Hi Max, thanks for your feedback. I guess you confuse the interfaces "Program" and "ProgramDescription". Using "Program" the use of main method is replaced by "getPlan(...)". However, "ProgramDescription" only adds method "getDescription()" which returns a string that explains the usage of the program (ie, short description, expected parameters).
Thus, adding "ProgramDescription" to the examples, does not change the
examples -- main method will still be uses. It only adds the ability
that a program "explains" itself (ie, give meta info). Furhtermore,
"ProgramDescription" is also not related to the new "ParameterTool".
-Matthias
On 05/26/2015 11:46 AM, Maximilian Michels wrote:
> I don't think `getDisplayName()` is necessary either. The class name and
> the description string should be fine. Adding ProgramDescription to the
> examples is not necessary; as already pointed out, using the main method is
> more convenient for most users. As far as I know, the idea of the
> ParameterTool was to use it only in the user code and not automatically
> handle parameters.
>
> Changing the interface would be quite API breaking but since most programs
> use the main method, IMHO we could do it.
>
> On Fri, May 22, 2015 at 10:09 PM, Matthias J. Sax <
> mj...@informatik.hu-berlin.de> wrote:
>
>> Makes sense to me. :)
>>
>> One more thing: What about extending the "ProgramDescription" interface
>> to have multiple methods as Flavio suggested (with the config(...)
>> method that should be handle by the ParameterTool)
>>
>>> public interface FlinkJob {
>>>
>>> /** The name to display in the job submission UI or shell */
>>> //e.g. "My Flink HelloWorld"
>>> String getDisplayName();
>>> //e.g. "This program does this and that etc.."
>>> String getDescription();
>>> //e.g. <0,Integer,"An integer representing my first param">,
>> <1,String,"An string representing my second param">
>>> List<Tuple3<Integer, TypeInfo, String>> paramDescription;
>>> /** Set up the flink job in the passed ExecutionEnvironment */
>>> ExecutionEnvironment config(ExecutionEnvironment env);
>>> }
>>
>> Right now, the interface is used only a couple of times in Flink's code
>> base, so it would not be a problem to update those classes. However, it
>> could break external code that uses the interface already (even if I
>> doubt that the interface is well known and used often [or at all]).
>>
>> I personally don't think, that "getDiplayName()" to too helpful.
>> Splitting the program description and the parameter description seems to
>> be useful. For example, if wrong parameters are provided, the parameter
>> description can be included in the error message. If program+parameter
>> description is given in a single string, this is not possible. But this
>> is only a minor issue of course.
>>
>> Maybe, we should also add the interface to the current Flink examples,
>> to make people more aware of it. Is there any documentation on the web
>> site.
>>
>>
>> -Matthias
>>
>>
>>
>> On 05/22/2015 09:43 PM, Robert Metzger wrote:
>>> Thank you for working on this.
>>> My responses are inline below:
>>>
>>> (Flavio)
>>>
>>>> My suggestion is to create a specific Flink interface to get also
>>>> description of a job and standardize parameter passing.
>>>
>>>
>>> I've recently merged the ParameterTool which is solving the "standardize
>>> parameter passing" problem (at least it presents a best practice) :
>>>
>> http://ci.apache.org/projects/flink/flink-docs-master/apis/best_practices.html#parsing-command-line-arguments-and-passing-them-around-in-your-flink-application
>>>
>>> Regarding the description: Maybe we can use the "ProgramDescription"
>>> interface for getting a string describing the program in the web
>> frontend.
>>>
>>> (Matthias)
>>>
>>>> I don't want to start working on it, before it's clear that it has a
>>>> chance to be
>>>> included in Flink.
>>>
>>>
>>> I think the changes discussed here won't change the current behavior, but
>>> they add new functionality which
>>> can make the life of our users easier, so I'll vote to include your
>> changes
>>> (given they meet our quality standards)
>>>
>>>
>>> If multiple classes implement "Program" interface an exception should be
>>>> through (I think that would make sense). However, I am not sure was
>>>> "good" behavior is, if a single "Program"-class is found and an
>>>> additional main-method class.
>>>> - should "Program"-class be executed (ie, "overwrite" main-method
>> class)
>>>> - or, better to through an exception ?
>>>
>>>
>>> I would give a class implementing "Program" priority over a random main()
>>> method in a random class.
>>> Maybe printing a WARN log message informing the user that the "Program"
>>> class has been choosen.
>>>
>>>
>>> If no "Program"-class is found, but a single main-method class, Flink
>>>> could execute using main method. But I am not sure either, if this is
>>>> "good" behavior. If multiple main-method classes are present, throwing
>>>> and exception is the only way to got, I guess.
