How to correlate SUPL WcdmaCellInformation with MLS cell id - supl

I'm trying to understand how to interpret data from a SUPL* messages containing a wcdmaCellInformation. I've captured the data from my handset, the relevant section looks like this:
locationId: LocationId ::= {
cellInfo: WcdmaCellInformation ::= {
refMCC: 204
refMNC: 8
refUC: 4247339
}
status: 1
}
I'm trying to look up this cell information in the mozilla location services data. I've downloaded the data from https://location.services.mozilla.com/downloads and extracted it.
I can easily find matches for the refMCC (mobile country code, 204 is Netherlands) and refMNC (8 is KPN), but I'm stuck on finding the right cell in the MLS data.
If I grep for the refUC I only find a few lines from different countries, like this:
GSM,724,6,2044,10333,,30.5240236,50.4392184,0,1,1,1424733937,1634217543,
LTE,250,1,11264,84247339,11,47.8775878,56.6526018,449,19,1,1462207606,1630887268,
Is there some kind of step I'm missing to be able to do a lookup from the refUC to the cell id?

It turns out that for some reason, there's an off-by-one either on the side of Mozilla Location Services, or on the side of the SET doing the request.
Subtracting one from the refUC seems to consistently find cellular base stations that are very close to where I actually am. Maybe MLS stores the IDs zero-based, while the SET uses 1-based IDs.

Related

How does resource.data.size() work in firestore rules (what is being counted)?

TLDR: What is request.resource.data.size() counting in the firestore rules when writing, say, some booleans and a nested Object to a document? Not sure what the docs mean by "entries in the map" (https://firebase.google.com/docs/reference/rules/rules.firestore.Resource#data, https://firebase.google.com/docs/reference/rules/rules.Map) and my assumptions appear to be wrong when testing in the rules simulator (similar problem with request.resource.data.keys().size()).
Longer version: Running into a problem in Firestore rules where not being able to update data as expected (despite similar tests working in the rules simulator). Have narrowed down the problem to point where can see that it is a rule checking for request.resource.data.size() equaling a certain number.
An example of the data being passed to the firestore update function looks like
Object {
"parentObj": Object {
"nestedObj": Object {
"key1": Timestamp {
"nanoseconds": 998000000,
"seconds": 1536498767,
},
},
},
"otherKey": true,
}
where the timestamp is generated via firebase.firestore.Timestamp.now().
This appears to work fine in the rules simulator, but not for the actual data when doing
let obj = {}
obj.otherKey = true
// since want to set object key name dynamically as nestedObj value,
// see https://stackoverflow.com/a/47296152/8236733
obj.parentObj = {} // needed for adding nested dynamic keys
obj.parentObj[nestedObj] = {
key1: fb.firestore.Timestamp.now()
}
firebase.firestore.collection('mycollection')
.doc('mydoc')
.update(obj)
Among some other rules, I use the rule request.resource.data.size() == 2 and this appears to be the rules that causes a permission denied error (since commenting out this rules get things working again). Would think that since the object is being passed with 2 (top-level) keys, then request.resource.data.size()=2, but this is apparently not the case (nor is it the number of keys total in the passed object) (similar problem with request.resource.data.keys().size()). So there's a long example to a short question. Would be very helpful if someone could clarify for me what is going wrong here.
From my last communications with firebase support around a month ago - there were issues with request.resource.data.size() and timestamp based security rules for queries.
I was also told that request.resource.data.size() is the size of the document AFTER a successful write. So if you're writing 2 additional keys to a document with 4 keys, that value you should be checking against is 6, not 2.
Having said all that - I am still having problems with request.resource.data.size() and any alternatives such as request.resource.size() which seems to be used in this documentation
https://firebase.google.com/docs/firestore/solutions/role-based-access
I also have some places in my security rules where it seems to work. I personally don't know why that is though.
Been struggling with that for a few hours and I see now that the doc on Firebase is clear: "the request.resource variable contains the future state of the document". So with ALL the fields, not only the ones being sent.
https://firebase.google.com/docs/firestore/security/rules-conditions#data_validation.
But there is actually another way to ONLY count the number of fields being sent with request.writeFields.size(). The property writeFields is a table with all the incoming fields.
Beware: writeFields is deprecated and may stop working anytime, but I have not found any replacement.
EDIT: writeFields apparently does not work in the simulator anymore...

