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From "Soumadeep" <soumad...@infravio.com>
Subject RE: SynapseObject - Reminder...
Date Tue, 21 Mar 2006 04:00:53 GMT
Hi Hari,
Interesting observation I must say. Please see my comments inline.

-----Original Message-----
From: Hariharasudhan.D [mailto:hari@infravio.com]
Sent: Monday, March 20, 2006 8:56 PM
To: synapse-dev@ws.apache.org
Subject: Re: SynapseObject - Reminder...

Hi,

I was out of this for a while but just wanted to know what is the
co-relation between ADB and xpath in this context. ADB is more of  a light
weight  schema compiler and xpath works on xml. How are we marrying these
two aren't they parallel?
You are right, the suggestion was more of a flip-flop, meaning if a user
wants to use ADB then they will generate the classes then write the logic to
do search (just like XMLBeans). On the other hand if they want to use XML
directly for configuration then they would use xpath to do search. Both can
be used in conjunction but handled separately. This is one of the reasons
the use case was provided. Using SynapseObject you don’t need handle it
separately everything is inbuilt. And if you have read the latest thread
SynapseObject would now operate on simple XML and not the way it was earlier
represented (Paul’s initial concern about the XML format)


The other obvious question is if we already have xmlBeans for data binding
then what's the need for ADB?
I don’t think I can comment on that!


Would highly appreciate if someone can enlighten me on this. FYI, I could
not make sense of what Saminda tried to explain. From the use case described
below I think SynapseObject would be very useful for handling mediators.

Hari

Davanum Srinivas wrote:
i *really* don't see a need for it. Let's make do with standard stuff
like saminda mentioned.

thanks,
dims

On 3/20/06, Vikas  <vikas@infravio.com> <mailto:vikas@infravio.com>  wrote:


Hi...

I am using SynapseObject to handle mediator data, it works as an extension.
Is there a problem in adding extensions??
Extensions are not compulsary or imposed on others, just for convenience...

But to make things clear and sum up the points:

The problem is not with using DOM / OM..
Its the XML structure that gives the meaning, the JAVA/in-memory
representation is just an enabler for that..

I did try writing the 'utility' methods for OM...
But based on a generic XML structure, it just doesn't work out...
The XML representation along with the Utility classes gives SynapseObject
the actual strength and the users the ease..

SynapseObject is not just about ObjectModel [AXIOM/DOM] or about XML [the
structure]
or the data-binding [XMLBeans/ ADB]...

Its a variation in-between, a blend to be more precise...

The very problem with XPath is that they are based on the XML structure,
change the structure =>change the X-Path...

But SynapseObject has only 2 structural constraints..
Every object has
* Attributes as child objects
* Has other SynapseObjects
In case I move an attribute from a parent to its child SynapseObject, the
search utility takes care of it, In case of an X-Path that mplies another
level of ../.. [hope you are not planning to use x-paths which always search
throughout i.e [//someName]

~Vikas..

----- Original Message -----
From: Saminda Abeyruwan

To:  synapse-dev@ws.apache.org <mailto:synapse-dev@ws.apache.org>

Sent: Monday, March 20, 2006 2:51 PM
Subject: Re: SynapseObject - Reminder...

Hi Devs,

My comments are in line,

On 3/19/06, Soumadeep  <soumadeep@infravio.com>
<mailto:soumadeep@infravio.com>  wrote:




Hi,

One thing I completely agree with Sanjiva is that this has been dragged

unnecessarily for this long. Let me emphasize here one thing, that the
intension is not to replace the concepts of data binding as used by XMLBeans
which is again an Apache project or trying to re-invent what has been
written. To this effect enough reasons have been provided as to why this
approach was taken.  For convenience let me give one of the use cases and
reasons for which SynapseObject was proposed:


Following reasons  is addressed by Axis2 's codegen concepts.





Reasons:
1) Java Properties class lets you handle name-value pairs in a very good

way but when it comes to representing complex objects it becomes very
difficult.

2) Using the concept of data binding introduces a very rigid and tight

coupling of data and schema. So if the schema changes the underlying data
handling mechanism needs to be changed (which includes the beans/classes to
hold the complex data structure)


This is why there are two entities exists in Axis2.  If the xml is  schema
compliant  i will use XSD2Java, if not i will write my beans and use
BeanUtil.





3) Intelligent search features are either driven by xpath/xqueries for

pure XML or embedded logic if beans are used, SynapseObject has inbuilt
search features by which you can perform complex searches

4) The reason people use Java Properties class is because name-value pairs

can be shared by other class without any dependency. SynapseObject is more
like a Properties Class with added features to handle Complex Objects and
also allow search features.


