What's the main purpose of this "issueRef" parameter? And why the samples just put
OpaqueBytes.of("1".getBytes()
or
OpaqueBytes.of(0x01)
Is it just to link an issued asset to an issuer? Could one give me a usage example?
It's a reference to allow Corda users to link the on-ledger assets they hold to real-world assets.
Related
I was watching a video on "Design Uber api mock interview".
for most of the APIs, the candidate just used "userId" and left on the system to resolve "rideId"
Example - cancelRide(userId: string)
For this api, user is just passing userId to cancelRide endpoint and now the system will have to resolve rideId to actually cancel the ride.
Now this may solve the problem at hand but in future Uber may want to enable multiple ride for single user (you can book ride for yourself and your mom too, at the same time)
With this kind of API design now we will have to make changes to cancelRide endpoint to accept rideId as well
cancelRide(userId: string, rideId: string)
Should we just design as per the problem at hand and make changes to the API/Design if there is some new requirement is coming in or We should at least consider some obvious/possible future requirements/change?
You should think ahead: What is the potential requirement/change they need in the future?
The reason is you are developing an API.
Assume that you have more than 100K external clients of your API, any change will enforce them to update, modify, rebuild their APP and a lot of work.
Thus, the YAGNI principle is inappropriate to API design issue. You should try the Open-Closed Principle (OCP).
Good examples of how attachments are meant to be used include:
Calendar data
Fixes (e.g. LIBOR)
Smart contract code
In what way can I leverage on attachment to parameterise values or even codify custom agreement rules so contract can validate using it?
i.e
"Custom contract code must pass." using openAttachment(hashId).run == true
I want to be able to create a state that has a template of rules, but at the same time, able to handle custom (any) new rules proposed by initiator, and accepted by counterparties.
Contract code is attached automatically. These are the contracts that are assigned to a state when adding state as an output within a transaction.
These would be the standard "template of rules" that everyone has pre-agreed to in the development of the CorDapp and are run by everyone to reach consensus.
In theory, you could add a custom contract in an attachment, have counterparties upload the contract class to their nodes and then run verify against them by calling verify explicitly against the class within the flow. I suspect you'd have to have counterparty nodes stop and restart to load the class dynamically onto the classpath though.
I know I can setup multiple namespaces for DoctrineCacheBundle in config.yml file. But Can I use one driver but with multiple namespaces?
The case is that in my app I want to cache all queries for all of my entities. The problem is with flushing cache while making create/update actions. I want to flush only part of my cached queries. My app is used by multiple clients. So when a client updates sth in his data for instance in Article entity, I want to clear cache only for this client only for Article. I could add proper IDs for each query and remove them manually but the queries are dynamically used. In my API mobile app send version number for which DB should return data so I don't know what kind of IDs will be used in the end.
Unfortunately I don't think what you want to do can be solved with some configuration magic. What you want it some sort of indexed cache, and for that you have to find a more powerful tool.
You can take a look at doctrines second level cache. Don't know how good it is now (tried it once when it was in beta and did not make the cut for me).
Or you can build your own cache manager. If you do i recommend using redis. The data structures will help you keep you indexes (Can be simulated with memcached, but it requires more work). What I meen by indexes.
You will have a key like client_1_articles where 1 is the client id. In that key you will store all the ids of the articles of client 1. For every article id you will have a key like article_x where x is the id the of article. In this example client_1_articles is a rudimentary index that will help you, if you want at some point, to invalidated all the caches of articles coming from client 1.
The abstract implementation for the above example will end up being a graph like structure over your cache, with possibly
-composed indexes 'client_1:category_1' => {article_1, article_2}
-multiple indexes for one item eg: 'category_1'=>{article_1, article_2, article_3}, 'client_1' => {article_1, article_3}
-etc.
Hope this help you in some way. At least that was my solution for a similar problem.
Good luck with your project,
Alexandru Cosoi
My requirement is :
I need to store all the details about a person manually by (for example)Admin.
Which Collection usage is best for above requirement means using Predefined Collection Accounts or User Defined Collection?
My Doubt is : If using Accounts package must be used password but my requirement doesn't contains password only person details.So what i can do for this problem using Accounts?
In case using User Defined Collection then how to provide security for this?
I didn't get any idea about this problem.So please suggest me what to do?
Create a collection, called something like "people", "customers", "students", etc (whatever makes sense for your particular use case). There are several important things you need to do to make it secure:
Use the built in accounts-password package to have your user log in to maintain the list.
Remove the insecure and autopublish packages.
Conditionally publish the relevant fields of the people collection, only to your authorized user.
Set allow and deny rules for inserting/updating/removing people documents. Your rules should check that the user is authorized.
Do not store sensitive information like passwords, credit card numbers, social security numbers, etc in clear text in your database.
Use SSL.
Read and watch these two links, where Emily Stark discusses security (specifically content security policies) in Meteor:
https://www.meteor.com/blog/2013/10/27/defense-in-depth-securing-meteor-apps-with-content-security-policy
https://www.meteor.com/blog/2013/08/02/meteor-devshop-6-devshop-live-security-meteor-ui
Remember that no matter what framework/system you use, there is no such thing as absolute, 100% security. You must use defense in depth to achieve the best possible security that you can.
Under the condition of "allow_versions" set to "FALSE" or "TRUE", for both cases, how Swift response for the scenario that a file is under overwriting while delete request come in simultaneously(with the order of overwriting first then deletion)?
Please share your thoughts.
Many thanks!
The timestamp assigned to the request coming in to the proxy is what will ultimately decide which "last" write wins.
If you have a long running upload and issue the delete during, the tombstone will have a later timestamp and will eventually take precedence even if the upload finishes after.
When using the container versioning feature, overwriting in a versioned container will cause the object data to be COPY'd off the current tip before the PUT data is sent to the storage node with the assigned timestamp. For deletes in a versioned container the "previous version" is discovered at the time the overwriting request is made and subject to eventual consistency in the container listing, but is only deleted once it has been copied into the current location for the object.
More information about object versioning is available here:
http://docs.openstack.org/developer/swift/overview_object_versioning.html
Well, a quick summary comes, though still a very high level view but hope it helps understanding how it works under the hood.
The diagram(below link) sets two simultaneous scenarios(A and B) against the enable/disable of the Swift object versioning feature. The outcome for each scenario is shown in the diagram.
Download the diagram.
Please share your thoughts if any.