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From Isuru Suriarachchi <isur...@gmail.com>
Subject Re: Supporting hierarchical service deployment
Date Fri, 04 Sep 2009 06:42:32 GMT
On Fri, Sep 4, 2009 at 11:32 AM, Chinmoy Chakraborty <cchinu@gmail.com>wrote:

>
>
> On Fri, Sep 4, 2009 at 10:22 AM, Amila Suriarachchi <
> amilasuriarachchi@gmail.com> wrote:
>
>>
>>
>>  On Fri, Sep 4, 2009 at 10:05 AM, Chinmoy Chakraborty <cchinu@gmail.com>wrote:
>>
>>> Paul,
>>>
>>> May be I dropped in from nowhere but I like to understand the idea. What
>>> is the purpose of maintaining duplicate data by allowing exact same AAR to
>>> be deployed in two different parts of hierarchy?
>>>
>>  It is not exact AAR file. It is basically organise your AAR file in a
>> directory structure without putting all of the in the root directory.
>>
>> eg.
>> repository/services/admin/AdminService.aar
>> repository/services/management/Management.aar
>> repository/services/tech/v1.1/Tech.aar
>> repository/services/tech/v1.0/Tech.aar
>>
>> if you take latter two cases, it may be two versions of same .aar file
>> which user wants to active at the same time.
>>
>
> CHINMOY>> OK.
>
>
>>
>>
>>> I guess Axis2 should also support same service name with different
>>> namespaces. I have this kind of requirement in our project but right now
>>> it's a limitation.
>>>
>> if you can describe your requirement then we can see how it can be
>> supported.
>>
>> As I understood what you want to have is same service name with different
>> name spaces to distinguish the version.
>> (I assume version depends on the namespace in your case)
>>
>
> CHINMOY>> Not exactly. I have two different services with same service name
> and they do absolutely two different tasks. let me explain: I have one
> function called ABS (returns absolute value, generally long) and a routinecalled ABS
(does some other work than ABS function). Let's say the namespace
> for ABS function is abc.function.ABS and the namespace for ABS routine is
> abc.routine.ABS.
>
> So we can have two different services for the same service name. In AXIS
> 1.x we could do that since there was concept of jws deployment and the
> directory structure was part of the url.
>
>>
>> Now the problem is what is the epr for these two services. In the above
>> solution epr is mapped to the folder structure. So people can invoke two
>> services with different eprs.
>>
>> In your solution how to determine the service to invoke once a request
>> receive?
>>
>
> CHINMOY>> If we have a parameter in services.xml like
> <serviceNameSpace>abc.function/routine</serviceNameSpace> then in the url
> the service name should be appened with namespace. e.g
>
> ../services/ABS (now)
> ../service/abc.function.ABS
>
> The logic should be just add namespace along with the servicename and the
> namespace is available from the services.xml.
>

Then how are we going to do this for the services like POJO, JAXWS etc..
which doesn't contain a services.xml?

And also, even with AAR services, you have to name your .aar file
differently as they are in the same folder.

Actually hierarchical services using directories address wider range of
problems. It allows you to manage your services separately  as you wish.
That is the natural way of managing stuff. And also that concept caters your
requirement as well.

Put your first ABS service in abc/function/ folder.
Put your second ABS service in abc/routine/ folder.