Synapse is a user of Axis2, so let it be a user of  Axis2's XSD2Java,
BeanUtil and Jaxen compliant Xpath.





Uses Cases:
A) Data-Sharing between mediators: Consumers need to be identified, once

it's identified the information could be shared by the SLA mediator which
depending on a consumer will set the priority. Below is the pseudo code  of
how this can be achieved using SynapseObject and how datasharing would
become easy.

Background Info:
-----------------------
ConsumerIdentification mediator needs to identify a client by the

following ways:

1) IP {eg. 192.168.5.*}
2) IP Range {eg. 192.168.5.20- 192.168.5.30}
3) WS-SEC auth token
4) HTTP auth token
5) certificate
(Other factors that need to be considered whether the incoming message was

first encrypted and then signed or was it signed and then encrypted).

Let's consider 1) IP

Using SynapseObject:
ConsumerIdentification
--------------------------------

xml frag:
<?xml version='1.0' encoding='windows-1252'?>
<SynapseObject name="ci">

 <SynapseObject name="consumer0">
   <Attribute name="CONSUMER_TYPE" type="String">GOLD</Attribute>

   <Attribute name="IP_ADDRESS_FROM" type="String">192.168.6.0</Attribute>

   <Attribute name="IP_ADDRESS_TO" type="String">192.168.6.255</Attribute>
   <Attribute name="HTTP_AUTH_USERNAME" type="String">john</Attribute>
   <Attribute name="WS_SEC_USERNAME" type="String">john</Attribute>
   <SynapseObject name="assignedService">
    <Attribute name="serviceid1"

type="String">stockQuote1</Attribute>

   </SynapseObject>
 </SynapseObject>
 <SynapseObject name="consumer1">
   <Attribute name="CONSUMER_TYPE"

type="String">SILVER</Attribute>

   <Attribute name="IP_ADDRESS_FROM"

type="String">192.168.6.255</Attribute>

   <Attribute name="IP_ADDRESS_TO" type="String">192.167.6.255</Attribute>
   <Attribute name="HTTP_AUTH_USERNAME" type="String">mary</Attribute>
   <Attribute name="WS_SEC_USERNAME" type="String">mary</Attribute>
   <SynapseObject name="assignedService">
    <Attribute name="serviceid1"

type="String">stockQuote</Attribute>

    <Attribute name="ip" type="String">192</Attribute>
   </SynapseObject>
 </SynapseObject>
</SynapseObject>


Back to  square  one,

Above  can be written as,
<ci>
     <consumer name="consumer0">
            <type>GOLD</type>
            <ip_address_from>192.168.6.0 </ip_address_from>
            <ip_address_to>192.167.6.255 </ip_address_to>
            <http_auth_username>Mary</http_auth_username>
             <ws_sec_username>Mary</ws_sec_username>
     </consumer>
     <service name="assingedservice">
        <!-- other stuff -->
     </service>
     <consumer name="consumer1">
         <!-- related suff -->
     </consumer>
        <!-- other services or consumers or related stuff -->
</ci>

which is much more readable,

If i want intelligent search i use xpath. A lot of users know how to use
xpath, so it's Zero training. If i write  simple beans, i can populate the
bean objects using BeanUtil. Now in production the above xml should be
schema aware. That's the whole point of inventing schema. So i will use
XSD2Java. Now these technologies are not going to hook into Synapse core.





in the ci mediator  code fragment

// the the requester ip
ip = {get the remote ip from the messageContext/SynapseContext }

//Identify if the consumer is there and get appropriate details and store

the consumer related details in the messageContext, one more things to note
is that storing shared data is by the mediator name itself eg. ci

SynapseObject obj =

consumerIdentification.findSynapseObjectByAttributeValueStartingWith(ip);

messageContext.setProperty(consumerIdentification.getName(),obj);
obj will contain all the required values if identified!

SLA
------

xml Fragment:

<SynapseObject name="SLA">
    <SynapseObject name="consumer0">
        <SynapseObject name="Service0">
            <Attribute name="EPR"

type="String"> http://www.webservicex.net/stockquote.asmx</Atrribute>

            <Attribute name="priority" type="Integer">0</Attribute>
        </SynapseObject>


        <SynapseObject name="Service1">
            <Attribute name="EPR"

type="String"> http://www.webservicex.net/findZIPCode.asmx</Atrribute>

            <Attribute name="priority" type="Integer">1</Attribute>
        </SynapseObject>
    </SynapseObject>
</SynapseObject>


IMHO  above xml fragment would treat as the prior.





in the SLA Mediator code fragment

//As there is a dependency between the SLA mediator and CI the SLA

mediator will pick information for its dependency (Note: we also proposed a
concept

//of MediatorContext which will have dependency and other information for

a particular mediator)


