I have these files (as a sample; I actually have much more):
/files/dir1/dir_a/f.xml
/files/dir1/dir_b/f.xml
/files/dir2/dir_a/f.xml
/files/dir2/dir_b/f.xml
and I need the following filter:
/files/*/dir_a/f.xml
I use Camel Ftp2 and AntPathMatcher, and it works fine.
However, Ftp2 lists first all the files and then validates each one with AntPathMatcher.
The problem is that I happen to have a lot of files in /files/*/dir_b/, and the ftp connection could be slow, so that it takes too long.
It would be better if Ftp2 and AntPathMatcher work together (not one after the other), so that Ftp2 knows that it does not need to scan all files at /files/*/dir_b/
Is it possible to achieve that in some way?
The FTP Client API would then need support for listing directories using filters (eg * as wildcard etc.). However I have not seen this supported. I wonder if thats even support in the "FTP standard".
Related
Currently i am using the REST interface to query vespa, which seems to work great but something tells me that i should be using searchers in the application to make the client(server side code) a bit lighter (bundle the jar file in the application package) to make it a bit smoother. I have managed to do some simple searcher/processor applications. But this is a bit overwhelming.
So are there any readily available examples ?
Basicially i want to:
Send to /search?query=someId
Do a ordinary search for the weighted set on this documentID (I guess this one can be handy: https://docs.vespa.ai/documentation/reference/inspecting-structured-data.html)
Take those items in the response and add it to a wand item(s) and query for a wand with wandsearcher on a given field. Similar to the yql:
"select * from sources * where wand(interest, some weightedsets));","ranking":"combined_score" and return the matches.
Just curious also, apart from the trouble of string building with the http request i am doing at the moment are there any performance gains of using a searcher or go the java route vs rest?
thanks for any insight or code help i can start with.
There is an example of using the WandItem (YQL wand)here https://docs.vespa.ai/documentation/advanced-ranking.html and see also https://docs.vespa.ai/documentation/using-wand-with-vespa.html as there are two wand implementations available in Vespa, it sounds from the description that the wand() is what you want to use for this use case. For the first call you probably want to have a dedicated document summary to reduce the amount of data fetched for your first query and also the option of serving it out of memory only (See https://docs.vespa.ai/documentation/document-summaries.html)
Also see https://docs.vespa.ai/documentation/searcher-development.html as a general resource on writing searchers.
For your use case it makes a lot of sense to write a searcher to perform these two queries as your second query depends on the first and you avoid the cost of rendering/http/yql parsing which might matter if your client is remote with high network latency.
Is there a such thing as a preprocessor whose statements, once processed, disappear completely and get replaced by the target language syntax permanently?
I want to research it on the web but I don't know what term to search for. If I search for "code generator", "templating language", "preprocessor directives", "mixins", "annotations" I get generators whose input becomes the source of truth.
The closest thing I can think of is a macro.
What I'm trying to do
I often have to write code that is verbose and unnecessary manual labor and am looking for a smarter way to input at least the majority of it and have it automatically transformed and only source-control the output (and hand edit if necessary). For example:
Java code - Instead of writing getters/setters, javadoc (perhaps the transformer can be a maven plugin)
HTML - I just want to add URLs, and have my preprocessor automatically convert them to links, images, videos, audio etc. depending on the file extension with some regex substitution (currently I run a perl script via a cron job)
I just want to use it as my own shorthand and not enforce it in my project and make the output editable so that others have to learn a new framework or language (like Protobuf, Stringtemplate, GWT, C hash-defines, PHP, JSP etc).
There should be no direct clue that I used a template/preprocessor to generate it.
What you want is a "program transformation system". See https://en.wikipedia.org/wiki/Program_transformation. (This is a superset of "transpilers" [ugly term]).
A good source-to-source transformation system will let you apply rewrite rules of the form of:
if you see *this*, replace it by *that* if *this_condition*.
You can then take your source code, and run a set of rewrite rules across that code to change it.
The resulting code is "transformed"; the rewrite rules are not visible.
It seems like Transpiler is one way to describe it.
Is there a way to achieve the following?
Source is a single .rst file where the translation in multiple languages coexist
Generate web page renditions per language (in .html files preferably).
This can be either a single file where readers can switch between languages, or multiple separate .html files
Preferably web page generation can be done by rst2html but other common tools are welcomed as well
Usecase I have in mind. In foo.rst (I don't mean I want exactly tags like these):
..lang_en:
She likes spinach the best.
..lang_de:
Sie mag am besten Spinat.
Result would be, as I mentioned, either a single foo.html, or a set of foo_en.html and foo_de.html.
