Hi Senaka
*public OMNode lookup(String key)*, only imply that for a given key you
will get a resource as a OMNode . You will not get any guarantee that
some other registry implementation will handle binary and pain text as
the way we are handling now. For example, someone can ignore completely
binary and pain text and return null if he only wants to use xml content
or someone may wraps the OMText with another OMElement and return that
OMElement as result. Very simply, *public OMNode lookup(String key)
*never expose the restriction to make sure that binary content and
plain text content are always wrapped inside a OMText as it is
completely implementation specific.
But one guarantee, currently all registry implementation behave as you
expected.
We discourage to use lookup(String key) method . Instead, you should use
*public Object getResource(Entry entry) *method to access registry
resources . It is the method that implements "the core Registry lookup
algorithm". All the caching at registry level will do there. Please look
at that. (AbstractRegistry)
You can use that API as follows
Entry entry = new Entry(key);
entry.setType(Entry.REMOTE_ENTRY);
regsirty.getResource(enrty);
Entry has methods to set cache expiryTime , etc.
If you can cache entry in somewhere, you can use it whenever you need to
access content of the resource. In synapse , we are caching those at
SynapseConfiguration.
To ensure that binary and text content would be accessed in a consistent
way with any registry implementation, we can move, the logic of binary
content handling to the *getResource(Entry entry) *where the lookup
algorithm has been already there. By doing that we can enforce that all
registry implementation will behave in a consistent way (binary and text
content handling and lookup algorithm).
Then we have to change
public Object lookup(String key);
To
public InputStream lookup(String key);
This is just for avoiding misusing lookup(String key) method . Now ,
this method is not depended on implementation ...always return a Stream
Actually, in the current implementation, if you are using this method,
there is no caching, no entry mapping to endpoint, and sequence at
registry level, etc. To get that, you have to use *getResource(Entry
entry)*. Actually, lookup method is a just helper method to
*getResource(Entry entry)* . Within, SynapseConfiguration, we only use
*getResource(Entry entry)*.
In additions, to ensure that resource handling is consistent, we have
two options,
We can make Registry interface is an abstract class and add
*getResource(Entry entry) *implementation to that and make that method
as final. Then, any registry implementation have to extend this and
cannot override *getResource(Entry entry) *as it final. And also this
add is-a relationship.
We can make existing method of getResource(Entry entry) implementation
at AbstractRegistry as a final method so that it cannot be overridden.
Then, it needs to document that use AbstractRegistry and extend it
instead of implementing Registry interface, whenever write a registry
implementation.
One thing to note, To covert a object into a Stream , you can use
SynapseConfigUtils. getInputStream(Object o) . Please look at that.
Then code look like...
Entry entry = new Entry(key);
entry.setType(Entry.REMOTE_ENTRY);
Object resource = regsirty.getResource(enrty);
InputStream in = SynapseConfigUtils. getInputStream(resource);
Thanks
Indika
Senaka Fernando wrote:
Hi Indika,
Yep, the latest fix seem to solve my problem. Btw, one more question.
I managed to read the contents of the DataHandler in the following manner.
OMNode textNode = registry.lookup(registryKey);
DataHandler dh = (DataHandler)(((OMText)textNode).getDataHandler());
BufferedReader br = new BufferedReader(new
InputStreamReader((InputStream)(dh.getContent())));
Do all Registries implemented by WSO2ESB or any in the future do
confirm to this layout? That means, am I certain that I can read
non-XML content from any registry in this manner?
Thanks,
Senaka
2008/8/10 Indika Kumara <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
Hi Senaka
There was an issue as there are no parent for wrapping OMText
Element that used to wrap binary and plain text as a DataHandler.
As I can remember , I had tested this scenario when I was adding
handling binary and plain text . But , there was no
result.detach() method at that svn revision. It seems that this
(result.detach()) was added for fixing an issue and after that it
seems to forget to test a scenario accessing resources with binary
and plain text content.
I have fixed this and update sample 350 to demonstrates this. That
sample use Java script files in native form.
Please update both synapse and ESB source and try out your
scenario again.
Thanks
Indika
Senaka Fernando wrote:
Hi all,
Recently when working on the ESB Registry,
(org.wso2.esb.registry.ESBRegistry), I discovered that I can
quite easily obtain the contents of an XML file using a
lookup(String). According to the implementation, it also seems to
handle non-XML file types (ex:- .txt) as well, and creates a
OMText along with the file attached as a DataHandler to it. Did I
get this correct? or am I mistaken?
If I got it right, it works fine upto, result.detach(). At this
point I get an exception,
org.apache.axiom.om.OMException: Elements that doesn't have a
parent can not be detached
at
org.apache.axiom.om.impl.llom.OMNodeImpl.detach(OMNodeImpl.java:195)
at org.wso2.esb.registry.ESBRegistry.lookup(ESBRegistry.java:207)
at
org.sciflex.plugins.synapse.esper.mediators.AxiomMediator.mediate(AxiomMediator.java:221)
at
org.apache.synapse.mediators.ext.ClassMediator.mediate(ClassMediator.java:78)
at
org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:58)
at
org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:95)
at
org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:58)
at
org.apache.synapse.mediators.filters.InMediator.mediate(InMediator.java:60)
at
org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:58)
at
org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:125)
at
org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:176)
at
org.apache.synapse.core.axis2.SynapseMessageReceiver.receive(SynapseMessageReceiver.java:89)
at
org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:170)
at
org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:275)
at
org.apache.synapse.transport.nhttp.ServerWorker.processPost(ServerWorker.java:244)
at
org.apache.synapse.transport.nhttp.ServerWorker.run(ServerWorker.java:185)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
It might most probably be that I'm making a mistake here. If so,
can you please tell me how I could for instance read a .txt file
that I save in the ESBRegistry?
Thanks,
Senaka
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