How to filter by both text and property in Chrome DevTool's network panel?

I want to filter Chrome DevTool's network panel by the method property and text in the URL. For example, if I am searching for the text chromequestion in the URL and only HTTP GET requests (ignore PUT, POST, DELETE, etc).
I am able to filter by text or by method:
I am not able to combine the filter to search by both text and method:
I read the documentation at https://developers.google.com/web/tools/chrome-devtools/network-performance/reference#filters and I am able to filter by multiple properties (.e.g, domain:*.com method:GET). However, I am unable to filter by text and property (e.g., method:GET chromequestion).
Unfortunately, it's not possible to do this currently. I played around in DevTools originally, but couldn't find a way. I later had a look into how the filtering was implemented, and can confirm there's a limitation preventing you from mixing the pre-defined filters and text filters.
Implementation details
This is a bit long but I thought it might be interesting for some to see how it's implemented. I will probably look into improving the implementation, either myself or I'll log it because it's limited.
There's a _parseFilterQuery function that parses the input field and categorises the entries into two arrays. The first is called filters, and it's the pre-defined filtering options, such as method:GET etc. The second is a text array filter, split up by spaces. The parser determines the difference fairly naively, by checking for the occurrence of :, and - at the start (for negation).
Scenario 1
You only input a pre-defined filter, or multiple filters. For each filter, the specific filter function, which looks at the different properties of the request object, is pushed to a network module filters array (this._filters). Later on, for each request, the function is called on it, and a match returns true, otherwise false. This will determine whether the request is shown. There's obviously a requirement for ALL filters to return true for the row to show.
Scenario 2
This is the interesting one, where you input both a pre-defined filter and a bit of text. This covers the Stack Overflow question. The _parseFilterQuery function looks at the text filters first, before the pre-defined ones. In Scenario 1, this was empty, so it was skipped.
We pass each text word to the _createTextFilter, and push each of the resulting filters to the network module filters array. However, the implementation of this is questionable. The only time the actual word passed in is used is to check whether its a negation filter for a bit of text. If the first character is -, it means the user doesn't want to see a request with the following word in the name. For example -icon means don't show any request with that in the name/page. If there is no negation, it simply returns the WHOLE input text as a regular expression, NOT the word passed in. In my case, it returns /method:GET icon/i.
The pre-defined filters are looked at next. In this case, method:GET is pushed.
Finally, it loops over the requests calling each filter on it. However, since the first filter is /method:GET icon/i, it makes ALL other filters redundant because it will NEVER pass. The text filters only apply to name and path, so method:GET in a text filter will be invalid.

Address an ordered list the RESTful way

I doubt what's the best way to address an ordered list in a RESTful API. Imagine the following example: Let's create a chart list of LPs, where you want to add new LPs, delete those which aren't in the TOP10 yet, and change their positions. How would you implement those methods in a RESTful JSON-API?
I thought of the following way:
GET / to return the ordered chart list like [{ "name": "1st-place LP", "link": "/uid123" }, { "name": "2nd-place LP", "link": "/uid987" }, ...]
GET /{uid} to return a LP by its unique ID, returning sth. like {"name": "1st-place LP", "ranking": 1 }
GET /ranking/{position} to access e.g. the current first-ranked LP, returning a 303 See Other with a Location-header like Location: /uid123
POST / with request body { "name": "my first LP title" } to create a new LP without specifying its current chart position
Now it's the question how we could change the current chart positions? One could simply PUT /{uid} to update the ranking attribute, but I think a PUT /ranking/{position} would be more natural. On the other hand it doesn't make sense to PUT against an URI which will return a 303 See Other when using GET.
What do you think would be the best way to address such a chart list? I don't like the solution of changing simply the ranking attribute in the LP-datasets as this could end in senseless states like two LPs with the same ranking and so on.
I see two questions. 1. What is the most RESTful (beautiful) way to design the API? 2. How do I make sure that two LPs does not get the same ranking?
1:
Your LPs could have several properties that are relative to eachother, e.g. different ranking on different charts. I would say that you want the ranking moved OUT of your LP resource. Keep the ranking on a certain list as a separate resource. Example:
GET /LPuid only returns properties about the LP, not relative properties, like rankings
GET /billboard/3 returns the URI to LP that has rankning 3 on the billboard list.
PUT /billboard takes a document of 100 LP URI's.
PUT /billboard/3 INSERTS an LP URI at that ranking and moves the other ones down.
2: That has nothing to do with rest and you would have that issue no matter how you design your API. Transactions is one solution.
You have two collection resources within your music service. As such, I would design a URI structure like this:
/ => returns links to collections (ergo itself a collection resource)
/releases => returns a list of LPs
/chart => returns the top 10 LPs, or redirects to the current chart URI
You would POST to /releases to add a new LP, and PUT or PATCH to /chart to define a new chart or alter the current chart. You will need to define what representation formats are transfered in each case.
This gives you the flexability to define thinks like /chart/2012-12-25 to show the chart as it stood on christmas day 2012.
I do not suggest using PUT /chart/{position} to insert an LP at a specific position and shuffle everything else down. Intermediarys would not know that a PUT to that URI causes other resources to change their URIs. This is bad for caching.
Also, as a user, I would hope you avoid the word "billboard" as the other answer suggests. A billboard conjures in the mind pictures of an advertising hoarding, and not anything to do with ranking charts!