Excuse me btw :)





//Get the identified consumer from the messagecontext
SynapseObject consumerIdentification =

(SynapseObject)messageContext.getProperty("ci");

// get the consumer name and consumer type
String consumerName = consumerIdentification.getName();
String consumerType =

consumerIdentification.getString("CONSUMER_TYPE");

//find the sla details for the identified consumer
SynapseObject consumer =

sla.findSynapseObjectByAttributeValue(consumerName);

String fromAddress =

(String)synapseMessageContext.getTo();

SynapseObject service =

consumer.findSynapseObjectByAttributeValue(fromAddress );

// The priority value would be used by the SLA mediator to forward the

request to the provider depending on the priority.

String priority = service.getString("priority");


Now as i can understand from the above code fragments, SynaspeObject has to
have a hook to Synapse core. As we agreed, SO should be  an extension.
Besides, as technology exists for manipulating the required xml, (xpath,
XSD2Java, BeanUtil) for mediators without having a hook to Synapse core, why
on earth we make SO a core feature?

Thank you

Saminda





Regards
Soumadeep


-----Original Message-----
From: Saminda Abeyruwan [ mailto:samindaa@gmail.com]
Sent: Saturday, March 18, 2006 6:59 PM
To:  synapse-dev@ws.apache.org <mailto:synapse-dev@ws.apache.org>
Subject: Re: SynapseObject - Reminder...


Hi Devs,

These are my concern regarding SynapseObject,

If the following XML is considered wrt SynapseObject semantics,

<SynapseObject name="sla">
     <attribute name="service"

type="STRING"> http://myhost:myport/Service</attribute>

     <SynapseObject name="consumer">
     <attribute name="ip" type="STRING">192.9.2.11</attribute>
     </SynapseObject>
</SynapseObject>

which is similar to,

<sla>
     <service>  http://myhost:myport/Service </service>
     <consumer>
          <ip>192.9.2.11</ip>
     </consumer>
</sla>

Now if we have Java beans as follows,

public class sla {
    private String service;
    private Consumer consumer;

   //getter and setters
}

public class Consumer {
     private String ip;

   //getter and setters
}

and using the Axis2's

org.apache.axis2.databinding.utils.BeanUtil.getPullParser(Object
beanObject, QName beanName);

i can get a XMLStreamReader and build the OMElement i need. And if i have

prior XML, using

Object []

org.apache.axis2.databinding.utils.BeanUtil.deserialize(OMElement
response, Object [] javaTypes); i can fill the bean object.

So if I'm a Mediator author, using BeanUtil i can manipulate XML with Zero

training.

Now if my XML is schema complaint, using XSD2Java i can generate Beans and

using XX.parse() method i can fill the beans.

So what is done by SynapseObject is already done by Axis2's BeanUtil and

XSD2Java and they can do much more. So  IMHO we do not need to reinvent the
wheel with SynapseObject.

Those are my concerns.

Thank you

Saminda




On 3/17/06, Sanjiva Weerawarana  <sanjiva@opensource.lk>
<mailto:sanjiva@opensource.lk>  wrote:

On Mon, 2006-03-27 at 18:44 +0530, Vikas wrote:

Hi,

This is regarding the Synapse object proposed by me and Soumadeep...

For convenience I am putting below the links for reference:


< http://mail-archives.apache.org/mod_mbox/ws-synapse-dev/200602.mbox/%
<http://mail-archives.apache.org/mod_mbox/ws-synapse-dev/200602.mbox/%25>

3cPOEHIPNLJGDMKMMBHILOAECICBAA.soumadeep@infravio.com
<mailto:3cPOEHIPNLJGDMKMMBHILOAECICBAA.soumadeep@infravio.com>

%3e>

and the source code has been available in the Scratch
<

http://svn.apache.org/repos/asf/incubator/synapse/trunk/scratch/infravio/syn
apse-SO

I feel that it an effective utility and have made use of it in a all
the mediators that I would like to commit . It sure has made handling
mediator's config data easier..
Would be checking in the cleaned up code for SynapseObject as an
extension...Which I guess is OK.

Please let me know if anyone has any concerns about it??

I do .. I will write an explanatory reply tomrrow my time .. sorry for
keeping quiet; I've been reading much of this thread but just haven't
had the time to jump in.

I *will* dive in tomorrow (later today my time really). I'm afraid its
going to have lots of -1s against SynapseObject features :( .. just to
give you a warning of where its going.

Sanjiva.





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--
Davanum Srinivas :  http://wso2.com/blogs/

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Regards,
Hariharasudhan.D.


When I do good, I feel good; when I do bad, I feel bad.That’s my religion .
- Abraham Lincoln
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