Hey everyone. This is my last week for UCOSP updates. I would like to thank all the mentors and those organizing UCOSP for giving me the opportunity to contribute to Freeseer as part of my course work. It has been a great experience and I will continue to keep Freeseer in my sights and hope to continue contributing in the future!
This week:
I learned how to format with restructured text.
I opened two new pull requests.
The first for the API development document. I edited and formatted the API development document I had been working on so that it could become part of the Freeseer development docs. The pull request can be found here.
The second for a developer document on how to get the Freeseer server running, and some more general points on Zeroconf protocol. Found here
Finally I closed my http error standardization pull request.
I still have an open pull request for broadcasting, but it should be complete after code reivew, and I will be sure to close it in the future.
Thanks for everything!
Monday 1 December 2014
Sunday 23 November 2014
Week 11: Updates
This week I finished the content of my development document. A commentable version is found here. I also made code changes based on code review.
Furthermore, I pushed some preliminary proof of concept code to discover Freeseer hosts on a client's network. There are a few bugs that I tried to get to the bottom of, but I didn't have much luck. Essentially when Freeseer tries to shutdown after running the server discovery process, I will get an exception that I believe is caused by a race condition.
Furthermore, I pushed some preliminary proof of concept code to discover Freeseer hosts on a client's network. There are a few bugs that I tried to get to the bottom of, but I didn't have much luck. Essentially when Freeseer tries to shutdown after running the server discovery process, I will get an exception that I believe is caused by a race condition.
This is the output I get. My guess is that some race condition is occurring when zeroconf.close() fires in the search() method of freeseer/frontend/controller/discover.py. If i add a 'sleep(1)' directly after it, I don't run into this error.
Anyway, the code that actually does the discovering of servers works fine.
Next week,
Obviously things are starting to wind down, I want to continue working towards closing all my pull requests. Furthermore, I have to format and put my API development document in the development wiki. Finally, I have to write a guide on running freeseer server, what dependencies are necessary, etc, which I will do this week.
My only blocks are that my school work load is getting a little insane.
Until next week,
Brenden Doyle
Sunday 16 November 2014
Week 10 Updates
Quick Update:
This week I began putting together a development document for developing APIs and endpoints. The first pass should be up shortly.
I continued working on my open pull requests, in particular the pull request for fleshing out the errors thrown by our REST framework, and I figured it would be a good place to do a bit of refactoring our validation code. Instead of having a tightly coupled validation module with one method per endpoint, I decided to have only a method that takes a request form and a schema to validate it against. In some APIs we will hardcode the schemas into a dict contained by the blueprint (recording api for example), but for request forms that mirror existing classes (Config API for example) there is a schema method that will generate a schemas at runtime. Either way, the main idea is that we keep the actual schemas away from the validate module, unlike in the past.
I had to make some changes to the test_validate.py module and I ended up making it more pytest-ish instead of unittest-ish.
Next week and beyond:
Finish up development document.
Close all open pull requests
Look at what tests should be added to improve test coverage. Implement new ones if necessary.
Sunday 9 November 2014
UCOSP: Week 9 updates
This week
I continued my research of service discovery options for Freeseer. I made a number of prototypes, got a windows box up and running to make a final decision about what service discovery method to use.
As I elaborated upon last week, there was no perfect broadcasting solution for the Freeseer service. The one that worked the best (avahi) was linux only, the other pure python implementations were very finicky, especially when working as servers. I looked at one final non-Zeroconf no-configuration library called minusconf, that seemed very promising at first, but found that if it was used in any sort of non-standard environment, (multiple NIC cards etc.), it would either work consistently or not at all.
In the end I decided that the best way to accomplish service broadcasting would be to use Avahi on the server side, and a pure python library called python-zeroconf on the client side. This means that only linux boxes will be able to work as headless Freeseer Hosts, but a client can be of any OS. This is a compromise that I am ok with, because Avahi is miles ahead of any pure python zeroconf implementation.
Since we haven't begun developing our Freeseer client yet, there's nothing stopping us from
I put together my implementation of that today, and opened a PR for that issue.
I also took a look at some other work related to revamping the way that HTTP_ERRORS are sent and displayed. I opened a PR for that issue as well. There is now a standard error message associated with any HTTP Error message (404, 401, ...), and an endpoint can decide to supply a description or not. That description will be included in the HTTP_ERROR message JSON returned by the endpoint. It's just to make things a little clearer for developers who will be developing against this REST api, and bring our REST api closer in line with REST best practices.
Next week
I will work on closing these PR's, and will take a look at expanding our test coverage. I also will start thinking of what will go into my API development document, as our time is starting to wind down.
Until next week.
I continued my research of service discovery options for Freeseer. I made a number of prototypes, got a windows box up and running to make a final decision about what service discovery method to use.
