We have some business requirements that call for versioning. We chose to use MarkLogic library services for that. We have an issue testing our code with XRAY and using transactions.
Our test is as follows:
declare function should-save-with-version-when-releasing() {
declare option xdmp:transaction-mode "update";
let $uri := '/some-document-uri.xml'
let $document := fn:doc($uri)
let $pre-release-version := c:get-latest-version($uri)
let $post-release-version := c:get-latest-version($uri)
let $result := mut:release($document) (:this should version up:)
return (assert:not-empty($pre-release-version),
assert:not-empty($result),
assert:not-equal($pre-release-version,$post-release-version),
xdmp:rollback())
The test will pass no matter what, and as it turns out ML rollback demolishes all the variables.
How do we test it using transactions?
Any helps greatly appreciated,
im
With MarkLogic an entire XQuery update normally acts like a single transaction. When mut:release adds an update to the transaction's stack, the rest of the query will not see that update until after it commits. From the point of view of the query, this normally happens after the entire query finishes, and is not visible to the query.
The docs have something useful to add about what http://docs.marklogic.com/xdmp:rollback does:
When a transaction is rolled back, the current statement immediately
terminates, updates made by any statement in the transaction are
discarded, and the transaction terminates.
So it isn't that the variables are demolished: it's that your program is over.
I think http://docs.marklogic.com/guide/app-dev/transactions#id_15746 has an example that is fairly close to your use-case: "Example: Multi-statement Transactions and Same-statement Isolation". It demonstrates how to xdmp:eval or xdmp:invoke to update a document and see the results within the same query.
Test it to see that it works, then replace the xdmp:commit with an xdmp:rollback. For me the example still works. Start replacing the rest of the logic with your unit test logic, and you should be on your way.
Related
I am working on an orchestration layer Microservice where I need to call a few APIs of different microservices in parallel. For that I am making use of subscribeOn(Schedulers.parallel) and subscribing to each response in Mono.zip. For example:
Mono<A> a = service1.api().subscribeOn(Schedulers.parallel());
Mono<B> b = service2.api().subscribeOn(Schedulers.parallel());
Mono<C> c = service3.api().subscribeOn(Schedulers.parallel());
return Mono.zip(a,b,c);
Now AFAIK, this zip will fail if any of the a, b OR c completes with an error. Assume that something went wrong in the third call, I want to handle this case in such a way that any operation done by service1.api() and service2.api() could be reverted, i.e. rolled-back like a transaction.
I apologize for any wrong statement I've made as I am a bit new in Spring WebFlux. Thanks for all the help in advance.
I believe there is no such provision to rollback individual calls. You can make use of Mono.zipDelayError to let complete the valid calls except the one which could fail. After that, on error return you can go for individual transaction rollback with explicitly implementing the same.
I am using C# to call BAPI to communicate with SAP. I am new to this topic so I want to clarify some of the concept.
Q1: If I call BAPI_GOODSMVT_CREATE, should I check RETURN table or MAT_DOC field of items table to see whether it is succeed or failed?
Q2: If it is failed, need I call BAPI_TRANSACTION_ROLLBACK, or just ignore it(because without BAPI_TRANSACTION_COMMIT, data will not be saved)?
Q3: I found sometimes, even if there is error message, if I continue call BAPI_TRANSACTION_COMMIT, the data will be saved. But sometimes it won't.
Thanks in advance.
Check RETURN table. If it's OK, issue a BAPI_TRANSACTION_COMMIT with the WAIT flag. If it's not OK, issue a BAPI_TRANSACTION_ROLLBACK.
Check RETURN from BAPI_TRANSACTION_COMMIT as there may be errors there as well (for example a database update issue).
Ad Q1 In that particular case I'd rather check if material document number is returned in MAT_DOC. This way you don't rely on return messages. If a material document is returned, it means BAPI call was successful irrespective of messages. I find BAPIs implementation of handling return message quite inconsistent. Some BAPIs return a success message, some don't.
Ad Q2, Q3 Always call BAPI_TRANSACTION_COMMIT or BAPI_TRANSACTION_ROLLBACK after a BAPI call depending on result. BAPI_TRANSACTION_COMMIT and BAPI_TRANSACTION_ROLLBACK not only execute commit / rollback work but also call BUFFER_REFRESH_ALL function.
I have two models: hotel and location. A location belongs to a hotel, a hotel has one location. I'm trying to create both in a single form, bear in mind that I can't use dm-nested for nested forms due to a dependency clash.
I have code that looks like:
if (#hotel.save && #location.save)
# process
else
# back to form with errors
end
Unfortunately, #hotel.save can fail and #location.save can complete (which confuses me because I didn't think the second condition would run in an AND block if the first one failed).
I'd like to wrap these in a transaction so I can rollback the Location save. I can't seem to find a way to do it online. I'm using dm-rails, rails 3 and a postgresql database. Thanks.
