You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@isis.apache.org by Erik de Hair <e....@pocos.nl> on 2015/04/01 12:33:23 UTC
Re: calling webservice only once from viewmodel
On 03/27/2015 12:26 PM, Dan Haywood wrote:
> Hi Erik,
>
> On 25 March 2015 at 12:42, Erik de Hair <e....@pocos.nl> wrote:
>
>> Hi,
>>
>> I have to call I web service from a view model but, when opening the view
>> model, the call to the web service is called twice. It doesn't matter if
>> the call is in de viewmodelinit or in some other method. May be there's
>> some way to track the state of the view model and let whether or not the
>> call is executed depend on that?
>>
> My guess is that you are seeing the view model called twice because we use
> (Wicket's support for) the redirect-after-post pattern.
>
> That is, when the action is invoked you are instantiating the view model
> (which calls the webservice), and then we return a 302 redirect to the
> browser so that it then re-requests the same URL, causing the view model to
> be recreated (and that webservice called).
>
> Perhaps you could confirm if that's what's happening?
The following is happening...
In the initial state the view model is rendered and the data that is
needed to call the web service is already available from the view model
memento. (This means that when refreshing the page the web service will
be called again. This is not much of a problem.)
Now, when clicking** the action button that opens the action for
re-entering the web service parameters, a request for the view model is
done:
0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:04:09 +0200] "GET
/portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwvanNvbj48L21lbWVudG8-?6-1.IBehaviorListener.0-theme-entity-entity~0-entityPropertiesAndCollections-entityProperties-leftColumn-memberGroup-1-properties-4-property-scalarIfRegular-additionalLinks-additionalLinkList-additionalLinkItem-0-additionalLink&_=1427882228283
HTTP/1.1" 200 12838 http-bio-8081-exec-4 2303
This way the web service is called again because the previous web
service parameters are still available from the view model memento.
After submitting the following requests are handled:
0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:17 +0200] "POST
/portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwvanNvbj48L21lbWVudG8-?6-1.IBehaviorListener.1-theme-actionPromptModalWindow-content-parameters-inputForm-okButton
HTTP/1.1" 200 91 http-bio-8081-exec-6 169
(web service called two times during this request)
0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:19 +0200] "GET
/portal/wicket/wicket/page?7 HTTP/1.1" 200 167629 http-bio-8081-exec-6 2582
(web service called once during this request)
>
> If it is, then one option might be to defer the fetching of the data until
> as late as possible, ie when it needs to be constructed.
I tried this but the method that exposes the data to the gui will always
call the method that fetches the data when constructing the view model.
So no matter how late the data will be fetched, it will always be fetched.
>
> Another option might be to have the view model use the HttpSession (via
> isis-module-servletapi addon) to keep track of state.
I'm still using Isis 1.7.0 and Eclipse complains about the module
missing some dependency. It does work however and I can prevent the web
service from being called by checking for a request method of GET during
the POST-request but there are still 3 calls left.
I didn't use the session object yet. Will try that.
>
> HTH
> Dan
>
>
>
>> The web service is fetching data, triggered by an action in the view
>> model, for the same view model. Do I always have to return a new view model
>> with the fetched data in it or can I use the data from the fetch method and
>> return the same view model?
>>
>> Thanks,
>> Erik
>>
Re: calling webservice only once from viewmodel
Posted by Dan Haywood <da...@haywood-associates.co.uk>.
Glad you got to a solution, Erik,
Cheers
Dan
On 7 April 2015 at 10:31, Erik de Hair <e....@pocos.nl> wrote:
>
> On 04/03/2015 09:03 AM, Erik de Hair wrote:
>
>>
>>
>>> Then the question is how to hold that server-side state. An HTTP Session
>>> object is one option; the other is to store the data in the database.
>>> That
>>> basically means converting the view model into an entity (analogous to a
>>> shopping cart entity); you could have some mechanism to clean up such
>>> session entities after a day or two.