Thanks,
~Isuru


>
> Chinmoy
>
>>
>> thanks,
>> Amila.
>>
>>>
>>> Chinmoy
>>>
>>>   On Thu, Sep 3, 2009 at 4:46 PM, Paul Fremantle <pzfreo@gmail.com>wrote:
>>>
>>>> Chinmoy
>>>>
>>>> I think that is cool, but I guess the aim of Isuru's initial proposal
>>>> was to allow the exact same AAR to be deployed independently in two
>>>> parts of the hierarchy. To me that is a good objective.
>>>>
>>>> Paul
>>>>
>>>> On Thu, Sep 3, 2009 at 11:59 AM, Chinmoy Chakraborty<cchinu@gmail.com>
>>>> wrote:
>>>> > Guys,
>>>> >
>>>> > How about introducing a new parameter (e.g ServiceClassNameSpace) in
>>>> the
>>>> > services.xml to support directory hierarchy in the service?
>>>> >
>>>> > Chinmoy
>>>> >
>>>> > On Thu, Sep 3, 2009 at 3:47 PM, Isuru Suriarachchi <isurues@gmail.com
>>>> >
>>>> > wrote:
>>>> >>
>>>> >> Hi all,
>>>> >>
>>>> >> As using '/' character may cause problems in dispatching, I just
used
>>>> a
>>>> >> separate character ('!') to represent the directory hierarchy in
the
>>>> >> service. This allows all types of services to be deployed
>>>> hierarchically
>>>> >> without any problems (Including RESTful services).
>>>> >>
>>>> >> Ex: if we deploy the Echo service at
>>>> >> /repository/services/foo/bar/1.0.0/echo.aar, service name will be
>>>> >> foo!bar!1.0.0!Echo and the EPR will be like
>>>> >> ../axis2/services/foo!bar!1.0.0!Echo/echoString
>>>> >>
>>>> >> I've attached a new patch to the JIRA
>>>> >> (https://issues.apache.org/jira/browse/AXIS2-4479). This patch
>>>> doesn't
>>>> >> contain any changes in dispatching logics. And also I've implemented
>>>> the
>>>> >> ability to deploy JAXWS, Pojo etc.. (which are coming from the
>>>> axis2.xml)
>>>> >> services hierarchically to make this effort complete. In addition
to
>>>> that,
>>>> >> I've written some deployment tests for hierarchical services.
>>>> >>
>>>> >> Thanks,
>>>> >> ~Isuru
>>>> >>
>>>> >> On Sun, Aug 30, 2009 at 2:48 AM, keith chapman <
>>>> keithgchapman@gmail.com>
>>>> >> wrote:
>>>> >>>
>>>> >>> I've been out of touch with the Axis2 list for some time. Took
a
>>>> while to
>>>> >>> read this thread. Just a few thouths on it.
>>>> >>>
>>>> >>> I don't think that this patch would effect the RESTfull behaviour
in
>>>> any
>>>> >>> way. Its just that the user needs to be extra carefull if he
wants
>>>> to use
>>>> >>> RESTfull services in cunjunction with the hierarchical services
>>>> concept. i.e
>>>> >>> if he has a services called foo do not use foo as a top level
folder
>>>> in your
>>>> >>> hierarchy. Its simple as that. I guess been careful is the price
you
>>>> have to
>>>> >>> pay if you wanna use hierarchical services.
>>>> >>>
>>>> >>> I like the idea of having hierarchical services in Axis2. Well
I did
>>>> it
>>>> >>> once using the extension points of Axis2 but I'm +1 for having
this
>>>> concept
>>>> >>> baked into Axis2.
>>>> >>>
>>>> >>> Also it would be good to base arguments on facts rather than
>>>> religious
>>>> >>> beleifs. Quite a few design desicions made back then when Axis2
was
>>>> designed
>>>> >>> did not take stuff such as this into consideration. Well i'm
not
>>>> blaming the
>>>> >>> initial Axis2 community for that. As the project evolves new
>>>> features such
>>>> >>> as this can be added. Good examples are features such as plugable
>>>> message
>>>> >>> builders/formatters (post 1.1), custom deployers (post 1.2 IIRC),
>>>> the
>>>> >>> binding hierarchy concept (post 1.3) are features that were
added
>>>> later in
>>>> >>> the cycle. I see the hierarchical service deployment feature
as just
>>>> another
>>>> >>> addition to the wide variety of features of Axis2.
>>>> >>>
>>>> >>> Thanks,
>>>> >>> Keith.
>>>> >>>
>>>> >>> On Sat, Aug 29, 2009 at 1:24 PM, Sanjiva Weerawarana
