The
PmaPanel object can offer its image in the Web browser (
Chrome,
Firefox,
Edge,
InternetExplorer ...) in the form of
dynamic HTML pages. These dynamic pages are
created automatically in the development environment and they are stored in the
Application.pra file.
So as the
PmaPanel object would offer its image to Web server, it is necessary to:
- and to fill in all other configurators on this tab correctly.
The client requiring data from this Web component is of the
PmWebClient type from the licence point of view.
Since version
Pm9.0.0 all Web panels in PROMOTIC are designed only for Web browsers supporting standard
HTML5 technology. It means for
Chrome,
Firefox,
Edge,
Opera,
Safari etc. The
InternetExplorer is supported only since version 11.
Since the version
Pm8.2.0 the HTML pages generated by the system were transformed to standard
HTML5 technologies so these can be displayed in alternative browsers (
Chrome,
Firefox,
Edge,
InternetExplorer ...) including their mobile versions.
Up to the PROMOTIC version
Pm8.2 the HTML pages generated by the system were designed only for
InternetExplorer.
Web panels basic principle:
-
Pmg objects are compiled into dynamic HTML pages (using so-called
Alax technology).
- If the client is opening panel, then the compiled dynamic HTML page is loaded from server (i.e. from the PROMOTIC application). Panel refreshing (see the "
Refresh period of the Web panel [s]" configurator) is called automatically and is based on periodically loading XML panel data, which are much smaller then the whole HTML page. For example if the panel is connected by data binding to 10 variables, then only 10 current values are periodically transferred. The server load is therefore minimal.
- The
scripts in events of
Pmg objects
are running on the client side (i.e. in the Web browser). Some restrictions are based on this fact and these are described below.
The main restriction is that it is unable to access directly in the script to other objects in the
Pma object tree, for example access for values in the
PmaData object (this limitation is valid for scripts - not for example in the "
PP - Pma object property" data binding - it can use references to other objects).
This limitation can be solved, by calling for example the panel method (i.e. in the event of the
Pmg object)
pMe.
PmPanel.
Methods.XXX(a,b,..). This calling the
"XXX" method makes the client send XML command to server and so the method is called on the server. In this panel method the script can be present, accessing other objects in the
Pma object tree. For additional info see more.
Limitations:
Here is a list of limitations that are put on panels that have to be offered to Web server in the form of a dynamic HTML page.
-
Limitations for writing of algorithm (scripts):
-
It is not possible to use the reference to other Pma objects in the
Pma object tree (e.g. to use
pMe.
Pm("/data/xy")). If writing to other object in the
Web panel is needed it, then is possible to do so:
-
The global Pm object: Many methods are functional on the Web but some are not. The description of each method of this object provides the information of Web functionality.
-
Limitations for Pmg objects::
-
PmgWCombo:
The "
Sort" configurator is not relevant.
The "
Type" configurator with
"Selection and edit" setting is not functional for the Web so far.
-
PmgActiveX:
This object is not functional on the Web because all modern Web browsers no longer support
ActiveX technology due to security reasons.
-
PmgMeterBox:
This object is obsolete and is not functional on the Web.
-
Limitations for calling the designer method of the PmaPanel object:
See
Designer methods in the PmaPanel object.
Called methods can have parameters and an output value (
pResult) only:
- simple data types (e.g. Integer, String, etc.)
- 1-dimensional array defined e.g.
Dim arr(20)- 2-dimensional array defined e.g.
Dim arr(10,20)- there must not be other arrays in the array items
Notes and directions:
Another algorithm for local panel and for Web panel:
A panel (created in the
PmaPanel object) can be opened directly in runtime of the application (local panel) or in the Web browser (Web panel). If in such panel calling an algorithm is needed (for example after pressing the button), which has to do something different in local panel than in the
Web panel, then it is recommended to use
the PmgRoot.ClientType property. The value of this property specifies whether the panel is opened in the application or in the Web browser. Examples see description of the
ClientType property.
Panel reentrancy:
When developing a Web panel, it is necessary to understand, that, multiple clients can see it simultaneously. So it is a bad idea for example to create one panel (one
PmaPanel object) able to display multiple devices according to a variable set in the application. In such case the clients would be rewriting this global variable mutually and see incorrect values as a consequence. If one panel displaying various data is needed, then the best way to do so, is:
Changing the initial panel after a new user logs in