>>>
>> My architecture didn't work correctly. I tried to put the data in the
> memento as json-object but this way the memento got to big, and this gives
> persisting problems for the auditing/publishing services. Right now I'm
> putting the same data in the HTTP session and this works as it should be.
>
> Thanks for your help,
> Erik
>
>
>
>>> Hope that helps provide some ideas...
>>>
>>> Cheers
>>> Dan
>>>
>>> Hi Dan,
>>
>> Thanks for your ideas. In the meantime I was changing the architecture of
>> the view model calling the web service. I let the web service return a json
>> string of al data to be returned and populate the datatables in the view
>> model by reconstructing view models based on this json string contained in
>> the view model memento.
>>
>> The web service will now only be called by the action asking for web
>> service parameters.
>>
>> Erik
>>
>>>
>>> On 1 April 2015 at 11:33, Erik de Hair <e....@pocos.nl> wrote:
>>>
>>> On 03/27/2015 12:26 PM, Dan Haywood wrote:
>>>>
>>>> Hi Erik,
>>>>>
>>>>> On 25 March 2015 at 12:42, Erik de Hair <e....@pocos.nl> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>>> I have to call I web service from a view model but, when opening the
>>>>>> view
>>>>>> model, the call to the web service is called twice. It doesn't matter
>>>>>> if
>>>>>> the call is in de viewmodelinit or in some other method. May be
>>>>>> there's
>>>>>> some way to track the state of the view model and let whether or not
>>>>>> the
>>>>>> call is executed depend on that?
>>>>>>
>>>>>> My guess is that you are seeing the view model called twice because
>>>>>> we
>>>>>>
>>>>> use
>>>>> (Wicket's support for) the redirect-after-post pattern.
>>>>>
>>>>> That is, when the action is invoked you are instantiating the view
>>>>> model
>>>>> (which calls the webservice), and then we return a 302 redirect to the
>>>>> browser so that it then re-requests the same URL, causing the view
>>>>> model
>>>>> to
>>>>> be recreated (and that webservice called).
>>>>>
>>>>> Perhaps you could confirm if that's what's happening?
>>>>>
>>>>> The following is happening...
>>>>
>>>> In the initial state the view model is rendered and the data that is
>>>> needed to call the web service is already available from the view model
>>>> memento. (This means that when refreshing the page the web service will
>>>> be
>>>> called again. This is not much of a problem.)
>>>>
>>>> Now, when clicking** the action button that opens the action for
>>>> re-entering the web service parameters, a request for the view model is
>>>> done:
>>>>
>>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:04:09 +0200] "GET
>>>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>>>>
>>>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>>>>
>>>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>>>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.0-theme-entity-entity~0-
>>>> entityPropertiesAndCollections-entityProperties-leftColumn-
>>>> memberGroup-1-properties-4-property-scalarIfRegular-additionalLinks-
>>>> additionalLinkList-additionalLinkItem-0-additionalLink&_=1427882228283
>>>> HTTP/1.1" 200 12838 http-bio-8081-exec-4 2303
>>>>
>>>> This way the web service is called again because the previous web
>>>> service
>>>> parameters are still available from the view model memento.
>>>>
>>>> After submitting the following requests are handled:
>>>>
>>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:17 +0200] "POST
>>>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>>>>
>>>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>>>>
>>>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>>>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.1-theme-
>>>> actionPromptModalWindow-content-parameters-inputForm-okButton HTTP/1.1"
>>>> 200 91 http-bio-8081-exec-6 169
>>>>
>>>> (web service called two times during this request)
>>>>
>>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:19 +0200] "GET
>>>> /portal/wicket/wicket/page?7 HTTP/1.1" 200 167629 http-bio-8081-exec-6
>>>> 2582
>>>>
>>>> (web service called once during this request)
>>>>
>>>> If it is, then one option might be to defer the fetching of the data
>>>>> until
>>>>> as late as possible, ie when it needs to be constructed.
