Forum OpenACS Development: Using the function "ad_set_client_property".

I have the following problem/doubt:

In order to avoid long URL's (and to make compatible the application with IE), I'm trying to use for some specially big variables the functions "ad_set_client_property"/"ad_get_client_property" instead of "export_vars".

The problem is that if I set with "ad_set_client_property" a lot of session variables, the values of some of these are lost.

The question are:

1) Is the problem above related with the util_memoize's size cache (and solved through the kernel parameter Caching/MaxSize)?

2) As I'm newbie and in special with the cache topics, I was trying to read something about it, and I found the following forum's entry: https://openacs.org/forums/message-view?message_id=1163553 . There, there is a phrase of Don that attracted my attention: "Long-term, I'd get rid of util_memoize entirely".
Under the light of this prhase, is some advice to come when it is wanted to pass variables of big size between pages?

Thanks a lot for the help.

Jorge.

I have a chain of 12 form's, each one receiving values from the precedent one, and I'm not using the wizard. Some of the variables are huge because are observations from the user (that can have any length).
Between each chain's step I'm using something as the following:

*********************************

-on_submit {

set newpage "add_neuron?[export_vars -override {{return_url $current}} { var1,...varn return_url }]"

ad_returnredirect $newpage

ad_script_abort
}

*********************************

At the final step I have a huge URL that works fine with Mozilla but not with IE.

Thanks a lot!

Jorge.

As consequence I am trying to implement the advice from the forum's entry, but I have the problem previously mentioned (some values are lost).

Thanks a lot!

Jorge.

Indeed, I am already using the data base 😊

Thanks to you and Dave for the help!

Jorge.

Seems to me that client properties should have their own cache, not the util_memoize cache, which is bounded on time but not on size. Does ns_cache support that style of use? (Or, perhaps keep the space bound, but make sure it's very large, and separate from whatever cache util_memoize uses?) You want non-persistent client properties to expire after a time, but while they're active you don't want AOLserver to throw them out just because they're large, right? Thoughts?

I'm not clear though, what happens if non-persistent client properties are evicted from the cache? Or if the AOLserver restarts, for that matter? What will the Tcl code and end user see?

In order to guarantee the permanence of the data I'm using the database. I have created the following table:

------ *******************************************
------ *******************************************
------ start SESSION_VARIABLES
------ *******************************************
------ *******************************************

-- start table SESSION_VARIABLES

CREATE TABLE session_variables (
session_id integer,
module_id varchar,
var_name varchar,
var_value varchar CONSTRAINT session_variables_var_value_nn
NOT NULL,
CONSTRAINT session_variables_pk
PRIMARY KEY(session_id, module_id, var_name)
);

COMMENT ON TABLE session_variables IS '
The table holds session variables. The programmer is in charge to delete the variables rows, if not the data is holded permanently.
';

COMMENT ON COLUMN session_variables.session_id IS '
The session ID of the user (obtained with the command [ad_conn session_id]).
';

COMMENT ON COLUMN session_variables.module_id IS '
The package key plus the package id ( "package_key_[ad_conn package_id]").
';

-- end table SESSION_VARIABLES

------ *******************************************
------ *******************************************
------ end SESSION_VARIABLES
------ *******************************************
------ *******************************************

I don't know if there is a better model, but this one is working fine to me.

Regards,

Jorge.

Indeed, the problem would seem to happen when the cache is full (at least it is solved when I have increased the kernel parameter MaxSize).

"But you should always be able to get it back out of the database": this means that I must explicitly query he table sec_session_properties (in order to avoid the error -lost values- that I get using ad_get_client_property)?

Thanks a lot for your help!

Jorge.