>>>> >>> <sanjiva@opensource.lk> wrote:
>>>> >>>>
>>>> >>>> I forgot to address the issue with not being able to support
>>>> RESTful
>>>> >>>> services. I think we can- we just need to change the REST
>>>> dispatcher (argh
>>>> >>>> if that's what its called its a terrible name!) to look
at the
>>>> context path
>>>> >>>> of the service(s) and try filtering those out first.
>>>> >>>>
>>>> >>>> Sanjiva.
>>>> >>>>
>>>> >>>> On Sat, Aug 29, 2009 at 8:51 PM, Sanjiva Weerawarana
>>>> >>>> <sanjiva@opensource.lk> wrote:
>>>> >>>>>
>>>> >>>>> Deepal, I've read this entire thread and I'm confused
as to why
>>>> you're
>>>> >>>>> objecting.
>>>> >>>>>
>>>> >>>>> First of all, I think Isuru sent this thread into a
bad start by
>>>> using
>>>> >>>>> versioning as the reason for wanting to introduce hierarchical
>>>> service
>>>> >>>>> deployment. That was a mistake but as Andreas' comment
pointed
>>>> out, this is
>>>> >>>>> nothing more than the contextPath concept found in Java
>>>> containers.
>>>> >>>>> Versioning is at most a special case but let's just
take that out
>>>> of the
>>>> >>>>> discussion because this is not about versioning. If
you disagree
>>>> please
>>>> >>>>> explain why.
>>>> >>>>>
>>>> >>>>> Secondly, this can be done outside of Axis2 totally.
All we need
>>>> to do
>>>> >>>>> is write a new deployer and a dispatcher. There's no
need to waste
>>>> time with
>>>> >>>>> this type of pretty un-objective / emotional debate.
However, it
>>>> was
>>>> >>>>> proposed as a mod to axis2 because it significantly
improves axis2
>>>> usability
>>>> >>>>> WITHOUT breaking any existing behavior. Or so was the
belief. So
>>>> let's go
>>>> >>>>> thru the discussion and if the view is that this is
not necessary
>>>> in axis2's
>>>> >>>>> default deployers etc. then no problem.
>>>> >>>>>
>>>> >>>>> Now I will explain why this approach is better than
alternatives.
>>>> The
>>>> >>>>> basic requirement is that having a single flat naming
scheme for
>>>> services is
>>>> >>>>> unnecessarily limiting. Why? Because it requires everyone
to agree
>>>> on the
>>>> >>>>> service name as those names are global. If you're using
Axis2 as a
>>>> library
>>>> >>>>> on a single developer machine that's not an issue. However,
if you
>>>> want to
>>>> >>>>> deploy an axis2 engine to host some number of services
for a
>>>> larger
>>>> >>>>> organization then that invariably results in name conflicts.
I
>>>> assume you
>>>> >>>>> agree that's global names are a limitation.
>>>> >>>>>
>>>> >>>>> How do you fix it? One option is to use some naming
convention
>>>> like
>>>> >>>>> what Java packages did for Java classes. So you can
have
>>>> >>>>> /services/us.finance.address and /uk.services/marketing.address
if
>>>> (say) US
>>>> >>>>> finance and UK marketing orgs both want to have a service
called
>>>> "address".
>>>> >>>>> That basically makes the fact that what you have are
>>>> hierarchically named
>>>> >>>>> services opaque to the Web infrastructure. For example,
if you
>>>> were
>>>> >>>>> analyzing http logs to see the traffic you can't get
a simple
>>>> answer to "how
>>>> >>>>> many times have UK guys' services been used?". That's
*exactly*
>>>> the kind of
>>>> >>>>> wrong-headed thinking that got WS-* in trouble with
the REST guys
>>>> for
>>>> >>>>> improper use of REST (and I'm absolutely one of the
early culprits
>>>> who made
>>>> >>>>> the mistake).
>>>> >>>>>
>>>> >>>>> Another approach is to have a way to specify the context
path in
>>>> the
>>>> >>>>> service itself. If you remember, we used to have the
concept of
>>>> service name
>>>> >>>>> you could specify in service.xml itself (maybe its still
there; I
>>>> have no
>>>> >>>>> idea) - the idea was it would override the .aar file