>>>>>
>>>>> I tried this but the method that exposes the data to the gui will
>>>> always
>>>> call the method that fetches the data when constructing the view model.
>>>> So
>>>> no matter how late the data will be fetched, it will always be fetched.
>>>>
>>>> Another option might be to have the view model use the HttpSession (via
>>>>> isis-module-servletapi addon) to keep track of state.
>>>>>
>>>>> I'm still using Isis 1.7.0 and Eclipse complains about the module
>>>> missing
>>>> some dependency. It does work however and I can prevent the web service
>>>> from being called by checking for a request method of GET during the
>>>> POST-request but there are still 3 calls left.
>>>>
>>>> I didn't use the session object yet. Will try that.
>>>>
>>>>
>>>> HTH
>>>>> Dan
>>>>>
>>>>>
>>>>>
>>>>> The web service is fetching data, triggered by an action in the view
>>>>>
>>>>>> model, for the same view model. Do I always have to return a new view
>>>>>> model
>>>>>> with the fetched data in it or can I use the data from the fetch
>>>>>> method
>>>>>> and
>>>>>> return the same view model?
>>>>>>
>>>>>> Thanks,
>>>>>> Erik
>>>>>>
>>>>>>
>>>>>>
>>
>
Re: calling webservice only once from viewmodel
Posted by Erik de Hair <e....@pocos.nl>.
On 04/03/2015 09:03 AM, Erik de Hair wrote:
>
>>
>> Then the question is how to hold that server-side state. An HTTP
>> Session
>> object is one option; the other is to store the data in the
>> database. That
>> basically means converting the view model into an entity (analogous to a
>> shopping cart entity); you could have some mechanism to clean up such
>> session entities after a day or two.
My architecture didn't work correctly. I tried to put the data in the
memento as json-object but this way the memento got to big, and this
gives persisting problems for the auditing/publishing services. Right
now I'm putting the same data in the HTTP session and this works as it
should be.
Thanks for your help,
Erik
>>
>> Hope that helps provide some ideas...
>>
>> Cheers
>> Dan
>>
> Hi Dan,
>
> Thanks for your ideas. In the meantime I was changing the architecture
> of the view model calling the web service. I let the web service
> return a json string of al data to be returned and populate the
> datatables in the view model by reconstructing view models based on
> this json string contained in the view model memento.
>
> The web service will now only be called by the action asking for web
> service parameters.
>
> Erik
>>
>> On 1 April 2015 at 11:33, Erik de Hair <e....@pocos.nl> wrote:
>>
>>> On 03/27/2015 12:26 PM, Dan Haywood wrote:
>>>
>>>> Hi Erik,
>>>>
>>>> On 25 March 2015 at 12:42, Erik de Hair <e....@pocos.nl> wrote:
>>>>
>>>> Hi,
>>>>> I have to call I web service from a view model but, when opening
>>>>> the view
>>>>> model, the call to the web service is called twice. It doesn't
>>>>> matter if
>>>>> the call is in de viewmodelinit or in some other method. May be
>>>>> there's
>>>>> some way to track the state of the view model and let whether or
>>>>> not the
>>>>> call is executed depend on that?
>>>>>
>>>>> My guess is that you are seeing the view model called twice
>>>>> because we
>>>> use
>>>> (Wicket's support for) the redirect-after-post pattern.
>>>>
>>>> That is, when the action is invoked you are instantiating the view
>>>> model
>>>> (which calls the webservice), and then we return a 302 redirect to the
>>>> browser so that it then re-requests the same URL, causing the view
>>>> model
>>>> to
>>>> be recreated (and that webservice called).
>>>>
>>>> Perhaps you could confirm if that's what's happening?
>>>>
>>> The following is happening...
>>>
>>> In the initial state the view model is rendered and the data that is
>>> needed to call the web service is already available from the view model
>>> memento. (This means that when refreshing the page the web service
>>> will be
>>> called again. This is not much of a problem.)
