I need to test an application that processes SIP requests. For now, I want to test the performance of the application, so I need a way to generate a big number of SIP requests.
I know there are tools for this (like SipP), but I don't know what is the maximum number of requests that a single computer can really send in a particular time interval.
I never done this type of test, i need help.
Thanks
Well sipp can generate requests pretty quickly and if you're testing call set up and tear down, i.e. INVITE requests an d associated transaction processing, it's almost certainly the tool for the job.
If you're not concerned about SIP transaction processing and instead just want to bombard your server with SIP requests you could just whip up a console application with a UDP socket and send dummy requests by using a template request and modifying the following:
The branchid parameter on the Via header,
The tag parameter on the From header,
The Call-ID header.
Since your app will only be doing a few string search and replaces and a UDP send it will be able to generate requests probably a 100 to 1000 times faster than a server on the same hardware, that needs to parse and understand the requests, will be able to process them.
Related
I have created a REST API - in a few words, my client hits a particular URL and she gets back a JSON response.
Internally, quite a complicated process starts when the URL is hit, and there are various services involved as a microservice architecture is being used.
I was observing some performance bottlenecks and decided to switch to a message queue system. The idea is that now, once the user hits the URL, a request is published on internal message queue waiting for it to be consumed. This consumer will process and publish back on a queue and this will happen quite a few times until finally, the same node servicing the user will receive back the processed response to be delivered to the user.
An asynchronous "fire-and-forget" pattern is now being used. But my question is, how can the node servicing a particular person remember who it was servicing once the processed result arrives back and without blocking (i.e. it can handle several requests until the response is received)? If it makes any difference, my stack looks a little like this: TomCat, Spring, Kubernetes and RabbitMQ.
In summary, how can the request node (whose job is to push items on the queue) maintain an open connection with the client who requested a JSON response (i.e. client is waiting for JSON response) and receive back the data of the correct client?
You have few different scenarios according to how much control you have on the client.
If the client behaviour cannot be changed, you will have to keep the session open until the request has not been fully processed. This can be achieved employing a pool of workers (futures/coroutines, threads or processes) where each worker keeps the session open for a given request.
This method has few drawbacks and I would keep it as last resort. Firstly, you will only be able to serve a limited amount of concurrent requests proportional to your pool size. Lastly as your processing is behind a queue, your front-end won't be able to estimate how long it will take for a task to complete. This means you will have to deal with long lasting sessions which are prone to fail (what if the user gives up?).
If the client behaviour can be changed, the most common approach is to use a fully asynchronous flow. When the client initiates a request, it is placed within the queue and a Task Identifier is returned. The client can use the given TaskId to poll for status updates. Each time the client requests updates about a task you simply check if it was completed and you respond accordingly. A common pattern when a task is still in progress is to let the front-end return to the client the estimated amount of time before trying again. This allows your server to control how frequently clients are polling. If your architecture supports it, you can go the extra mile and provide information about the progress as well.
Example response when task is in progress:
{"status": "in_progress",
"retry_after_seconds": 30,
"progress": "30%"}
A more complex yet elegant solution would consist in using HTTP callbacks. In short, when the client makes a request for a new task it provides a tuple (URL, Method) the server can use to signal the processing is done. It then waits for the server to send the signal to the given URL. You can see a better explanation here. In most of the cases this solution is overkill. Yet I think it's worth to mention it.
One option would be to use DeferredResult provided by spring but that means you need to maintain some pool of threads in request serving node and max no. of active threads will decide the throughput of your system. For more details on how to implement DeferredResult refer this link https://www.baeldung.com/spring-deferred-result
I am working on Apache Jmeter. I am going to simulate DOS attack with this software, so I need a script for benign client and script for malicious client. benign client send a request every second and malicious client send 10 request per second. How should I do it?
HTTP Request sampler will be quite enough to simulate your scenario.
Make sure that you provide enough threads on Thread Group level
Amount of request per second can be precisely controlled by Constant Throughput Timer
Similar questions have been asked before and they all reached the conclusion that AJAX will not become obsolete. But in what ways is ajax better than websockets?
With socket.io, it's easy to fall back to flash or long polling, so browser compatibility seems to be a non-issue.
Websockets are bidirectional. Where ajax would make an asynchronous request, websocket client would send a message to the server. The POST/GET parameters can be encoded in JSON.
So what is wrong with using 100% websockets? If every visitor maintains a persistent websocket connection to the server, would that be more wasteful than making a few ajax requests throughout the visit session?
I think it would be more wasteful. For every connected client you need some sort of object/function/code/whatever on the server paired up with that one client. A socket handler, or a file descriptor, or however your server is setup to handle the connections.
With AJAX you don't need a 1:1 mapping of server side resource to client. Your # of clients can scale less dependently than your server-side resources. Even node.js has its limitations to how many connections it can handle and keep open.
The other thing to consider is that certain AJAX responses can be cached too. As you scale up you can add an HTTP cache to help reduce the load from frequent AJAX requests.
Short Answer
Keeping a websocket active has a cost, for both the client and the server, whether Ajax will have a cost only once, depending on what you're doing with it.