>>>
>>>
>>> I think the best effort approach "one class with main() found" is good.
>> In
>>> case of multiple main methods, a helpful exception is the best approach
>> in
>>> my opinion.
>>>
>>>
>>> If the manifest contains "program-class" or "Main-Class" entry,
>>>> should we check the jar file right away if the specified class is there?
>>>> Right now, no check is performed and an error occurs if the user tries
>>>> to execute the job.
>>>
>>>
>>> I'd say the current approach is sufficient. There is no need to have a
>>> special code path which is doing the check.
>>> I think the error message will be pretty similar in both cases and I fear
>>> that this additional code could also introduce new bugs ;)
>>>
>>>
>>>
>>>
>>> On Fri, May 22, 2015 at 9:06 PM, Matthias J. Sax <
>>> mj...@informatik.hu-berlin.de> wrote:
>>>
>>>> Hi,
>>>>
>>>> two more thoughts to this discussion:
>>>>
>>>> 1) looking at the commit history of "CliFrontend", I found the
>>>> following closed issue and the closing pull request
>>>> * https://issues.apache.org/jira/browse/FLINK-1095
>>>> * https://github.com/apache/flink/pull/238
>>>> It stand in opposite of Flavio's request to have a job description. Any
>>>> comment on this? Should a removed feature be re-introduced? If not, I
>>>> would suggest to remove the "ProgramDescription" interface completely.
>>>>
>>>> 2) If the manifest contains "program-class" or "Main-Class" entry,
>>>> should we check the jar file right away if the specified class is there?
>>>> Right now, no check is performed and an error occurs if the user tries
>>>> to execute the job.
>>>>
>>>>
>>>> -Matthias
>>>>
>>>>
>>>> On 05/22/2015 12:06 PM, Matthias J. Sax wrote:
>>>>> Thanks for your feedback.
>>>>>
>>>>> I agree on the main method "problem". For scanning and listing all
>> stuff
>>>>> that is found it's fine.
>>>>>
>>>>> The tricky question is the automatic invocation mechanism, if "-c" flag
>>>>> is not used, and no manifest program-class or Main-Class entry is
>> found.
>>>>>
>>>>> If multiple classes implement "Program" interface an exception should
>> be
>>>>> through (I think that would make sense). However, I am not sure was
>>>>> "good" behavior is, if a single "Program"-class is found and an
>>>>> additional main-method class.
>>>>> - should "Program"-class be executed (ie, "overwrite" main-method
>>>> class)
>>>>> - or, better to through an exception ?
>>>>>
>>>>> If no "Program"-class is found, but a single main-method class, Flink
>>>>> could execute using main method. But I am not sure either, if this is
>>>>> "good" behavior. If multiple main-method classes are present, throwing
>>>>> and exception is the only way to got, I guess.
>>>>>
>>>>> To sum up: Should Flink consider main-method classes for automatic
>>>>> invocation, or should it be required for main-method classes to either
>>>>> list them in "program-class" or "Main-Class" manifest parameter (to
>>>>> enable them for automatic invocation)?
>>>>>
>>>>>
>>>>> -Matthias
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 05/22/2015 09:56 AM, Maximilian Michels wrote:
>>>>>> Hi Matthias,
>>>>>>
>>>>>> Thank you for taking the time to analyze Flink's invocation behavior.
>> I
>>>>>> like your proposal. I'm not sure whether it is a good idea to scan the
>>>>>> entire JAR for main methods. Sometimes, main methods are added solely
>>>> for
>>>>>> testing purposes and don't really serve any practical use. However, if
>>>>>> you're already going through the JAR to find the ProgramDescription
>>>>>> interface, then you might look for main methods as well. As long as it
>>>> is
>>>>>> just a listing without execution, that should be fine.
>>>>>>
>>>>>> Best regards,
>>>>>> Max
>>>>>>
>>>>>> On Thu, May 21, 2015 at 3:43 PM, Matthias J. Sax <
>>>>>> mj...@informatik.hu-berlin.de> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I had a look into the current Workflow of Flink with regard to the
>>>>>>> progressing steps of a jar file.