>>>
>>> Now, when clicking** the action button that opens the action for
>>> re-entering the web service parameters, a request for the view model is
>>> done:
>>>
>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:04:09 +0200] "GET
>>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>>>
>>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>>>
>>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.0-theme-entity-entity~0-
>>> entityPropertiesAndCollections-entityProperties-leftColumn-
>>> memberGroup-1-properties-4-property-scalarIfRegular-additionalLinks-
>>> additionalLinkList-additionalLinkItem-0-additionalLink&_=1427882228283
>>> HTTP/1.1" 200 12838 http-bio-8081-exec-4 2303
>>>
>>> This way the web service is called again because the previous web
>>> service
>>> parameters are still available from the view model memento.
>>>
>>> After submitting the following requests are handled:
>>>
>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:17 +0200] "POST
>>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>>>
>>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>>>
>>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.1-theme-
>>> actionPromptModalWindow-content-parameters-inputForm-okButton HTTP/1.1"
>>> 200 91 http-bio-8081-exec-6 169
>>>
>>> (web service called two times during this request)
>>>
>>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:19 +0200] "GET
>>> /portal/wicket/wicket/page?7 HTTP/1.1" 200 167629
>>> http-bio-8081-exec-6 2582
>>>
>>> (web service called once during this request)
>>>
>>>> If it is, then one option might be to defer the fetching of the
>>>> data until
>>>> as late as possible, ie when it needs to be constructed.
>>>>
>>> I tried this but the method that exposes the data to the gui will
>>> always
>>> call the method that fetches the data when constructing the view
>>> model. So
>>> no matter how late the data will be fetched, it will always be fetched.
>>>
>>>> Another option might be to have the view model use the HttpSession
>>>> (via
>>>> isis-module-servletapi addon) to keep track of state.
>>>>
>>> I'm still using Isis 1.7.0 and Eclipse complains about the module
>>> missing
>>> some dependency. It does work however and I can prevent the web service
>>> from being called by checking for a request method of GET during the
>>> POST-request but there are still 3 calls left.
>>>
>>> I didn't use the session object yet. Will try that.
>>>
>>>
>>>> HTH
>>>> Dan
>>>>
>>>>
>>>>
>>>> The web service is fetching data, triggered by an action in the view
>>>>> model, for the same view model. Do I always have to return a new view
>>>>> model
>>>>> with the fetched data in it or can I use the data from the fetch
>>>>> method
>>>>> and
>>>>> return the same view model?
>>>>>
>>>>> Thanks,
>>>>> Erik
>>>>>
>>>>>
>
Re: calling webservice only once from viewmodel
Posted by Erik de Hair <e....@pocos.nl>.
> Hi Erik,
>
> OK, well, as you know, any time the view model is interacted with it, Isis
> basically reconstructs the view model; it is completely stateless
> architecture and the view model's state is basically the information in its
> OID (=URL).
>
> I think for your use case it might be worth introducing some sort of
> server-side state, so that the view model's OID is basically a key to that
> server-side state (a UUID would suffice).
>
> Then the question is how to hold that server-side state. An HTTP Session
> object is one option; the other is to store the data in the database. That
> basically means converting the view model into an entity (analogous to a
> shopping cart entity); you could have some mechanism to clean up such
> session entities after a day or two.
>
> Hope that helps provide some ideas...
>
> Cheers
> Dan
>
Hi Dan,
Thanks for your ideas. In the meantime I was changing the architecture
of the view model calling the web service. I let the web service return
a json string of al data to be returned and populate the datatables in
the view model by reconstructing view models based on this json string
contained in the view model memento.
The web service will now only be called by the action asking for web
service parameters.
