Question: Merge Links

[sbna]

Hi,

I am wondering if it is possible in your library to merge two outputs coming from two different tasks in a single output port (aka Merge datalinks in taverna)?

Thanks.

Simone

[jongiddy]

Merging outputs does not work currently. I had planned to support it by allowing multiple inputs to the same named port to automatically create a merge task, but I had no need for it myself, so it was low priority.

One way to merge now is to create a BeanShell with two (or more) inputs that concatenates them together into a single output port. This also gives you more control over how the ports are merged.

[sbna]

I have solved by changing the t2flow/exportSinkXML function:

def exportSinkXML(self, xml):
    with xml.namespace("http://taverna.sf.net/2008/xml/t2flow") as tav:
        is_linked = False
        link_type = "dataflow"
        for dataLink in self.flow.dataLinks:
            if(dataLink.sink.name == self.name):
                if(is_linked==True):
                    link_type = "merge"
                    break
                is_linked = True
        with tav.sink(type=link_type):
            tav.port >> self.name

and concatenates two task outputs into a single workflow output port:

data_left_stderr = tasks[myinstance.content].output['STDERR']
data_right_stderr = flow.output['Log']
data_left_stderr | data_right_stderr
data_left_stdout = tasks[myinstance.content].output['STDOUT']
data_right_stdout = flow.output['Log']
data_left_stdout | data_right_stdout