>>>>>>>
>>>>>>> If I got it right it works as follows (not sure if this is documented
>>>>>>> somewhere):
>>>>>>>
>>>>>>> 1) check, if "-c" flag is used to set program entry point
>>>>>>> if yes, goto 4
>>>>>>> 2) try to extract "program-class" property from manifest
>>>>>>> (if found goto 4)
>>>>>>> 3) try to extract "Main-Class" property from manifest
>>>>>>> -> if not found through exception (this happens also, if no
>> manifest
>>>>>>> file is found at all)
>>>>>>>
>>>>>>> 4) check if entry point class implements "Program" interface
>>>>>>> if yes, goto 6
>>>>>>> 5) check if entry point class provided "public static void
>>>> main(String[]
>>>>>>> args)" method
>>>>>>> -> if not, through exception
>>>>>>>
>>>>>>> 6) execute program (ie, show plan/info or really run it)
>>>>>>>
>>>>>>>
>>>>>>> I also "discovered" the interface "ProgramDescription" with a single
>>>>>>> method "String getDescription()". Even if some examples implement
>> this
>>>>>>> interface (and use it in the example itself), Flink basically ignores
>>>>>>> it... From the CLI there is no way to get this info, and the WebUI
>> does
>>>>>>> actually get it if present, however, doesn't show it anywhere...
>>>>>>>
>>>>>>>
>>>>>>> I think it would be nice, if we would extend the following functions:
>>>>>>>
>>>>>>> - extend the possibility to specify multiple entry classes in
>>>>>>> "program-class" or "Main-Class" -> in this case, the user needs to
>> use
>>>>>>> "-c" flag to pick program to run every time
>>>>>>>
>>>>>>> - add a CLI option that allows the user to see what entry point
>>>> classes
>>>>>>> are available
>>>>>>> for this, consider
>>>>>>> a) "program-class" entry
>>>>>>> b) "Main-Class" entry
>>>>>>> c) if neither is found, scan jar-file for classes implementing
>>>>>>> "Program" interface
>>>>>>> d) if still not found, scan jar-file for classes with "main"
>>>> method
>>>>>>>
>>>>>>> - if user looks for entry point classes via CLI, check for
>>>>>>> "ProgramDesciption" interface and show info
>>>>>>>
>>>>>>> - extend WebUI to show all available entry-classes (pull request
>>>>>>> already there, for multiple entries in "program-class")
>>>>>>>
>>>>>>> - extend WebUI to show "ProgramDescription" info
>>>>>>>
>>>>>>>
>>>>>>> What do you think? I am not too sure about the "auto scan" of the jar
>>>>>>> file if no manifest entry is provided. We might get some "fat jars"
>> and
>>>>>>> scanning might take some time.
>>>>>>>
>>>>>>>
>>>>>>> -Matthias
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 05/19/2015 10:44 AM, Stephan Ewen wrote:
>>>>>>>> We actually has an interface like that before ("Program"). It is
>> still
>>>>>>>> supported, but in all new programs we simply use the Java main
>> method.
>>>>>>> The
>>>>>>>> advantage is that
>>>>>>>> most IDEs can create executable JARs automatically, setting the JAR
>>>>>>>> manifest attributes, etc.
>>>>>>>>
>>>>>>>> The "Program" interface still works, though. Most tool classes (like
>>>>>>>> "PackagedProgram") have a way to figure out whether the code uses
>>>>>>> "main()"
>>>>>>>> or implements "Program"
>>>>>>>> and calls the right method.
>>>>>>>>
>>>>>>>> You can try and extend the program interface. If you want to
>>>> consistently
>>>>>>>> support multiple programs in one JAR file, you may need to adjust
>> the
>>>>>>> util
>>>>>>>> classes as
>>>>>>>> well to deal with that.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, May 19, 2015 at 10:10 AM, Matthias J. Sax <
>>>>>>>> mj...@informatik.hu-berlin.de> wrote:
>>>>>>>>
>>>>>>>>> Supporting an interface like this seems to be a nice idea. Any
>> other
>>>>>>>>> opinions on it?
>>>>>>>>>
>>>>>>>>> It seems to be some more work to get it done right. I don't want to
>>>>>>>>> start working on it, before it's clear that it has a chance to be
>>>>>>>>> included in Flink.
>>>>>>>>>
>>>>>>>>> @Flavio: I moved the discussion to dev mailing list (user list is
>> not
>>>>>>>>> appropriate for this discussion). Are you subscribed to it or
>> should
>>>> I
>>>>>>>>> cc you in each mail?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -Matthias
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 05/19/2015 09:39 AM, Flavio Pompermaier wrote:
>>>>>>>>>> Nice feature Matthias!
>>>>>>>>>> My suggestion is to create a specific Flink interface to get also
>>>>>>>>>> description of a job and standardize parameter passing.
>>>>>>>>>> Then, somewhere (e.g. Manifest) you could specify the list of
>>>> packages
>>>>>>>>> (or
>>>>>>>>>> also directly the classes) to inspect with reflection to extract
>> the
>>>>>>> list
>>>>>>>>>> of available Flink jobs.