Erik
>
> On 1 April 2015 at 11:33, Erik de Hair <e....@pocos.nl> wrote:
>
>> On 03/27/2015 12:26 PM, Dan Haywood wrote:
>>
>>> Hi Erik,
>>>
>>> On 25 March 2015 at 12:42, Erik de Hair <e....@pocos.nl> wrote:
>>>
>>> Hi,
>>>> I have to call I web service from a view model but, when opening the view
>>>> model, the call to the web service is called twice. It doesn't matter if
>>>> the call is in de viewmodelinit or in some other method. May be there's
>>>> some way to track the state of the view model and let whether or not the
>>>> call is executed depend on that?
>>>>
>>>> My guess is that you are seeing the view model called twice because we
>>> use
>>> (Wicket's support for) the redirect-after-post pattern.
>>>
>>> That is, when the action is invoked you are instantiating the view model
>>> (which calls the webservice), and then we return a 302 redirect to the
>>> browser so that it then re-requests the same URL, causing the view model
>>> to
>>> be recreated (and that webservice called).
>>>
>>> Perhaps you could confirm if that's what's happening?
>>>
>> The following is happening...
>>
>> In the initial state the view model is rendered and the data that is
>> needed to call the web service is already available from the view model
>> memento. (This means that when refreshing the page the web service will be
>> called again. This is not much of a problem.)
>>
>> Now, when clicking** the action button that opens the action for
>> re-entering the web service parameters, a request for the view model is
>> done:
>>
>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:04:09 +0200] "GET
>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.0-theme-entity-entity~0-
>> entityPropertiesAndCollections-entityProperties-leftColumn-
>> memberGroup-1-properties-4-property-scalarIfRegular-additionalLinks-
>> additionalLinkList-additionalLinkItem-0-additionalLink&_=1427882228283
>> HTTP/1.1" 200 12838 http-bio-8081-exec-4 2303
>>
>> This way the web service is called again because the previous web service
>> parameters are still available from the view model memento.
>>
>> After submitting the following requests are handled:
>>
>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:17 +0200] "POST
>> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
>> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
>> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
>> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.1-theme-
>> actionPromptModalWindow-content-parameters-inputForm-okButton HTTP/1.1"
>> 200 91 http-bio-8081-exec-6 169
>>
>> (web service called two times during this request)
>>
>> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:19 +0200] "GET
>> /portal/wicket/wicket/page?7 HTTP/1.1" 200 167629 http-bio-8081-exec-6 2582
>>
>> (web service called once during this request)
>>
>>> If it is, then one option might be to defer the fetching of the data until
>>> as late as possible, ie when it needs to be constructed.
>>>
>> I tried this but the method that exposes the data to the gui will always
>> call the method that fetches the data when constructing the view model. So
>> no matter how late the data will be fetched, it will always be fetched.
>>
>>> Another option might be to have the view model use the HttpSession (via
>>> isis-module-servletapi addon) to keep track of state.
>>>
>> I'm still using Isis 1.7.0 and Eclipse complains about the module missing
>> some dependency. It does work however and I can prevent the web service
>> from being called by checking for a request method of GET during the
>> POST-request but there are still 3 calls left.
>>
>> I didn't use the session object yet. Will try that.
>>
>>
>>> HTH
>>> Dan
>>>
>>>
>>>
>>> The web service is fetching data, triggered by an action in the view
>>>> model, for the same view model. Do I always have to return a new view
>>>> model
>>>> with the fetched data in it or can I use the data from the fetch method
>>>> and
>>>> return the same view model?
>>>>
>>>> Thanks,
>>>> Erik
>>>>
>>>>
Re: calling webservice only once from viewmodel
Posted by Dan Haywood <da...@haywood-associates.co.uk>.
Hi Erik,
OK, well, as you know, any time the view model is interacted with it, Isis
basically reconstructs the view model; it is completely stateless
architecture and the view model's state is basically the information in its
OID (=URL).
I think for your use case it might be worth introducing some sort of
server-side state, so that the view model's OID is basically a key to that
server-side state (a UUID would suffice).
Then the question is how to hold that server-side state. An HTTP Session
object is one option; the other is to store the data in the database. That
basically means converting the view model into an entity (analogous to a
shopping cart entity); you could have some mechanism to clean up such
session entities after a day or two.