Long Answer
Websockets are often misunderstood because of this whole "Hey, use Ajax, that will do !". No, Websockets are not a replacement for Ajax. They can potentially be applied to the same fields, but there are cases where using Websocket is absurd.
Let's take a simple example : A dynamic page which loads data after the page is loaded on the client side. It's simple, make an Ajax call. We only need one direction, from the server to the client. The client will ask for these data, the server will send them to the client, done. Why would you implement websockets for such a task ? You don't need your connection to be opened all the time, you don't need the client to constantly ask the server, you don't need the server to notify the client. The connection will stay open, it will waste resources, because to keep a connection open you need to constantly check it.
Now for a chat application things are totally different. You need your client to be notified by the server instead of forcing the client to ask the server every x seconds or milliseconds if something is new. It would make no sense.
To understand better, see that as two persons. One of the two is the server, the over is the client. Ajax is like sending a letter. The client sends a letter, the server responds with another letter. The fact is that, for a chat application the conversation would be like that :
"Hey Server, got something for me ?
- No.
- Hey Server, got something for me ?
- No.
- Hey Server, got something for me ?
- Yes, here it is."
The server can't actually send a letter to the client, if the client never asked for an answer. It's a huge waste of resources. Because for every Ajax request, even if it's cached, you need to make an operation on the server side.
Now the case I discussed earlier with the data loaded with Ajax. Imagine the client is on the phone with the server. Keeping the connection active has a cost. It costs electricity and you have to pay your operator. Now why would you need to call someone and keep him on phone for an hour, if you just want that person to tell you 3 words ? Send a goddamn letter.
In conclusion Websockets are not a total replacement for Ajax !
Sometimes you will need Ajax where Websocket usage is absurd.
Edit : The SSE case
That technology isn't used very widely but it can be useful. As its name states it, Server-Sent Events are a one-way push from the server to the client. The client doesn't request anything, the server just sends the data.
In short :
- Unidirectional from the client : Ajax
- Unidirectional from the server : SSE
- Bidirectional : Websockets
Personally, I think that websockets will be used more and more in web applications instead of AJAX. They are not well suited to web sites where caching and SEO are of greater concern, but they will do wonders for webapps.
Projects such as DNode and socketstream help to remove the complexity and enable simple RPC-style coding. This means your client code just calls a function on the server, passing whatever data to that function it wants. And the server can call a function on the client and pass it data as well. You don't need to concern yourself with the nitty gritties of TCP.
Furthermore, there is a lot of overhead with AJAX calls. For instance, a connection needs to be established and HTTP headers (cookies, etc.) are passed with every request. Websockets eliminate much of that. Some say that websockets are more wasteful, and perhaps they are right. But I'm not convinced that the difference is really that substantial.
I answered another related question in detail, including many links to related resources. You might check it out:
websocket api to replace rest api?
I think that sooner or later websocket based frameworks will start to popup not just for writing real-time chat like parts of web apps, but also as standalone web frameworks. Once permanent connection is created it can be used for receiving all kinds of stuff including UI parts of web application which are now served for example through AJAX requests. This approach may hurt SEO in some way although it can reduce amount of traffic and load generated by asynchronous requests which includes redundant HTTP headers.
However I doubt that websockets will replace or endanger AJAX because there are numerous scenarios where permanent connections are unnecessary or unwanted. For example mashup applications which are using (one time) single purpose REST based services that doesn't need to be permanently connected with clients.
There's nothing "wrong" about it.
The only difference is mostly readability. The main advantage of Ajax is that it allows you fast development because most of the functionality is written for you.
There's a great advantage in not having to re-invent the wheel every time you want to open a socket.
WS:// connections have far less overhead than "AJAX" requests.
As other people said, keeping the connection open can be overkill in some scenarios where you don't need server to client notifications, or client to server request happens with low frecuency.
But another disadvantage is that websockets is a low level protocol, not offering additional features to TCP once the initial handshake is performed. So when implementing a request-response paradigm over websockets, you will probably miss features that HTTP (a very mature and extense protocol family) offers, like caching (client and shared caches), validation (conditional requests), safety and idempotence (with implications on how the agent behaves), range requests, content types, status codes, ...
That is, you reduce message sizes at a cost.
So my choice is AJAX for request-response, websockets for server pushing and high frequency low latency messaging
If you want the connection to server open and if continuous polling to the server will be there then go for sockets else you are good to go with ajax.
Simple Analogy :
Ajax asks questions(requests) to server and server gives answers(responses) to these questions. Now if you want to ask continuous questions then ajax wont work, it has a large overhead which will require resources at both the ends.
I'm working on a web application that submits tasks to a master/worker system that farms out the tasks to any of a series of worker instances. The work queue master runs as a separate process (on a separate machine altogether) and tasks are submitted to the master via HTTP/REST requests. Once tasks are submitted to the work queue, client applications can submit another HTTP request to get status information about tasks.
For my web application, I'd like it to provide some sort of progress bar view that gives the user some indication of how far along task processing has come. The obvious way to implement this would be an AJAX progress meter widget that periodically polls the work queue for status on the tasks that have been submitted. My question is, is there a better way to accomplish this without the frequent polling?
