add json serialization #124

duglin · 2018-03-24T03:15:49Z

Closes #17

I would actually prefer if we just move this into the main spec itself since its so small, but for now I started out with it being in a separate doc with the assumption that we can decide on whether we want to merge it later.

Signed-off-by: Doug Davis dug@us.ibm.com

SeanFeldman

A few minor comments.

SeanFeldman · 2018-03-24T14:42:06Z

serialization.md

+  "cloud-events-version": "cloud-events-version value",
+  "event-id": "event-id value",
+  "namespace": "namespace value",
+  "source": {


@duglin isn't source a URI?

Not yet :-)

Fair enough. Pending #123 🙂

SeanFeldman · 2018-03-24T14:43:06Z

serialization.md

+}
+```
+
+Note:


nitpicking - sais Note, but these are notes.

SeanFeldman · 2018-03-24T14:43:41Z

serialization.md

+```
+
+Note:
+- the use of whitespace is not significant


Capitalize?

markpeek · 2018-03-24T18:41:36Z

serialization.md

@@ -0,0 +1,43 @@
+# CloudEvents Serialization Profile - Version 0.1
+
+This document specified how a CloudEvent is to be serialized into certain


Should this be applied here? s/specified/specifies/

fixed the "specified" typo. What did you mean by "should this applied here?" ?

markpeek · 2018-03-24T18:54:23Z

serialization.md

+}
+```
+
+Notes:


Should there be a comment about extra fields in the serialized data? Such as:

- It is undefined whether extra fields are passed along or removed depending on the usage role and implementation. Those fields are best placed in the extensions map.

I expanded on the thought a little - see what you think.

Thanks for the update. LGTM.

markpeek · 2018-03-24T21:41:03Z

serialization.md

+}
+```
+
+Notes:


Thanks for the update. LGTM.

markpeek · 2018-03-24T21:44:34Z

spec.md

@@ -26,6 +26,11 @@ Enter CloudEvents, a specification for describing event data in a common way.
 CloudEvents seeks to ease event declaration and delivery across services,
 platforms and beyond.

+The [Serialization Profile](serialization.md) specified how to


This might be better as "specifies". (Or am I being too tense?)

No, you're right - just a disconnect between the brain and fingers.

inlined · 2018-03-28T22:16:51Z

serialization.md

+
+```
+{
+  "cloud-events-version": "cloud-events-version value",


I'm curious whether it would be more useful to use valid fake values rather than prose in quotes.

I struggled with this because if we put fake values in there then we need something to say "property X from the spec goes into json property 'x'". While in many cases it should be really really obvious, I felt that a spec should be more explicit about it. If all we cared about was JSON I actually would have proposed that we have the serialization of each property next to its definition in the spec itself. But I didn't want to assume everyone would be ok with JSON getting special treatment.

@inlined I added an example to try to address your concern. See if that helps.

inlined · 2018-03-28T22:21:17Z

serialization.md

+  "extensions": {
+    ... extensions values ...
+  },
+  "data": ... data value ...


As an FYI: though Google&Firebase started out with a model like this where all context is at the top level with one magic field called "data", we generally considered this to be a mistake. Many languages have better ways to expose context (e.g. Golang's Context.context, or JavaScript's variadic parameter system) so we are migrating to a world where data & context are exposed separately/natively our runtimes. Alpha testers have given very positive feedback for this because it allows any existing function(SomeNativeType) to be a CloudFunction<SomeNativeType>.

To match this, the REST JSON is being migrated to a two-field JSON object with {"context", "data"}

I could live with that. What do other people think?

@inlined would extensions be under context or another sibling at the root level?

@inlined where would "could-events-version" go? I can see it being useful as a top-level thing since we may choose to rename data or context in a future version, but I can also see a need for that info to be passed downstream so people know how to interpret the context attributes based on our spec's version number.

I do want to explore this option, it feels cleaner - would make for a great follow-on PR

@duglin I agree with @inlined that context and data should be on the same level as he suggested.

One more thing:
Do we need rules how to encode data, if the content-type is something binary or text/xml?

would that be something that the definition of the content-type (e.g. json spec) would need to define?

afaik json spec does not cover this explicitly. Most people seem to base64 encode data.

yea, I did a quick search too and didn't find a lot. I guess we could offer some recommendations...

Honestly I don't have the practical experience with content-type and cloud-events-version that I do with the other fields. Here's my first SWAG:

In my opinion, content-type is/should be meta to the whole spec (why are we dictating the content type within a payload that's already explicitly JSON encoded?). This should be dictated in the transport layer, not the encoding layer.

cloud-events-version looks cleanest at the top level in JSON though if it's going to show up in the programming model it might be easier to put it in context.

I have the strong opinion (weakly held) that extensions should be in context. The developer is likely to depend on these extensions and they should be easily accessible.

@inlined My understanding is that this PR is about how to package an arbitrary cloudevent into json. I was just wondering what happens if the content-type (the context attribute) is text/xml or image/png. The result is supposed to be a valid json object. So data would need to be encoded somehow. I don't see how this can be delegated to another layer. For events that use json for their data section, there is of course no need for encoding.

Signed-off-by: Doug Davis <dug@us.ibm.com>

duglin · 2018-03-29T13:21:07Z

Added an example and one line to make it clear that optional fields are still optional, but if present then they MUST adhere to the rules defined. I think it was implied before but now its explicitly stated.

ultrasaurus · 2018-03-29T16:15:47Z

This will have to be modified to be consistent with changed accepted today

duglin · 2018-03-29T17:45:22Z

Approved on 3/29 call

duglin force-pushed the serialize branch 2 times, most recently from 9a6e2c7 to 3d5a1cd Compare March 24, 2018 03:53

SeanFeldman reviewed Mar 24, 2018

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duglin force-pushed the serialize branch 2 times, most recently from 349dab1 to c4fd2d5 Compare March 24, 2018 14:47

markpeek reviewed Mar 24, 2018

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duglin force-pushed the serialize branch from c4fd2d5 to 588f5f8 Compare March 24, 2018 19:12

markpeek reviewed Mar 24, 2018

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duglin force-pushed the serialize branch from 588f5f8 to a94019c Compare March 24, 2018 23:14

inlined reviewed Mar 28, 2018

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add json serialization

6e74891

Signed-off-by: Doug Davis <dug@us.ibm.com>

duglin force-pushed the serialize branch from eac2547 to 08e2f31 Compare March 29, 2018 13:15

add example and make it clear optional stuff is optional

ae3820b

Signed-off-by: Doug Davis <dug@us.ibm.com>

duglin force-pushed the serialize branch from 08e2f31 to ae3820b Compare March 29, 2018 13:16

duglin merged commit 1db322f into cloudevents:master Mar 29, 2018

duglin deleted the serialize branch March 31, 2018 12:14

duglin mentioned this pull request Mar 31, 2018

method context attribute #26

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add json serialization #124

add json serialization #124

duglin commented Mar 24, 2018

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ultrasaurus commented Mar 29, 2018

duglin commented Mar 29, 2018

+              }
+              ```
+              Note:

		@@ -0,0 +1,43 @@
		# CloudEvents Serialization Profile - Version 0.1

		This document specified how a CloudEvent is to be serialized into certain

+              }
+              ```
+              Notes:

add json serialization #124

add json serialization #124

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duglin commented Mar 29, 2018

ultrasaurus commented Mar 29, 2018

duglin commented Mar 29, 2018

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