I used to set up a Fabric network and deployed a fabric network and basic application using a Fabric and Fabric GoLang SDK. I'm able to do the query and write to the chain.
Is there any way to retrieve the Block Info? Like block height and current hash?
+ I'm unable to find out a documentation for GoLang Fabric SDK.
I followed following code and tutorial,
Fabric Basic App - Tutorial
https://chainhero.io/2017/07/tutorial-build-blockchain-app/
Fabric Basic App using GoLang SDK - Code
https://github.com/chainHero/heroes-service/
GoLang SDK - Official SDK
https://github.com/hyperledger/fabric-sdk-go
In general, the sdk will provide the basic method such you said GetBlockInfo,I have search for the GoLang SDK, it can not be found. While Java sdk provide this such method reference this java test .
Another way to use these method(you must know a little fabric source code), in fact these method are included in the system chaincode, you could invoke the system chancode just like you invoke the normal chaincode.
A example is following:
from the go sdk test ,you could see this,
response, err := chClient.Query(chclient.Request{ChaincodeID: ccID, Fcn: "invoke", Args: integration.ExampleCCQueryArgs()})
just change the params
response, err := chClient.Query(chclient.Request{ChaincodeID: "qscc", Fcn: "invoke", Args: integration.ExampleCCQueryArgs("GetChainInfo")})
qscc is a system chancode,you could download the fabric source code,and from qscc file,you could see(it provide many invoke service):
GetChainInfo string = "GetChainInfo"
GetBlockByNumber string = "GetBlockByNumber"
GetBlockByHash string = "GetBlockByHash"
GetTransactionByID string = "GetTransactionByID"
GetBlockByTxID string = "GetBlockByTxID"
Go sdk(fabric-sdk-go/pkg/client/ledger) provides several methods for getting information about blockchain. For example:
...
client, err := ledger.New(channelContext)
block, err := client.QueryBlockByHash(blockHash)
block, err = client.QueryBlock(blockNumber)
The Go SDK now includes methods for querying block information. These methods are contained within the ledger client package.
You can see an example in the ledger client integration test.
Related
Now I have a Golang Application deployed on GAE, with stackdriver trace.
About stackdriver Trace, to get custom span data, I did set up on my code, like
exporter, err := stackdriver.NewExporter(stackdriver.Options{
ProjectID: os.Getenv("GOOGLE_CLOUD_PROJECT"),
})
if err != nil {
log.Fatal(err)
}
trace.RegisterExporter(exporter)
client := &http.Client{
Transport: &ochttp.Transport{
// Use Google Cloud propagation format.
Propagation: &propagation.HTTPFormat{},
},
}
ref. https://cloud.google.com/trace/docs/setup/go
On GAE, I succeed in viewing trace on my GCP console.
but, I DON'T want to trace these log on my local developing environment (I'm using docker).currently, I try to run my application on docker, nil pointer panic shows up on Span.Export() which may be called from Span.End().
So, I wonder if someone knows the way to DISABLE stackdriver trace on specific environment (with my case, on docker).
Otherwise, should I check condition of trace configuration, like as below ?
if trace.projectId != "" {
ctx := reque.Context()
_, span := trace.StartSpan(ctx,"Span blahblah")
defer span.End()
}
There is no point for Google in adding an extra logic like you need into the Trace code, the GAE apps are instrumented with, in order to disable that Trace code when the GAE App is executed somewhere in a third party environment like Docker on-prem. Most likely an answer to the question is "No, there is no magic config for that". Hence it is up-to-you how to sort this out.
As a general idea: following up an approach with [NoopExporter] offered by Emile Pels and having admitted the fact we can't get rid of the Trace code with "magic config", if I developed my app in Python I'd considered using decorator as a wrapper to bring piece of intelligence into the Trace calls, or redefining them as mock functions. It seems Golang does not have direct analog of Python decorators but this functionality could be implemented somehow. This is being discussed in the Internet, for example here:
Go Decorator Function Pattern
Redefine function so that it references its own self
So I have some different types of aws resources tagged as xxx/yyy/<generated_id>. I need to fetch them using go-sdk.
Here is a sample code for subnets, the filters look the same for every other resource.