I figured out by using sphinx-intl; it creates folders per language, and update the translations based on the change in the master file take a few steps (which requires careful operation), but I'm satisfied.
If you need a concrete example, in this project holds I'm maintaining English and Japanese renditions.
I'm looking for a way to conditionally handle messages based on the aggregation of messages. I've looked into a lot of ways to do this, but it seems that Apache Camel doesn't support it. I'll explain the scenario and then the solutions I tried.
Scenario:
I'm trying to conditionally clean a directory. I poll from the directory every x days and fetch all the files (file://...). I route this into an aggregation, that aggregates the files into a single size (directorySize). I then check if this size passes a certain threshold.
Here is where the problem lies. I now want to remove certain files if this condition passes, but I don't have access to the original messages anymore because they were aggregated in a new exchange.
Solutions:
I tried to fetch the files again to process them. Problem is that you can't make a consumer fetch on demand as far as I know. I tried using pollEnrich, but that will only fetch a single file and not all files in the directory.
I tried to filter/stop the parent route. The problem here is that filter()/choice...stop()/end() will only stop the aggregated route with the directory size and not the parent route with the file messages. I can't conditionally process these.
I tried to move the aggregated condition to another route that I would call, but this causes the same problem as the first solution.
Things I consider doing:
Rewrite the aggregation strategy to not only aggregate the size, but also the files itself into a groupedExchange. This way I can split the aggregation again after the check. I don't really like this solution because it causes a lot boilerplate, both in code as during runtime.
Move the file size calculator to a processor instead of the aggregator. This would defeat the purpose of using camel in the first place.. I would manually be fetching the files and adding the sizes.. And that for every single file..
Use a ControlBus to dynamically start the delete route on that directory. Once again a lot of workaround to achieve something that I feel should be able to be done in a simple route.
I would like to set the calculated size on every parent message, but I have no clue how this could be achieved?
Another way to stop the parent route that I haven't thought of?
I'm a bit stunned that you can't elegantly filter messages based on the aggregation of these messages. Is there something that I missed in Camel that would provide an elegant solution? Or is this a case of the least bad solution?
Simple Schema
Message(File)
Message(File) --> AggregatedMessage(directorySize) --> delete certain Files?
Message(File)
Camel is really awesome, but sometimes it's sure difficult to see exactly which design pattern to use ;)
Firstly, you need to keep a copy of the file objects, because you don't know whether to delete them or not until you reach your threshold - there are basically (at least) two ways to do this.
Alternative 1
The first way is to use a List in an exchange property. This property will hang around no matter what you do with the exchange body. If you have a look at the source code for GroupedExchangeAggregationStrategy, it does precisely this:
list = new ArrayList<Exchange>();
answer.setProperty(Exchange.GROUPED_EXCHANGE, list);
// ...
list.add(newExchange);
Or you could do the same thing manually on your own exchange property. In any case, it's completely fine to use the Grouped aggregation strategy as you have done.
Alternative 2
The second way to "keep" old messages is to send a copy to a stopped SEDA queue. So you would do to("seda:xyz"). You define this queue as .noAutoStartup(). Then you can send messages to it and they will queue up on an internal queue, managed by camel. When you want to process the messages, you simply start it up via controlbus and stop it again afterwards.
Generally, messing around with starting and stopping queues should be avoided unless absolutely necessary, but that's certainly another way to do it
Suggested solution
I suggest you do as you have done (i.e. alternative 1):
aggregate via GroupedExchangeAggregationStrategy to keep the individual files in a list
Compute the total file size (use a processor, or do it along the way with a custom aggregation strategy)
Use a filter(simple("${body} < 123"))
"Unwind" your aggregation via a splitter(simple("${property.CamelGroupedExchange}"))
Delete your files one by one
Please let me know if this doesn'y makes sense, or if I have misunderstood your problem in any way.
The current XML Helper in CakePHP doesn't give you the ability to specify if you want the whitespace to be significant or non-significant. Normally it wouldn't matter, but I'm working with a strict API that requires certain values to have no excess characters surrounding the value (no \n's or \t's). I'd like to modify the Cake source to support this ability, and if anyone has done this before and has any tips or advise on how to start, I'd appreciate it. Actually I believe the most helpful thing would be if someone has a flowchart of how Cake comes together (ie: starts in index.php and flows through router.php or what-not). I'd like to get a better understanding of how Cake is constructed (even from a high level).
Thanks!
If you want to change one of the built-in helpers, just copy it into your /app/views/helpers/ directory and edit it from there. The version in your app will be used instead of the original.