Does anyone know how to modify weblogic settings to set the HTTP cache header to a far future date?
For example in my current setup weblogic sets the http cache headers to expire in 5 hours (as a response of HTTP/1.1 304 Not Modified).
This is the cache header value on a .gif file ... Date: Tue, 16 Mar 2010 20:39:13 GMT.
I have re-checked and it's always 5 hours. There must be some for of settings that I can tweak to change it.
Thanks for your time!
You can use this property :
<wls:container-descriptor>
<wls:resource-reload-check-secs>-1</wls:resource-reload-check-secs>
</wls:container-descriptor>
The element is used to perform metadata caching for cached resources that are found in the resource path in the Web application scope. This parameter identifies how often WebLogic Server checks whether a resource has been modified and if so, it reloads it.
The value -1 means metadata is cached but never checked against the disk for changes. In a production environment, this value is recommended for better performance.
Static content is served by a weblogic.servlet.FileServlet that all web applications have by default but I couldn't find any way to configure HTTP headers. So either replace this servlet with your own servlet or use a Filter.
But the above comment is right, using a web server to serve static content is the "right" way to go: a web server does a better job at this and the application server has other things to do than serving static files.
Related
I'm using memcached and Apache with the following default configuration
CacheEnable socache /
CacheSocache memcache:IP:PORT
MemcacheConnTTL 30
What will the behavior be when 30 seconds expire and a request for the same URL comes in? Is there a way to configure the cache key? I.e. what are the info which make a request unique?
What if the server can't get an answer? (like timeout to fetch the newly updated object) Can it be configured to serve the old object?
Thanks
What will the behavior be when 30 seconds expire and a request for the same URL comes in
Apache would simply create a new connection to memcached. It doesn’t mean something would happen to the data stored in memcached
https://httpd.apache.org/docs/2.4/mod/mod_socache_memcache.html#memcacheconnttl
Set the time to keep idle connections with the memcache server(s)
alive (threaded platforms only).
If you need to control for how long an object will be stored in a cache, check out CacheDefaultExpire
Is there a way to configure the cache key
An url is used to build the key, but you can partially configure which parts of the url are used, check out
CacheIgnoreQueryString, CacheIgnoreURLSessionIdentifiers
I.e. what are the info which make a request unique
https://httpd.apache.org/docs/2.4/mod/mod_cache.html#cacheenable
The CacheEnable directive instructs mod_cache to cache urls at or
below url-string
Notice that not all requests can be cached, there’s a lot of rules on it
What if the server can't get an answer? Can it be configured to serve the old object
You need CacheStaleOnError
https://httpd.apache.org/docs/2.4/mod/mod_cache.html#cachestaleonerror
When the CacheStaleOnError directive is switched on, and when stale
data is available in the cache, the cache will respond to 5xx
responses from the backend by returning the stale data instead of the
5xx response
I have a war with some static files (mostly images) in the webapp deployed on Wildfly. Sometimes the application needs to update some of those files, which then get replaced in the filesystem.
However Wildfly/Undertow seem to think that nothing has changed and the Last-Modified header in the response keeps showing the time before the update.
So I wonder what is Undertow using to determine the Last-Modified header shown. I've tried "touching" the parent directory, but to no effect.
In fact it looks like wildfly/undertow caches the last modified time after the first time it loaded a given resource.
Update
It's clearly a problem with the cache, since if I remove one of the files I requested before and request it again I get 500 Internal Server Error and stacktrace!
As pointed out in this thread the exploded war directory is not the right place for static resources that can be changed.
Instead one should use some other directory on the filesystem and configure the undertow subsystem to serve those pages. See for example this question.
I sense I'm going to end up embarrassed for asking such a simple question, but I've been researching for days and can't any useful information.
What determines the HTTP response header that a server sends? If I control the server (if we need concreteness, let's say Apache), then what file can I edit to change the response header? For example, to set it to include Content-Length instead of Transfer-Encoding: chunked?
I'm aware that PHP and Java Servlets can be used to manipulate headers. The existence and content of response headers is fundamental to HTTP, though, so there ought to exist a way to edit these without using outside technology, no?
Certain headers are set automatically. They are part of the HTTP spec and the server takes care of them for you. That’s what a web server is for and why it differs from, say, an FTP server or a fileshare. For example Content-Length is easily calculated by the webserver and needs to be set so the server just does it.
Certain other headers are set based on config. Apache usually loads a main config file (often called httpd.conf or apache2.conf) but then, to save this file getting into a big unwieldy mess it often loads other files from within that. Those files are just text files with lines of configuration text to change behaviour of the server. Other web servers may use XML configuration files and may have a GUI to control the config (e.g. IIS)
So, for some of the headers, you might not explicitly set the header value but you basically configure the server and it then uses that config to figure out the appropriate headers to send. For example you can configure the server to gzip certain files (e.g. text files but not jpgs which are already compressed). In Apache this is handled by the mod_deflate module and the config options it gives you. Once the appropriate config is added to the server config, the server will do the necessarily processing (e.g. gzip the file or not depending on type) and then automatically add the headers. So an Apache module is basically something that changes how the server works and this may or may not the also set headers. Another example is for sending caching headers to tell the browser how long to cache files for. This is controlled by adding the mod_expiries module and all the config options it allows. While some of these headers could be hardcoded (e.g. Cache-Control) others depend on Apache doing calculations (e.g. Expires) so better to use the module to do this for you based on your config.
And finally you can explicitly set headers in your server (in Apache this is done using the mod_headers module). This is useful for new features added to browsers for example (e.g. HSTS, CSP or HPKP) where the server doesn't need to do anything but just add the header and the client (e.g. the web browser) knows what to do with them. You could add a JonahHuron header for example by adding this config to httpd.conf:
Header always set JonahHuron "Some Value"
As to whether that header is used depends entirely on the program receiving the response.
Is there any php.ini setting which could cause isset($_SERVER["CONTENT_LENGTH"]) to never be set on one server, but work fine on another, where the application code is the same and php.ini upload settings are the same? In an uploader library I'm using, the content length check always fails because of this issue. On PHP5.3, CentOS and Apache. Thanks for any help
EDIT: I should add that in the Request Headers, Content-Length:33586 - but when trying to process $_SERVER["CONTENT_LENGTH"], it isn't set.
Content-Length is sent by the server application, it's not part of the HTTP request.
Your application is the one that will be setting that, however you should not be doing that from within PHP as PHP does this automatically.
If you're dealing with input from something like an upload, then you will only get the Content-Length if the HTTP request is not CHUNKED. When sending a chunked request, the data length is not known to the recipient until all the chunks have been sent.
I have a question about using AFNetworking with SDURLCache.
In my application. I can see they work together fine, for repeated queries, responses from local cache will be used correctly.
But, let's say the server xml is updated one minute ago, in my app, cache is still used.
This doesn't match my client's expectation, the client's expectation is:
I need to check http header, if it is 200, load the file from server, if it is 304 (not modified), just use local cache from disk/
Any chance this is a built-in behaviour? Or I have to manually hack the class somewhere so that it can behave like this?