what is the difference between doc.Content.Text and doc.Range(start, end).Text

Could you please explain what is the difference between doc.Content.Text and doc.Range(start, end).Text
Actually, if I extract a string like
doc.Content.Text.SubString(start, lenofText)
and if I do the same with
doc.Range(start, start + lenofText)
I get correct result for doc.Content.Text but incorrect result with doc.Range ... do you know the reason? I need to find a text and then convert it to a Hyper LINK but the doc.Range does not give the me the correct results...
Your description is a little vague (for instance, how is it not the correct results?) but a document is actually comprised of as many as 17 story parts (which includes things like the main story [the document area], footers, headers, footnotes, and comments). 'Content' refers specifically to the main text story. ‘Doc.Range’ is broader and can include more than one story. If the results are not correct because it looks like the text is offset by a certain number of characters, it may be counting other stories. If you want to limit the results to the body text, specify one of the following:
doc.Content
doc.StoryRanges(wdMainTextStory)

RESTful URL design for search

I'm looking for a reasonable way to represent searches as a RESTful URLs.
The setup: I have two models, Cars and Garages, where Cars can be in Garages. So my urls look like:
/car/xxxx
xxx == car id
returns car with given id
/garage/yyy
yyy = garage id
returns garage with given id
A Car can exist on its own (hence the /car), or it can exist in a garage. What's the right way to represent, say, all the cars in a given garage? Something like:
/garage/yyy/cars ?
How about the union of cars in garage yyy and zzz?
What's the right way to represent a search for cars with certain attributes? Say: show me all blue sedans with 4 doors :
/car/search?color=blue&type=sedan&doors=4
or should it be /cars instead?
The use of "search" seems inappropriate there - what's a better way / term? Should it just be:
/cars/?color=blue&type=sedan&doors=4
Should the search parameters be part of the PATHINFO or QUERYSTRING?
In short, I'm looking for guidance for cross-model REST url design, and for search.
[Update] I like Justin's answer, but he doesn't cover the multi-field search case:
/cars/color:blue/type:sedan/doors:4
or something like that. How do we go from
/cars/color/blue
to the multiple field case?
For the searching, use querystrings. This is perfectly RESTful:
/cars?color=blue&type=sedan&doors=4
An advantage to regular querystrings is that they are standard and widely understood and that they can be generated from form-get.
The RESTful pretty URL design is about displaying a resource based on a structure (directory-like structure, date: articles/2005/5/13, object and it's attributes,..), the slash / indicates hierarchical structure, use the -id instead.
Hierarchical structure
I would personaly prefer:
/garage-id/cars/car-id
/cars/car-id #for cars not in garages
If a user removes the /car-id part, it brings the cars preview - intuitive. User exactly knows where in the tree he is, what is he looking at. He knows from the first look, that garages and cars are in relation. /car-id also denotes that it belongs together unlike /car/id.
Searching
The searchquery is OK as it is, there is only your preference, what should be taken into account. The funny part comes when joining searches (see below).
/cars?color=blue;type=sedan #most prefered by me
/cars;color-blue+doors-4+type-sedan #looks good when using car-id
/cars?color=blue&doors=4&type=sedan #also possible, but & blends in with text
Or basically anything what isn't a slash as explained above.
The formula: /cars[?;]color[=-:]blue[,;+&], though I wouldn't use the & sign as it is unrecognizable from the text at first glance if that's your thing.
** Did you know that passing JSON object in URI is RESTful? **
Lists of options
/cars?color=black,blue,red;doors=3,5;type=sedan #most prefered by me
/cars?color:black:blue:red;doors:3:5;type:sedan
/cars?color(black,blue,red);doors(3,5);type(sedan) #does not look bad at all
/cars?color:(black,blue,red);doors:(3,5);type:sedan #little difference
possible features?
Negate search strings (!)
To search any cars, but not black and red:
