[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17711197#comment-17711197
]
Carsten Ziegeler commented on SLING-8047:
-
This is open for over four years now. Is this still a problem or can we resolve?
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16698664#comment-16698664
]
Julian Sedding commented on SLING-8047:
---
[~mundt], thanks for the test and sorry for the delay. The only other thing you
could do t help is give me some time ;)
I commented on your github branch. Could you please address the comment and
create a PR? Thanks!
I'll solicit some feedback on the mailing list, as my proposed change would be
a slight change of behaviour in a core passage of the code.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16698593#comment-16698593
]
Philip Mundt commented on SLING-8047:
-
Is there anything else I could do to help with this issue?
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16678258#comment-16678258
]
Philip Mundt commented on SLING-8047:
-
[~jsedding] thanks again for your alternative fix. I allowed myself to rebase
your commit in my fork and add a test case for the underlying issue. I'd be
happy to hear/get your input on it.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16668614#comment-16668614
]
Philip Mundt commented on SLING-8047:
-
[~jsedding] that's what I'm wondering too. I wasn't able to find the root cause
yet. But it seems that the buffer is overwritten somewhere, if not flushed in
the {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer}}.
Regarding your question: it's a fake response implementation that wraps (in our
case) a {{java.io.ByteArrayOutputStream}} in a {{java.io.OutputStreamWriter}}
and passes it to the {{java.io.PrintWriter}} ({{autoFlush}} is set to
{{true}}). The response object does not implement the {{#flushBuffer()}}
method, but even if I do (I quickly tried, flushing print writer and output
stream) nothing changes. The only working solution up until now was flushing
the writer in the JSON renderer.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16668402#comment-16668402
]
Julian Sedding commented on SLING-8047:
---
Thanks [~mundt] for the feedback. That's interesting, I wonder if/how the
{{DefaultGetServlet}} is getting special treatment.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16668381#comment-16668381
]
Philip Mundt commented on SLING-8047:
-
Hey [~jsedding] thanks for chiming in and providing an alternative fix. I tried
it and it works for the model exporter
({{org.apache.sling.models.impl.ExportServlet}}) scenario. However, when using
{{org.apache.sling.servlets.get.impl.DefaultGetServlet}} (via
{{org.apache.sling.servlets.get.impl.helpers.JsonRenderer}}) the output is
still an empty string.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16667273#comment-16667273
]
Julian Sedding commented on SLING-8047:
---
[~mundt] could you please check if the fix on [my fork of Sling
Engine|https://github.com/jsedding/sling-org-apache-sling-engine/tree/SLING-8047]
addresses your issue? It implements the approach mentioned in my previous
comment.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16665079#comment-16665079
]
Julian Sedding commented on SLING-8047:
---
If this same issue affects multiple servlets, then I doubt that the root cause
is in the servlets.
My hypothesis is the following: the root issue is in the Sling Engine, where
responses are not (auto-)flushed after processing if the RequestProcessor is
used. I could imagine that this wouldn't be a problem for scenarios where
requests are processed via the SlingMainServlet, because the HTTP container
(app-server, Felix Jetty, ...) would perform the flush. In the scenario where
the RequestProcessor is used, there is no HTTP container, hence we can
experience the described issue.
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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[jira] [Commented] (SLING-8047) Rendered/exported JSON requested via SlingRequestProcessor is not written to output stream
[
https://issues.apache.org/jira/browse/SLING-8047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16664263#comment-16664263
]
Jason E Bailey commented on SLING-8047:
---
Thank you for raising this issue! I see you also created a pull request against
the models. Could you do one for the default get servlets as well?
> Rendered/exported JSON requested via SlingRequestProcessor is not written to
> output stream
> --
>
> Key: SLING-8047
> URL: https://issues.apache.org/jira/browse/SLING-8047
> Project: Sling
> Issue Type: Bug
> Components: Feature Model, Servlets
>Reporter: Philip Mundt
>Assignee: Jason E Bailey
>Priority: Major
> Attachments:
> SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch,
> SLING-8047-ExportServlet-does-not-write-to-output-stream.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> While trying to facilitate the {{SlingRequestProcessor}} to get a rendered or
> exported JSON representation of a resource, we ran into the problem of the
> response always being empty. The HTML rendering worked without any issue.
> (See example code of [Get the rendered HTML for an AEM resource, component or
> page|http://www.nateyolles.com/blog/2015/10/get-rendered-html-for-an-aem-resource-or-component]
> or [https://stackoverflow.com/a/34218708])
> Main, observed difference seem to be the method calls to print writer:
> h4. JsonRenderer
> {{org.apache.sling.servlets.get.impl.helpers.JsonRenderer#render}} uses
> {{#write}} method of response's print writer.
> h4. ExportServlet (via JacksonExporter)
> {{org.apache.sling.models.impl.ExportServlet#doGet}} uses {{#write}} method
> of response's print writer.
> h4. HTMLRenderer
> {{org.apache.sling.servlets.get.impl.helpers.HtmlRenderer#render}} uses
> {{#print}} and {{#println}} methods of response's print writer.
> h3. Further observations
> When the print writer's {{autoFlush}} property is set to true and one uses
> the {{#println}} method instead of {{#write}}, the {{JsonRenderer}} will
> flush the print writer's buffer to the output stream. Due to wrapping the
> response in
> {{org.apache.sling.scripting.core.impl.helper.OnDemandWriterResponse}} (where
> {{autoFlush=false}}) this does not work for the {{ExportServlet}}.
> When adding implicit {{#flush()}} calls to both classes, both request
> scenarios will work. According to the servlet specification, it should not be
> necessary to flush the print writer, as the container must immediately flush
> all remaining content to the client upon "termination of the service method
> of the servlet".
> Please find two test cases for (where implicit {{#flush()}} calls were added):
> * JsonRenderer ({{sling-org-apache-sling-servlets-get}}):
> [^SLING-8047-DefaultGetServlet-does-not-write-to-output-stream.patch]
> * ExportServlet ({{sling-org-apache-sling-models-impl}}):
> [^SLING-8047-ExportServlet-does-not-write-to-output-stream.patch]
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