The Wikipedia page of BitTorrent says regarding Multitracker torrents, "One disadvantage to this is that it becomes possible to have multiple unconnected swarms for a single torrent where some users can connect to one specific tracker while being unable to connect to another. This can create a disjoint set which can impede the efficiency of a torrent to transfer the files it describes."
Can someone please give me an example of this?
Thanks.
The information on the wikipedia page is old and no longer relevant.
Split swarms was only a problem between the introduction of:
Multi-trackers extension:BEP12 around 2004
and the introduction of:
PeerEXchange(PEX):BEP11 and the DHT distributed tracker:BEP5 around 2005.
These three extensions working together creates a single unified swarm.
Related
Our application is heavily based on email (it's a helpdesk ticketing system) and I'd like to protect our users and block 3rd party tracking from incoming messages HTML (mainly tracking pixels).
We're already doing HTML/DOM parsing (to "sanitize" dangerous and unwanted tags), so HTML-parsing is not really a technical challenge. The challenge is how to detect 3rd party trackers? Are there any common characteristics we could use?
Currently I came up with 2 approaches:
Use a set of rules like:
img has external src
src with query-parameters
low dimensions (0 or 1 pixel width/height)
Simply use an existing filter list (uBlock Origin, for example, publishes their lists here) and remove all tags pointing to dangerous destinations
Any other ideas that I'm missing? Would love to hear some input from someone who's dealt with this before.
I think that's about all you can do, though blocking all external resources would be safer - there's no definitive link between image size and tracking, though it is a common pattern.
There are lists of known trackers here ad here. Hey.com may also have some resources to help block trackers.
I am new to this tech but I am close to the concept of Channel. I understand that the channel are ledgers within a bigger ledger( i.e. small chain specific to some users only within the entire blockchain). Based on this I have few questions.
Lets say there are retail markets where there is scope for negotiations in rate and hence each vendor can sale same thing to different people with different prices. So assuming that there are 1000 people and 1000 vendors possibly there could be many channels. How these are managed?
I understand that the blockchains are linear data structure (unless two blocks are created simultaneously, there is a word for this but I forgot it), If I have to access previous data for certain user. How efficient it is going to be for such operations? i.e. take an example of bank credit card transactions. If I want to see all my transactions for last 5 months. How efficient it is going to be?
I am not claiming that I am completely correct in my understanding but these things are bugging me.It would be very nice if someone help me clear these?
Thanks :)
Update
I have gone through this link it also talks about something related to my questions in below comments. i.e. related to businesses (questions private blockchain).
I like more the definition of channels as different blockchains using a common network or common parts of a network. It allows privacy and different organisation structures.
Yes, it could have possibly so many channels as vendor-people pair. Of course, it depends on which privacy you want to achieve.
If you want to access previous datas for previous operations, you have the possibility to have a state database running alongside the peers, which are a state representation of the linear structure. You can use LevelDB or CouchDB. CouchDB allows you to use complex rich queries to access your data.
ledger can only exists in channel. And the channel is composed of peers. the peers out of the channel cannot get access to the ledger data.
I am not sure what you mean by "Operation". You can create it and close it(this will be supported in later version) When you need it ,create it and you can close after use.
If the business is independent, you have to create so many channels. you just say vendor can sale same thing to different people with different prices. . each of them will be used for different scenario.
if you want to get access to the previous data, of course you can. But not maybe as efficient as you the bank card now. But this is doable. Now we use sdk to access. maybe later with more development of the sdk, more graphic tool will be developed, enabling it used as easy as possible.
I'm getting familiar with DHT and I mostly understand how it works. However, I don't quite understand what happens if you want to have separate DHTs with different entry types in each. Is this possible?
If I use a popular DHT library, does that mean I put and get entries using the same DHT as every user of said library? Or is DHT universal for everyone? How do you define an owner of a DHT, or how do you define a separate, contained DHT?
Yes, you can make separate DHTs. However you need to make the 'on the wire' protocols slightly diffrent so they can't speak to each other and get mixed up.
You can actually have unlimited numbers of DHTs using the same protocol as long as peers don't know each other.
This is the important part when you set up a network. You have to know a second peer to intitially create the network. The next peer would have to know one of the two initial nodes, the next one needs knowledge of one of the three above and so forth.