This doesn't work.
var resp *ec2.DescribeSubnetsOutput
resp, err = d.ec2Client().DescribeSubnets(&ec2.DescribeSubnetsInput{
Filters: []*ec2.Filter{
{
Name: aws.String("vpc-id"),
Values: []*string{&d.VpcId},
},
{
Name: aws.String(fmt.Sprintf(`tag:"xxx/yyy.[*]"`),
Values: []*string{aws.String("owned")},
},
},
})
This does:
aws ec2 describe-subnets --filters `Name=tag:"xxx/yyy.[*]",Values=owned`
I'm obviously doing something wrong, can someone point out what?
There is nothing in the API documentation to suggest that DescribeSubnets accepts a regular expression in filter names: https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeSubnets.html
If it works in the CLI, that's likely something the CLI is doing on top of what the SDK offers. The Go SDK is like any other AWS SDK; it exposes the AWS API in a language-specific way. The AWS CLI adds convenience features on top of the API to make it more useful on the command line, but that doesn't mean those features are exposed by the API or any published SDK.
I stepped with this problem recently, my issue was the version of the sdk I was using;
Filters: [ ]*ec2.Filter{
is for v1 sdk mod and it was not working as I was importing github.com/aws/aws-sdk-go-v2/aws, while
Filters: [ ]types.Filter{
is for v2 and this one worked in my case.
https://aws.amazon.com/blogs/developer/aws-sdk-for-go-version-2-general-availability/
I have a Go Application that needs to consume a GraphQL service, now the documentation of graphQL is more oriented to the GraphQL server and not as a client. How can I do that?
I checked this example but some things are not clear to me:
Should I have a Resolve function to each field that I am going to retrieve?
Should I have defined the variable 'fields' with the data structure that I am expecting?
Where can I find a very simple example of a GraphQL client in Golang?
You should check this project: https://github.com/machinebox/graphql .
If you don't want to use an external library inside in your project, you could look the code and see how can you implement a simple client.
One of the module that I would recommend is shurcool
client = graphql.NewClient("http://<<graphqlEndpoint>>", nil)
err := client.Query(context.Background(), &query, nil)
if err != nil {
// Handle error.
}
fmt.Println(query.Me.Name)
How can i using internal database for example (sqlite) for offline app in nativescript without using any plugin.
i'm searched every were how i can installed or used sqlite or other internal database for nativescript but i didn't have any answer.
Just like you would do with any code that you need to access the native APIs
e.g. (JavaScript) Android example
var query = "select sqlite_version() AS sqlite_version";
var db = android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(":memory:", null);
var cursor = db.rawQuery(query, null);
var sqliteVersion = "";
if (cursor.moveToNext()) {
sqliteVersion = cursor.getString(0);
console.log(sqliteVersion);
}
The API references for SQLite in Android here and that said you can now follow a basic Android database tutorial and implement it step by step in your NativeScript application using JavaScript or TypeScript
Still, the plugin could provide all that wrapped in a ready-to-go functionality so unless you are lacking something it will be easier to use the nativescript-sqlite and avoid writing native code for Android and then for iOS.
I'm testing out deploying my own parse server following the steps in the Parse Server Guide. I've got the server up and running and have been able to create and fetch objects via curl. I built a simple iOS app using the Parse SDK (1.14.2). I've initialized the SDK with the app id and server url as described in the Parse Server Guide. When I try to make requests, I get back unauthorized from the server. Digging further, I noticed that the SDK is not sending the application id header to the server. I modified the SDK to send the application id header and everything works. Am I missing a configuration step somewhere?
This is because you are not passing the ClientKey. In swift 3 you would pass it like this in the didFinishLaunchingWithOptions.
// Init Parse
let configuration = ParseClientConfiguration {
$0.applicationId = PARSE_APP_KEY
$0.clientKey = PARSE_CLIENT_KEY
$0.server = PARSE_SERVER_URL
$0.isLocalDatastoreEnabled = true
}
Parse.initialize(with: configuration)
If you are falling when trying to test CloudCode, then its because your parse-server is not passing the Javascript key. So just make sure you initialize the server to do so if this issue is related to Parse.Cloud function.