As I elaborated upon last week, there was no perfect broadcasting solution for the Freeseer service. The one that worked the best (avahi) was linux only, the other pure python implementations were very finicky, especially when working as servers. I looked at one final non-Zeroconf no-configuration library called minusconf, that seemed very promising at first, but found that if it was used in any sort of non-standard environment, (multiple NIC cards etc.), it would either work consistently or not at all.
In the end I decided that the best way to accomplish service broadcasting would be to use Avahi on the server side, and a pure python library called python-zeroconf on the client side. This means that only linux boxes will be able to work as headless Freeseer Hosts, but a client can be of any OS. This is a compromise that I am ok with, because Avahi is miles ahead of any pure python zeroconf implementation.
Since we haven't begun developing our Freeseer client yet, there's nothing stopping us from
I put together my implementation of that today, and opened a PR for that issue.
I also took a look at some other work related to revamping the way that HTTP_ERRORS are sent and displayed. I opened a PR for that issue as well. There is now a standard error message associated with any HTTP Error message (404, 401, ...), and an endpoint can decide to supply a description or not. That description will be included in the HTTP_ERROR message JSON returned by the endpoint. It's just to make things a little clearer for developers who will be developing against this REST api, and bring our REST api closer in line with REST best practices.
Next week
I will work on closing these PR's, and will take a look at expanding our test coverage. I also will start thinking of what will go into my API development document, as our time is starting to wind down.
Until next week.
Sunday 2 November 2014
Zeroconf Safari: Week 8 Update
This week:
This week was quite busy, despite not having committed any code, I had to do a lot of research with regards to broadcasting the Freeseer server across networks. Right now, it is trivial to set up our REST api endpoint so that anyone on our network who knows the IP address of the computer running the server, as well as the port number the server is broadcasting over, they can send api requests from some client. For example, if the Freeseer host machine has an local ip address of 192.168.0.11, and the Freeseer server is running on port 5000, any other computer connected to that network should be able to send api requests to that box with "curl -i -X GET http://192.168.0.11:5000/<endpoint>".
This is only one part of the puzzle however. We want Freeseer servers and clients to be able to be set up and run by people without too much knowledge of ip addresses and networking. What would be ideal is if we could configure things so that Freeseer clients were aware of all instances of Freeseer servers running on a network merely by being connected to it. Even better if we can do this without any configuration necessary. We were aware of at least one way to accomplish this: Zerconf (Zero-configuration networking), implemented by Bonjour on Mac and Windows, and Avahi on Linux. In the most basic terms, Zeroconf is what allows your iTunes to be aware of all iTunes libraries shared on your network auto-magically. So this week I spent researching and prototyping existing implementations of Zeroconf on Python to determine which one was the best to be used by Freeseer.
We had a few critieria for choosing which would be the best:
Basically all we needed was some solution that would broadcast an IP address, a port number, and some other information (name and description of the Freeseer server, for example).
Avahi
Avahi worked really well and painlessly. The only problem is that Avahi is only available for linux, and while headless Freeseer servers are probably only going to be used on linux boxes, we want to run clients on Windows boxes. Therefore, we would need a separate implementation for Windows boxes, and we should be able to accomplish this with only one library.
pybonjour
This library is cross platform, unlike the Avahi solution. I didn't try to make a prototype solution because the code is apparently is very old and unmaintained (last commit 2009), and not particularly well designed according to mtomwing.
mtomwing talked about the possibility of forking and improving.
python-zeroconf
This library actually manages to work fairly well without any external dependencies (relies entirely on socket programming). It caused me a lot of headaches this weekend because Avahi was able to run on a host-only network and python-zeroconf could only work in bridge mode. I have the feeling that even though I managed to get it to work, my gut feeling is that it may only play well with very specific types of network configurations, basically home networks. For example, it makes a call to ip address '4.2.2.1' to get an ip address to bind to. If some network had no DNS server, there is no route to that host and python-zeroconf would falls back to the host IP, (on debian boxes, the host ip is always '127.0.1.1', which useless for us). Avahi has worked extremely well in all the network configurations I've used thus far, including those with no DNS.
I think, the best use for this library would be to use it for clients that don't run avahi. It is just a little too low-level and lacks the robustness of avahi or bonjour to be used for servers.
zeroconf (python module)
This module would work cross platform (ostensibly from looking at the code, I don't have a Windows box to test against). My prototype worked very well. The two biggest issues is that it relies on a number of calls to shell, and it is not installable from pip, meaning we'd have to bring the whole module into our code base.
non-Zeroconf solutions (multicasting, ssdp)
When considering all the problems these three solutions had we tried looking in a different direction and to move away from Zeroconf, and look for some other solution. Without getting into too many details, they all worked well, but they were all held back by the fact that you needed to specify the interface you wished to broadcast over, which infringes on our first 'must' which is that it must be runnable without dealing with ip addresses and interfaces.
