I need to implement a "winning-configuration-property" algorithm in my application.
For example:
for property: dashboard_material
i would create a file (I am planning to represent each property as a file. This is slightly negotiable)dashboard_material.yml , with the following value
(which format i believe presents a consolidated view of the variants of the property and is more suitable for impact analysis when someone changes values in a particular scenario) :
car_type=luxury&car_subtype=luxury_sedan&special_features=none : leather
car_type=luxury&car_subtype=luxury_sedan&special_features=limited_edition : premium_leather
car_type=economy : pseudo_leather
default : pseudo_leather
I need the closest match. A luxury car can be a sedan or a compact.
I am assuming these are "decorators" of a car in object oriented terms, but not finding any useful implementation for the above problem from sample decorator patterns.
For example an API:
GET /configurations/dashboard_material should return the following values based on input parameters:
car_type=economy : pseudo_leather
car_type=luxury & car_subtype=luxury_sedan : leather
car_type=luxury : pseudo_leather (from default. Error or null if value does not exist)
This looks very similiar to the "specifications" or "queryDSL" problem with GetAPIs - in terms of slicing and dicing based on criteria.
but basically i am looking for a run-time determination of a config value from a single microservice
(which is a spring config client. I use git2consul to push values from git into consul KV. The spring config client is tied into the consul KV. I am open to any equivalent or better alternatives).
I would ideally like to do all the processing as a post-processing after the configuration is read (from either a spring config server or consul KV),
so that no real processing happens after the query is recieved. The same post processing will also have to happen after every spring config client "refresh" interval based
on configuration property updates.
I have previously seen such an implementation (as an ops engineer) with netflix archaius implementation, but not again finding any suitable text on the archaius pages.
My trivial/naive solution would be to create multiple maps/trees to store the data and then consolidate them into a single map based on the API request effectively overriding some of the values from the lower priority maps.
I am looking for any open-source implementations or references and avoid having to create new code.
Related
Spring Cloud Gateway appears to be reordering my query parameters to put duplicate parameters together.
I'm trying to route some requests to one of our end points to a third party system. These requests include some query parameters that need to be in a specific order (including some duplicate parameters), or the third party system returns a 500 error, but upon receiving the initial request with the parameters in the proper order, the Spring Cloud Gateway reorders these parameters to put the duplicates together by the first instance of the parameter.
Example:
http://some-url.com/a/path/here?foo=bar&anotherParam=paramValue2&aThirdParam=paramValue3&foo=bar
Becomes:
http://some-url.com/a/path/here?foo=bar&foo=bar&anotherParam=paramValue2&aThirdParam=paramValue3
Where the last parameter was moved to be by the first parameter because they had the same name.
The actual request output I need is for the query parameters to be passed through without change.
The issue lays in the UriComponentsBuilder which is used in RouteToRequestFilter.
UriComponentsBuilder.fromUri(uri) is going to build up a map of query params. Because this is a LinkedMultiValueMap you see the reordering of the used query params.
Note that RFC3986 contains the following
The query component contains non-hierarchical data that, along with data in the path component (Section 3.3), serves to identify a resource within the scope of the URI’s scheme and naming authority (if any).
Therefor I don’t think there needs to be a fix in Spring Cloud Gateway.
In order to fix this in your gateway, you'll need to add a custom filter which kicks in after the RouteToRequestFilter by setting the order to RouteToRequestUrlFilter.ROUTE_TO_URL_FILTER_ORDER + 1.
Take a look at the RouteToRequestUrlFilter how the exchange is adapted to go to the downstream URI.
Hope that helps! :)
I wanted to provide functionality to clients from my service to get the data based on different fields or sometimes combination of fields. Eg.
getByA
getByB
getByC
getByAandB
getByAandC
In domain driven design, while designing the GET APIs, what should I do out of the following 2:
Should I create individual get api for all such functionalities I wanted to provide?
Should I create one get API with all the possible gets by using all these fields in query parameter. Eg.
get?A=?&B=?&C=?
Which one is the better way to do this? Any suggestions on best practice?
There is a middle path between using individual GET APIs for each of these queries and creating one GET API.