The usual way to wrap database operations in DataMapper is to do something like this:
#hotel.transaction do
#hotel.save
#location.save
end
Notice that #hotel is quite arbitrary there; it could as well be #location or even a model name like Hotel.
In my experience, this works best when you enable exceptions to be thrown. Then if #hotel.save fails, it will throw an exception, which will be caught by the transaction block, causing the transaction to be rolled back. The exception is, of course, reraised.
I'm having an issue where I'm preaty not sure how to resolve this and I want to know what is the best approach I should consider in order to achieve this task.
We are developping an application VB.net 2.0 and SQL 2005. Users are allowed to cancel a reception based on a purchase which may contains many received goods. But, during the process of cancellation, some questions are asked to users such as "Do you want to cancel Good #1". If yes, delete. Then, "Do you want to cancel Good #2", no, do not delete and one another question (if received item is issued, a process must be made manualy by the user). And, at the end, if all goods were successfully cancelled, we have to cancel the reception itself. But sometime, if an error occurs or some conditions occurs once asked to user in this process, we want to cancel any actions made from the beginning and make it back to his original state. So I thought about Transaction.
I know there is Transaction for SQL which can be used and I know good enough how to use it, but I can't realy use this as user must perform actions which possibly cancel this transaction.
I also remembered TransactionScope from .NET 2.X and over which can achieve something similar and I also know as well how to use it. The problem comes with TransactionScope and MSDTC. When using this, we still getting an error which said :
Network access for Distributed Transaction Manager (MSDTC) has been disabled. Please enable DTC for network access in the security configuration for MSDTC using the Component Services Administrative tool.
I've tried what is describe here in another stack post and it works great... until user restard their computer. EVERY time users restart their computer, they must put value back. Plus, per default, no computer have this value set to On. At least on 10 computers bases, none were activated. There is something like 300 computers on which this program is installed so it's surely not the good things to consider neither.
So anyone have an idea of how I can acheive this? Is there anything else doing transaction via code which I can use?
NOTE1 : I know some would say, first ask conditions to user and maintain values in memory. Once done, if everything went well, go with delete. But what if an error occurs when deleting let's say, goods #4? And how can I give to a store procedure a dynamic list of goods to be deleted?
NOTE2 : Sorry for my english, I usualy talk french.
NOTE3 : Any exemple in C# can be provide also as I know both VB and C#.
Assuming you already have similar stored procedure to manage cancelation:
create proc CancelGood (#goodID int)
as
SET NOCOUNT ON
SET XACT_ABORT ON
begin transaction
update table1 set canceled = 1
where GoodID = #GoodID
update table2 set on_stock = on_stock + 1
where GoodID = #GoodID
commit transaction
VB code adds a string to some canceledGoods list if user selects 'Oui'. I'm not familiar with VB.Net; in c# it would look like:
canceledGoods.Add (string.Format("exec dbo.CancelGood {0}", goodID));
Than, if there is at least one string in canceledGoods, build and execute batch:
batch = "BEGIN TRANSACTION" +
" BEGIN TRY " +
string.Join (Environment.NewLine, canceledGoods.ToArray()) +
" END TRY" +
" BEGIN CATCH " +
" -- CODE TO CALL IF THERE WAS AN ERROR" +
" ROLLBACK TRANSACTION" +
" RETURN" +
" END CATCH" +
" -- CODE TO CALL AFTER SUCCESSFULL CANCELATION OF ALL GOODS" +
" COMMIT TRANSACTION"
conn.ExecuteNonQuery (batch);
I've been asked to try to roll back some database changes if there was an error.
Before I even start trying to use a TRANSACTION with either COMMIT or ROLLBACK, could someone tell me if I can do the following in MS Access?
void Start() {
try {
AccessDatabaseOpen(); // Opens the access database
foreach (File in FileList) {
AccessTransactionStart(); // Starts the Transaction
AccessWriteSectionDataFromFile();
AccessWriteEmployeeDataFromFile();
AccessWriteSomethingElseFromFile();
} // go to next File in FileList
AccessTransactionCommit();
} catch {
AccessTransactionRollback();
} finally {
AccessDatabaseClose();
}
}
The syntax is crappy, but you should get the point: Can a routine in code start a transaction, call several other routines, and either commit or rollback the whole thing or is this idea make believe?
Thanks,
Joe
Can a routine in code start a
transaction, call several other
routines, and either commit or
rollback the whole thing
Yes, this is the basic idea of transaction handling and your outlined example would be a standard approach to deal with them from code. Details will vary depending on particular situation/needs and of course the database system used (e.g. nested transactions, scope, concurrency handling, etc.).
If a database abstraction layer is involved, check for specifics of that, as they often come with some implicit transaction handling that can often be configured by some settings/parameters.