I tried both multicast with socket programming and ssdp (simple service discovery platform) with a small python module, and there was no way that they would be without zero configuration unless we went way beyond the scope of our current project.
Winner? Avahi + python-zeroconf?
So, essentially all of them have their own positives and heavy drawbacks. I think what will probably happen is we use avahi bindings to create our headless server, and avahi/python-zeroconf for our clients? Perhaps we may just need to fork and refactor pybonjour for our own use.
NEXT WEEK:
Hopefully I will be in the spot where I can put together an implementation this week. I have to discuss where we will go next with the Freeseer mentors. Until next week!
This week was quite busy, despite not having committed any code, I had to do a lot of research with regards to broadcasting the Freeseer server across networks. Right now, it is trivial to set up our REST api endpoint so that anyone on our network who knows the IP address of the computer running the server, as well as the port number the server is broadcasting over, they can send api requests from some client. For example, if the Freeseer host machine has an local ip address of 192.168.0.11, and the Freeseer server is running on port 5000, any other computer connected to that network should be able to send api requests to that box with "curl -i -X GET http://192.168.0.11:5000/<endpoint>".
This is only one part of the puzzle however. We want Freeseer servers and clients to be able to be set up and run by people without too much knowledge of ip addresses and networking. What would be ideal is if we could configure things so that Freeseer clients were aware of all instances of Freeseer servers running on a network merely by being connected to it. Even better if we can do this without any configuration necessary. We were aware of at least one way to accomplish this: Zerconf (Zero-configuration networking), implemented by Bonjour on Mac and Windows, and Avahi on Linux. In the most basic terms, Zeroconf is what allows your iTunes to be aware of all iTunes libraries shared on your network auto-magically. So this week I spent researching and prototyping existing implementations of Zeroconf on Python to determine which one was the best to be used by Freeseer.
We had a few critieria for choosing which would be the best:
- Code must work well.
- Must work without any configuration necessary on the part of the user.
- Should refrain from making calls to shell.
- Should be cross platform compatible.
- Should be available through pip.
Basically all we needed was some solution that would broadcast an IP address, a port number, and some other information (name and description of the Freeseer server, for example).
Avahi
Avahi worked really well and painlessly. The only problem is that Avahi is only available for linux, and while headless Freeseer servers are probably only going to be used on linux boxes, we want to run clients on Windows boxes. Therefore, we would need a separate implementation for Windows boxes, and we should be able to accomplish this with only one library.
pybonjour
This library is cross platform, unlike the Avahi solution. I didn't try to make a prototype solution because the code is apparently is very old and unmaintained (last commit 2009), and not particularly well designed according to mtomwing.
mtomwing talked about the possibility of forking and improving.
python-zeroconf
This library actually manages to work fairly well without any external dependencies (relies entirely on socket programming). It caused me a lot of headaches this weekend because Avahi was able to run on a host-only network and python-zeroconf could only work in bridge mode. I have the feeling that even though I managed to get it to work, my gut feeling is that it may only play well with very specific types of network configurations, basically home networks. For example, it makes a call to ip address '4.2.2.1' to get an ip address to bind to. If some network had no DNS server, there is no route to that host and python-zeroconf would falls back to the host IP, (on debian boxes, the host ip is always '127.0.1.1', which useless for us). Avahi has worked extremely well in all the network configurations I've used thus far, including those with no DNS.
I think, the best use for this library would be to use it for clients that don't run avahi. It is just a little too low-level and lacks the robustness of avahi or bonjour to be used for servers.
zeroconf (python module)
This module would work cross platform (ostensibly from looking at the code, I don't have a Windows box to test against). My prototype worked very well. The two biggest issues is that it relies on a number of calls to shell, and it is not installable from pip, meaning we'd have to bring the whole module into our code base.
non-Zeroconf solutions (multicasting, ssdp)
When considering all the problems these three solutions had we tried looking in a different direction and to move away from Zeroconf, and look for some other solution. Without getting into too many details, they all worked well, but they were all held back by the fact that you needed to specify the interface you wished to broadcast over, which infringes on our first 'must' which is that it must be runnable without dealing with ip addresses and interfaces.
I tried both multicast with socket programming and ssdp (simple service discovery platform) with a small python module, and there was no way that they would be without zero configuration unless we went way beyond the scope of our current project.
Winner? Avahi + python-zeroconf?
So, essentially all of them have their own positives and heavy drawbacks. I think what will probably happen is we use avahi bindings to create our headless server, and avahi/python-zeroconf for our clients? Perhaps we may just need to fork and refactor pybonjour for our own use.