You are also able to be connected to multiple DHTs on the same host without the two interferring (at least in terms of data exchange, not in terms of local ressources). And you are also able to joins those two DHTs by telling one of them about the peers you are connected to in the other DHT. Though that might be not as easy as it sounds.
This is my first time dabbling in NLP so please excuse my ignorance. I'm looking for a method to extract interests/likes/hobbies from users' social profiles. Here is an example where all the interests/likes/hobbies are in bold:
"I consider myself a pretty diverse character... I'm a professional
wrestler, but I'd take a bullet for Wall•E. I train like a one-man genocide machine in the gym, but I cried at
"Armageddon." I'll head bang to AC/DC, and I'm seriously
considering getting a Legend of Zelda tattoo. I'm 420-friendly. I
like to party it up with the frat crowd one night, hang out with
my Burning Man friends the next, play Halo and World of
Warcraft the next, and jam with friends that aren't any younger than
40 the next. My youngest friend is 16, my oldest friend is 66. I'll
sing karaoke at the bars, and I'm my friends' collective
psychiatrist/shoulder."
The profiles are plain text. There are no meta tags or ids associated with any of it, it's just a paragraph of text.
My naiive idea was to take each noun and match it against Freebase to see if it's an activity/artist/movie/book etc. The problem is that although most entities mentioned will be things the user likes, she will also mention things she doesn't like and I have no means of distinguishing the 2.
I have 2 questions:
What sub field of NLP should I be looking at? Some googleable algorithms/techniques/authors would be greatly appreciated.
How hard is this problem?
Thanks!
First, unless using NLP to do this is a particular objective for you, check your problem domain to see if you can avoid it completely.
For instance:
do these profiles have tags (supplied either by the Site or by the
user)?
what does the Site's API make available (assuming that's how you are accessing this data; if you are scraping it, then this doesn't of course apply)? A good example, Facebook. if you read a user's posts, you'll see words like "wrestler", "karaoke", etc. but if you look at what fields are exposed via the Graph API, you'll see that these activities nearly always have an associated FB ID.
I am not a specialist in this field, but I can recommend a couple of resources directed to NLP and which are accessible to the non-specialist or novice. The first is a text processing API. This simple web service uses REST and JSON IO. It is free and seems to have a fairly large rate limit.
This API appears to rely heavily on the excellent Natural Language Tooolkit (NLTK) which is a mature stable library in python, that includes modules directed to the problem in your Question, e.g., Sentiment Analysis, Tagging and Chunk Extraction, etc.
Which particular sub-domain is most relevant to solving the Question in the OP? I don't know, but I suspect there's a module somewhere in the NLTK that does what you need. Finding that module is hopefully just a matter of skimming the API Documentation (which is organized by module); reading the Getting Started section which contains an excellent survey of NLTK's modules as well as demos for all of each of them.
I am very new to GIS development, and to be be frank I have no background about it at all. I searched the web but the tutorials I found seemed to assume the reader has some background information.
the thing is that I am confused about what to read or learn, there seems to be lots of technologies, and I feel lost since some speak about openlayers, geoserver, mapserver, google maps, and open street maps.
So here is what I am supposed to develop, and I hove you could give me an advice about which technology to use, and where should I start reading - given that I know almost nothing -.
Case 1: a closed system for about 20 users only, who can specify locations on the map, and the web application will store the latitude and longitude of the locations and show the markers. I wanted to use google maps api, but I cancelled that since there license requires you to purchase the service if the system is a closed one. so what technology should I use in such case? I need a free option, also I will be only using web server, so if the solution includes using my own geoserver, or something like that I won't be able to do it.
Case 2: I am supposed to display the roads and routes between two given points, and probably add some notes on the map. For this I case I can use my own map server/geo server, but again I want your suggestions.
of course the solution need to be open source
finally, I hope you could tell me what to start reading first,
Start by looking over at https://gis.stackexchange.com/, starting with the tags [web-mapping] and
Some topics in particluar you may want to look at are:
https://gis.stackexchange.com/questions/8113/steps-to-start-web-mapping
https://gis.stackexchange.com/questions/8238/where-how-to-learn-about-getting-started-with-web-gis
https://gis.stackexchange.com/questions/13868/looking-for-a-developer-friendly-web-gis
As for skills and tuorials, look at:
https://gis.stackexchange.com/questions/17227/free-gis-workshops-tutorials-and-applied-learning-material
https://gis.stackexchange.com/questions/913/web-gis-development-skill-sets