Hope that helps provide some ideas...
Cheers
Dan
On 1 April 2015 at 11:33, Erik de Hair <e....@pocos.nl> wrote:
>
> On 03/27/2015 12:26 PM, Dan Haywood wrote:
>
>> Hi Erik,
>>
>> On 25 March 2015 at 12:42, Erik de Hair <e....@pocos.nl> wrote:
>>
>> Hi,
>>>
>>> I have to call I web service from a view model but, when opening the view
>>> model, the call to the web service is called twice. It doesn't matter if
>>> the call is in de viewmodelinit or in some other method. May be there's
>>> some way to track the state of the view model and let whether or not the
>>> call is executed depend on that?
>>>
>>> My guess is that you are seeing the view model called twice because we
>> use
>> (Wicket's support for) the redirect-after-post pattern.
>>
>> That is, when the action is invoked you are instantiating the view model
>> (which calls the webservice), and then we return a 302 redirect to the
>> browser so that it then re-requests the same URL, causing the view model
>> to
>> be recreated (and that webservice called).
>>
>> Perhaps you could confirm if that's what's happening?
>>
> The following is happening...
>
> In the initial state the view model is rendered and the data that is
> needed to call the web service is already available from the view model
> memento. (This means that when refreshing the page the web service will be
> called again. This is not much of a problem.)
>
> Now, when clicking** the action button that opens the action for
> re-entering the web service parameters, a request for the view model is
> done:
>
> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:04:09 +0200] "GET
> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.0-theme-entity-entity~0-
> entityPropertiesAndCollections-entityProperties-leftColumn-
> memberGroup-1-properties-4-property-scalarIfRegular-additionalLinks-
> additionalLinkList-additionalLinkItem-0-additionalLink&_=1427882228283
> HTTP/1.1" 200 12838 http-bio-8081-exec-4 2303
>
> This way the web service is called again because the previous web service
> parameters are still available from the view model memento.
>
> After submitting the following requests are handled:
>
> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:17 +0200] "POST
> /portal/wicket/entity/*nl.pocos.dom.access.availability.PostalCodeCheck:
> PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPG1lbWVudG8-PGpzb24-
> eyJwb3N0YWxDb2RlIjoiNTYxNEFFIiwiaG91c2VOdW1iZXIiOiIxNTIifTwv
> anNvbj48L21lbWVudG8-?6-1.IBehaviorListener.1-theme-
> actionPromptModalWindow-content-parameters-inputForm-okButton HTTP/1.1"
> 200 91 http-bio-8081-exec-6 169
>
> (web service called two times during this request)
>
> 0:0:0:0:0:0:0:1 - - [01/Apr/2015:12:06:19 +0200] "GET
> /portal/wicket/wicket/page?7 HTTP/1.1" 200 167629 http-bio-8081-exec-6 2582
>
> (web service called once during this request)
>
>>
>> If it is, then one option might be to defer the fetching of the data until
>> as late as possible, ie when it needs to be constructed.
>>
> I tried this but the method that exposes the data to the gui will always
> call the method that fetches the data when constructing the view model. So
> no matter how late the data will be fetched, it will always be fetched.
>
>>
>> Another option might be to have the view model use the HttpSession (via
>> isis-module-servletapi addon) to keep track of state.
>>
> I'm still using Isis 1.7.0 and Eclipse complains about the module missing
> some dependency. It does work however and I can prevent the web service
> from being called by checking for a request method of GET during the
> POST-request but there are still 3 calls left.
>
> I didn't use the session object yet. Will try that.
>
>
>> HTH
>> Dan
>>
>>
>>
>> The web service is fetching data, triggered by an action in the view
>>> model, for the same view model. Do I always have to return a new view
>>> model
>>> with the fetched data in it or can I use the data from the fetch method
>>> and
>>> return the same view model?
>>>
>>> Thanks,
>>> Erik
>>>
>>>
>