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https://issues.apache.org/jira/browse/OLINGO-124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13874458#comment-13874458
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Michael Bolz edited comment on OLINGO-124 at 1/17/14 5:45 AM:
--------------------------------------------------------------
Hi Miki,
at your sample you have to define the {{List<Schema>}} or the {{ODataService}}
as {{static}} fields.
{code}
private static List<Schema> schemas = new ArrayList<Schema>();
{code}
and
{code}
private static ODataService theODataService = null;
{code}
Best practice for only caching metadata generation would be to define only the
{{EdmProvider}} as {{static}}.
Then in your {{EdmProvider}} implementation you can use your code example from
above.
Below is a sample in which therefore the [Initialization on demand holder idiom
is used|http://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom].
{code}
private static class EdmProviderHolder {
private static final EdmProvider INSTANCE = new ScenarioEdmProvider();
}
@Override
public ODataService createService(final ODataContext context) throws
ODataException {
DataContainer dataContainer = new DataContainer();
return createODataSingleProcessorService(
EdmProviderHolder.INSTANCE,
new ListsProcessor(new ScenarioDataSource(dataContainer)));
}
{code}
Can you please try it and give feedback whether this solution fit for your use
case.
I would then use this issue as first _question_ for an _FAQ_ in our wiki ;o)
Kind regards,
Michael
was (Author: mirbo):
Hi Miki,
at your sample you have to define the {{List<Schema>}} or the {{ODataService}}
as {{static}} fields.
{code}
private static List<Schema> schemas = new ArrayList<Schema>();
{code}
and
{code}
private static ODataService theODataService = null;
{code}
Best practice for only caching metadata generation would be to define only the
{{EdmProvider}} as {{static}}.
Below is a sample in which therefore the [Initialization on demand holder idiom
is used|http://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom].
{code}
private static class EdmProviderHolder {
private static final EdmProvider INSTANCE = new ScenarioEdmProvider();
}
@Override
public ODataService createService(final ODataContext context) throws
ODataException {
DataContainer dataContainer = new DataContainer();
return createODataSingleProcessorService(
EdmProviderHolder.INSTANCE,
new ListsProcessor(new ScenarioDataSource(dataContainer)));
}
{code}
Can you please try it and give feedback whether this solution fit for your use
case.
I would then use this issue as first _question_ for an _FAQ_ in our wiki ;o)
Kind regards,
Michael
> Caching of metadata document
> ----------------------------
>
> Key: OLINGO-124
> URL: https://issues.apache.org/jira/browse/OLINGO-124
> Project: Olingo
> Issue Type: Question
> Components: odata2-core
> Affects Versions: V2 1.0.0
> Reporter: M Carissimi
> Assignee: Michael Bolz
> Priority: Minor
>
> We generate the metadata at runtime using custom database queries and in
> odata4j we can cache the metadata document to avoid having to rebuild it
> every time a request is received. How can metadata be cached between requests
> in olingo? Following the simple read example on the olingo website, we use an
> ODataServiceFactory to create a service using method
> createODataSingleProcessorService(), but these methods are invoked during
> each request.
> Hello Michael,
> the only remaining question I have is about caching of the schemas. I have
> already attempted to cache the schema list in my custom EdmProvider in the
> getSchemas() method, but this has had no effect.
> {code}
> private List<Schema> schemas = new ArrayList<Schema>();
> ...
> public List<Schema> getSchemas() throws ODataException
> {
> if (schemas.size() == 0)
> {
> Schema schema = new Schema();
> ...
> schemas.add(schema);
> }
> return schemas;
> }
> {code}
> Running the code in debugging mode, I can see that method createService() of
> the service factory class configured as initi-parameter of the
> CXFNonSpringJaxrsServlet servlet is invoked during each invocation and this
> forces the creation of a new EdmProvider class on each invocation
> {code}
> private ODataService theODataService = null;
> ...
> @Override
> public ODataService createService(ODataContext ctx) throws ODataException
> {
> if (theODataService == null)
> {
> EdmProvider edmProvider = new ResourceNoLinksProvider();
> ODataSingleProcessor singleProcessor = new ResourceSingleProcessor();
> theODataService = createODataSingleProcessorService(edmProvider,
> singleProcessor);
> }
> return theODataService;
> }
> {code}
> Do you have any other suggestion about caching the schemas or metadata? In
> odata4j, we were able to cache the metadata represented by EdmDataServices
> using a similar approach to the one above. The main difference is that the
> factory class was invoked by Jesey rather than CXF.
> Regards
> Miki
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