You could use the Specification pattern to expose one GET API, but translate it into a Domain Specification Object before passing it on to the Domain layer for querying. You typically do this transformation in your View Controller, before invoking the Application Service.
Martin Fowler and Eric Evans have published a great paper on using Specifications: https://martinfowler.com/apsupp/spec.pdf
As the paper states, The central idea of Specification is to separate the statement of how to match a candidate, from the candidate object that it is matched against.
Note:
You are fine if you are using this pattern for the Query side as you have outlined in your question, and avoid reusing it in different contexts. For ex., DO NOT use a specification object on both the query side and command side, if you are using (or plan to use) CQRS. You will be creating a central dependency between two parts, that NEED to be kept separate.
Specifications are handy when you want to represent a domain concept. Evaluate your queries (getByAandB and getByAandC) to draw out the question you are asking to the domain (For ex., ask your domain expert to describe the data he is trying to fetch).
We have an application and where we are tracing the whole logs using a custom correlation header i.e. X-CID with a value as for example, 615b7eea-6d4c-4efb-9431-fcbba084ea3f. Recently we have integrated the Spring Sleuth with the train version as Greenwich.BUILD-SNAPSHOT in our application and using brave's Span and tracer to create trace and span ad sending it to Zipkin.
What we are looking for a mechanism where we can use or set the CID value as a traceId rather than using the auto generated one from Sleuth.
The rational behind is, we would like to make it uniform CID value to use or search in Zipkin UI rather than two different values i.e. CID value and Spring Sleuth traceId to trace the complete API calls.
Please note that, we would like to reuse the X-CID from request which is already supplied in the request header.
Are there any APIs to override this behavior or any alternate way to achieve this ?
Hi I'm a student and I'm working for the first time on the broker. I understood how the creation of entities works and their updating through "update" queries. My question is: you can create an entity that contains variables (eg geolocation) defined with value "null" or "zero" and then initialize them with values that interest me. So as to have dynamic and non-static variables (ie that require user update)?
Or do we need interaction with the CEP to do this?
From what I have read in the fiware-orion guide when I create an entity (ex car having attributes and velocity coordinates: geopoint). The values of these 2 attributes must be set in a static way (ex: speed 100 and position coordinates 40.257, 2.187). If I understand the values of these attributes I can only update them by making an update query. So my question is:
Is it possible to update the value of the attributes that contain the position or the speed of the car in a dynamic way, ie without having to write the values from the keyboard? Or does this require the use of the CEP of orion?
If I could not explain myself more generally I would like to know if it is possible to follow the progress of a moving car without me having to add the values from the keyboard.
Thanks.
Orion Context Brokker exposes a REST-based API that (among other things) allows you to create, update and query entities. From the point of view of Orion, it doesn't matter who is the one invoking the API: it can be done manually (for instance, using Postman or curl) or can be an automated system developed by you or a third party (for instance, a software running in a sensor in the car that measures the speed and periodically sends an update using a wireless communication network).
From a client-server point of view (in the case you are familiar with these concepts), Orion takes the server of the API role and the one updating the speed (either manually or automatically) takes the role of client of the API.
I am new to Cassandra and I am having some difficulties fetching data.
I looked into the function:
list<KeySlice> get_range_slices(column_parent, predicate, range, consistency_level)
But, I do not understand what the column_parent is supposed to be.
Anybody any idea?=
Thanx,
Granit
column_parent is basicly used for indicator of ColumnFamily(but in rare cases it can indicate a supercolumn). In java you would put : new ColumnParent("Posts") there. but there should be one more parameter for namespace in get_range_slices query, I guess you are not using thrift but a client api. then you should check your client's documentation.
Edit:
the definition of ColumnParent in cassandra api :
The ColumnParent is the path to the
parent of a particular set of Columns.
It is used when selecting groups of
columns from the same ColumnFamily. In
directory structure terms, imagine
ColumnParent as ColumnPath + '/../'.
Frail is correct, but the real answer is "don't use raw Thrift, use one of the clients from http://wiki.apache.org/cassandra/ClientOptions instead."