I've considered having the client web application open up a server socket on which it could listen for notifications from the work master. Another similar thought I've had is to use XMPP or a similar protocol for the status notifications. (Of course, the master/worker system would need to be updated to provide notifications either way but I own the code for that so can make any necessary updates myself.)
Any thoughts on the best way to set up a notification system like this? Is the extra effort involved worth it, or is the simple polling solution the way to go?
Polling
The client keeps polling the server to get the status of the response.
Pros
Being really RESTful means cacheable and scaleable.
Cons
Not the best responsiveness if you do not want to poll your server too much.
Persistent connection
The server does not close its HTTP connection with the client until the response is complete. The server can send intermediate status through this connection using HTTP multiparts.
Comet is the most famous framework to implement this behaviour.
Pros
Best responsiveness, almost real-time notifications from the server.
Cons
Connection limit is limited on a web server, keeping a connection open for too long might, at best load your server, at worst open the server to Denial of Service attacks.
Client as a server
Make the server post status updates and the response to the client as if it were another RESTful application.
Pros
Best of every worlds, no resources are wasted waiting for the response, either on the server or on the client side.
Cons
You need a full HTTP server and web application stack on the client
Firewalls and routers with their default "no incoming connections at all" will get in the way.
Feel free to edit to add your thoughts or a new method!
I guess it depends on a few factors
How accurate the feedback can be (1 percent, 5 percent, 50 percent) Accurate feedback makes it worth pursuing some kind of progress bar and comet style push. If you can only say "Busy... hold on... almost there... done" then a simple ajax "are we there yet" poll is certainly easier to code.
How timely the Done message has to be seen by the client
How long each task takes (1 second, 10 seconds, 10 minutes)
1 second makes it a bit moot. 10 seconds makes it worth it. 10 minutes means you're better off suggesting the user goes for a coffee break :-)
How many concurrent requests there will be
Unless you've got a "special" server, live push style systems tend to eat connections and you'll be maxed out pretty quickly. Having to throw more webservers in for a fancy progress bar might hurt the budget.
I've got some sample code on 871184 that shows a hand rolled "forever frame" which seems to work out well. The project I developed that for isn't hammered all that hard though, the operations take a few seconds and we can give pretty accurate percent. The code uses asp.net and jquery, but the general techniques will work with any server and javascript framework.
edit As John points out, status reporting probably isn't the job of the RESTful service. But there's nothing that says you can't open an iframe on the client that hooks to a page on the server that polls the service. Theory says the server and the service will at least be closer to one another :-)
Look into Comet. You make a single request to the server and the server blocks and holds the connection open until an update in status occurs. Once that happens the response is sent and committed. The browser receives this response, handles it and immediately re-requests the same URL. The effect is that of events being pushed to the browser. There are pros and cons and it might not be appropriate for all use cases but would provide the most timely status updates.
My opinion is to stick with the polling solution, but you might be interested in this Wikipedia article on HTTP Push technologies.
REST depends on HTTP, which is a request/response protocol. I don't think you're going to get a pure HTTP server calling the client back with status.
Besides, status reporting isn't the job of the service. It's up to the client to decide when, or if, it wants status reported.
One approach I have used is:
When the job is posted to the server, the server responds back a pubnub-channel id (one could alternatively use Google's PUB-SUB kind of service).
The client on browser subscribes to that channel and starts listening for messages.
The worker/task server publishes status on that pubnub channel to update the progress.
On receiving messages on the subscribed pubnub-channel, the client updates the web UI.
You could also use self-refreshing iframe, but AJAX call is much better. I don't think there is any other way.
PS: If you would open a socket from client, that wouldn't change much - PHP browser would show the page as still "loading", which is not very user-friendly. (assuming you would push or flush buffer to have other things displayed before)
We are currently developing a server whereby a client requests interest in changes to specific data elements and when that data changes the server pushes the data back to the client. There has vigorous debate at work about whether or not it would be better for the client to poll for this data.
What is considered to be the ideal method, in terms of performance, scalability and network load, of data transfer in a near real time environment?
Update:
Here's a Link that gives some food for thought with regards to UI updates.
There's probably no ideal method for every situation, but push is usually better and used more often. It allows to optimize server caching and data transfers, which helps performance and scalability, and cuts network traffic a bit by avoiding client requests and empty responses. It can be important advantage for a server to operate in it's own pace and supply clients with data when it is ready.
Industry standarts - such as OPC, GID - support both. Server pushes updates to subscribed clients, but client can pull some rarely used data out without bothering with subscription.
As long as the client initiates the connection (to get passed firewall and NAT problems) either way is fine.
If there are several different type of data you need to send, you might want to have the client specify which type he wants, but this is only needed once per connection. Then you can have the server continue to send updates as it has them.
It would be less network traffic to have the server send updates without the client continually asking for updates.
What do you have on the client's side? Many firewalls allow outgoing requests but block incoming requests. In other words, pull may be your only option if you are crossing the Internet unless you are sending out e-mails.