>>>>>>>>>> Something like:
>>>>>>>>>>
>>>>>>>>>> public interface FlinkJob {
>>>>>>>>>>
>>>>>>>>>> /** The name to display in the job submission UI or shell */
>>>>>>>>>> //e.g. "My Flink HelloWorld"
>>>>>>>>>> String getDisplayName();
>>>>>>>>>> //e.g. "This program does this and that etc.."
>>>>>>>>>> String getDescription();
>>>>>>>>>> //e.g. <0,Integer,"An integer representing my first param">,
>>>>>>>>> <1,String,"An
>>>>>>>>>> string representing my second param">
>>>>>>>>>> List<Tuple3<Integer, TypeInfo, String>> paramDescription;
>>>>>>>>>> /** Set up the flink job in the passed ExecutionEnvironment */
>>>>>>>>>> ExecutionEnvironment config(ExecutionEnvironment env);
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> What do you think?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Sun, May 17, 2015 at 10:38 PM, Matthias J. Sax <
>>>>>>>>>> mj...@informatik.hu-berlin.de> wrote:
>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> I like the idea that Flink's WebClient can show different plans
>> for
>>>>>>>>>>> different jobs within a single jar file.
>>>>>>>>>>>
>>>>>>>>>>> I prepared a prototype for this feature. You can find it here:
>>>>>>>>>>> https://github.com/mjsax/flink/tree/multipleJobsWebUI
>>>>>>>>>>>
>>>>>>>>>>> To test the feature, you need to prepare a jar file, that
>> contains
>>>> the
>>>>>>>>>>> code of multiple programs and specify each entry class in the
>>>> manifest
>>>>>>>>>>> file as comma separated values in "program-class" line.
>>>>>>>>>>>
>>>>>>>>>>> Feedback is welcome. :)
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> -Matthias
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 05/08/2015 03:08 PM, Flavio Pompermaier wrote:
>>>>>>>>>>>> Thank you all for the support!
>>>>>>>>>>>> It will be a really nice feature if the web client could be able
>>>> to
>>>>>>>>> show
>>>>>>>>>>>> me the list of Flink jobs within my jar..
>>>>>>>>>>>> it should be sufficient to mark them with a special annotation
>> and
>>>>>>>>>>>> inspect the classes within the jar..
>>>>>>>>>>>>
>>>>>>>>>>>> On Fri, May 8, 2015 at 3:03 PM, Malte Schwarzer <m...@mieo.de
>>>>>>>>>>>> <mailto:m...@mieo.de>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Flavio,
>>>>>>>>>>>>
>>>>>>>>>>>> you also can put each job in a single class and use the –c
>>>>>>>>> parameter
>>>>>>>>>>>> to execute jobs separately:
>>>>>>>>>>>>
>>>>>>>>>>>> /bin/flink run –c com.myflinkjobs.JobA
>>>>>>>>> /path/to/jar/multiplejobs.jar
>>>>>>>>>>>> /bin/flink run –c com.myflinkjobs.JobB
>>>>>>>>> /path/to/jar/multiplejobs.jar
>>>>>>>>>>>> …
>>>>>>>>>>>>
>>>>>>>>>>>> Cheers
>>>>>>>>>>>> Malte
>>>>>>>>>>>>
>>>>>>>>>>>> Von: Robert Metzger <rmetz...@apache.org <mailto:
>>>>>>>>> rmetz...@apache.org
>>>>>>>>>>>>>
>>>>>>>>>>>> Antworten an: <u...@flink.apache.org <mailto:
>>>>>>> u...@flink.apache.org
>>>>>>>>>>>
>>>>>>>>>>>> Datum: Freitag, 8. Mai 2015 14:57
>>>>>>>>>>>> An: "u...@flink.apache.org <mailto:u...@flink.apache.org>"
>>>>>>>>>>>> <u...@flink.apache.org <mailto:u...@flink.apache.org>>
>>>>>>>>>>>> Betreff: Re: Package multiple jobs in a single jar
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Flavio,
>>>>>>>>>>>>
>>>>>>>>>>>> the pom from our quickstart is a good
>>>>>>>>>>>> reference:
>>>>>>>>>>>
>>>>>>>>>
>>>>>>>
>>>>
>> https://github.com/apache/flink/blob/master/flink-quickstart/flink-quickstart-java/src/main/resources/archetype-resources/pom.xml
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Fri, May 8, 2015 at 2:53 PM, Flavio Pompermaier
>>>>>>>>>>>> <pomperma...@okkam.it <mailto:pomperma...@okkam.it>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Ok, get it.
