I can create a muc room. But if i gave the room name as existing one in the database, the server rejects it.So is it possible to create two rooms with same name in ejabberd server(MYSQl backend)?
If possible, then what are the consequences? For example, i created two rooms with unique name say "newGroupChat" and same user list(user1, user2). How can ejabberd identifies it? If i send messages in "newGroupChat", does those messages appear in one room or both of the rooms.
Its hard to specifically no what you are trying to achieve, but I came across this in another XMPP server setup( Its pretty much generic with few config differences on different servers), and the idea I got is like this:
If you use different systems( different IP) it is possible to have the same room across multiple domains, hence you can mirror the rooms but the room name has to be the same thing, for example "newGroupChat#conference.serverIP1" , and one the second system "newGroupChat#conference.serverIP2", and when you send messages on System 1, system 2 users can also see the same messages if they are online and logged into the room.
If it's the same system I don't know how you intend to set a boundary on it, there are two ways to do this I figured out, using different OS(maybe bridged networking) and also separating databases. If you use an embedded database there is no way you can re-create the same room, you might try adding extensions to the name to see if it would work as such : "newGroupChat#conference.serverIP1/ID1" and "newGroupChat#conference.serverIP1/ID2", the above also applies to an external database such as SQL. These are a few suggestions and muc setup might have slight config setup in contrast to the examples I gave, but that's a general idea, if you have better explanations you can also share with me, as I am looking into LAN chatting on different systems with the same muc room.
In Xmpp world, room#service is used as an identifier for a room, so here the room is unique. That's why use failed to create when using a existing name.
I think you can try use subject configure for this purpose.
Xmpp MUC Xep-0045
Room, A virtual space that users figuratively enter in order to participate in real-time, text-based conferencing with other users.
Room ID, The localpart of a Room JID, which might be opaque and thus lack meaning for human users (see under Business Rules for syntax); contrast with Room Name.
Room JID, The address of a room.
Room Name, A user-friendly, natural-language name for a room, configured by the room owner and presented in Service Discovery queries; contrast with Room ID.
I can create a muc room. But if i gave the room name as existing one
in the database, the server rejects it.So is it possible to create two
rooms with same name in ejabberd server(MYSQl backend)?
No.It is not possible to create two room with same name in a host in ejabberd(as per XEP-45,too).
Related
On a ride booking app, it is required communication between driver and user.
Now the case, if user A contacts the driver via website or app, call or sms can be achieved via Twilio, we don't want to expose their contact numbers to each other.
If three users A, B and C contacts the driver and driver has no app installed, in fact the driver wants call back and sms reply. How the driver can reach users on Caller ID.
There could be large number of users and we can't buy separate twilio number for each user.
Please advise the solution.
How many users are likely to need to contact each individual driver at any one time? Not many I wouldn't think.
Buy 10 Twilio numbers, assign them incrementally as users call/SMS their driver and save the assignment for user/driver numbers in your database.
If the driver calls/SMS a number in response query the database and route the call/SMS to the user it was assigned to when they called the driver.
Recycle the 1st assignment once the 11th user calls/SMS the driver, rinse and repeat.
Twilio developer evangelist here.
In order to maintain anonymous communications in this way you need as many numbers as the maximum number of relationships one person in your system has. The best explanation of this is in this article on masked text messaging with Twilio (though it applies to calls too).
Your comment on miknik's answer suggests you want to keep these relationships alive forever. This is not the way that most services build out this feature. They normally give a particular length to the relationship, Uber for example will recycle the phone number a number of minutes after a ride ends.
If you are looking for an easier way to manage this kind of number pooling and masking, check out Twilio Proxy, it handles a lot of the logic for you. It is still in developer preview right now, but you can apply for early access.
is there any way whereby I can query for example a list of muc rooms but specify certain constraints.
I have attached the location of each room in each room's configuration form under the description field. I want to find out what is the best way to get all the rooms within 500m of the user's location.
On the backend, I have ejabberd server. It will be great if anyone can point me to the right documentation for this particular example
There is no such feature in Multi-User Chat extension (XEP-0045) and as such ejabberd does not implement anything special.
To implement your business logic, you will need to write a custom ejabberd module that find the room for your user based on your location criteria and return the result.
I am developing an ios app like Tinder. Users can chat only in private 1:1.
Should I have to open one channel for every single "match"? Is this the correct design pattern for this case study? What about performance if i have one channel per "match".
*Match" is when a user matches to another and can start a private chat.
If one person can have multiple matches, you can ask PubNub client to open separate channel for each nothing person. So, when you have two matching persons, you take some unique identifiers from both of them and using known algorithm create unique name of the channel for which both clients will subscribe to communicate.
One channel for whole application - really bad idea, because of possible massive flow of data, which for most of subscribers will be useless, because consumer is one of other subscribers.
Yes, the best approach is that every "match" should have it's own channel on which both participants publish/subscribe to communicate. PubNub has no limit on channels (nor does it charge based on channels), so this shouldn't create a performance or cost issue.
To add access control to the "match" channel (if you want to ensure no one else can access that channel), use PubNub Access Manager, documented here: http://www.pubnub.com/docs/javascript/tutorial/access-manager.html (use dropdown to change programming language)
If you want to provide chat history, so that the two participants can see messages from previous chat sessions, enable PubNub Storage & Playback, and use the PubNub.History() API, documented here: http://www.pubnub.com/docs/javascript/overview/storage-playback.html
If you want to see when those two participants are connected to the Match channel, use PubNub Presence, documented in the same place.