name if
>>>> thats' there.
>>>> >>>>> This is similar- you can have in foo.aar a setting saying
>>>> >>>>> contextPath="finance/foo" and that means that's where
the service
>>>> is
>>>> >>>>> deployed.
>>>> >>>>>
>>>> >>>>> The advantage of simply using the file system hierarchy
to compute
>>>> that
>>>> >>>>> is just simplicity. The context hierarchy is visible
to everyone
>>>> by simply
>>>> >>>>> looking at the directory structure. If you check in
the repository
>>>> into SVN
>>>> >>>>> (which I know a bunch of people do) it gives a simple
way to
>>>> manage
>>>> >>>>> authorization for deployment for different people.
>>>> >>>>>
>>>> >>>>> I actually think we should support a contextPath=xxx
option in
>>>> >>>>> services.xml as well. However, treating the file system
hierarchy
>>>> as a
>>>> >>>>> hierarchy is, you know, rather natural.
>>>> >>>>>
>>>> >>>>> I think Isuru has shown that there is no extra performance
loss or
>>>> any
>>>> >>>>> other loss by supporting hierachically deployed services.
You
>>>> DON'T need to
>>>> >>>>> use them unless you want to of course - and if there's
no
>>>> hierarchy there's
>>>> >>>>> no change at all (subject to having enough unit tests
to make sure
>>>> that old
>>>> >>>>> and new behavior for the old feature is not changed).
>>>> >>>>>
>>>> >>>>> Sanjiva.
>>>> >>>>>
>>>> >>>>> On Sat, Aug 29, 2009 at 7:05 PM, Deepal jayasinghe <
>>>> deepalk@gmail.com>
>>>> >>>>> wrote:
>>>> >>>>>>
>>>> >>>>>> >
>>>> >>>>>> >
>>>> >>>>>> > On Fri, Aug 28, 2009 at 8:30 PM, Andreas Veithen
>>>> >>>>>> > <andreas.veithen@gmail.com <mailto:andreas.veithen@gmail.com>>
>>>> >>>>>> > wrote:
>>>> >>>>>> >
>>>> >>>>>> >     Guys,
>>>> >>>>>> >
>>>> >>>>>> >     Are we actually discussing the right question?
Looking at
>>>> the
>>>> >>>>>> > patch
>>>> >>>>>> >     proposed by Isuru, I have the impression
that versioning is
>>>> >>>>>> > merely one
>>>> >>>>>> >     use case, but that (in contrast to modules)
the code
>>>> doesn't
>>>> >>>>>> > make any
>>>> >>>>>> >     assumption about the meaning of the hierarchy
in the
>>>> repository
>>>> >>>>>> > (it
>>>> >>>>>> >     could be version number, but it could also
something
>>>> completely
>>>> >>>>>> >     different). Fundamentally the change is
not about
>>>> versioning,
>>>> >>>>>> > but
>>>> >>>>>> >     about giving the user the possibility to
define the
>>>> structure of
>>>> >>>>>> > the
>>>> >>>>>> >     endpoint URL.
>>>> >>>>>> >
>>>> >>>>>> >
>>>> >>>>>> > yes. this should be the idea. it is to support
hierarchical
>>>> service
>>>> >>>>>> > folder structure to mange
>>>> >>>>>> > services. Versioning is only one possible use
case.
>>>> >>>>>> > I think this is a common requirement. For an
example if we take
>>>> a
>>>> >>>>>> > web
>>>> >>>>>> > site people don't put
>>>> >>>>>> > all their .jsp or .html files in the root directory.
They
>>>> manage
>>>> >>>>>> > them
>>>> >>>>>> > in a some meaningful
>>>> >>>>>> > folder structure and even page url maps to
it.
>>>> >>>>>> You are mistaken in the case of web site .jsp files
are like
>>>> .class
>>>> >>>>>> files. So even in Web Service we have package hierarchy.
>>>> >>>>>> > I can hardly think of any reason for opposing
to introduce such
>>>> >>>>>> > feature to axis2 service deployment provided
>>>> >>>>>> > that it *does not break existing functionality*.
>>>> >>>>>> If you look at the directory structure (as I told
you before)
>>>> >>>>>> information repeat it self. It is analogous to "Shop
is closed
>>>> because
>>>> >>>>>> it is not open".
>>>> >>>>>> Just because feature X is good in project Y, we
should not
>>>> introduce
>>>> >>>>>> that to Axis2.
>>>> >>>>>> If you or someone want to do such a feature of course
they can do