>>>>>>>>>>>> And is there a reference pom.xml for shading my
>>>> application
>>>>>>>>> into
>>>>>>>>>>>> one fat-jar? which flink dependencies can I exclude?
>>>>>>>>>>>>
>>>>>>>>>>>> On Fri, May 8, 2015 at 1:05 PM, Fabian Hueske <
>>>>>>>>> fhue...@gmail.com
>>>>>>>>>>>> <mailto:fhue...@gmail.com>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> I didn't say that the main should return the
>>>>>>>>>>>> ExecutionEnvironment.
>>>>>>>>>>>> You can define and execute as many programs in a
>> main
>>>>>>>>>>>> function as you like.
>>>>>>>>>>>> The program can be defined somewhere else, e.g., in
>> a
>>>>>>>>>>>> function that receives an ExecutionEnvironment and
>>>>>>> attaches
>>>>>>>>>>>> a program such as
>>>>>>>>>>>>
>>>>>>>>>>>> public void buildMyProgram(ExecutionEnvironment
>> env) {
>>>>>>>>>>>> DataSet<String> lines = env.readTextFile(...);
>>>>>>>>>>>> // do something
>>>>>>>>>>>> lines.writeAsText(...);
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> That method could be invoked from main():
>>>>>>>>>>>>
>>>>>>>>>>>> psv main() {
>>>>>>>>>>>> ExecutionEnv env = ...
>>>>>>>>>>>>
>>>>>>>>>>>> if(...) {
>>>>>>>>>>>> buildMyProgram(env);
>>>>>>>>>>>> }
>>>>>>>>>>>> else {
>>>>>>>>>>>> buildSomeOtherProg(env);
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> env.execute();
>>>>>>>>>>>>
>>>>>>>>>>>> // run some more programs
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> 2015-05-08 12:56 GMT+02:00 Flavio Pompermaier
>>>>>>>>>>>> <pomperma...@okkam.it <mailto:pomperma...@okkam.it
>>>> :
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Fabian,
>>>>>>>>>>>> thanks for the response.
>>>>>>>>>>>> So my mains should be converted in a method
>>>> returning
>>>>>>>>>>>> the ExecutionEnvironment.
>>>>>>>>>>>> However it think that it will be very nice to
>>>> have a
>>>>>>>>>>>> syntax like the one of the Hadoop ProgramDriver
>> to
>>>>>>>>>>>> define jobs to invoke from a single root class.
>>>>>>>>>>>> Do you think it could be useful?
>>>>>>>>>>>>
>>>>>>>>>>>> On Fri, May 8, 2015 at 12:42 PM, Fabian Hueske
>>>>>>>>>>>> <fhue...@gmail.com <mailto:fhue...@gmail.com>>
>>>>>>> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> You easily have multiple Flink programs in a
>>>>>>> single
>>>>>>>>>>>> JAR file.
>>>>>>>>>>>> A program is defined using an
>>>>>>> ExecutionEnvironment
>>>>>>>>>>>> and executed when you call
>>>>>>>>>>>> ExecutionEnvironment.exeucte().
>>>>>>>>>>>> Where and how you do that does not matter.
>>>>>>>>>>>>
>>>>>>>>>>>> You can for example implement a main
>> function
>>>>>>> such
>>>>>>>>>>> as:
>>>>>>>>>>>>
>>>>>>>>>>>> public static void main(String... args) {
>>>>>>>>>>>>
>>>>>>>>>>>> if (today == Monday) {
>>>>>>>>>>>> ExecutionEnvironment env = ...
>>>>>>>>>>>> // define Monday prog
>>>>>>>>>>>> env.execute()
>>>>>>>>>>>> }
>>>>>>>>>>>> else {
>>>>>>>>>>>> ExecutionEnvironment env = ...
>>>>>>>>>>>> // define other prog
>>>>>>>>>>>> env.execute()
>>>>>>>>>>>> }
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> 2015-05-08 11:41 GMT+02:00 Flavio
>> Pompermaier
>>>>>>>>>>>> <pomperma...@okkam.it <mailto:
>>>>>>> pomperma...@okkam.it
>>>>>>>>>>>>> :
>>>>>>>>>>>>
>>>>>>>>>>>> Hi to all,
>>>>>>>>>>>> is there any way to keep multiple jobs
>> in
>>>> a
>>>>>>> jar
>>>>>>>>>>>> and then choose at runtime the one to
>>>> execute
>>>>>>>>>>>> (like what ProgramDriver does in
>> Hadoop)?
>>>>>>>>>>>>
>>>>>>>>>>>> Best,
>>>>>>>>>>>> Flavio
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>
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