I'm creating a twilio service with three actors:
The customer, a person who calls a company
The company, a company who forwards calls to the service-provider
The service-provider (that's us), an entity that services the customer on behalf of the company
Herein lies the catch: The service provider needs to be able to identify the company associated with the customer but it may only use a single phone number. We cannot use multiple phone numbers for cost reasons (the margins are that low). We cannot use the caller id because a single customer may be associated with multiple companies.
I am familiar with Twilio's ForwardedFrom field but as mentioned here it isn't always reliable. In fact, forwarding from my cell-phone carrier results in a null ForwardedFrom field.
How can we (reliably) identify the company who redirected a customer to us without using multiple phone numbers?
You can use the number + extension. http://www.twilio.com/docs/howto/ivrs-extensions
Perhaps you could build a sort of phone tree system, asking the caller the nature of their problem, which would be an indicator of the company their call is related to.
My guess is that you wouldn't want an outright "which company are is your call related to?" question, because that would feel cheap to the customer. So, maybe you could formulate a question or series of questions that wouldn't be overtly asking which company their calling about, but the answer(s) would clearly indicate on the service-provider end which company the call is about.
This could be further whittled down on the service-provider end by doing a company lookup based on the customer's calling number - if it matches a certain company (or set of companies), then that automatically limits the potential company they could be calling about.
Another possibility (if it fits in your use case) is some sort of we'll-call-you setup. Perhaps the customer could text/email requesting a call, and the information they'd provide in the text/email/online-form-submission would indicate the company they wish to speak about (again, you could use questions that aren't overtly "which company do you want a call from?").
Then again, if it's such a low-margin operation, maybe the companies are ok with a phone-tree style call-in number, where the customer needs to select a company they're calling about which is then indicated to the service-provider.
This doesn't seem to be possible at this time (2013). I will keep an eye out for new answers and will accept them if this becomes possible at a later time.
In general, I'd recommend separate numbers per customer but since you say that's not an option, here's another approach:
When the call comes into the Company, that individual leg gets a CallSid which is a unique identifier. When the call is forwarded to the Service Provider, that separate leg also gets a CallSid. Let's call them CallSidOne and CallSidTwo respectively.
If you then query based on CallSidTwo, you'll get back its instance properties as listed here:
http://www.twilio.com/docs/api/rest/call#instance-properties
The key property here is "parent_call_sid" which should be CallSidOne. Therefore, you can connect the two segments together.. then you can query on CallSidOne which gives you the ability to track who called which customer called which customer when.
Does that solve your problem?
~Twilio employee
Social networking website probably maintain tables for users, friends and events...
How do they use these tables to compute friends events in an efficient and scalable manner?
Many of the social networking sites like Twitter don't use an RDBMS at all but a Message Queue application. A lot of them start out with a already present application like RabbitMQ. Some of them get big enough they have to heavily customize or build their own. Twitter is in the process of doing this for the second time.
A message queue application works by holding messages from one service for one or more other services. For instance say service Frank is publishing messages to a queue foo. Joe and Jill are subscribed to Franks foo queue. the application will keep track of whether or not Joe or Jill have recieved the messages and once every subscriber to the queue has recieved the message it discards it. Frank fires messages and forgets about it. Joe and Jill ask for messages from foo and get whatever messages they haven't gotten yet. Joe and Jill do whatever they need to do with the message. Perhaps keeping it around perhaps not.
The message queue application guarantees that everyone who is supposed to get the message can and will get the message when they request them. The publisher can send the messages confident that subscriber can get them eventually. This has the benefit of being completely asynchronous and not requiring costly joins.
EDIT: I should mention also that usually the storage for these kind of things at high scale are heavily denormalized. So Joe and Jill may be storing a copy of the exact same message. This is considered ok because it helps the application scale to billions of users.
Other reading:
http://www.rabbitmq.com/
http://qpid.apache.org/
The mainstay data structure of social networking sites is the graph. On facebook the graph is undirected (When you're someone's friend, they're you're friend). On twitter the graph is directed (You follow someone, but they don't necessarily follow you).
The two popular ways to represent graphs are adjacency lists and adjacency matrices.
An adjacency list is simply a list of edges on the graph. Consider a user with an integer userid.
User1, User2
1 2
1 3
2 3
The undirected interpretation of these records is that user 1 is friends with users 2 and 3 and user 2 is also friends with user 3.
Representing this in a database table is trivial. It is the many to many relationship join table that we are familiar with. SQL queries to find friends of a particular user are quite easy to write.
Now that you know a particular user's friends, you just need to join those results to the updates table. This table contains all the user's updates indexed by user id.
As long as all these tables are properly indexed, you'd have a pretty easy time designing efficient queries to answer the questions you're interested in.
Travis wrote a great post on this ,
Activity Logs and Friend Feeds on Rails & pfeed
For the small scale doing a join on users.friends and users.events and query caching is probably fine but does slow down pretty quickly as friends and events grow. You could also try an event based model in which every time a user creates an event an entry is created in a join table (perhaps called "friends_events"). Thus whenever a user wants to see what events their friends have created they can simply do a join between their own id and the friends_events table and find out. In this way you avoid grabbing all a users with friends and then joining their friends with the events table.