Last week, I implemented a basic visual Karajan workflow composition interface which eases wokflow composition. This is the related post:
http://zhenhua-guo.blogspot.com/2007/12/karajan-workflow-composition.html.
This week, I fixed several bugs and made some improvements on top of it.
(1) The configuration of Karajan workflow is stored in a javascript object like this:
{
elements: {},
namespaces: {
kernel:{
elements:{
import:{
properties: [],
widgetProps: {}
}
},
namespaces:{
}
},
sys: {
namespaces: { },
elements: {
execute: {
properties: ["executable", "host", "stdout", "provider", "redirect"],
widgetProps: {height:"40px, width:"40px"}
},
echo: {
properties: ["message", "nl"],
widgetProps: {}
}
}
}
}
}
Note the element of which color is blue. Name of that Karajan element is "import" which is also a keyword of Javascript. As a result, the object above is not legal javascript object!!! So more work is needed here. To work around this problem and make the architecture more scalable, I add one more layer between the configuration object above and the code that uses it.
I construct an element tree called KarajanElementTree of which nodes are KarajanNSNode or KarajanElementNode. KarajanNSNode corresponds to a namespace in Karajan and KarajanElementNode corresponds to an usable element in Karajan. In other words, given a workflow configuration, I build a tree based on it. The tree has a set of fixed interface which can be used by programmers to access the information of various workflow elements. When underlying workflow configuration is modified, I just need to change implementation of the tree with interface staying the same. In other words, workflow configuration and use of the workflow are completely separated so that change of one part does not require change of the other part.
Concretely speaking:
(*) underlying workflow configuration
For those elements of which names are keywords of Javascript, I append a '_' to the element name and add a new property called "truename" to record the real name. Some people may argue that the real name can be obtained by removing the '_' character from the end of the name. Yes, that is right. However, considering the future expansion, my choice is better. For example, maybe one day "import_" becomes a keyword of javascript as well or '_' charater can not be contained in name of a property. Then we need to modify the code which handles the extraction of the real name from the element name.
{
elements: {},
namespaces: {
kernel:{
elements:{
import_:{
truename: "import",
properties: [],
widgetProps: {}
}
},
namespaces:{
}
},
sys: {
namespaces: { },
elements: {
execute: {
properties: ["executable", "host", "stdout", "provider", "redirect"],
widgetProps: {height:"40px, width:"40px"}
},
echo: {
properties: ["message", "nl"],
widgetProps: {}
}
}
}
}
}
(**) Intermediate Element Tree
KarajanElementNode:
[ properties ]:
name: name of the element, this is the name used to retrieve the object corresponding to that name in Javascript;
truename: real Karajan name of the element.
properties: properties of the Karajan elements;
widgetProps: properties of the corresponding widget
KarajanNSNode:
[ properties ]:
name: same as above;
truename: same as above;
elements: contains all elements in this namepace;
namespaces: contains all sub namespaces in this namespace.
KarajanElementTree:
[ properties ]:
root: root of the tree. Typically, type of the root is KarajanNSNode.
(***) Upper layer that uses the Karajan workflow
var workflowele = getEle( KarajanElementTree, elementname );
var realname = workflowele.truename;
Now, to get the information of a Karajan element, we don't need to know the underlying mechanism. For example, name of the element can be gotten by accessing property "truename".
(2) Empty namespace and element list elimination
In previous implementation, a new accordion panel is created for every namespace and element list no matter whether they are empty. As a result, the widget toolbox looks jumbly.
Now, I improve it. When a namespace is empty or an element list is empty, don't create an accordion panel for it at all.
(3)Add Pop-Up Window to display element description
In Karajan, there are hundreds of elements. Besides that, users can define their own customized elements. It is hard for a user to remember usage of so many elements. Sometimes, a user has used a certain element, but he/she cannot remember the usage of the element. At this time, a simple suggestive message is enough.
So, I add a new property "description" to every element which describes the usage and functionality of that element. When user moves cursor over a widget, the corresponding description is displayed in a pop-up message window. When user moves cursor out, the window disappears.
Screenshot:
(4) Better Support in Element insertion
In previous implementation, a Karajan element can just be inserted into current caret position. It is possible that user wants selected text to be enclosed by a certain element.
For example, we have workflow like this:
<project>
<transfer srchost="aaa.com" srcfile="file1" desthost="localhost" destfile="file1"/>
<transfer srchost="bbb.com" srcfile="file2" desthost="localhost" destfile="file1"/>
<transfer srchost="ccc.com" srcfile="file3" desthost="localhost" destfile="file1"/>
</project>
The three transfer jobs are independent of each other. We would like to let them executed in parallel. Karajan element "parallel" can be used now. If we just support insertion of elements into current caret position, the user needs to first insert element "parallel" somewhere, and then copies "</parallel>" and paste it after the last transfer job. What is better is that user can select the jobs that want to be executed in parallel and element "parallel" will enclose the selected jobs during insertion.
Now, I have implemented this functionality. However, it sometimes does not work well in IE....
(5)
Add more Karajan elements into the configuration object Karajan workflow contains so many built-in elements so that it is not practical to add all the elements into the javascript configuration object at a time. I decide to gradually add them to the object. Now, I have added many, but still many left...
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