Hi Sebastian et al, yesterday I dived for the first time into ezcWorkflow to check whether I can use it for a new project. We need to crawl a large abount of web sites and define data extraction "workflows" for different types of sites. These workflows consist of filters that are applied on the original html source. Filters can be chained and the output of one filter can be the input of n filters, which leads to a directed acyclic graph. So my problem seems to be in the domain of graph oriented programming and ezcWorkflow has many characteristics I need. Still it does not fit due to four problems. Some of these problems may transform in feature requests:
1. There are no means to pipe data from one node to the next. This is the major problem, which I don't think will be addressed, because it's not the scope of an activity based workflow engine like ezcWorkflow. 2. Exceptions are not supported. If the data extraction process fails, I need to stop the workflow execution, but still needs to preserve the current state for later debugging. I'd like to simply throw a PHP exception from my custom workflow nodes. In such case the execution engine should freeze the execution and NOT delete the workflow from the database. 3. The state of executed nodes is not persisted after execution left the node, but we want to know the state of all nodes in case of errors. This may be a feature request: Have a flag to preserve the state of already executed nodes until the whole workflow has successfully been executed. 4. There is no predefined way to model the fact, that certain nodes require certain types of input. This is a problem for my use case, but does not fit into ezcWorkflow I think. Best regards, -- Thomas Koch, Software Developer http://www.koch.ro Young Media Concepts GmbH Sonnenstr. 4 CH-8280 Kreuzlingen Switzerland Tel +41 (0)71 / 508 24 86 Fax +41 (0)71 / 560 53 89 Mobile +49 (0)170 / 753 89 16 Web www.ymc.ch -- Components mailing list Components@lists.ez.no http://lists.ez.no/mailman/listinfo/components