NEXT WEEK:
Hopefully I will be in the spot where I can put together an implementation this week. I have to discuss where we will go next with the Freeseer mentors. Until next week!
Monday 27 October 2014
UCOSP Week 7 Updates
This week
This week my pull request for the logic refactor of recording api was finally accepted after a number of code review changes.
Most of my work this week involved researching what I should do next, and how to implement it. I began doing some research on authentication schemes, and have a clear vision for how authentication should be carried out between client and server. After some conversations with Michael Tom-Wing, he noted that it would be better to think about how the server could be broadcasted onto a network and then worry about an authentication scheme later, which will probably rely on shared keys instead of a user/password model. I began looking into what would be the best library for broadcasting, and I'm still researching. The library that seems the most promising thus far is python-zerconf, which is compatible with both avahi and bonjour, so it should be usable by Windows and OSX as well. I was looking at pybonjour, which is also cross-platform, but does not have support for python 3.
I also thought about a more consistent way to throw and present errors in the REST framework. My plan is to have a table of generic messages associated with each http error in the http error class (400, 404, ... etc.). When an endpoint wants to throw an http error, it then supplies any endpoint specific message it wants to send to the constructor.
I was also sick with the flu Saturday night into Sunday, so I was unable to attend the meeting.
Next week and beyond
I have a clear direction for the last few weeks working on getting our Freeseer REST server to broadcast on a network, so that will be my main focus, as well as small changes to the way errors are thrown by the REST server. As well, I plan on writing a small document about what a developer will need to take note of when developing new endpoints. If I run out of things to do, I always need to expand test coverage. I've modified my proposal to take notes of these changes.
Until next time,
Brenden Doyle
This week my pull request for the logic refactor of recording api was finally accepted after a number of code review changes.
Most of my work this week involved researching what I should do next, and how to implement it. I began doing some research on authentication schemes, and have a clear vision for how authentication should be carried out between client and server. After some conversations with Michael Tom-Wing, he noted that it would be better to think about how the server could be broadcasted onto a network and then worry about an authentication scheme later, which will probably rely on shared keys instead of a user/password model. I began looking into what would be the best library for broadcasting, and I'm still researching. The library that seems the most promising thus far is python-zerconf, which is compatible with both avahi and bonjour, so it should be usable by Windows and OSX as well. I was looking at pybonjour, which is also cross-platform, but does not have support for python 3.
I also thought about a more consistent way to throw and present errors in the REST framework. My plan is to have a table of generic messages associated with each http error in the http error class (400, 404, ... etc.). When an endpoint wants to throw an http error, it then supplies any endpoint specific message it wants to send to the constructor.
I was also sick with the flu Saturday night into Sunday, so I was unable to attend the meeting.
Next week and beyond
I have a clear direction for the last few weeks working on getting our Freeseer REST server to broadcast on a network, so that will be my main focus, as well as small changes to the way errors are thrown by the REST server. As well, I plan on writing a small document about what a developer will need to take note of when developing new endpoints. If I run out of things to do, I always need to expand test coverage. I've modified my proposal to take notes of these changes.
Until next time,
Brenden Doyle
Sunday 19 October 2014
UCOSP Update, Week 6
This week
This week I had a pretty crazy week with midterms. I managed to make changes based on Michael's code review, but I haven't had too much time to think about the code.
Essentially the biggest change this week I made was in the test framework. Our tests require a number of temporary folders to stick files necessary to carry out tests. Before, we would create these temporary folders and delete them on our own, but now the test framework makes use of a pytest fixture called 'tmpdir' that takes care of creating any temporary folders we need to carry out tests and deleting them automatically.
Other than that, there were minor changes here and there to the test framework.
Next week
The main thing I am thinking of right now is changes that can be made to the way we handle errors in the framework, and have a standardized way to handle errors that all new endpoints can adhere to, and how to handle authentication. As soon as my current pull request is closed, I can start to work on either of those.
Until next week.
This week I had a pretty crazy week with midterms. I managed to make changes based on Michael's code review, but I haven't had too much time to think about the code.
Essentially the biggest change this week I made was in the test framework. Our tests require a number of temporary folders to stick files necessary to carry out tests. Before, we would create these temporary folders and delete them on our own, but now the test framework makes use of a pytest fixture called 'tmpdir' that takes care of creating any temporary folders we need to carry out tests and deleting them automatically.
Other than that, there were minor changes here and there to the test framework.
Next week
The main thing I am thinking of right now is changes that can be made to the way we handle errors in the framework, and have a standardized way to handle errors that all new endpoints can adhere to, and how to handle authentication. As soon as my current pull request is closed, I can start to work on either of those.
Until next week.
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