I want to send a bunch of XML files from my client (iPad) to my application server(Web)..Is there any way I can pass them to server using HTTP POST? I assume HTTP POST only allows embedding strings not attaching as files..We don't want to use FTP due to securuty reasons. We even thought of web service, but not sure whether attachments are possible..Pleas advise if you know any ways of transferring files from client to server.
The maximum length of a POST variable is massive - so no worries there, you can send XML fine. POST can send any type of data, just make sure you set the Content-Type header correctly or you may get unexpected results.
It is no less / more secure than FTP however.
Related
I would like to try send requests.get to this website:
requests.get('https://rent.591.com.tw')
and I always get
<Response [404]>
I knew this is a common problem and tried different way but still failed.
but all of other website is ok.
any suggestion?
Webservers are black boxes. They are permitted to return any valid HTTP response, based on your request, the time of day, the phase of the moon, or any other criteria they pick. If another HTTP client gets a different response, consistently, try to figure out what the differences are in the request that Python sends and the request the other client sends.
That means you need to:
Record all aspects of the working request
Record all aspects of the failing request
Try out what changes you can make to make the failing request more like the working request, and minimise those changes.
I usually point my requests to a http://httpbin.org endpoint, have it record the request, and then experiment.
For requests, there are several headers that are set automatically, and many of these you would not normally expect to have to change:
Host; this must be set to the hostname you are contacting, so that it can properly multi-host different sites. requests sets this one.
Content-Length and Content-Type, for POST requests, are usually set from the arguments you pass to requests. If these don't match, alter the arguments you pass in to requests (but watch out with multipart/* requests, which use a generated boundary recorded in the Content-Type header; leave generating that to requests).
Connection: leave this to the client to manage
Cookies: these are often set on an initial GET request, or after first logging into the site. Make sure you capture cookies with a requests.Session() object and that you are logged in (supplied credentials the same way the browser did).
Everything else is fair game but if requests has set a default value, then more often than not those defaults are not the issue. That said, I usually start with the User-Agent header and work my way up from there.
In this case, the site is filtering on the user agent, it looks like they are blacklisting Python, setting it to almost any other value already works:
>>> requests.get('https://rent.591.com.tw', headers={'User-Agent': 'Custom'})
<Response [200]>
Next, you need to take into account that requests is not a browser. requests is only a HTTP client, a browser does much, much more. A browser parses HTML for additional resources such as images, fonts, styling and scripts, loads those additional resources too, and executes scripts. Scripts can then alter what the browser displays and load additional resources. If your requests results don't match what you see in the browser, but the initial request the browser makes matches, then you'll need to figure out what other resources the browser has loaded and make additional requests with requests as needed. If all else fails, use a project like requests-html, which lets you run a URL through an actual, headless Chromium browser.
The site you are trying to contact makes an additional AJAX request to https://rent.591.com.tw/home/search/rsList?is_new_list=1&type=1&kind=0&searchtype=1®ion=1, take that into account if you are trying to scrape data from this site.
Next, well-built sites will use security best-practices such as CSRF tokens, which require you to make requests in the right order (e.g. a GET request to retrieve a form before a POST to the handler) and handle cookies or otherwise extract the extra information a server expects to be passed from one request to another.
Last but not least, if a site is blocking scripts from making requests, they probably are either trying to enforce terms of service that prohibit scraping, or because they have an API they rather have you use. Check for either, and take into consideration that you might be blocked more effectively if you continue to scrape the site anyway.
One thing to note: I was using requests.get() to do some webscraping off of links I was reading from a file. What I didn't realise was that the links had a newline character (\n) when I read each line from the file.
If you're getting multiple links from a file instead of a Python data type like a string, make sure to strip any \r or \n characters before you call requests.get("your link"). In my case, I used
with open("filepath", 'w') as file:
links = file.read().splitlines()
for link in links:
response = requests.get(link)
In my case this was due to fact that the website address was recently changed, and I was provided the old website address. At least this changed the status code from 404 to 500, which, I think, is progress :)
How can I detect if a given URL is a file to be downloaded?
