download inform / progress

[landam]

Inform user about download data.

Option 1: "Downloading output data, please wait ..."

Option 2: "Downloading data 5%..."

[jachym]

At the moment, the files are downloaded with help of OWLib, which has not so nice implementation of file download:

1. It loads content of the response to the memory (could potentially crash the client machine)
2. it downloads the data not in chunks, but in one request

Suggestion:

Rewrite OWSLib, https://github.com/geopython/OWSLib/blob/51df57989877670b7a19f633f04a4b8cf774d9f1/owslib/wps.py#L1483 so it uses something like

        # write out content
                if content is not None:
                    if self.fileName == "":
                        self.fileName = self.identifier
                    self.filePath = path + self.fileName
                    with open(self.filePath, 'wb') as out:
                         data = content.read(8192)
                         while data:
                                  out.write(data)
                                  data = content.read(8192)

and using something like

def write_file():
    chunk = 0
    with open("output.bin", "wb") as out:
        with open("/dev/random", "rb") as inpt:
            data = inpt.read(1024)
            while data and chunk <= 10:
                out.write(data)
                data = inpt.read(1024)
                chunk += 1
                yield chunk

for i in write_file():
    print(i)

construction - yield generator output could be then passed to the progressbar dialog

Same applies for https://github.com/geopython/OWSLib/blob/51df57989877670b7a19f633f04a4b8cf774d9f1/owslib/wps.py#L902

[jachym]

done in the 18_progress branch

But you have to use https://github.com/jachym/owslib/tree/782_wps_download branch

[landam]

@jachym Tested on http://lincalc-02.fsv.cvut.cz/services/wps

start: 01/01/2018
end 10/01/2018

No data downloaded, process finished on server. Client frozen.

[landam]

Service for testing: http://157.90.183.85:8080/services/wps

[landam]

Result of testing: no download progress show

[landam]

See related PR: geopython/OWSLib#784