Unique and monotonically increasing.
> Burn
> On Fri, Sep 2, 2016 at 5:36 AM, Peter Kl├╝gl <peter.kluegl@averbis.com>
> wrote:
>> Same here.
>> It looks like that we are now also starting to use the address, and I am
>> also thinking of using it more in Ruta (internal indexing).
>> Btw, I did some simple experiments lately concerning the stability of
>> the addresses when using CasIOUtils. Can it happens that the addresses
>> change if you just deserialize the same CAs twice without serializing it
>> in between?
>> Best,
>> Peter
>> Am 01.09.2016 um 19:29 schrieb Richard Eckart de Castilho:
>>> FS IDs are IMHO a very useful thing. Providing out-of-band (i.e.
>> out-of-type-system) unique identifiers for feature structures facilitates
>> handling them in e.g. in editors. We use that quite a bit in WebAnno.
>>> In WebAnno, we do not rely on any heap arithmetics - an ID is just
>> expected to be a unique identifier. However, I could imagine cases where
>> people might rely on the ID to increment monotonically for new FSes.
>>> Most binary formats do not preserve the ID across a save/load cycle.
>> However, SERIALIZED and SERIALIZED_TSI *do* preserve the ID, and WebAnno
>> makes used of that. It allows to keep references to FSes without having to
>> keep the CAS in memory all the time.
>>> There should continue to be a V3 serialization format which preserves
>> IDs across a load/save cycle.
>>> I do presently not see a case where a strong similarity between V2 and
>> V3 IDs would be important. It would be nice if deserializing a V2
>> SERIALIZED or SERIALIZED_TSI into V3 would restore the V2 IDs - I expect it
>> to be an easy thing to do.
>>> Cheers,
>>> -- Richard
>>>> On 01.09.2016, at 16:09, Marshall Schor <msa@schor.com> wrote:
>>>> UIMA V3 implementation includes in many places extra code (takes time /
>> space)
>>>> whose goal is to make things look closer to version 2.  Some of this is
>> for
>>>> interoperability with version 2 artifacts, like serialized forms.
>>>> An example: in v2, many serialization forms include "references" to
>> other
>>>> Feature Structures (FSs), and for those, the encoding is the "address"
>> in the
>>>> heap of the FS.
>>>> In v3, there is no heap, but the FSs have "ids", which are (at the
>> moment) an
>>>> int which increments by 1.  This mis-matches the "address" in v2, so
>> many parts
>>>> of the serialization code builds a map at serialization time from the
>> v3 id's to
>>>> v2 "addresses", and uses the latter in the serialization form.
>>>> Currently, this is done for various binary serializations, so that
>> these can be
>>>> read back in by v2 code.
>>>> Currently, it's not done for JSON or XMI (and maybe XCAS - haven't
>> checked).  So
>>>> the serialized forms for these differ between v2 and v3, in that the
>> numbers
>>>> used to represent references to other FSs are different.
>>>> The deserialization code for XMI and JSON doesn't depend on these
>> numbers being
>>>> anything other than unique per FS, so there's no issue in
>> deserializing.  But
>>>> the UIMA community may have built other things that depend on these
>> identifiers
>>>> not changing.
>>>> What's your opinion: should the XMI and JSON etc serialization in V3 be
>> changed
>>>> to reproduce (approximately) the same reference numbers as v2?  I say
>>>> approximately, because other factors might affect these, such as the
>> ordering
>>>> for things not in "ordered" indexes, etc. between v2 and v3.
>>>> -Marshall

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