?color=!black,!red
color:(!black,!red)
Joined searches
Search red or blue or black cars with 3 doors in garages id 1..20 or 101..103 or 999 but not 5
/garage[id=1-20,101-103,999,!5]/cars[color=red,blue,black;doors=3]
You can then construct more complex search queries. (Look at CSS3 attribute matching for the idea of matching substrings. E.g. searching users containing "bar" user*=bar.)
Conclusion
Anyway, this might be the most important part for you, because you can do it however you like after all, just keep in mind that RESTful URI represents a structure which is easily understood e.g. directory-like /directory/file, /collection/node/item, dates /articles/{year}/{month}/{day}.. And when you omit any of last segments, you immediately know what you get.
So.., all these characters are allowed unencoded:
unreserved: a-zA-Z0-9_.-~
Typically allowed both encoded and not, both uses are then equivalent.
special characters: $-_.+!*'(),
reserved: ;/?:#=&
May be used unencoded for the purpose they represent, otherwise they must be encoded.
unsafe: <>"#%{}|^~[]`
Why unsafe and why should rather be encoded: RFC 1738 see 2.2
Also see RFC 1738#page-20 for more character classes.
RFC 3986 see 2.2
Despite of what I previously said, here is a common distinction of delimeters, meaning that some "are" more important than others.
generic delimeters: :/?#[]#
sub-delimeters: !$&'()*+,;=
More reading:
Hierarchy: see 2.3, see 1.2.3
url path parameter syntax
CSS3 attribute matching
IBM: RESTful Web services - The basics
Note: RFC 1738 was updated by RFC 3986
Although having the parameters in the path has some advantages, there are, IMO, some outweighing factors.
Not all characters needed for a search query are permitted in a URL. Most punctuation and Unicode characters would need to be URL encoded as a query string parameter. I'm wrestling with the same problem. I would like to use XPath in the URL, but not all XPath syntax is compatible with a URI path. So for simple paths, /cars/doors/driver/lock/combination would be appropriate to locate the 'combination' element in the driver's door XML document. But /car/doors[id='driver' and lock/combination='1234'] is not so friendly.
There is a difference between filtering a resource based on one of its attributes and specifying a resource.
For example, since
/cars/colors returns a list of all colors for all cars (the resource returned is a collection of color objects)
/cars/colors/red,blue,green would return a list of color objects that are red, blue or green, not a collection of cars.
To return cars, the path would be
/cars?color=red,blue,green or /cars/search?color=red,blue,green
Parameters in the path are more difficult to read because name/value pairs are not isolated from the rest of the path, which is not name/value pairs.
One last comment. I prefer /garages/yyy/cars (always plural) to /garage/yyy/cars (perhaps it was a typo in the original answer) because it avoids changing the path between singular and plural. For words with an added 's', the change is not so bad, but changing /person/yyy/friends to /people/yyy seems cumbersome.
To expand on Peter's answer - you could make Search a first-class resource:
POST /searches # create a new search
GET /searches # list all searches (admin)
GET /searches/{id} # show the results of a previously-run search
DELETE /searches/{id} # delete a search (admin)
The Search resource would have fields for color, make model, garaged status, etc and could be specified in XML, JSON, or any other format. Like the Car and Garage resource, you could restrict access to Searches based on authentication. Users who frequently run the same Searches can store them in their profiles so that they don't need to be re-created. The URLs will be short enough that in many cases they can be easily traded via email. These stored Searches can be the basis of custom RSS feeds, and so on.
There are many possibilities for using Searches when you think of them as resources.
The idea is explained in more detail in this Railscast.
Justin's answer is probably the way to go, although in some applications it might make sense to consider a particular search as a resource in its own right, such as if you want to support named saved searches:
/search/{searchQuery}
or
/search/{savedSearchName}