I came across the content-disposition header, however it seems that this isn't a part of http 1.1 directly.
Is there a more standard way to detect if the response for a GET request made to a given URL is actually a file to/can be downloaded?
That is the response is not html or json or anything similar, but something like an image, mp3, pdf file etc.?
HTTP is a transfer protocol - which is a very different thing to hard drive storage layouts. The concept of "file" simply does not exist in HTTP. No more than your computer hard drive contains actual paper-and-cardboard "files" that one would see in an office filing system.
Whatever you may think the HTTP message or URL are saying the response content does not have to come from any computer file, and does not have to be stored in one by the recipient.
The response to any GET message in HTTP can always be "downloaded" by sending another GET request with that same URL (and maybe other headers in the case of HTTP/1.1 variants). That is built into the definition of what a GET message is and has nothing to do with files.
I ended up using the content-type to decide if it's an html file or some other type of file that is on the other end of a given URL.
I'm using the content-disposition header content to detect the original file name if it exists since the header isn't available everywhere.
Could checking for a file extension be a possibility? Sorry I can't enlarge on that much without knowing more, but I guess you could consider using PHP to implement this if HTML doesn't have enough functionality?
I've got a problem trying to run a test plan in JMeter which contains a
multipart/form-data POST. For some reason the web server does not respond
with the expected response when JMeter does the POST (which was recorded
with the proxy).
Please tell me the exact configuration to handle it(if any).
As per Upload and Download Scenarios with Apache JMeter guide
Check that “Use multipart/form data for POST” is ticked
Check that files for upload actually exist in their relative location or use the full paths
Provide the correct MIME Type
The combination of above should do the trick for you.
If your file upload assumes authenticated user, make sure that you have HTTP Cookie Manager is present and enabled and in case of any dynamic parameters, like viewstate input value or JSESSIONID cookie you pass them properly. Use a sniffer tool like WireShark to ensure that your request is an exact replica of browser request.
Does HTTP PUT have advantages over HTTP POST, particularly for File Uploads? Data transfer should be highly secure. Your ideas / guidance on this will be of great help.
PUT is designed for file uploads moreso than POST which requires doing a multipart upload, but then it comes down to what your server can do as to which is more convenient for you to implement.
Whichever HTTP method you use, you'll be transmitting data in the clear unless you secure the connection using SSL.
I think the choice of PUT vs. POST should be more based on the rule:
PUT to a URL should be used to update or create the resource that can be located at that URL.
POST to a URL should be used to update or create a resource which is located at some other ("subordinate") URL, or is not locatable via http.
Any choices regarding security should work equally with both PUT and POST. https is a good start, if you are building a REST API then keys, authorisation, authentication and message signing are worth investigating.
Does HTTP PUT have advantages over HTTP POST, particularly for File Uploads?
You can use standard tools for sending the data (i.e. ones that don't have to be aware of your custom scheme for describing where the file should be uploaded to or how to represent that file). For example, OpenOffice.org includes WebDAV support.
Data transfer should be highly secure
The method you use has nothing to do with that. For security use SSL in combination with some form of authentication and authorization.
Use-case: Upload a simple image file to a server, which clients could later retrieve
Designate a FTP Server for the job.
HTTP Put: It can directly upload files to a server without the need of a server side
component to handle the bytestream.
HTTP Post: Handle the bytestream by the server side component.
I think to safely use PUT on a public website requires even more effort than using POST (and is less commonly done) due to potential security issues. See http://bitworking.org/news/PUT_SaferOrDangerous.
OTOH, I think there are plenty of resources for safely uploading files with POST and checking them in the server side script, and that this is the more common practice.
PUT is only appropriate when you know the URL you are putting to.
You could also do:
4) POST to obtain a URL to which you then PUT the file.
edit: how are you going to get the HTTP server to decide whether it is OK to accept a particular PUT request?
What I usually do (via PHP) is HTTP POST.
And employ PHP's move_uploaded_file() to get it to whatever destination I want.