>>>> >>>>>> that,
>>>> >>>>>> just ad a new deployer  to handle the they want,
even in you case
>>>> we
>>>> >>>>>> can
>>>> >>>>>> do the same. Let's create a new deployer and manage
anyway you
>>>> like,
>>>> >>>>>> and
>>>> >>>>>> then if you think it is ok, then commit the new
deployer to
>>>> Axis2.
>>>> >>>>>>
>>>> >>>>>> However I am not ok with introducing new URL pattern,
I think
>>>> Isuru
>>>> >>>>>> already agreed to replace "/" with "-"
>>>> >>>>>> >
>>>> >>>>>> > Deepal,
>>>> >>>>>> > I feel you have given over weight to the versioning
support
>>>> which is
>>>> >>>>>> > a
>>>> >>>>>> > use case of this. In the way to have told
>>>> >>>>>> > people can have versioning without any support
of axis2, by
>>>> just
>>>> >>>>>> > naming service in the way they need.
>>>> >>>>>> Yes. At the end of the day whether it is "/" or
"-" would become
>>>> a
>>>> >>>>>> unique name. So it is the service name.
>>>> >>>>>> >
>>>> >>>>>> > Comming into the other point of probable break
of existing
>>>> >>>>>> > functionality Can you please come up with the
>>>> >>>>>> > set of use case scenarios for this? Then we
can ask Isuru to
>>>> provide
>>>> >>>>>> > integration test for all these scenarios. This
may test the
>>>> existing
>>>> >>>>>> > functionality as well :)
>>>> >>>>>> I am sorry I do not have time to comeup with scenarios
when
>>>> someone
>>>> >>>>>> add
>>>> >>>>>> new features, specially even without going through
the existing
>>>> JIRA.
>>>> >>>>>> >
>>>> >>>>>> > I think we should not be pessimistic and think
deployment
>>>> engine is
>>>> >>>>>> > done for ever and any change will break it.
>>>> >>>>>> Not at all, how many changes we made, in this case
my concern is
>>>> not
>>>> >>>>>> the
>>>> >>>>>> deployment engine it is the URL pattern.
>>>> >>>>>> >
>>>> >>>>>> > Isuru,
>>>> >>>>>> > Please provide a set of integration tests for
the scenarios
>>>> >>>>>> > mentioned.
>>>> >>>>>> :)
>>>> >>>>>>
>>>> >>>>>> Thanks,
>>>> >>>>>> Deepal
>>>> >>>>>
>>>> >>>>>
>>>> >>>>>
>>>> >>>>> --
>>>> >>>>> Sanjiva Weerawarana, Ph.D.
>>>> >>>>> Founder, Director & Chief Scientist; Lanka Software
Foundation;
>>>> >>>>> http://www.opensource.lk/
>>>> >>>>> Founder, Chairman & CEO; WSO2, Inc.; http://www.wso2.com/
>>>> >>>>> Member; Apache Software Foundation; http://www.apache.org/
>>>> >>>>> Visiting Lecturer; University of Moratuwa;
>>>> http://www.cse.mrt.ac.lk/
>>>> >>>>>
>>>> >>>>> Blog: http://sanjiva.weerawarana.org/
>>>> >>>>
>>>> >>>>
>>>> >>>>
>>>> >>>> --
>>>> >>>> Sanjiva Weerawarana, Ph.D.
>>>> >>>> Founder, Director & Chief Scientist; Lanka Software
Foundation;
>>>> >>>> http://www.opensource.lk/
>>>> >>>> Founder, Chairman & CEO; WSO2, Inc.; http://www.wso2.com/
>>>> >>>> Member; Apache Software Foundation; http://www.apache.org/
>>>> >>>> Visiting Lecturer; University of Moratuwa;
>>>> http://www.cse.mrt.ac.lk/
>>>> >>>>
>>>> >>>> Blog: http://sanjiva.weerawarana.org/
>>>> >>>
>>>> >>>
>>>> >>>
>>>> >>> --
>>>> >>> Keith Chapman
>>>> >>>
>>>> >>> blog: http://www.keith-chapman.org
>>>> >>
>>>> >>
>>>> >>
>>>> >> --
>>>> >> Senior Software Engineer,
>>>> >> WSO2 Inc. http://wso2.org/
>>>> >> Blog : http://isurues.wordpress.com/
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>> --
>>>> Paul Fremantle
>>>> Co-Founder and CTO, WSO2
>>>> Apache Synapse PMC Chair
>>>> OASIS WS-RX TC Co-chair
>>>>
>>>> blog: http://pzf.fremantle.org
>>>> paul@wso2.com
>>>>
>>>> "Oxygenating the Web Service Platform", www.wso2.com
>>>>
>>>
>>>
>>
>>
>> --
>> Amila Suriarachchi
>> WSO2 Inc.
>> blog: http://amilachinthaka.blogspot.com/
>>
>
>


-- 
Senior Software Engineer,
WSO2 Inc. http://wso2.org/
Blog : http://isurues.wordpress.com/

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