I use two approaches to implement searches.
1) Simplest case, to query associated elements, and for navigation.
/cars?q.garage.id.eq=1
This means, query cars that have garage ID equal to 1.
It is also possible to create more complex searches:
/cars?q.garage.street.eq=FirstStreet&q.color.ne=red&offset=300&max=100
Cars in all garages in FirstStreet that are not red (3rd page, 100 elements per page).
2) Complex queries are considered as regular resources that are created and can be recovered.
POST /searches => Create
GET /searches/1 => Recover search
GET /searches/1?offset=300&max=100 => pagination in search
The POST body for search creation is as follows:
{
"$class":"test.Car",
"$q":{
"$eq" : { "color" : "red" },
"garage" : {
"$ne" : { "street" : "FirstStreet" }
}
}
}
It is based in Grails (criteria DSL): http://grails.org/doc/2.4.3/ref/Domain%20Classes/createCriteria.html
This is not REST. You cannot define URIs for resources inside your API. Resource navigation must be hypertext-driven. It's fine if you want pretty URIs and heavy amounts of coupling, but just do not call it REST, because it directly violates the constraints of RESTful architecture.
See this article by the inventor of REST.
In addition i would also suggest:
/cars/search/all{?color,model,year}
/cars/search/by-parameters{?color,model,year}
/cars/search/by-vendor{?vendor}
Here, Search is considered as a child resource of Cars resource.
There are a lot of good options for your case here. Still you should considering using the POST body.
The query string is perfect for your example, but if you have something more complicated, e.g. an arbitrary long list of items or boolean conditionals, you might want to define the post as a document, that the client sends over POST.
This allows a more flexible description of the search, as well as avoids the Server URL length limit.
RESTful does not recommend using verbs in URL's /cars/search is not restful. The right way to filter/search/paginate your API's is through Query Parameters. However there might be cases when you have to break the norm. For example, if you are searching across multiple resources, then you have to use something like /search?q=query
You can go through http://saipraveenblog.wordpress.com/2014/09/29/rest-api-best-practices/ to understand the best practices for designing RESTful API's
Though I like Justin's response, I feel it more accurately represents a filter rather than a search. What if I want to know about cars with names that start with cam?
The way I see it, you could build it into the way you handle specific resources:
/cars/cam*
Or, you could simply add it into the filter:
/cars/doors/4/name/cam*/colors/red,blue,green
Personally, I prefer the latter, however I am by no means an expert on REST (having first heard of it only 2 or so weeks ago...)
My advice would be this:
/garages
Returns list of garages (think JSON array here)
/garages/yyy
Returns specific garage
/garage/yyy/cars
Returns list of cars in garage
/garages/cars
Returns list of all cars in all garages (may not be practical of course)
/cars
Returns list of all cars
/cars/xxx
Returns specific car
/cars/colors
Returns lists of all posible colors for cars
/cars/colors/red,blue,green
Returns list of cars of the specific colors (yes commas are allowed :) )
Edit:
/cars/colors/red,blue,green/doors/2
Returns list of all red,blue, and green cars with 2 doors.
/cars/type/hatchback,coupe/colors/red,blue,green/
Same idea as the above but a lil more intuitive.
/cars/colors/red,blue,green/doors/two-door,four-door
All cars that are red, blue, green and have either two or four doors.
Hopefully that gives you the idea. Essentially your Rest API should be easily discoverable and should enable you to browse through your data. Another advantage with using URLs and not query strings is that you are able to take advantage of the native caching mechanisms that exist on the web server for HTTP traffic.
Here's a link to a page describing the evils of query strings in REST: http://web.archive.org/web/20070815111413/http://rest.blueoxen.net/cgi-bin/wiki.pl?QueryStringsConsideredHarmful
I used Google's cache because the normal page wasn't working for me here's that link as well:
http://rest.blueoxen.net/cgi-bin/wiki.pl?QueryStringsConsideredHarmful